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#79511 - 03/08/14 07:30 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: CNC-Dude #5585]
TheSilverBuick Offline
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Registered: 12/22/10
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Loc: Ely, NV
 Originally Posted By: Mean buzzen half dozen A.K.A. Hank
Not sure if you know this, but Tlowe had epoxied his injector bungs also, with turbo boost pressure they became loose.


I wouldn't doubt that as a possibility. Epoxy adhesion strength is highly dependent on surface prep and I do not know how tlowe prepped his intake and bungs, though I do know he is a pretty smart guy. I intentionally chattered the grinding bit in the hole for a rough angular surface on the intake and I put a rough grind finish on the aluminum bung. And after that explanation, I don't intend on running boost through this intake =P IF this engine sees any boost, it'll be through a fabbed up intake with either threaded or welded in bungs.

 Originally Posted By: CNC-Dude #5585
To have taken such a radical departure from the normal build, you seem to have had very little issues getting this on the road. Great job! And a really nice build thread.


Thanks! I'd like to say it was a well thought out plan but really it was a rough idea with each part figured out as I got to it. Things I would of done differently are, ran a 2" pipe from the front exhaust flange until it merged with the other pipe, ran the exhaust out the driver's side (the fuel lines are on the passenger side at the gas tank). Some one else I know now going down this route is using short LS injectors, and that may clear the thermostat housing quite well (and an aftermarket intake with longer runners to pull from the head).

I've been driving it as much as possible because I intend on the last weekend of this month to drive it down to southern California and will be a 1,200+ mile round trip in 4 days. Gotta get it shook down!! lol.

Today I think I will drop the transmission valvebody and make a few more shift modifications (and re-seal the drain plug I installed) and possibly install an idle air valve.
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#79548 - 03/12/14 07:12 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
TheSilverBuick Offline
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I did a bit of checking of stuff after work. I drove it to work today, so when I got home it was nice and warm so I popped the spark plugs out of it and ran a compression test. Before I did that though, I took a laser temp gun to each exhaust port as a check because I know those numbers will be subject to a fair amount of variation. Overall I'm pretty pleased. It's definitely pulling oil from somewhere, but I am suspecting mostly the valve guides at the moment.

The numbers as I got them. The compression numbers are probably about 20% lower than if it were taken at sea level given my elevation. That would put the numbers around 155-160psi. I'm considering playing with the fuel injector trims, particularly on cylinders 1 and 5 that are measured ~30F cooler than the other cylinders with the same compression. Maybe a little to gain on #6? Looking at the plugs, it looks like I should lean out 1 and 5 a hair to at least get them closer to balanced (in theory..).
.....PSI F
#1 130 350
#2 135 415
#3 135 400
#4 130 385
#5 135 385
#6 128 320

Pictures of the plugs. Expert opinion says to put a hotter plug in it, so I'll see about getting a hotter set. The engine runs nice going down the highway at 18:1 AFR's with 42 of timing. I will continue to try and lean it out more to see about gaining some mpg's (with 4.56 gears, lol).






And I finally stuck a timing light on it. Yup, still spot on from idle to 4,000+rpm.


Edited by TheSilverBuick (03/12/14 07:13 PM)
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#79550 - 03/12/14 08:04 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 do not see why the "expert opinion" says to run a hotter plug, they look good in the pics, maybe they look different in person? Maybe too much soot/carbon on the top of threaded portion?

What is the heat range now? Autolite 65 is equal to what in an AC or Champion plug?


MBHD
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#79551 - 03/12/14 08:34 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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Expert opinion is of a guy I certainly trust as I've seen dyno and MPH results of his readings. His reasoning on these is exactly as you mention, looking at the threads aren't showing any heat and there is still a decent amount of carbon on them, aka not hot enough to be self cleaning. Be mindful as well, the LS coils have pretty hot and long duration sparks too, so the plug is the limiting factor.

Delco 44 and Champion 12
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#79553 - 03/12/14 09:33 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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Not sure if these plugs have been in your engine when adjusting your mixtures from the start?

When did you take the plugs out after a W.O. T. run, steady state cruise, idling for a while then pulling the plugs?

If you had run rich w/your plugs while adjusting your EFI, it is kinda hard to burn off the sooty black carbon build up when your mixtures were rich @ one point or another.

I would not necessarily go to a hotter plug, those plugs are a fairly warm plug. Might have old carbon build up when the mixtures were off?

What is the A/F ratio @ idle?
Having an advanced timing like you seem to have will make the plugs run cooler. Maybe run it a bit leaner @ idle?

