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#80857 - 06/03/14 08:31 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
TheSilverBuick Offline
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Registered: 12/22/10
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Loc: Ely, NV
I thought I'd try and see how degreeing the cam with the head off in prep of having the engine apart soon. I have some variance between the intake and exhaust that I think should be mirrored (straight pattern) that I attribute to not having the lash adjusters locked down enough. I put some hose clamps around the top of the lash adjusters that the followers would sit on, but it was not perfect. After I had the cam housing and everything together I opened my degree wheel kit and noticed there are light weight springs in the kit, so when I do the other head/cam I'll use the light springs (and I think some o-rings) to further reduce the compression of the lash adjusters. The goal will be to pin down the intake and exhaust opening points at minimum and mark those points on a sprocket in relation to the dowel. Then I can use the degree wheel on the crank and reference those points on the sprocket.


I had some issues locking down the lash adjusters. I wrapped hose clamps around the top to limit how much the follower can compress it. When I got my degree wheel out I noticed it comes with simple weak springs, so when I check the good head/cam I'll use the weak springs and maybe add some stiff o-rings to the hose clamps to keep the lash adjusters from collapsing. Or maybe I'll modify/ internally shim two spare lash adjusters.


You can kind of see the sharpie marks I made on the sprocket. I'll have to do some math if I want to convert the crank degrees to the cam degree's, but as I mentioned, if I can at least mark out the opening and closing points on the sprocket in relation to the dowel pin I will have something to work with.
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#80863 - 06/04/14 07:37 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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I'm heading to California after work tomorrow and heading home Monday, and should round trip around 1,100 or so miles I figure. I did a few minor things and upgraded the radiator fan assembly. I backed off the cam advance a few more degree's so it should be right at 4º advanced. It seemed to be struggling to get to crest 5,000rpm so this should help. Also smeared some ultra black RTV on the top of the underside and top of oil dipstick cap where the stick comes through the cap in an effort to seal it better for the vacuum pump. I found it whistles from time to time.

It's supposed to be 108 ºF in Las Vegas on Monday when I am heading home, so on the radiator side, I got one of the $50 HHR fan assemblies with shroud and it matched up mint. I shaved about 1/4" from the front and it cleared everything nicely. The tabs that stick out the side touching the tanks keep the fan a good distance from the radiator. At least I hope I haven't goofed up and find my self with a holed radiator. So far it doesn't touch and I can feel the air being pulled at the grill. The engine is running in this picture.


From the top. I put a slit of rubber hose on the top and bottom. Going from ~1,250cfm to ~3,000cfm ought to help. The battery voltage was good at the warm up high idle while I had it running as a test, so on the fan menu of the MegaSquirt I turned on the "idle up" option to make sure in stop and go traffic it wouldn't be depleting the battery. The GEN light lights up to let me know if voltage drops below 12.2v.


Edited by TheSilverBuick (06/04/14 08:31 PM)
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#80871 - 06/04/14 11:01 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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Looks good!

Did you ever check the amp draw from both fan assembly's?

At one time I tried a 1992 Camaro electric fan.
It drew a lot of amps, IIRC 20-30 AMP range, killed my stock low amp alternator.

It was not the correct set-up for sure.

Was wondering if you ever talked to anyone on how far a Sprint engine would actually make power to?

I am thinking you are trying to go past what the camshaft actually makes power to.
Just a thought.

Good luck on the road.

MBHD
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#80873 - 06/05/14 09:45 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
TheSilverBuick Offline
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Loc: Ely, NV
No I haven't checked, but I am running a 140amp alternator and at idle rpm with my two electric fuel pumps, electric crank case vacuum pump and the radiator fan going the voltage was over 12.5v, and goes up from there with rpm.

With the small cam advanced around 2* (due to the thicker head gasket), it was pulling to 5,800rpm, and seemed to peak about 5,300rpm. General consensus is the engine/head/cam should peak around 5,400rpm. With the cam timing fiddling, my goal is to get it to peak around 5,500rpm, and with the porting and valve springs, try and get it to pull to 6,000rpm. Factory redline was 6,500rpm, but again, general consensus is the engines, from the factory, rarely did well past 5,400-5,500rpm. I want to keep it advanced enough that I make up for lower compression than a 4bbl Sprint head (by closing the intake valve sooner), but at the same time I don't kill off the top end rpms entirely.

