The Pontiac OHC Six

[TheSilverBuick]

Re: The Pontiac OHC Six

No and No :'( :'( I got to get on that!

You wouldn't happen to know the shipping costs on those headers would you? (89301) My only thing is, they probably aren't very close for a turbo application, and are probably worth more money to sell to some one to use them as is rather than me hack and cut them.

I haven't looked too hard at piston availability. There are a few people that have turbo'd etc these engines on the OHC forum, so there may be a source for them.

[horsewidower]

Re: The Pontiac OHC Six

Sonic check the cylinder walls before you decide to bore it .060. I prefer as much meat as possible.

Your money is better spent fitting a custom piston to a thick cylinder wall than boring to an unacceptably thin wall in order to fit less expensive commonly available pistons.

I really don't see high rpm having a place in this build. Boost it and gear it to go fast. Don't spin it.

[milner351]

Re: The Pontiac OHC Six

^^^^ yea what he said.

These things don't grow on trees - machine with great care.

[TheSilverBuick]

Re: The Pontiac OHC Six

I'll definately have the cylinder thicknesses checked. Internet rumor is some people are punching these out to a 4.00" Bore :o But that's not the route I intend to go. I am perfectly OK leaving the parts(dimensions) alone and letting the turbo do the work. On that same token, I really really want to see some rpm in this thing. It's OHC and I want it to spin until it's cost me a small fortune. The turbo is supposed to be the airflow crutch for the small ports that limit it's rpm.

Not the route I intend to go, but check out this intake/exhaust set up, looks slick.

[milner351]

Re: The Pontiac OHC Six

are those headers custom made?

if not - those could be a good place to start.

if you are planning on cutting up the headers anyway - I could cut mine up and send them to you in a smaller box! ;D

[Monk]

Re: The Pontiac OHC Six

I'll definately have the cylinder thicknesses checked. Internet rumor is some people are punching these out to a 4.00" Bore :o But that's not the route I intend to go. I am perfectly OK leaving the parts(dimensions) alone and letting the turbo do the work. On that same token, I really really want to see some rpm in this thing. It's OHC and I want it to spin until it's cost me a small fortune. The turbo is supposed to be the airflow crutch for the small ports that limit it's rpm.

Not the route I intend to go, but check out this intake/exhaust set up, looks slick.

Aw man.......that's sweet!

[TheSilverBuick]

Re: The Pontiac OHC Six

I figured I'd keep my stuff simple. Run the exhaust "header" pipes to right next to the block and bolt the turbo to them, then figure out a nice intake set up for the EFI, you know, probably straight pipe for a few inches before the actual head port with the injectors some where in there. It's going to be dirt simple and probably side ways mounted throttle body form a V8 car in the junkyard. I'm definately using an intercooler.

[milner351]

Re: The Pontiac OHC Six

You put a welder on your Christmas list didn't you?

[TheSilverBuick]

Re: The Pontiac OHC Six

Every other week is Christmas if I let it :P I just have to bring myself to go shopping.

[TheSilverBuick]

Re: The Pontiac OHC Six

Just dropping some information off so I have it all in one place ;D

The actual port volume of a '69 1bbl head is 110cc for the intake and 85cc for the exhaust.

250 Bore = 3.875
250 Stroke = 3.531

Intake Valve = 1.920
Exhaust Valve = 1.600

Chamber sizes: The chambers we've measured all are larger than the published values. We have measured the 1-BBl at ~80 cc and the 4-Bbl at ~68-70.

I'm also following the same parts formula for boosting the OHC. I started out with a '69 1bbl head with flattop L2314F pistons, then changed to a '67 4bbl head for the better flow. This required that I machine a 35cc dish into the tops of my pistons. After verifying that the top of the piston would still have enough meat left after carving out the dish, I machined the dishes to match the shape of the combustion chamber, keeping the quench pads on both sides of the chamber. So now I have 8.3:1 c.r.,

http://egge.com/

[horsewidower]

Re: The Pontiac OHC Six

I don't think you need to go as low as 8.3:1

[squirrel]

Re: The Pontiac OHC Six

might, with such a crappy chamber design and gobs of boost

[TheSilverBuick]

Re: The Pontiac OHC Six

It's just some notes. I picked up a harmonic balancer puller today, so I'm going to go pop that off and also drain the oil while I remember, that's right, it's still full of oil :D

[horsewidower]

Re: The Pontiac OHC Six

It'll be pretty soggy off boost. But, your point is well taken.

[TheSilverBuick]

Re: The Pontiac OHC Six

Advertised compression is 8.75:1, so it's probably 8.5'ish stock.