I run 14.7-15.2 A/F range on my Syclone while idling.

I also run 1 -2 steps colder plug than stock, but it's turbocharged & I try to stay away from any detonation.

MBHD
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#79554 - 03/13/14 10:37 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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The plugs hadn't been pulled since they were installed a few months back. Same plugs were in the engine when running on the engine stand. Couple hundred miles on the plugs now.

The previous 15 minutes prior to them being pulled for the compression test and picture is about ten or so minutes of 2,900-3,000rpm steady state on the highway at 18:1 AFR and ~42 of timing, then a few minutes of idle while I shot the EGT numbers with the temp gun. I idle it at 13.8:1 AFR as it provides the stablest idle at 650rpm. Timing was around 10-12 but wobbles a bit at idle as the Megasquirt is using timing to control idle speed since I don't have an IAC.

(On my Buick I run a static timing number during idle and may do so here if I get an IAC on it, and my Buick also idles around 15:1 as richening it up doesn't seem to smooth out the idle any on that engine)
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#79560 - 03/13/14 09:06 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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[quote=2,900-3,000rpm steady state on the highway at 18:1 AFR and ~42 of timing, [/quote]

Must have been in the slow lane & at what speed w/those 456 gears?

Some guys hear think low gears are the way to go, "let the engine rev" & not get any mileage from it, OD, don't need OD. yeah when your engine cant make enough power I guess you need low gears?. \:D Rant rant

MBHD
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#79564 - 03/14/14 07:22 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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70-75mph with the 200-4r and locked torque converter.

The clock doesn't lie, this thing is sloooooow to 60+mph, but it feels and sounds like a rocket ship the whole way! Going back and forth between my Skylark (w/ ~500-550HP,455, 5-speed, 3.89 gears) and the Firebird, is night and day. I blink in the Skylark and I'm doing 60mph, Firebird takes just shy of 12 seconds, but its fun getting there and sure seems closer to 8 seconds, but a dozen measured tests say otherwise. I'll be putting the bigger cam in this May. The factory rated the bigger cam at 40 more HP than the small cam, but that also came with a compression boost I won't have, and I may have of already gotten some of that with the 4bbl intake and dual exhaust manifold. That rating is a 22% boost in HP, I should be able to get probably 15% of that. After the cam is broke in I'll install stiffer valve springs for a bit more rpm. At that point I should really be able to tell the difference.

The real mpg test will be at the end of the month when I take it on a 1200 mile trip.
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#79565 - 03/14/14 07:32 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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The problem with less gear and a relatively tight stock type torque converter is the rpm drops on the shifts pull it out of it's power band. Even with the well split 200-4r, and 4.56 gears, shifting at 5,700rpm with a 27" tire drops the rpm's nearly to 3,200rpm (not accounting torque converter slip) and it just takes time to pull it back up to 5,700rpm again. That's the only reason I don't want to switch to taller gears, like 3.42 to even 4.11's.
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#79570 - 03/14/14 04:54 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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Yeah, forgot you had the .67 OD. Excellent choice on the 200R4 BTW.
You do not need the taller gears until you install your turbo set-up. Then it will make gobs of torque.

What compression ratio do you want to run when you switch over to a turbo?

Does it smoke the tires in 1st?

MBHD
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#79583 - 03/15/14 08:17 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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Nothing has been settled on the turbo build except the cam. I currently expect to target the compression around 9.0:1, but may go as much as a point lower or half point higher.

Gears at that point will be switched out to something in the middle to high 3's and there will be a lot more stall in the converter. I'll be using a 4L60e/65e/70e at that point in time for better transmission control.

Since I adjusted the rear brakes (which with manual drum all around helped a ton in stopping power), it doesn't power brake nearly as easily as before, but can get them going. From a stand still, I still have a bog in the tune when I hammer the throttle from an idle that keeps it from possibly lighting them up from a stop. Off idle tuning is tricky without a throttle position sensor. Imagine tuning a carb with no accelerator pump, except I do have a crutch that the EFI can read a rapid vacuum change and apply a pump shot to it, but it is still reactionary to vacuum signal. I should be able to dial it in eventually (or add a TPS), but I haven't sat down and dedicated time to dial it in.
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#79600 - 03/15/14 08:32 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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I found with mine the bog went away when I adjusted the "pump shot" or acceleration enrichment to be less. That was with the turbo EFI 292.
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#79601 - 03/15/14 09:16 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: tlowe #1716]
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When you do go turbo remember that the available torque is non-linear. This causes issues with line pressure - with out being able to reference the line pressure to boost - you end up running high line pressures.