In this configuration I'd like to at least rev to 5,400rpm, but will only have to live with it another week before I take it all apart, port the head and shave a few hundredths off the head to gain some compression back. Then perhaps I won't need to advance the cam to up my dynamic compression and will be able to better cater to the upper rpm's.
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#80877 - 06/05/14 06:17 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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Was wondering why 2 electric fuel pumps?

I do not know too much about those 6's, but are the cylinder head that bad flowing stock?

They have good size valves it seems.

I would think that what is mostly holding back the engine from RPM,ing is that the camshaft specs are short on duration.

A 300 Horse 350 10:25.1 SBC cams specs are I: 212, E:222 @ .050" .

I do not think GM would even put a camshaft with those specs in a 250.

But, I could be wrong, we need to find the actual specs of duration @ .050".
There should be some info out there somewhere.
Or get it cam doctored.
I am just thinking it's mostly the cam holding it back.

Found this just now.
"The camshaft had .400 inches of lift and 228 degrees of duration "
Duration at what though?

Sprint engine: .438 inches of lift and 244 degrees of duration

sprint” produced 207 bhp at 5200 rpm and 228 lb-ft of torque at 3800 rpm. This “spirited” six-cylinder was also capable of revs to 6500 rpm and beyond.

I thought the high compression Sprint engine was a 230 CI? Or did they make a 10.5:1 250 CI sprint?

Any who, If it was a 230, & you are using the sprint camshaft in a 250 CI engine, most likely the engine will not make the same RPM, should be a little less.

So it says it could rev to 6500 RPM, but at 6500 RPM it would make less power.

Just trying to do some research.

http://www.youtube.com/watch?v=sxxlhgbvGmI

This guy had a larger than "H" cam on an engine dyno

http://www.youtube.com/watch?v=gwZgizg88nM

"

This is a 67 Sprint now displacing 255 CID. The head has SS valves installed as well as hardened valve seats and bronze guides. The cam is 260 duration with .465" lift at the valve. (slightly larger than the factory H grind) The Headers are Clifford Shorty type. The engine makes power to 5000 rpm then drops off. We revved the engine to about 5500 rpm."

MBHD
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#80878 - 06/05/14 07:18 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
CNC-Dude #5585 Offline
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The 69 model 250 made 230 BHP@5400 RPM and 260 ft.lbs torque@3600 RPM with an "H" cam that had more duration than the previous 244 duration cam.
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#80901 - 06/07/14 03:03 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
TheSilverBuick Offline
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Valve stems are a measured 11/32, I thought they were 3/8, but I measured them when I had the cam housing off. All the OHC L6's were 230's in 1966 & 1967, and 250's in 1968 & 1969.

Duration numbers I figured were all measured at .006" per some old literature.

Looking at my 1bbl cam that I took measurements off (the sprocket picture with the degree wheel behind it), it looks like about 180º of duration at 0.050" on the intake, which is subject to error of +/- 10º IMO between my lash adjuster compressing, how I measured and how I've eyeballed it to the degree wheel. I have a measured ~240º at first measured movement and the spec's say 228. As mentioned before, the OHC design also fast ramps the valve. When I have the engine apart I'll probably look at taking measurements at 0.010" lift increments to see the true slope of the valve acceleration. It appeared very fast, and actually looked like closing was faster than opening, but then again I was turning the cam directly rather than the crank so the valve events were moving twice as fast as I'm used to with my V8's. Real measurements would settle the question.

Advantages I have going for me are, I'm not turning a water pump, I'm not pushing a mechanical fuel pump (you should feel the difference in turning the accessory drive!!) and my timing is far more tightly controlled as well as fuel distribution should be as well. I don't have tuned headers, but I do have a fairly opened exhaust, at quite a bit more so than OE. My turbo cam has a bit over 260º duration with a bit more on the exhaust side.

I'm hoping to get mine to a chassis dyno at some point, should be interesting. The turbo engine I'm hoping to engine dyno it before installing it. As a friend of mine says, RPM is king, get the head to flow and wind it up, and that is my plan, watch for the point of diminishing returns and shift there.

