Inliners International Forums General Discussion Blown and Injected Tearing down 25 year old 250 build.

Since my 250 I built 25 years ago has been sitting for about 10 years not running.
I decided to tear it apart & take a look to see if there are things I need to address before I install my turbo onto it.

Had some rust in the bores, hopefully not too bad.
One piston had the top ring stuck in the top groove (from the rust)

Everything else looked OK. IIRC, this engine has about 10-15 K miles on it after I rebuilt it.

Here is the cyl head me & my friend did.
Cant remember the CC's off hand, but it was in the high 80's?




I believe the intake is a 2.0" valve (cut down from a 2.02" valve) 1.6" exhaust.
We opened up the chambers quite a bit to lower the compression.
For when I installed a Paxton supercharger. Sold a long time ago.




Here are the upper lumps I made out of chunks a billet I hand ground, took forever & I got impatient, they did not come out the way I wanted them to.
I installed them to increase port velocity it also picked up CFM, can't recall what it helped CFM wise.

Maybe I will update them.



Here are the 307 forged SBC flap top w/4 valve relief pistons.
If you look on the inside of the piston, you can see where I milled out the inside to reduce weight.

Also the rods side grinded, polished & then shot peened.



Piston top 307 SBC.
Note the top of the bore chamfer, if you can see it?
Helps improve airflow.





Home made piston stop



Tiny degree wheel to check for TDC.
Getting it ready to install the SDS E.F.I.
I installed 1/8" magnets from the SDS system in a typical SBC 8" damper.
This damper is what really made my engine want to rev high. Smoothed out the vibs



Tywraps attached to push rods, labeled so when I reinstall them, I will install them the same way they came out.



Lifter galley



Cam gear.



Camshaft. Solid lifter, IIRC, specs are 238 in, 248 @ .050" exhaust on a 114 lobe center & .560 -.580 lift? It was made for my Paxton blower, I will reuse it for the turbo also. I think it is an Ultradyne cam.



Note: no lumps
Also intake port is stock size.
I think I will look into getting some lumps this time around.



Crane Gold 1.7 BBC rocker arms.



MBHD

I think it would be good to see how the lumps work in conjunction with your upper ones.

It's funny, just last night I set the head gasket on my Pontiac L6 and noticed the gasket had flairs around the bores, and I thought about tapering the bore to the gasket like you have done. I know on the V8 Pontiac's it's common to notch the bores like that on the 326/350 blocks to stick 455 heads on them.

Side note, how do you get proper torque on the head bolt in the port? All the torque wrenches I've seen are too tall with a socket on the end to fit in a port.

And thanks for sharing, I always like seeing a good tear down.

Chamfering the tops of the bore should help your cause in hopes to gain more flow. Your valves are large & the bores are smallish.

I use an extension that goes through the top of the intake port & use a socket to torque the nut

You could also use a torque adaptor & actually go through the intake port & torque it that way.
http://www.amazon.com/Stanley-Proto-J5118-Adapter-16-Inch/dp/B001HWEAEC

As long as the torque adaptor is 90 degrees to the torque wrench, you do not need to use a mathematical formula & compute the length of the torque adaptor..

At work I have had to make torque adaptors out of cutting up wrenches & add a 3/8 square drive adaptor just to reach certain areas on Gulfstream G5 BR710 engines.
It is just easier to have the torque adaptor 90 degrees & not worry about using the math formula every time you need to torque something.

I do not think this cyl head w/the 2.0" intake valves flows good, (not because of chamber shrouding the valves) but because we had to sink the valves to make the chambers bigger in order to lower the compression. IIRC, the compression ratio worked out to be 8.4:1.

I was not too worried @ the time about the flow because I had the Paxton supercharger forcing the air/fuel mixture into the engine.
Even though the cyl head probably does not flow too good, it was the fastest combination any my 250 ever ran. It ran low to mid 12's, but that is only because it was supercharged blowing through 3 48 MM Weber DCOE's.

I will most likely have my friend flow test my cylinder head, just to see where it is lacking & add the lumps & flow test again.

MBHD

Many people don't realize that the cylinder bore is equally important to the airflow of the cylinder head, and that the airflow doesn't stop when the last bit of air leaves the combustion chamber. If the chambers need to be unshrouded because of larger valves or just for poor chamber design, most times the cylinder bores also need to be notched to further enhance and help the head flow to its fullest potential. A cylinder head won't flow 260 CFM,(if it flows that on a flowbench), if the cylinder bore shrouds the valves.
Flowing a cylinder head on a fixture that correctly locates the cylinder head relative to that engines bore/chamber location is important in that regard, or it just leads you to incorrect conclusions as to its abilities.
Winston Cup teams still flow test all of their cylinder heads in a final evaluation with the heads bolted and torqued onto the actual engine block the heads will be raced on so they can get as accurate of a account of how it will flow in the environment it will be used in.

This is why it is important for the facility that is doing the flow testing to also have the correct bore size on the fixture.

