stephen p

i may not have this in the right section, but im looking at a buying a '70 GTO, and it has a 400, and if i get it , i may even build a 455, but what heads should i look for?

LS1W66

Depends on your HP goals and whether you want to run pump gas or not.
The old Pre `71 400 heads on a 455 will bring compression above 11;1.
Some late model 6X heads on a properly cammed 455 can make upwords of 450 HP and still run 93 octane fuel. Or theres always the aftermarket aluminum heads.

500hpZ06

iTrader: (11)

I don't have my Pontiac head spec sheet anymore (got out of the 'old iron' years ago). But you should be able to find some good tech on a TRUE Pontiac forum/site. When comparing old Poncho heads, it sometimes helps to have the two letter code off the block, of course you need the casting numbers/letters over the center exhaust ports, plus the production year helps, but is not always totally necessary (having/measuring valves sizes helps, too).
If that '70 still has the original engine, it may have decent heads on it. Somewhere around '71-'72 they started gradually going downhill, dropping compression. Flow also started to suffer because valve sizes were also getting smaller, and HP was no longer a priority. They were still very torquey, but didn't have much snot past 4,500 RPM.
Those '70 400 heads may even work on a 455. They will bump compression up, but you would need the exact tech specs to know how much (if TOO much). The thing is, any reasonably priced 455 will most likely be a later 'smog' engine with fairly lame heads. The really early 70's (?'70-'73?) 455 heads may still have some potential, but they are getting harder to find.
Now don't forget, there is nothing wrong with a well built 400. You can't get very wide tires under these older cars, so big torque is not always the best answer.
I believe with some machine work, a 455 crank in a 400 block ends up as a 428, which makes for a nice Poncho street engine. Also, Scat and a few others are offering 'budget minded' cranks (and rods), that may come in various strokes, in the two common main sizes (generally, the stock Pontiac connecting rod is their 'weak link').
Hope this helps.

Captainofiron

iTrader: (1)

it really depends what you are looking for 6x heads arent the best, they are just plentiful

if you want a small compression chamber look for something pre 70

After 70 they still have big valves but they also have big chambers on them

The Ram Air heads are always nice and you can usually find some on Ebay that is of course if you are willing to spend the cash.

I have a set of 7K3 heads that I have been trying to get rid of, they were pulled off my working 400, they have the big compression chamber i think maybe 128 cc's and the big valves 2.11/1.77
if you want them let me know.

But what I use on my 400 now is a set of 670 heads from a GTO

But honestly, the Edelbrock heads are amazing, and I think worth the money if you dont care about keeping appearances, I think once I get the money I will be buying a set of lightly ported Edelbrock heads from Butler

The only thing that sucks is they use the round port style headers and those are sometimes a pain to find

check out http://forums.performanceyears.com/forums/

BAD2000TA

iTrader: (6)

As mentioned, depends on your goals. It also depends on the engine you end up using - 400 or 455.

If you use a 455, here are my thoughts:

#96 head (from the '71 400). Gives great compression on a 455, not expensive.

Kaufmann Racing D-Port aluminum heads. Can use non-round port headers/exhaust manifolds. Produces GREAT power.

Edelbrock 87cc head. Great out of the box. Needs round-port headers/exhaust manifolds.

If you use a 400:

Ram Air 3 heads. Might be hard to find, though.

Edelbrock 72cc heads.

Other D-ports with big valves.


Try this Pontiac Forum: http://forums.performanceyears.com/forums/


Good luck!

90TSiAWD

The best D-Port pontiac head is the #16 Casting with the big valves (2.11/1.77) they also came with the smaller 1.96/1.66Valves the have 72cc chambers.
You want a pre '71 Head if you using the stock style pistons because there combustion chambers are pretty big.

And any pontiac head will fit on any pontiac motor, and as stated above you can put a 455 crank in a 400.

Wallaceracing.com....is a good website to get lots of information on pontiac motors when I had my Poncho thats were I got the majority of my info.

LS1W66

Just wanted to add that a 455 crank will work in a 400 block as long as the mains are cut .250" then IIRC theres a small area inside the block that needs to be ground for counterweight clearance.
455 use a 3.25" main while 400/428's use a 3.00" main.
455's have a 4.21" stroke with a 4.15 bore
428's have a 4.00" stroke with a 4.12 bore
400's have a 3.75" stroke with a 4.12 bore

IRONFIST

You are going to want different heads depending on application. Right now you have a 400, not a 455, so you'll want heads to go with it. Now I have 6x-4 heads on my 400, and that's great for a cruiser. With those head a little head work, and a decent cam my 76 Firebird keeps up with my 99 WS6. I chose the 6x-4's because they are cheap, and let me run regular unleaded gas.

Now the same heads on the 455 would make much more power, because compression would be bumped up, and so would displacement, I'd also never be able to run on 87octane, and I'd do more port work.

Do you plan on building a 455 or a 400, you should decide that first for sure, then decide what you want from the engine... and go from there.

blackls1ta00

iTrader: (27)

ram air IV heads

ncbirdfan

If you can find a set of 670 heads, they have the big valves, screw-in rocker studs and flow better than any other D-port head but they aren't cheap. They were only offered in 1967 and you will need plenty of octane because they are high compression heads (only like 72 or 76cc's). A set of 670 heads, the "041" RAIV cam and 1.65 rockers is an awesome combination for a 400.

BAD2000TA

iTrader: (6)

Terribly poor suggestion!!!

Here's why:

1. Cost. Try finding a set of RAIV heads. Let alone the fact that they will likely need to be rebuilt. Leave them to the guys trying to restore GTO's and Firebirds originally equipped with RAIV engines.

2. Can't realistically use on a 455 - the compression ratio is too high for street use. You're over 12:1 on a 455. That mean race fuel only.

3. RAIV heads (and SD455 heads) won't perform any better than the Edelbrock's, plus you save a ton of weight with the Edelbrock heads.

4. Plenty of other options that will make power close to and exceed stock RAIV heads. Look to SD Performance out of Canada for their CNC-ported D-port heads that flow 250CFM+!! http://www.sdperformance.com/viewPro...p?productID=43

Captainofiron

iTrader: (1)

They dont flow the best, that is a common misconception, They flow the best with low lift camshafts, but with big cams they have a tendency to limit flow because of the compression chamber being a closed design