Two fuel pumps because instead of a sump in the fuel tank I'm running a surge tank, but the surge tank requires a lift pump to get fuel to it. Then the high pressure EFI pump pulls from the bottom of the surge tank. This is so it doesn't hiccup when intermittently sucking air when low on fuel. I use the OE mechanical pump on my Skylark instead of an electric. And speaking of which, the lift pump gave me fits on Thursday, so I ended up taking the Skylark to CA. So I may be changing out the fuel system in the car while the engine is out. Move it all over to the driver's side and get the pumps and stuff in a better spot.
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#80957 - 06/11/14 08:08 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
TheSilverBuick Offline
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I'm hoping to pull the engine tonight after work. I have everything disconnected except two bellhousing bolts, which I couldn't get to with the transmission cross member in place, so I need to remove the cross member and lower the rear of the engine/trans to get the last two bolts then out it should come.
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#80971 - 06/12/14 08:47 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Finally got the engine out today after work and I pulled the head off. The cam and followers are looking good.



The pistons were carboned up as I expected them to be given the blue smoke on start up and the substantial blow by.


Chambers also carboned up as expected. Valves appear as I'd expect.


In the ports, the intakes looked pretty much as I expected with some carbon on the back side of the intake valves, but the exhaust's color has me surprised. I've never seen the yellow/tan exhaust valves, but some engine people I trust say it's normal, so I'm good with it.


I am a little surprised at the clean spot on the valve stems,but otherwise pleased with how clean the port is.


All my exhaust port photo's are over exposed, but the yellow color is just odd to me. Nothing surprising about the ports to me.


Tomorrow I'll disassemble the head and start the measuring of the chambers and porting. I think the port work needs to be prioritized because I want to take the head to the machine shop next Friday, so I need it done before then. I'll start on the short block when I am done with the head.
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#80973 - 06/13/14 10:21 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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Wow, that was an oil burner!
Freshened up engine should run much better.
Re-ring & bearings?
If reusing pistons, maybe get the pistons knurled to get rid of the slop? Old timers trick, actually helps oil retain oil on the piston skirts. Better lubrication?
What is the deck height? How far down the holes are the pistons?


That short turn radius looks terrible. (It's missing the radius/short turn. )
Wonder if possible to install lumps into that head?

All these different colors on the valves are thanks to fuel additives.

Are you going to make it a true 12 port head also?
You are doing the porting or that one guy that knows Pontiac 6 OHC heads?

This head is not for the turbo?
If not, going to shave it to try & bump up the compression?
Mill it .060"?

Two pistons have been changed?

MBHD
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#80976 - 06/13/14 11:27 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
CNC-Dude #5585 Offline
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These heads have 6 individual intake ports and lumps aren't going to help it. These engines were also built more with a performance goal in mind because of John Delorean's involvement with them and don't have a lot of the shortcomings that the Chevy 250 engines have. I think he mentioned his next build was going to be a turbo version, meaning this one maybe. I also saw some head flow data on a ported head and dyno tests on several engines on another site a while back. They have a lot of potential for sure.
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#80977 - 06/13/14 12:04 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
TheSilverBuick Offline
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It's getting new rings with a dingle ball hone this time instead of the flat stone hone I used last time (which probably did more harm than good). New 0.001" oversized bearings to tighten up the bottom end. As for knurling, I didn't measure out the bore versus piston diameter, but I'm not sure how much run time this engine got after the over bore, but there is no ridge at the top of the cylinder, but on the same token, if there was ever a cross hatched hone done, it was gone.

I'm going to be measuring how far the pistons are in the hole. I measured it when I pulled it apart a few years ago but cannot remember the number now. All the pistons are 0.030" over, so I guess whom ever rebuilt it last could only come up with four pistons from one supplier and got the other two to round out the engine. When I first disassembled the engine after getting it I was expecting just the two cylinders to be overbored, lol.

I still am having a pro do my turbo head, this is just going to be me working it over.

I'm going to smooth out the ports and open up around the backside of the valves and smooth out the valve guide bosses. Along with reshaping the chamber around the intake valve. Also remember, for the short turn radius that these valves are canted, not straight up and down. I'll cc all the chambers and match them up best I can then run the compression calc's with all the other pertinent measurements and then shave the head accordingly to bring the compression up to 9.0-9.5:1 if I can, but it may be tough to even get that high with these pistons. I'm thinking about having the intake/exhaust surface shaved some, but I don't think it can be shaved enough to true up the 1/16th to 1/8th inch gap on the intake. When I call the machine shop on Monday I'm going to see how much and if he can install bronze inserts on the valve guides to tighten up the seal around the valve stems. Or speaking of knurling, maybe I'll inquire about doing that to the valve guides.