I have seen some places flow test a head that the customer has a 4" bore on his engine , but the place flow testing the cyl head has a 4.125" fixture for the bore.
This will give a higher reading & not an accurate of a person having a 4" bore.

MBHD

Exactly!

Hey guys,

I am needing a engine gasket set for my 1970 250 inline Chevy 6.
I don't' need one w/a head gasket.
I would like one w/rubber gaskets if possible & not cork.
Is it still Felpro?

What is a part number for such a set?

It has been a long time since I ordered one, I am not sure if there are ones with better oil pan gaskets other than cork?

Also, part number for a standard Mellings oil pump, or should I look for something different?

Thanks for any help.

MBHD

Is this thing on?

Bumpity.

MBHD

I've seen the rubber side cover gaskets and rubber oil pan gaskets separately on ebay before. Not sure if you can buy them in a kit all together that way or not though.

I almost have your emblems finished up!

Great!
Are the rubber pan gaskets Felpro also? P.N. FEL-1819?
Thank you.

MBHD

Do they still make Reactor flexplates? 153?

Found them.
http://www.reactorproducts.com/mainProducts.html

I really didn't notice. I just noticed them as I was browsing.

Just got the pan gasket set.
These are the better gaskets.





The gasket set came in a huge box from Summit. Must have ran out of smaller boxes.

Not sure if the Reactor flexplate company is still around?
http://www.reactorproducts.com/mainProducts.html

I sent an email & it was returned back to me.

MBHD

Is that gasket rubber or fiber? The pan and crank seal cover gasket on my L6 are some kind of fiber.

It said it is Rubber coated fiber.

Should be better than just the cork ones I normally use on some engine builds.

MBHD

That's what it looked like to me in the pictures. Not sure what to think of it. It was a pain to clean off the pan, cover and engine on disassembly but due to other engine oil control issues I could not tell if it was leaking through the gaskets or not. I normally dislike painting over gaskets (ironically prefer the clean look of painted then assembled), but this time I assembled the engine then intentionally put a coat of paint over all the gasket mating surfaces as an end play to try and further seal the engine from oil leaks and then possibly more easily identify where leaks are coming from if it starts.

Funny enough, the coat of paint kept the oil in my Buick's oil pan for a year and a half before a piece flaked off and drained half the oil out where I had burned through the pan welding baffles in and didn't notice when re-painting.

Here is one way to torque the head bolt.

https://www.youtube.com/watch?v=lrvHQ3ohkgY

MBHD

You got any more detailed pics of your bore chamfer? And an explanation of how/why it's done? Is it like deshrouding but on the bore instead of the side of the combustion chamber? Does it not affect ring seal/piston wear? Or do you just have make sure it isn't deep enough to contact the ring?

Did you click on my picture I posted? Then click it 2 more times to make it bigger.

You can see the chamfer, it is where your 1025 head gasket flares out more. That (1025) head gasket it not a perfect circle.

You do not chamfer down to where the rings seal, just above that point.

Doing this mod allows for more airflow.

MBHD

Well I asked because I couldn't tell if what I was looking at was chamfer or a reflection of the valve reliefs in the piston. Did you just chamfer the intake side of that bore?

Yes, just the intake side.

MBHD

Made a 3/8 304 stainless water feed line for the turbocharger.

It is a bit tight so I massaged the SPA manifold if you can see the massaging, it's close to the "B" nut. It's plenty thick there.







Random pic of the stage 5 turbine wheel, looks restrictive , but it's all I have for now.



MBHD

Billet lower intercooler mounts.
Before alodine & after, the painted pics are blurry.





MBHD

Can you take pics of the water cooling feed and return to the block? Was wondering about how turbo water cooling was connected the other day

Sure, I am plumbing the return tonight.

I already posted pics of one side.

OK, I just bent up some 304 stainless 3/8" tubing & flared them to 37 degrees.









MBHD

Thanks. Good pics. So you plumbed it into the lower thermostat housing? I'm not home to look at mine but was that return hole already there or did you buy a housing with that in there or did you just tap a hole for it?

Also where are you planning to run the coolant return line from the turbo?

Yep, lower t-stat housing.

The aluminum housing already had a hole & tapped w/3/8 NPT.

IIRC, the housing is from a 1975 & newer 250.
The heater hose outlet comes out in a 45 degree angle.
I already posted pics of the water supply line to the turbo. (2 pics)

I was not sure how to plumb the water for the turbo, but the guys here told me where to plumb them.

MBHD

Will there also be hot water to the intake manifold or is that not needed with injection? Does the turbo warm the intake?

No water for the manifold. The manifold does not have provisions for water.

I would not run water even if it had provisions.

It never really gets that cold here to need intake manifold heating IMO.

Having a exhaust manifold directly under the intake manifold is plenty hot for me on a N.A. engine.

Having a turbo exhaust manifold under the intake manifold, that is just like having a BBQ on high,, no way would I ever want to add heat to that manifold, a turbo charged exhaust manifold runs so hot I don't see how they survive in the first place.

If you have ever opened a hood on a turbocharged car in the summer time, you will understand what I am talking about, talk about extreme heat.

MBHD