The other end is torque converter selection - you may want to wait to select the stall speed until you know where the boost will kick in...
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#79606 - 03/16/14 07:13 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: efi-diy]
TheSilverBuick Offline
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 Originally Posted By: tlowe #1716
I found with mine the bog went away when I adjusted the "pump shot" or acceleration enrichment to be less. That was with the turbo EFI 292.


Being as there is not throttle position sensor it's extra sensitive to having the VE table tuned exactly right for the pump shot. Admittedly right now the pump shot is extra heavy because when I first got the car running I had a bad lean pop when I'd stomp on the throttle, and a big pump shot stopped that. I have reduced the size of the pump shot significantly since I first got it running, but I'm at the point I need to spend more time in the low vacuum/low rpm part of the fuel table before I can reduce it any further. The only time the engine operates in that part of the table is when stomping on the throttle from a stop, so I just have to dedicate some time to doing that and making adjustments.


 Originally Posted By: efi-diy
When you do go turbo remember that the available torque is non-linear. This causes issues with line pressure - with out being able to reference the line pressure to boost - you end up running high line pressures.

The other end is torque converter selection - you may want to wait to select the stall speed until you know where the boost will kick in...


The fuel pressure regulator is vacuum/boost regulated. I have a vacuum line going to it currently. I'm thinking I will probably engine dyno the the turbo engine prior to install to know better what it'll do.

The layout of the fuel system will change significantly for the turbo engine (moving the whole fuel system to the driver's side, and off the firewall), but I'll be using the same regulator.


Thanks for the suggestions.


Edited by TheSilverBuick (03/16/14 07:16 AM)
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#79714 - 03/23/14 10:32 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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Not sure if you ever considered a different hood?

I always liked this hood, plus it should be lighter.
http://www.ebay.com/itm/1969-69-Pontiac-...24e3e3d&vxp=mtr

My friend used to a have a 69 Firebird w/a 400 hood w/tach.

I helped him take off his hood a few times & could not believe just how damm heavy the hood was as compared to my standard 69 Camaro hood.

Anyways, just a thought, I know how much heavier the 69 Firebird is compared to the 69 Camaro & I always try to find a way to lighten up my Camaro because lets face it we are at a disadvantage as compared to the V-8's LS1,2,3, etc.

MBHD
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#79727 - 03/23/14 06:56 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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If I change hoods it'll be a long ways off, but I do agree it would save a ton of weight. I am thinking eventually I'll get an aftermarket engine cross member that'll save me some weight. This summer I'll switch the front end to disc brakes, and will probably get tubular A-arms at the same time. For now, I'll use the 4.56 gears to my advantage =P

Today I got the idle control valve setup by using a plate of aluminum and drilled and threaded it directly to the original PCV port that goes into the intake plenum, then had a 90 fitting on it with a hose going straight up to the air filter housing. Which I drilled a hole in the housing, inserted a rubber grommet and a hose barb. It is an early 90's Ford 5.0 valve.
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#79733 - 03/24/14 06:26 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
GH Offline
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when we ran the Buick with the carb/MS for ignition I made a TPS using a small chain going to the sensor, it worked.

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#79734 - 03/24/14 06:27 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
GH Offline
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when we ran the Buick with the carb/MS for ignition I made a TPS using a small chain going to the sensor, it worked.

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#79735 - 03/24/14 06:27 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
GH Offline
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when we ran the Buick with the carb/MS for ignition I made a TPS using a small chain going to the sensor, it worked.

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#79736 - 03/24/14 07:07 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: GH]
TheSilverBuick Offline
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 Originally Posted By: GH
when we ran the Buick with the carb/MS for ignition I made a TPS using a small chain going to the sensor, it worked.


That's what I need to do. I have a TPS sensor with a nice arm on it, and have got chain for it. I just need to figure out where/how to mount it.
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#79749 - 03/24/14 08:42 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Started upgrading the alternator today. I found a 140amp CS130 alternator from an '89 Caprice that my local NAPA stocked for $140. Unfortunately the case is larger than the old SI, which didn't fit the adjustment bracket very well due to me spacing the bracket out a bit for the crank sensor bracket, so I went and got one of those threaded couplers (I think that is what they are called?) to adjust the belt tension. The alternator came with a serpentine belt pulley, so I replaced it with a dual groove pulley and will run two belts on it just to make sure it does slip under load. Unfortunately both parts stores closed before I had it together enough to know what size belts I needed to get.


