[74Grandville]

I wouldn’t touch them. One of the best porters in the business got them where they are now on a more difficult head to port. ( short turn potential in the middle of the port stock)

Go aluminum instead, you’ll be much further ahead.


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[tom s]

Try a cam change first.236-242 400ish love lift.Tom

[scott70]

Originally Posted by tom s

Try a cam change first.236-242 400ish love lift.Tom

Have one in mind? HFT

[Dragncar]

64s are a great pump gas head for a 400. 455, not so much.
SD CNC ported a set of 48s for me and they went 272cfm. They did nice work, wish I still had them.

[tom s]

Scott,I’m out of town and have not done a hft cam in awhile.Maybe talk to Paul K on this site.400 lobe might not be avail with ft so higher rocker can help.Tom

[zippy]

NICE!!!, Someone else who runs #64 heads!!! I ported mine years ago, then took to Dave at SD to have new guides and seats done. He asked who Ported them. I said, Me, why are they that bad? He said No, you got them pretty darn to max! I was thrilled. I went slow, lots of measuring. Over 40hrs per head I spent. Didn't have them flowed, but they do work well on my 455!

[tom s]

I had a set on my 63 Cat 421.Tom

[25stevem]

It’s been like 35 years since I had a set of stripped down #64s set down in front of me to look at, but what can say about there size in terms of port volume is that part of them being smaller is due to the deeper chamber.

Next if I recall right the intake valve bowl looked to be machined a little like the 1967 and up D port heads that are fitted with the smaller 1.96” intake valves.

The basic casting is the same which would allow porting work to take the flow up to over 270 cfm like I now have a set of casting number small valve 15s
flowing since they have been fitted with the normal 2.11” intake valve.

Even with a compromise short turn due to the deeper chamber another 10 cfm should be able to be had out of them unless rust has taken its toll on your particular castings.

[scott70]

I know it's hard to guess but what kind of realistic power increase if I could find someone to squeeze another 15 cfms out of them? On the dyno it made 491 hp @ 5200 /570 trq. with 1.75 headers. I use the ra manifolds which lost 18hp. Just trying to figure out if it's worthwhile .

[ponchonlefty]

Originally Posted by scott70

I know it's hard to guess but what kind of realistic power increase if I could find someone to squeeze another 15 cfms out of them? On the dyno it made 491 hp @ 5200 /570 trq. with 1.75 headers. I use the ra manifolds which lost 18hp. Just trying to figure out if it's worthwhile .

i wonder if you ported the manifolds would it be a better option?might not chance ruining the heads? you trying to hit 500 hp?

[Dragncar]

I have a set of 64s and the 455 HO block.

[scott70]

I port matched the exhaust manifolds and massaged the outlets. It's a older pair of reproduction ra manifolds. I think the ID of the outlets are still around 2.25" I didn't want to grind through. I'd be curious to compare them to a set of the 2.45" manifolds. Still,,,, I tried 1.75 hooker headers on the dyno...491 hp with headers,,473 hp with current ra manifolds. I thought the head porting would be a significant power gain but maybe not. If the head porting got me to 500 hp with ra manifolds that would be a decent gain of 27hp.

Dragncar,,,what car did your heads and block come from? Mine is the original WA block.

[Dragncar]

Originally Posted by scott70

I port matched the exhaust manifolds and massaged the outlets. It's a older pair of reproduction ra manifolds. I think the ID of the outlets are still around 2.25" I didn't want to grind through. I'd be curious to compare them to a set of the 2.45" manifolds. Still,,,, I tried 1.75 hooker headers on the dyno...491 hp with headers,,473 hp with current ra manifolds. I thought the head porting would be a significant power gain but maybe not. If the head porting got me to 500 hp with ra manifolds that would be a decent gain of 27hp.

Dragncar,,,what car did your heads and block come from? Mine is the original WA block.

70 GTO. I traded my WT 48 350 HP 400 engine for it. Did the swap myself. I still have my intake and a pair of the correct 48 heads but always keep my eye out for a 69 WT block.
The guy totaled the 70 GTO 3 months after the swap. I could have had my original engine for 200$ from a wrecking yard but I was living in a apartment and had no place to keep it. I always thought one would show up, still looking. A member has one but its .060 over.