What engine should I put in my 67 Firebird?

[wiknight]

Hello, I'm new here and need some help with my 67 Firebird. It doesn't have an engine or trans in it. The engine it originally came with was a 326. I was thinking going with a pontiac 400, and I hear the 67-71 had the most horse power due to pre emission. I hear a lot of different opinions about getting a junkyard engine and not to bother rebuilding one. And never get a later model 72-78? PONTIAC 400 engine.(I don't understand why becouse if I use different heads and came wouldn't I get the same horsepower from a late model 400 as an early model? I'm not that savy on all that. I guess what I'm asking is for some of your expert opinions on what I should do for an engine, and where to get one. Another option I keep hearing about is an LS1 engine. I guess If I went that rout I would carberate it due to all the mods I would have to do for fuel inj. What do all of you think? And does anyone have an engine I could purchase? Thanks-Randy

[MrPbody]

Well, I'm a "month late" here. Sorry. Been unable to get back into the site until today...

The 400 block and crank are functionally the "same' from '67-'79. There are subtle differences over the years. You're surmise is correct. Add the early heads and a decent cam, and it WILL make the same power as the early engines.

Lots of experience here with the Pontiac. Let me know what you want to do and I'll hook you up.

Jim

[wiknight]

Hi Jim, Thanks for the info. I was watching an old video clip from horsepower tv a few weeks ago. They were rebuilding a 1973 pontiac 400 motor and ended up with a little over 300hp, which I would be happy with. I bought a 74 pontiac 400 and i'm in the process of taking it apart. Anyway, in the video the main upgrades were, a 214/224 flat tappet cam, dual plain intake manifold from Edlebrock, exchanged the 4x heads for 6x heads,(which I have a set of both 4x and 6x) headers,750 carbureter, 1.6 rocker arms, bored 30 over pistons. This sound good to you? Any advice would be helpful, Thanks again Jim. Oh, I'm looking for this to be a daily summer driver, and I will be adding power disc brakes to it.

[MrPbody]

We have a completely different "approach" to making power with the Pontiac.

The 4X heads are every bit "as good" as the 6X, only superstition makes the 6X more popular. In fact, most d-port heads (the shape of the exhaust ports) flow about the same with the same valve sizes. Compression ratio will be quite low on a 400 using either head. Measure the chambers. If the 6Xs are "-4s" (secondary stamping on the vertcal ri, just below the valve cover rail, to the left), they can be milled up to .060" to get "down" to about 85 CCs. That will yield right at 9:1.

We use Comp XE grinds for the low compression engines. For a mild idle (gurgly, not "lopey") and "stock" torque converter, XE262H is the popular grind. For more "attitude" and high-end power, XE274H is popular. The latter requires a slightly higher than stock "stall" speed" if running an automatic.

300 HP is pretty wimpy... (:-

GTOs had more than that "stock". No reason your 400 can't be more like them!

A good read is Jim Hand's book "How to Build Max-performance Pontiac V8s", published by SA Designs. It's the most "current" study of the ol' Injun. It's 7 years old now, so some of the info about cams, carbs and porting is "dated", but all the info about the "quirks" of the Pontiac, and how to build a tough one, is still accurate. I wrote "Chapter 2: Building Your Shortblock".

Jim