I'm going to cut and grind the divider out of the intake plenum as well to promote intake flow. Its also getting more valve spring pressure so I can wind up the engine as high as I want to find peak HP. There is minimal harm in over springing an engine as long as it doesn't eat the cam.
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#80979 - 06/13/14 05:18 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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Knurling the guides & pistons are just a cheap way to temporarily fit/fix things.
Doing this to the guides helps promote lubrication of the guides & valve stems, but it does not last long.

I have not checked lately but last I did, bronze guides cost about $10 each installed? Probably more now.

If you could make it a 12 port, you are probably going to adjust your fueling tables as it will not be a Siamese port any longer.
But since the gap is not too big from the factory, it might not need changing at all? Let us know your findings.
Easy to do, just a heads up.

My 4.3 Chevy V-6 heads have a bad gap also.
Please excuse the non inline pics.






MBHD
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#80980 - 06/13/14 06:03 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
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He already milled the port face back on page 2 of this thread to eliminate the small gap at the intake port opening, so its already a true 12 port head. Oldsmobile did that also to their V8 engines back in the 60's and 70's. I never understood what the logic was to that and why they kept doing it even on the V6's.
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#80982 - 06/13/14 09:11 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
TheSilverBuick Offline
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To give you an idea how canted the valves are and the air flow rushing to the backside of the valve and how opening up the chamber on the far side has lots of benefits to flow.




The gap in the intake port divider isn't nearly as bad as your 4.3 head. Looking at it, I am tempted to ask the machinist to shave down the face some to see if it trues up reasonably. Though I don't have a sealed gasket for it (yet..?). I'd have to remove the freeze plugs in the face before hand.


Pulled the valve and springs off the head and did a bunch of measuring today. CC'd the chambers and the pistons valve reliefs (both types are surprisingly within 1cc of each other) as well as measured how far the piston was in the hole and how thick the head gasket is. Crunching the numbers still show I have very low compression, PipeMax calculates it at 8.022:1. The service manual advertises 9.0:1. The chambers have a horrid 76cc's, the pistons have 8cc valve reliefs (much less than I figured), the pistons are 0.034" in the hole, and measured head gasket thickness was 0.047", which is the same as the new gasket I have, so I'm guessing it crushes down to some number, probably around 0.040" for my compression calculation.

My handy dandy home made valve spring compressor worked like a champ.


I also outlined the ports to get an okay estimate of the current port area. Light coat of oil on the port, and a blue shop towel works great. I did the chambers to so I can try and figure out how much compression I can try and gain back by shaving the head.


A pane of glass for some back lighting and traced them out on some scaled engineering paper and can do a rough calc of area here, but I'll probably digitize the shapes to scale and let some computer software calculate the areas. Then I'll average the intake ports together to use as an intake number and then average 1 & 6 exhaust together and then 2, 3, 4 & 5 together for the two exhaust numbers.


Now I can begin the porting!


Edited by TheSilverBuick (06/13/14 09:13 PM)
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#80983 - 06/13/14 09:34 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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The intake port looks close to being flush. Might clean up @ .010-.015"?

Are you using stock size valves on this head?

That is pretty low compression, too bad you cannot find some other pistons w/a higher compression height.
There might be something available.

What CC's are the chambers supposed to be?

I believe anytime you can create a better short turn radius the better the head will flow.
That is why I suggested some lumps.

Factory Pontiac V-8 heads flow pretty crappy. Even the SD heads have a lot to be desired.
The Edelbrock heads flow much better.

Nice pic of the cutaway OHC head. THX.

The OHC head looks like you could raise the intake port & it would be a good candidate for the floors to be filled in with brazing rod to improve the intake floor short turn.

That is the way I see it anyways.

I think part of the reason the OHC head flows mostly on the long turn radius side & why they need opening up on that particular chamber area is because the short turn radius needs a lot of improvement.

What degree is the OHC valves canted back?

SBC are 24*,

If you look @ the short turns radius's on the LS heads, they have huge never ending short turns.

When there is no good short turn radius, the air naturally follows the long turn side, if there is not a good short turn radius, the air will be more turbulent & not follow it.

Canted valve layout looks like a typical SBC to me.

GM learned it is better to have the valves more upright than canted, they just raised the roof & also the short turn followed.