(sorry about the over exposure, I forgot I had the exposure turned up)
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#79832 - 04/01/14 02:13 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
TheSilverBuick Offline
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Trip summary.

From Friday night to Monday night I drove just shy of 1,200 miles. I didn't track the mpg's while driving around town in California, but out on the highway there and back it was averaging 20mpg. Seemed to consume/lose about a quart of oil every 250-300 miles which to me is a ton of oil. Basically I checked it when ever I stopped at a gas station and topped it off. All in all, I knew the used engine would likely have some issues, rather it was oil consumption, low oil pressure, or low compression on a cylinder or two, and it appears it only has an oil consumption issue at present so I cannot complain too much as the EFI and other modifications I made to it portion worked like a champ.

About an hour into my drive out of town, 60 or so miles, my external oil line let loose and sprayed the engine bay with around 1.5 quarts of oil by the time I noticed the oil pressure fluxuations and shut the engine off. FYI, that is a bunch of oil in the engine bay =P So the pink oil line I had couldn't stand up to the heat, and what is worse is I figured as much, bought a replacement 1/8 EFI fuel line hose that would have no issue with it and forgot to both install it or bring it with me d'oh! Since I was only an hour out of town I called a friend for a big favor of swinging by my house, grabbing the hose I bought and bringing it to me. I was up and running within five minutes of his arrival. I had five quarts of oil with me since I was unsure of it's oil consumption rate at sustained highway speeds. Turns out it's quite a bit so far. Cruising between 2,800-3,100rpm seems to suck oil out of the thing. I drove a tad slower home, but it didn't make much difference. I think this engine would do well with gears that would put the cruising speed right at 2,600rpm. I haven't calculated what ratio that would be yet. My oil air separator(pipe) isn't working nearly as well as I'd like it too either, so more work will have to be done there. I'm getting quite a bit of oil out the breather even when the reservoir isn't even close to being full. And getting around 20mpg, which isn't terrible considering the 4.56 gears and rpm's turning. a friend of mine says the cruising speed is equivalent to driving with 3.25 gears and no overdrive.

Here are a few trip pictures.

On the road.


On the side of the road.


Back on the road, and actually this was in California.


It didn't run hot, it climbed all the 6% grades in overdrive at 70mph with out issue, and made the trip with out fuss after the oil line repair. Funny thing about climbing hills. I programmed the electric water pump to be on when ever the engine is under a higher load, basically calibrated it so that if the torque converter disengages the water pump should probably be on. The logic is if I go WOT it'll pump cool water into the head regardless of the engine temperature to keep detonation at bay (which has turned out to be a non-issue so far), which will be helpful when I have a turbo engine in the car. The funny thing is, when I was pulling the first real mountain, about 10 miles of 5%-6% grade outside of Primm, NV, I noticed the engine temps dropped to 140F and kind of sat there until I crested the mountain then it started to climb back up to normal 185-195F range that I have programmed in. It took me several miles before I remembered the pump stays on under load, lol. The only time I think the radiator fan kicked on was while I was in a Carl's Jr. drive through for a while, and so far has been more than adequate at keeping the engine temperature in control.

Sunday was the big car day, went to two car shows and helped a fellow cammer set an engine and transmission in his '67 Firebird. The first car show I went too, the car had a constant crowd around it. When ever I'd go look at other cars my friend's would call my cell phone and say "Dude, get back here, these guys have lots of questions!" haha. Then and helped out setting in an engine and trans then made it to the tail end of a Buick get together in the same area. I'll post a couple more pictures later, but by the time I remembered to take some pictures of my Firebird there were only two other guys there. Got the same reaction though from the folks there.

A common sight around the car (I'm the guy in the hooded jacket with his back to the camera). People were equally interested in the engine setup as the shifter setup. Definitely made a conversationalist piece if nothing else.
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#79836 - 04/01/14 04:53 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Great Job \:\) \:\)
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#80059 - 04/19/14 11:00 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Twisted6 I.I #3220]
Mean buzzen half dozen A.K.A. Hank Offline
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Turbo engine build is next?
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#80094 - 04/21/14 10:22 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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Yes. Forged pistons, ported head and reground cam with the knowledge it's going to be a turbo build. I will be making the intake manifold first and probably install it on this N/A engine to make sure it clears things like the wiper motor, etc.
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#80288 - 05/08/14 01:20 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Memorial weekend I'm going to swap in a new E-cam and followers. I'm going to keep the used 1bbl springs in there during break in. After some driving I may follow it up with the re-ground cam (for the turbo engine, and it's own set of new followers) for break in purposes. I need to decide at that point though if I'm going to lash cap the valvestems or dedicate a cam housing and shave the housing. I'm leaning towards lash caps.

