The Break Down of a '69 Pontiac OHC inline six

When I first saw the two blocks together, I thought it was op-art. 7 mains is good. IIRC, the Chevy 250 had the same thing. I had a '69 Nova with a 250 CI six that I wouldn't mind having now. The only reason it's gone is because my wife didn't enjoy leaning way over to put a kid in a car seat. She's not all that strong. Fast forward 20 years, if I had kept it, I wouldn't be driving a Toyota to work. That Nova was bullet proof, was easy to fix and wasn't all that far off in the mileage. The Poncho, iirc, had a lot more torque and power, though. Plus, you could get it with a Q-J on top!

 

Two major differences between the Pontiac 230/250 straight six and the Chevy's, other than the obvious OHC set up, is the block has a deep skirt design, thus more rigid and the valves are larger.

The most a Chevy 250 engine ever left the factory with was 155Hp or so (quick wiki lookup). The base model low compression 1bbl Pontiac engine started with 175Hp, where as the 4bbl, most compression, best factory cam one cranked out around 230Hp (quick wiki lookup). 75HP more, or rather 30% more HP is rather noticable.

 

here are those pics you asked for bud

 

here are some more

 

Fantastic pictures, THANK YOU!! :beers2:

 

forgot the pics told ya i wasnt to good at this:laugh:

 

That second picture is the $64,000 picture I was looking for! Now to look for a front steer F-body subframe conversion. Thanks again! :beers2:

 

i have it up in the air to give her a complete detail here are a coulpe of other ones

 

good luck let me know when your coming out here maybe we can hook up i can show you my rides and the project car later joseph....:TU:

 

Beautiful job.

 

Oh boy that is shiny. I like your spark plug wires holder, nice touch with the GM emblem. I'll let you know the next time I head to Fontana.

 

I'm about to make some progress on assembling this engine now. I picked up a car and want to convert it from the 400 to the OHC so I have better idea's on mocking up the Turbo plumbing. I plan on EFI'ing it from the start and picked up a 3ft length of blank fuel rail from Summit (Holley) and will start mocking up and modifying an intake manifold. I'm basically just going to slap together a running engine from parts I have, with a few mods. It looked like both engines had low mileage on them before the cam wiped effectively decomissioning the engines.

My Christmas present to myself:


Bought a one way plane ticket to Alabama and drove it home. 1,600 miles! I like the view.

 

your out of control r.b:3gears:

 

Haha, so I am! I'm sure you remember my old Firebird and Merry Christmas Chris!

 

Very Nice!

 

Thanks!

 

My first car.... Lots of memories there..

 

A '69 Firebird was my second car (my Skylark was my first given to me by grandma =D ), but the first one I bought, with money earned washing cars. Good memories too working on it and driving it when in College. Unlicensed and uninsured driver running a red light took it out :*(

I loosely bolted together an engine yesterday, fuel rail alignment is going to be interesting as there is interference with the thermostat housing above the #1 intake port using a stock 4bbl intake. One more reason to make my own intake and exhaust, but I think I can make it work.

 

I'm starting on an EFI system for a base engine build (the final build will have home built exhaust and intake and a turbo), and it could be a few months before I get it started up, but here is a start.

The first problem was to over come was clearing the thermostat housing and the throttlebody/carb mount. This interference just wouldn't do. (Ah, the images won't show)




So taking a cue from Cadillac EFI systems from the 70's, and using steel lines that can be bent around problem areas I've opted to angle the #1&2 (and #5&6) injectors so they will clear the thermostat housing and give a straighter shot into the port, then injectors for #3&4 will be a bit more upright to clear the throttle body/carb.


So today I started work on the fuel rails. The parts store didn't have enough of the end fittings but they should have them in tomorrow. So I'll get the tube bender out and start working on bending up the lines to link three 4" fuel rails holding a pair of injectors each. I also have two potential fittings that may be useful on the intake manifold. i.e. a screw in injector bung. I have a jeep intake manifold to practice on drilling the intake and see how the threading works (or doesn't).

So the first iteration.


Cheaper than AN fittings and available locally.


Should be more than adequate for the EFI pressure.



Then just for the heck of it, I turned the engine upside down and looked up the bores at the bolted on head. Don't see a picture like this too often. The valves definitely fill the bore!


Kinda looks like the face of this robot or confused.


And a video of the Firebird idling just because.
http://www.youtube.com/watch?v=1AQjROrQ0dI

 

Any updates?