It allows for more valve lift, that is why our 194-292's can go w/a pretty high lift w/out the valves coming close to the pistons, the valves are more upright, but our ports suck also.
That and Siamese ports suck.

MBHD
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#80985 - 06/14/14 01:33 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
TheSilverBuick Offline
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I'd have to find it again, but I seem to recall that they are canted at 14*. I agree, the Pontiac bath tub chamber is terrible and have no idea what the engineers were thinking. I've roughed in all the chamber mod's (as I watch even more compression wash away..) but still need to cc each chamber to balance them out. I'm going to tell the machinist to shave as much as he is comfortable doing. Worse case, if the chambers end up too small I'll grind some more out. I've read numbers from 68cc to 80cc's. Using a 68cc with a stock shim head gasket would put the engine at 9.0:1 compression, but that is not what I've measured.

Here are some flow measurements that the guy that helped develop the port and chamber shape of the good head. Reading, up on the work he did, he started with a '69 1bbl like I am using (it's what I have), and testing 4bbl heads that have about 0.2" longer short side fattened up flow up to about 0.2" lift, balances out around .3" and matches up from .4" on. Which of course the loss of low end flow does hurt, but at least it's a fast ramp cam design.
 Quote:

The longer short side radius helps as long as it raises the port enough, but on this port, it makes for a noticeable cutoff right after mid-lift. By allowing the air a more direct path to the valve, the high lift flow is enhanced. I think of it as using more of the perimeter of the valve, but it may also reduce turbulence like you said.
One trick that I use is to get a spray can of machinist's dye and give it a quick squirt into the intake while on the flow bench. This simulates the wet flow of the fuel and tends to deposit the dye on the back side of the chamber, but it will tell you if you have made any gains on the short side by widening the spray pattern. Using the entire perimeter of the valve is the key, and is why a "long" approach to the valve head works so well IMHO.

Here's what I got on the stock 69 250 1bbl head #9795456
28" plenum pressure, STP corrected
lift--Intake--Exhaust
.05 ----28.92----26.02
.10 ----54.09----49.59
.15 ----76.10----69.72
.20 ----99.78----85.96
.25 ---122.14----98.76
.30 ---143.22---103.80
.35 ---153.62---109.29
.40 ---165.69---112.83
.45 ---172.95---116.19

.50 ---176.03---117.87
.55 ---179.05---119.51

'69 1bbl head. No port work, cleaned up behind the valve and chamber work.
Lift------Intake-----Exhaust
.050-----35.11-----29.23
.100-----67.02-----51.57
.150-----98.39-----75.70
.200----124.93-----94.53
.250----151.24----110.80
.300----175.17----121.87
.350----196.79----132.70
.400----209.74----139.04
.450----216.40----145.23

.500----220.14----149.20
.550----217.57----153.04



The first time I ported a set of heads I swore I'd never do it again. There is a reason professionals are paid good money, as my limitations are quite apparent. Hopefully though there is a net positive result.

[IMG]https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-9/10402663_10203323053530749_540049495606708404_n.jpg?oh=56e129f098f2bced2cca3833528673d9&oe=540DF2EE&__gda__=1412194257_fab731282c308fab26efb81bc15647a9[/IMG]
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#80986 - 06/14/14 07:39 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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That head actually flows OK after it was cleaned up in the valve area & chamber work were done.


https://fbcdn-sphotos-h-a.akamaihd.net/h...6efb81bc15647a9

From your pics, the long turn can use a lot more opening up, IF, the casting allows you to do so?

Another way of seeing how the air flow is by using a stick & attach a piece of tape to it & insert the stick w/tape into the port & see where the tape goes.

Good luck with the porting, it is a time consuming art & takes a lot of patience.

Don't worry about polishing , that is just cosmetics for the most part. Makes the customer say WOW! \:D

What tool are you using for porting & what bits/tips?

MBHD
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#80990 - 06/15/14 07:03 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
GH Offline
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Hank, I agree, siamese ports do suck, actually, they stink.

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#80991 - 06/15/14 08:41 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: GH]
TheSilverBuick Offline
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Just the run of the mill burr's available at the hardware and parts store. I really wish I had a set that were longer. I just have the ball, cylinder and pine cone shaped ones. A friend of mine that does professional porting (Nick for GH) says I need to get an egg shaped one as it's what he uses most, and also showed me a set that would certainly be nice to have but the limited amount I'd use them I couldn't justify purchasing. I'm going to make him cringe again when I lap the valves again, lol.
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#80998 - 06/15/14 01:07 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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A great valve job cam make a huge difference in cyl head flow.

