69 Firebird

[classiccardude69]

Ive been working on my firebird for over 4 years now and it has always had a "wimpy" 350 pontiac under the hood. So, I saw an ad on craigslist and purchased a 68 Catalina 4-door with a 400. Now I need to build it up!!!!! Any ideas poncho fans?

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The 400. It has 15 casting heads and is factory rated at 290hp with 1.96/1.66 valves. The block is a YC code.

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[George]

400 .035 over with 455 crank (the increased bore and 4.25 stroke make it a 461 I think), aluminum heads and EFI. This will make 500-600 hp easily.

After I finsh my 67 firebird I want to do a 68 Bird with either that engine or a 400 0.065 over (same bore as 455 0.03 over) and put in a 4" stroke crank to get 440ci.... Trying to get peak HP at a little higher RPM with the shorter stroke. And also do aluminum heads to cut weight and increase compression, and EFI.

HPP did a 440 Pontiac build that made 500+ hp at 6,000+ rpm, but that was at 11.5:1 compression ration and 108 fuel. I would do 9.5:1 or a little higher with aluminum heads to run on pump gas and mid 400 hp ranges I would guess.

Edit: Actually here is their 468 build (which is a 0.065 over 400 block with 4.25" stroke crank) that is pushin 640 hp on pump gas over 6k rpm, so maybe my theory of the shorter stroke doesnt help highend power and the ability to rev faster is negated by less hp....
http://www.highperformancepontiac.com/tech/hppp_0708_pontiac_engine_build_dyno_test/index.html

[classiccardude69]

I went to a local swap meet on friday and found some Pontiac heads to put on the 400 for now. They aren't going to produce the power that higher flowing aluminum heads would, but should work until I can afford some better ones. I just couldn't resist a pair of GTO/Firebird 670 casting heads for $100!

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They aren't perfect. There is a bent valve or two and one has a place that looks like its been welded on before.

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As of now, I still havent pulled the 350 form the bird yet. I waiting on paint and bodywork to be finished before messing with the drivetrain. Most of the bodywork has been done though. I replaced the quarters and got the doors, roof, and one fender done. Now I have to get the passenger fender fit and the hood too. After that, it should be able to be jambed! I can't wait.

This is the 350:

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Its not fancy. The motor is from a 71 Lemans and I think its a YN block (can't remember off the top of my head). The heads are 94 castings (96cc :P) and the engine is factory rated at 250 hp. Might make a little more though now because it has a holley street dominator intake and 600 cfm edelbrock carb (way better than the factory 2barrel). I can't wait for the 400 though.

[opnwide]

Those 350 pontiacs aren't too bad. The same heads that work for a 455 work on those little 350s too. Flow is not an issue for that "little" motor.
Also check out Pontiac Zone in the forced induction forum. Someone there has a turbo'd pontiac 350.

[LeighP]

Watch the CR with those 670 heads.....you might end up with something that doesn't like pump gas.
I'm more partial to flat top forged pistons and 6X-4 heads....puts you in the mid 9's on CR.

Have a look at Butlers or Pacific Performance Racing or Kens Speed & Machine for stroker kits for a 400 to make 455+ CI. All inclusive, no need to cut down an existing 455 crank to fit the smaller 400 main bearings etc.

Good luck with that project.

[classiccardude69]

The 670 heads are 72cc and were put on a lot of pontiac 400s. I think that they bring the compression to somewhere in the 11's? My dad's 67 400 car had them from the factory and pump gas was not an issue. I think the same should go for me. Why does everyone love 6x heads so much? lol

And I don't think that my 350 is a bad motor. When worked up correctly they can make some power!!! Now I need to buy another pontiac project to put the 350 in... well, when this one is done.