67 GTO 400 WW Code

[68FBODY]

Originally Posted by 7firebird1

I don't have heads yet. I was gonna go with maybe 670. I have thought about even going with an LS engine, but I love the look of "old muscle" . Tim.

Personally I would keep it with a Pontiac motor. Ok 670 heads have a 72cc chamber with 2.11/1.77 valves and would be great, however are you going to have them ported? Are you going to utilize the stock 400 crank, rods, pistons?

[72blackbird]

A block without caps is nothing but a PITA and IMO not worth working on, since you cannot just get caps from another 400 and bolt them on- you have to get them milled down and have the main journals align bored/ honed to assure the main journal bore is perfectly straight (pricey machine work usually reserved for fitting 4-bolt caps to 2-bolt blocks).

Earlier blocks also only have 2 motor mount holes on the sides, and you need the later 5-hole block to mount it in a '71 Firebird. I personally would find a later 70-75 no.481988 400 block and start from there.

Geno

[jst8a5.0]

Geno is right. Pontiac mills with the caps in place and when they do that those caps fit that motor only. Otherwise it's a crap shoot to see if you can find others to somewhat fit then have the machining done.

And just go and get some edelbrocks unless your 670's have already been done. They may also be too much compression for iron heads and todays pump gas. With the e heads at least they are aluminum and can dissapate that heat so you are safe with those 72 cc chambers. I ran mine for years and wound up at 11.9 at 114 without really tuning it and in a non wieght reduced street car.

[7firebird1]

So do you think I would be better off selling this block to someone who may have a 67 GTO with a cracked block that acn utilize his main caps? I just hate to dispose of something that really in my mind is a piece of history (a GTO engine). I may just buy an LS engine....duno.

[jst8a5.0]

Post it in the classifieds. Maybe an LSx would be cheaper or better suited to your needs. They are getting more and more plentiful and can be steals sometimes. Just make sure that you get everything you need like wiring, computer, etc.

[72blackbird]

The LS-series are good motors, but for a second gen 'Bird I'd stay with pure Poncho power- less high tech but cooler and old school. I'm building a 455 for my '72 Bird this summer, but if I didn't get that 455 I would have built a 400/462 stroker out of a 400 2-bolt block, and put the 4-bolt splayed caps on it.

The big advantage with the stroker is the 4.25/3.0/6.8 combo lets you rev it faster than the 4.21/3.25/6.625 combo in a stock 455. The stroker is also alot easier on the bearings and stronger than the 455 in the main web area. Add a forged crank and aftermarket 4-bolt splayed caps and you can buzz that mill to 6500 all day. Of course you need to have heads that can use the RPM- some 310 cfm KRE's or wideport E-heads would do the job nicely. Add a solid roller and you're making 600+ hp/ 575+ ft-lbs on pump gas.

Geno

[7firebird1]

Thank's guys. I think I will do that. To the classifieds it goes.

[OLDFLM]

If you decide to stay with the 400 I’ve got a set of #13 heads… ready to bolt on and run! They flowed 220cfm @ 28” on Rocky Rotella’s bench with just a mild cleanup and were visually inspected by Jim Hand after porting.
They were professionally assembled with all the good stuff: Ferrea valves, Comp Springs, hardened seats etc. Let me know if you’re interested… made right at 400hp/400lbft in my 400 with a Bullet 224/230 .485/.491 110LSA cam.

I have a 71 too btw so let me know what you need or if you have any questions as I've probably researched it for you already! LOL

Welcome to the site! This is a great community of incredible people!!

V/R,

Ty