A lousy valve job can just plain kill airflow.

I.M.O., if you are going through the trouble of porting, unshrouding the valves/chamber work, having a great valve job can complement your work.

Since you are not going high lift, I would try & get the airflow early in the lift range & use a 55-60 degree cut under the 45 degree valve seat.

The solid carbide are the best for burrs.
I use them for various other types of jobs other than porting.
So, there are other uses for them.

I made the inlet radius with carbide burrs for my K&N filter to attach to.



Not using the aluminum elbow , just the velocity stack for the K&N



MBHD
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#81000 - 06/15/14 02:16 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
TheSilverBuick Offline
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I 100% agree with you Hank on the valve job, and this head can seriously use one. The back side of the valves can certainly use improvements as well, but out of scope for this head. These engines are so sensitive to valve stem height, that if the seats were not installed and cut to the correct depth that it'd eat the cam among other things. So I just don't even want to open that pandora's box with the machinist at this time, I want a same day turn around time, so he is just going to shave the head, probably shave the intake/exhaust surface as well and maybe knurl or insert bronze valve guide seals.

Got the head as done as I'm going to take it. I was going to cc the chambers and balance them out, but I think I'll wait until after the head is shaved to cc them and balance them at that time.



A quick measurement of the before and after intake port diameter where it necked down looks like a bit over a 1/4 square inch was added to the cross sectional area behind the intake valves, which is about 17.5% more area if my math holds. Circles are funny things.




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#81005 - 06/15/14 10:58 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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I understand.
You could still back cut the valves if they do not have any.

Should not effect the valve height.

I was noticing the turbo head you posted earlier pics of.
From the pic it looks like the guy only opened up the chamber on the long turn side, not the short turn radius side.

MBHD
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#81008 - 06/16/14 08:40 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
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Yes, in the picture of the cleaned up head, that was a high compression head so there was very little material on the short turn side of the valve, basically the short turn side is "mostly" unshrouded on that head so they left it alone. On my low compression head the chamber is much deeper so I took steps to unshroud the short turn side, even though my short turn radius still blows.

I'm wondering if I could safely shave 0.10" off the bottom of the head? That would put my compression, even with the chamber mod's, right at 9.0:1, maybe a smidge higher.
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#81009 - 06/16/14 09:28 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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You will just have to get the deck surface of the head sonic checked to see if it is thick enough to take that big of a cut. You'll also have to compensate for your cam timing if you take that much off of it too. Maybe broach another keyway in the gear or something.
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#81010 - 06/16/14 09:56 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
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I figure a tenth is waaaay out there, but thought I'd ask. The shop did sonic check my engine blocks, so perhaps they can do the deck too? .050" would get me around 8cc's back using the standard chamber shape.

Cam timing is not an issue with the adjustable sprocket, it has tons of adjustment. Something ridiculous like 16-18 crankshaft degrees.
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#81011 - 06/16/14 10:13 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Will belt tension be a problem if decking that much. I think .050" of milling will be a good compromise.
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#81012 - 06/16/14 10:54 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
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The belt tensioner/accessory drive is barely off it's minimum adjustment and there is at least 3/4" more adjustment.

I just got off the phone with the machine shop, they can install bronze valve guide inserts the same day as milling the head and they can sonic check the head deck as well to establish a safe number. This is always a chance the head has been milled before too, which would be bad for me!
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#81013 - 06/16/14 11:11 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Get hold of Dick - BOR they ran the OHC pontiac before deciding that they wanted to set the record and switched to the 4200.

They have many unobtainum parts for this engine.
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#81014 - 06/16/14 11:19 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: efi-diy]
Mean buzzen half dozen A.K.A. Hank Offline
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Back to the OHC Pontiac.

You could deck the block & mill the head to get some sort of compression & get some quench going for you.

Unless the guy installing the bronze guides can drill them exact(not likely) you will have to get a valve job done.
I could be wrong?

Good luck.

BTW, your porting looks OK from the pics I can see.

MBHD
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#81015 - 06/16/14 11:33 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
TheSilverBuick Offline
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Dammit Hank, I was thinking decking the block was out of scope, but now you have me thinking. The short block is still together, but I could have it completely disassembled by the end of tonight if I wanted..........