When I go to do the valve springs for the E-cam I have to come up with either a good part number for a single spring (I don't think dual springs fit on an unmodified 1bbl head) or shim the springs I currently am using. BUT I'm considering pulling the whole engine and doing it a little more proper now. Still a weekend rebuild, but put new piston rings in and dingle ball the cylinder walls in an effort to reduce the blow by and while it's out install 0.001" undersized rod/main bearings to bring up the oil pressure some, and perhaps a minor port job on the head and chamber.

If I can't find approapriate springs, I might, might, maybe, snowball, take the head to a machine shop to cut the head for dual springs. And if I do that, I may use my remaining stock of new valves and get a valve job and surface the head. Of course I'll be hammering the valve stem height spec into my machinist's head if I get to that point.

The main motivation for wanting to pull the engine is to reduce oil consumption because it's making me hesitate driving it out of town (around town is fine). The Car Craft Anti-Tour is in July and involves an 1/8th mile track and I'm indecisive on bringing my Skylark which had significant upgrades since the last time it made it to the track or the Firebird. I'd like to see if I can get the OHC decently healthy (aka not blow oil every where..) and have the bigger E-cam and more spring pressure for some RPM's and take it down the track. Remember, mini-spool and 4.56 gears!
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#80393 - 05/13/14 06:53 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
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Pulled the car into the shop to start pulling the cam housing. I might take this time to pull the engine wiring harness off to lengthen it a few inches as well as possibly pull the oil pump on the accessory drive apart for inspection.


A new E cam and new followers ready to go. I've numbered stamped them 1 through 12 to keep them matched to the lobes when I go to do the springs. I'll do the same for the 1bbl cam when I pull them.
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#80423 - 05/14/14 09:10 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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Specs on new cam?

MBHD
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#80428 - 05/15/14 08:31 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
Current Cam is a "C" Cam, aka 1bbl. 0.400" lift with 1.5 follower ratio.
1968-69 Pontiac 250/175hp
IVO 14.0 IVC 46.0 IDUR 240.0 LIFT 0.267
EVO 46.0EVC 14.0 EDUR 240.0 LIFT 0.267
OLAP 28.0 ICL 106.0 ECL 106.0 LSA 106.0

New Cam on the bench there is an "E" Cam, aka 4bbl automatic. 0.438" lift with 1.5 follower ratio.
1969 Pontiac 250/215hp Auto "E" 546670
IVO 14.0 IVC 50.0 IDUR 244.0 LIFT 0.292
EVO 52.0 EVC 12.0 EDUR 244.0 LIFT 0.292
OLAP 26.0 ICL 108.0 ECL 110.0 LSA 109.0

My reground cam was off a semi-blank E cam core and has .460" lift and slight split pattern on duration and change in LSA.

One of the things to consider is the OHC design in effect has the equivalent of a fast ramp lobe. The lift numbers always look tiny to me, but dyno testing says .460" is a good number and dimishing returns after that, something about port velocity.

There are a few folks making over 300HP naturally aspirated with a similarly spec'd re-ground cam (from the same guy that re-ground my cam), mine is tweaked slightly for a turbo. Ultimate goal is 600HP at the flywheel with the turbo. Here is a pretty cool SAE engineering report on the '66 230.
http://s412.photobucket.com/user/SPRINT-6/slideshow/S%20A%20E

Recap on the turbo plans to get to that 600HP. Ported head and chamber re-worked, forged pistons, big intercooler on the car, reverse flow cooling to keep the head cool, custom intake to separate it from the exhaust heat, EFI with sequential injection and possibly individual cylinder fuel trims to make sure each cylinder is running equal AFR's, precise timing from the crank trigger and individual coils and then cram as much boost into it as possible with a safe tune on 91 octane. I'll step up to a meth injection system if I'm just short of 600HP. If I can get to 300HP naturally aspirated, then 15psi ought to do it, but I'm going to go as high as practical, so if I make more than 600HP, I'll be okay with that too. I'll probably realistically be building two engines, first one is going to be a stock forged rod engine and heavy (stock syle) forged piston, second will be an aftermarket forged rod and light weight forged piston. I have reconditioned with ARP bolt rods and old forged TRW(?) pistons already.


