The Silver Buick's 1969 Firebird OHC six project.

[OHC 6 Sprint]

There is always this mod as well.

With that mod, you would get great results with an adapter to a square bore throttle body, rather than using a Q-Jet baseplate as a throttle body.

[Beagle]

Small displacement, going to try some tricks in the book to try and maximize the HP out of every cylinder. I want to see if I can 'make' a tuned length runner.

I'm with you - you should "make" several! That was why I put the Weber picture up there really - you can put as much or little runner length as you have room for using silicone hose and clamps to hold the mid-section in (if that makes sense). You could also jack with plenum volume like the old BXR Ford manifold if you get carried away:

http://ollav.com/naturalaspiration/bxr/

that'd be pretty straight forward using butt weldments into a box with a spaceable box plate maybe? Then you could use any dirt cheap commonly available throttle body... yeah, I know. You got it. Just living your dream man. Grin.

[OHC 6 Sprint]

how much does it matter with boost? not being a smartass here, I'm curious.

He's building 2 motors. The first is not boosted, so he needs to get as much out of the intake system as he can. The factory manifold flows better than all aftermarket versions in this application for a single carb. When it's ported as shown in the pic, it reaches its maximum. For the triple Webers, using Weber-style TBAs would be the way to go over carbs. Then the whole injector location, angle, interference, etc. problem dies down to nothing.

For the boosted motor, all that makes not one iota of difference.

[DanStokes]

I'd be surprised if the Crower Sportsman rods wouldn't work just fine. The SBC rods have the narrow big end and the 250 rods are, as expected, wider. I can measure them if that would be helpful. I bought 5.7 long but you can get 6" if wanted/needed. My forged pistons work with the 5.7 rod length.

This is a GREAT project.

Dan

[OHC 6 Sprint]

I'd be surprised if the Crower Sportsman rods wouldn't work just fine. The SBC rods have the narrow big end and the 250 rods are, as expected, wider. I can measure them if that would be helpful. I bought 5.7 long but you can get 6" if wanted/needed. My forged pistons work with the 5.7 rod length.

This is a GREAT project.

Dan

If I recall, the Crower / Chevy 250 OHV rods are 0.947" wide on the big end. The Pontiac OHC rods are 1.029" wide. But measure what you have, in case I've gotten confused. It's always possible!

[OHC 6 Sprint]

Nice pic of a Jag engine ... I think this was what you're going for?



The triple Weber intake is also available from Clifford ... that would be my first choice for going "out of the box."

[Bob Holmes]

That is a bit of sweetness. I'd take that any day over a belly-button SBC.

[Beagle]

Nice pic of a Jag engine ... I think this was what you're going for?



The triple Weber intake is also available from Clifford ... that would be my first choice for going "out of the box."

Yes, and yes. I picked the first one out of the search window. Dang brakes got in the way here?

[SuperBuickGuy]

how are you going to determine which runner length is correct? granted, all of my experience is on Land Cruisers (250), but the biggest problem was the extreme differences in length of runners - which you could bandaid with a holley carb, but truly the best solution was paired or individual carbs at the port ala webers.

[TheSilverBuick]

Like Gary Hart's intake on his straight six GMC engine except I'm going to go up with it. Have the straight/tapered runners going into a common tube parallel to the length of the engine, opening in the front for a modern single plate throttle body. Hopefully the intercooler's outlet will line up with it. This would be a final intake design for the turbo engine. I'll use pipemax to approximate the runner length and taper (if I'm skilled enough to get it to taper...).

Gary Hart's intake. He sloped it down so he could run the turbo up higher for packaging.


So like this one but with a common plenum tube like Gary's.

[OHC 6 Sprint]

Yes, and yes. I picked the first one out of the search window. Dang brakes got in the way here?

Yes - and worse with a power brake booster getting in the way. This is where the Plymouth Slant Six approach makes a whole lot of sense, or having a 90* intake with downdraft carbs instead of side draft carbs. (No such animal exists - hood clearance!) It would be nice if the triple Weber intake wasn't quite so bulky, but you work with what you can on the OHC, or you make your own.

This picture is a great tutorial for what fits where and how on the OHC in a Firebird.

[TheSilverBuick]

The car is currently a manual steering and manual brakes (drum). I'll eventually get some disc brakes up front.

[OHC 6 Sprint]

So like this one but with a common plenum tube like Gary's.

That's (if I recall accurately) an Algon injection system on the LSR "Black Opel" that ran in 2005 at Bonneville with a 230 OHC in a 1970-ish Opel GT. There is a similar system on a Hydroplane motor (that's currently for sale), so there was some interest way back when ...

[TheSilverBuick]

The common plenum will make filtering air and plumbing boost simpler.

[Scott Liggett]

Your factory four barrel intake/exhaust manifold looks insanely heavy?

I dont check in for a few days and I see tons of pics of OHC coolness.