If I can get the chambers down to 70cc's, which a .050" cut should get me close or there, and zero deck, then I'd be a hair over 9.0 compression.....
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#81016 - 06/16/14 12:30 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Now that I've unwound myself =P I'm going to stick with plan A. Mill the head, with a sonic check to maximize it, and the valve guide seals if they can do it without a full valve job. If not, I'll ask for knurling or simply live with it.

If I can get to the 70cc mark it will get me to 8.4:1 compression and I can live with that, and continue towards building my good engine. If I happen to find a 4bbl high compression head for cheap, it's a simple head swap and my compression would go to somewhere between 9.2 and 9.8 depending on which year 4bbl. Decking the block would put the compression up much higher than I'd want.
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#81017 - 06/16/14 02:24 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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That's cool stick w/a plan that you & your budget calls for.

I was just throwing out some ideas, ("the while your at it syndrome") \:D

I was just mentioning that if you could get close to a zero deck your quench would be better, less likely of detonation will occur.

As far as having too much compression w/a 4bbl head, easy to open up the chambers & drop the compression as you already have.

Just some thoughts. I just do not like to leave HP (or a better running engine) on the table & not in the engine. Time to spank some of those V-8 things.

MBHD
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#81019 - 06/16/14 03:24 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
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Did you ever determine what the stock deck clearance was on the OHC?
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#81020 - 06/16/14 03:37 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
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No I haven't, but I measured the pistons at 0.034" in the hole.
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#81030 - 06/17/14 11:45 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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 Originally Posted By: TheSilverBuick
No I haven't, but I measured the pistons at 0.034" in the hole.


That is a lot!!!!!

MBHD
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#81039 - 06/17/14 07:23 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
TheSilverBuick Offline
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Pulled the bottom end out of the block today. The bearings and crank journals looked good as expected for the low run time and the bores actually look better now than when I first assembled it. Some run time did their appearances good. Cleaned up the gasket surfaces and going to grind the rivets that hold the internal baffling in place out so I can make some extra baffling and then I'll bolt the OE baffles back into place. I pulled the deck's dowel pins out and will take the block with me to the machine shop and if they can also deck it the same day as the head work I'll ask them to scrape .035" off the top. I measured two pistons today as 0.037"-.038" in the hole, so .035" will give me a little buffer for errors in my measuring or difference in the other four pistons. The head gasket is thick if nothing else =P If I get both the head and block milled I might actually see 9.0:1 compression.



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#81040 - 06/17/14 07:39 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
Mean buzzen half dozen A.K.A. Hank Offline
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Hurray!

Hope it all works out.

I asked my friend (works @ a cyl shop for 20+ years, might be 25 yrs) about your short turn radius & he believes there is no air flow entering on the short turn radius side.
So in short, he thinks you opened up that side of the chamber for no gains & you lowered your compression.

Sorry to bring potential bad news.

Onward & upward to make more power.

Your getting it done quickly, keep it going.

MBHD
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#81055 - 06/18/14 07:57 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
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Other's I've talked too say any time you can unshroud any part of the valve is a gain. Sure not as much as an awesome short side radius, but with the port taper it's going to flow some on that side so still have a net gain. Loosing maybe 1.5cc's on that side isn't going to radically alter the compression.

I'm going to work on the exhaust manifold tonight, there is some bad casting flash in two of the ports and a few other spots that could use some opening and rounding. I've decided I'm going to drill it for EGT probes as well. They are 1/8" NPT threads, so I'll put iron pipe plugs in the holes until I pony up the dollars for the probes and IO box to connect them to the MegaSquirt.
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#81069 - 06/18/14 07:24 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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I grinded and chiseled out the rivets holding the internal oil baffles in place, so now the block is about as bare as it gets.

I once again proved to myself I cannot drill and tap straight (much like when I cut things...), and because I find nothing sacred, I drilled some holes in the exhaust manifold for future EGT probes where the A.I.R. injection ports would go that will be functional enough. For reference, only the '67 exhaust manifolds actually got the A.I.R. set up. I ground down the choke's heat well casting as well so when I get EGT probes in there I won't have any interference turning a hex nut.




Cleaned up and smoothed out the number 1 and 6 ports as well.

Number 1 looked okay, just a little on the bottom right and smoothed out a bit of casting flash further in.


Number 6 on the other hand had all sorts of over casting! So I ground it out and smoothed it up.
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