Edited by TheSilverBuick (05/15/14 08:35 AM)
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80439 - 05/15/14 12:06 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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Cool,

I thought the 4BBL Poncho 6 had over 10:1 compression & the 1 BBL version had much less?

Were the pistons different or cylinder heads between the 4bbl engine vs. the 1 BBl version?
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#80440 - 05/15/14 12:46 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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Registered: 12/22/10
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Loc: Ely, NV
The cylinder heads have different size chambers machined into them. Pontiacs have machined as opposed to cast chambers, and the 4bbl heads had less depth to them. I'm using 1bbl heads in all cases.

The advertised compression was 9:1 on the 1bbl and 10.5:1 on the 4bbl, but every person I've heard that did actual measuring (including myself) show the compressions closer to 8.0:1 and 9.5:1. So something is amiss between the advertised spec and what has been measured. At full lift the valves don't extend past the head deck very far and the piston valve relief's are way over kill so I'll probably make up some compression when I go to a custom lightweight piston. I don't have the cc's on the old forged pistons to compare to the OE cast ones.
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80444 - 05/15/14 01:25 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 is the problem with production tolerances a lot of times.

Our 250 inline 6's are supposed to be 8.5:1. depending on year of course.

But when you have pistons sitting down the deck, chambers being larger than what they are supposed to be etc, we would be lucky to have 8:1 \:D

MBHD
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#80452 - 05/15/14 03:53 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: Mean buzzen half dozen A.K.A. Hank]
GH Offline
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Posts: 185
Loc: Springfield, MO
Randal, that's great compression ratios for a big blower or turbo.

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#80465 - 05/15/14 08:35 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: GH]
TheSilverBuick Offline
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Registered: 12/22/10
Posts: 460
Loc: Ely, NV
I agree Gary, but I'd like to stay above 8.0 if I can as it may be as low as 7.5'ish.

Took me about 20 minutes to remove the cam housing and all looks well under there.



I got a hold of a water jetting company in Las Vegas to cut me flanges for the intake and exhaust for $45. I'm going to get two sets made up so I can start working on my sheet metal intake manifold. So I can pretend to be like GH for a while, lol.
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80552 - 05/19/14 07:45 PM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
TheSilverBuick Offline
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I'm getting serious again. For $318 after shipping and taxes I bought a full engine gasket kit, rod and main bearings .001" undersized, new piston rings and an appropriately sized and gritted ball hone. Now I need to come up with the proper valve springs for the E cam to reach 6,500+ rpm so when I blow the engine apart in a couple weeks to R&R it properly I can install better valve springs.
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80567 - 05/20/14 07:19 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: TheSilverBuick]
lowboygmc Offline
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Good job keep it up! How did you make the fuel rail do you have the bit?
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72 gmc lwb air ride 5 speed (soon) turbo 292 II# 6102

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#80568 - 05/20/14 07:34 AM Re: Hacking together EFI on an Pontiac OHC Six [Re: lowboygmc]
TheSilverBuick Offline
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Registered: 12/22/10
Posts: 460
Loc: Ely, NV
I bought the special sized bit. I forget the exact size but it's like 17/32" or so.

The super duper bit has three steps on it so it drills a hole into the feed passage but leaves a step for the o-ring to stop against as well as bevel the edge so it doesn't cut the o-ring going into the rail. I don't have that bit, I have a straight bit. So I drilled it slowly and in a learning moment, found that I should of stopped short of drilling all the way through and left the step for the o-ring, but I didn't so I installed some clips on the tops of the injectors that keep the injector from pushing too far into the rail, then I took a dremel and small grinding bit and manually bevelled the edges to slide the o-ring in smoothly. Next time I may use a cut down stepper bit to bevel the edges. This is all done on a Craftsman drill press.
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80569 - 05/20/14 08:29 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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Registered: 09/23/04
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Here is the bit I used for my fuel rails.





MBHD
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#80570 - 05/20/14 08:44 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
^^^ That's the fancy proper stuff!
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#80571 - 05/20/14 09:19 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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Registered: 09/23/04
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 Originally Posted By: TheSilverBuick
^^^ That's the fancy proper stuff!


Yes, pricey I will say, I had borrowed it from my friend.

I am not suggesting to ask to borrow the tool from him, but if you need your fuel rails machined & tapped, he can do that.

Cool guy. Here are his websites if you guys are looking for turbo stuff (parts), machining parts CNC, water jet cut flanges etc.

http://www.raceprovenmotors.com/

http://www.theboostdepot.com/

http://www.rpmmachineshop.com/

MBHD
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