The Pontiac OHC Six

[Monk]

Re: The Pontiac OHC Six

I'm itchin to hear this thing fired up

[TheSilverBuick]

Re: The Pontiac OHC Six

I'm itchin to hear this thing fired up

It's going to be a good while. Plenty of research to do. Assuming I get a welder shortly, I need to develop enough skill to fab an intake/exhaust :P And I need to get associated parts. Then at minimum get the block and such to a machine shop for a proper cleaning and double checking that everything is square. I'll be impressed if it's done by this time 2011 :-\


(I may have a girlfriend now, which ought to slow things up some. That may require a project thread of it's own, LOL!)

[Monk]

Re: The Pontiac OHC Six

I'm itchin to hear this thing fired up

It's going to be a good while. Plenty of research to do. Assuming I get a welder shortly, I need to develop enough skill to fab an intake/exhaust :P And I need to get associated parts. Then at minimum get the block and such to a machine shop for a proper cleaning and double checking that everything is square. I'll be impressed if it's done by this time 2011 :-\


(I may have a girlfriend now, which ought to slow things up some. That may require a project thread of it's own, LOL!)

We used a Schoenfeld kit building our headers and
worked out great

Can she weld?
;D

[nesabo]

Re: The Pontiac OHC Six

(I may have a girlfriend now, which ought to slow things up some. That may require a project thread of it's own, LOL!)

D'oh! So much for you making it to DW :-[

;D

[Pumpkin]

Re: The Pontiac OHC Six

(I may have a girlfriend now, which ought to slow things up some. That may require a project thread of it's own, LOL!)

may being the operative word ;). And Randal, we'll need pics of the new project thread :P.

[TheSilverBuick]

Re: The Pontiac OHC Six

I had to go to the basement so while I was down there I thought I'd make a good effort to pop out the oil restrictor tube. Looks like the little hole is what feeds the lash adjusters, where as the remainder of the oil goes up and into the cam. So I guess if I were to go to an externally regulated pressure regulator for the lash adjusters I'd make a new tube that doesn't have that little hole.

The Mysterious Tube.


Where it sets in the head.


The backside of the head, there is the oil galley plug I'd use for an external oil regulator feed if I go that route.

[WarShrike]

Re: The Pontiac OHC Six

Makes me think of the crank case vents that is sold in Jegs/Summit. Is there a hole in the block that lines up with that tube? Follow the rabbit hole and maybe we'll find out

[TheSilverBuick]

Re: The Pontiac OHC Six

Huh? The hole the tube slides into is the oil passage that comes right up from the crankshaft mains.

[Aircooled]

Re: The Pontiac OHC Six

A few suggestions along the kiss principle.
The intake and fuel injection are going to be a big enough of a challenge. Don't compound it by trying to make an ideal header. Use the factory iron manifold and and some Buick GN's cast off turbo. This may not be optimum, but after you sort out the other stuff you can come back to this part. Besides, anything less than 321 stainless between the head and the turbo will eventually crack and fail, and welding 321 is not for beginners.

That is one ugly combustion chamber. Check to see if the higher compression head has a better chamber.
Balancer: Reciprocation weight all balances out on a straight six, but you do need to worry about torsionals. I bet the 292 crank has some nasty torsionals.
An 383 stroker piston for an LS1 is 3.903 diameter and ~1.3 compression height, SBC pin.

[milkovich]

Re: The Pontiac OHC Six

welding 321 is not for beginners.

I disagree. It's so pure it welds like copper but takes more heat so you can really put the power to it. Aluminum is harder for me... and I'm definitely a beginner.

That said, there are a lot of REALLY fast guys out there running mild steel headers on a turbo. That's the route I plan to go.

[TheSilverBuick]

Re: The Pontiac OHC Six

Thanks for the piston suggestion!

I'm all for the kiss principle believe it or not. The EFI is a cake walk. The intake and exhaust making will be the chore. I had no delusions about making either an ideal header or exhaust (there was some comment back there about saying hell with it and using boxed tubing :P).

Pete posted this turbo exhaust manifold for the Chevy L6, this engine has slightly different flanges on the head though. Not saying it wouldn't work, but I'd at least like to mock up a stock chevy 250 exhaust manifold up to see how it does/doesn't line up and if any grinding/drilling would solve the problem.

http://cgi.ebay.com/ebaymotors/194-230-250-292-Chevy-6-Cylinder-SPA-T4-Turbo-Manifold-_W0QQcmdZViewItemQQhashZitem2c58d1066dQQitemZ190468654701QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Can you say specifically what is ugly about this combusion chamber? It's machined rather than cast which I figured would be better/smoother. The high compression head looks almost identical, just enough material added around to bump compression up. I have a hard time visually distinguishing the low compression chamber from the higher one.

[67pete300]

Re: The Pontiac OHC Six

Hopefully in March/April the Chevelle gets split/dual exhaust. Then I'll have an extra stock 250 exhaust manifold laying around....

[DanStokes]

Re: The Pontiac OHC Six

I have a couple. Want me to send one on? The big difference (from looking at the pics) is the lack of the doglegs in the end ports of the Chevy.

Dan

[Aircooled]

Re: The Pontiac OHC Six

welding 321 is not for beginners.

I disagree. It's so pure it welds like copper but takes more heat so you can really put the power to it. Aluminum is harder for me... and I'm definitely a beginner.

That said, there are a lot of REALLY fast guys out there running mild steel headers on a turbo. That's the route I plan to go.

g
On welding 321 stainless, I don't have any personal experience, so I will defer to you.

On the mild steel turbo headers, it not the power, its the thermal cycles that kills them. A REALLY fast car may only put 100 cycles a year on the headers. A street car could rack that up in a month. Talk to the Buick GN guys about trying to run cheap mild steel headers on the street.

[CTX-SLPR]

Re: The Pontiac OHC Six

We'll see how long my mild steel Turbo6 headers hold up (they are Postons and have a fairly good rep). When they go, I'm going to fab my own 321 stainless set of headers and tack them together then have them welded by someone who knows what thier doing unless I've taken some classes before then. Race between the mild steel cracking and me getting into a welding class at the local comunity college.