[SD455DJ]

Going with larger valves, or sticking with stock? Dennis

[footjoy]

Originally Posted by SD455DJ

Going with larger valves, or sticking with stock? Dennis

Staying with stock

[footjoy]

I pulled ahead off and its got the dreaded 8VR pistons bored .040.

Its not a race car

[footjoy]

when doing compression calculator is the 8VR considered a straight flat top no dish?

[FrankieT/A]

I believe the intake valve on those heads is 2.11" already, if that's the case it would certainly be worth putting in the 1.77" exhaust. You would end up with a killer set of heads. And of course, now is the time to do it. JMHO

[SD455DJ]

FrankieT/A, The 1970 #15's are the small valve 85 - 90 cc chamber head on the 360hp 455's standard in Bonneville's and optional in other B-bodies, not to be confused with the optional 370 hp 455HO (360 hp in the A-bodies and GP) with the large valve #64 heads.

Dennis

[SD455DJ]

Originally Posted by footjoy

when doing compression calculator is the 8VR considered a straight flat top no dish?

Greg, I believe that the std. 4 vr pistons (flat top) are rated at 6 cc volume. The 8 vr piston is more like 10 cc. Does the perimeter also have the bevel cut? I also heard the pin height on these were changed to drop them a little lower in the bore to account for some deck planning. You'll have to measure the deck height to know for sure. Post a picture of one of the pistons at TDC.

Dennis

[footjoy]

Originally Posted by SD455DJ

Greg, I believe that the std. 4 vr pistons (flat top) are rated at 6 cc volume. The 8 vr piston is more like 10 cc. Does the perimeter also have the bevel cut? I also heard the pin height on these were changed to drop them a little lower in the bore to account for some deck planning. You'll have to measure the deck height to know for sure. Post a picture of one of the pistons at TDC.

Dennis

So for clarification if it s 10cc with 87 cc chamber does that make it 77cc or 97cc chamber.

thanks Greg

[SD455DJ]

Originally Posted by footjoy

So for clarification if it s 10cc with 87 cc chamber does that make it 77cc or 97cc chamber.

thanks Greg

Greg, did you try using the Wallace Racing calculator?

Dennis

[SD455DJ]

Just playing around on the Wallace Racing compression calculator, I got 8.77:1 using 87cc chambers, 10cc vr, .030 head gasket, 4.30" gasket dia., .015 deck for your .040 over 400 (408). It would be 9.18:1 with '0' deck pistons, all else the same.

Dennis

[footjoy]

Originally Posted by SD455DJ

Just playing around on the Wallace Racing compression calculator, I got 8.77:1 using 87cc chambers, 10cc vr, .030 head gasket, 4.30" gasket dia., .015 deck for your .040 over 400 (408). It would be 9.18:1 with '0' deck pistons, all else the same.

Dennis

I plan on running 91 octane.

On another subject how come pontiac head gaskets are so expensive?

Thanks Greg

[FrankieT/A]

Originally Posted by SD455DJ

FrankieT/A, The 1970 #15's are the small valve 85 - 90 cc chamber head on the 360hp 455's standard in Bonneville's and optional in other B-bodies, not to be confused with the optional 370 hp 455HO (360 hp in the A-bodies and GP) with the large valve #64 heads.

Dennis

Dennis,
Not confused at all, I just couldn't remember if they had the big intake and small exhaust or both small valves. The 15 head is great head to convert to high performance for a 455 yielding 10:1 being 64's availability and cost being what it is. I wouldn't put 15's on a 400 though, the compression would be too low for my taste. But that's me. That's why they make chocolate and vanilla. If you look through the thread you will notice I was the first one to suggest a head swap. I'm a firm believer that acceleration is directly proportional to compression.

[SD455DJ]

FrankieT/A, Sorry I didn't mean you were confused, just clarifying the differences between the '70 455 heads. Another seldom seen '70 head is the #16 small valve high compression (10.0:1 advertised) head used on the 290hp (2-bbl) and the 330hp (4-bbl) 400's. The 290hp was only in the B-bodies while the 330hp 400 was both A (non-GTO) & B body installations. It has a 78 cc chamber.

Greg, My brother used the dreaded 8vr pistons (+ .030) in a simple rebuild to a '73 400 4-bbl in a Bonneville a few years ago. He measured the vr's and they were 14.5 cc's! He couldn't recall if they had the bevel around the piston crown or not. He calculated the compression to be 7.5-ish, but the car ran strong and was peppy. So that would bring your compression down almost a half point.

Dennis

[footjoy]

Originally Posted by SD455DJ

FrankieT/A, Sorry I didn't mean you were confused, just clarifying the differences between the '70 455 heads. Another seldom seen '70 head is the #16 small valve high compression (10.0:1 advertised) head used on the 290hp (2-bbl) and the 330hp (4-bbl) 400's. The 290hp was only in the B-bodies while the 330hp 400 was both A (non-GTO) & B body installations. It has a 78 cc chamber.

Greg, My brother used the dreaded 8vr pistons (+ .030) in a simple rebuild to a '73 400 4-bbl in a Bonneville a few years ago. He measured the vr's and they were 14.5 cc's! He couldn't recall if they had the bevel around the piston crown or not. He calculated the compression to be 7.5-ish, but the car ran strong and was peppy. So that would bring your compression down almost a half point.

Dennis

So if it is 7.5 what will I do with this K2801 cam that I just got. It says 9.0 compression.

[SD455DJ]

Greg, No, my brothers 400 had 7.5 compression. You'll be in the mid-8's with those 8-vr pistons. Did you check to see what deck height you have to determine the head gaskets you need to buy? I have a new Summit 2800 cam & lifter kit I'll trade you for if you need too.

Dennis

[SD455DJ]

BTW, I have the 2801 in my stock 455HO (actual 8.4:1 compression) motor and it is sooo mild. Let's see where your actual static compression is to select to best cam.

Dennis

[JC455]

Originally Posted by footjoy

I am looking for some Ferrera 1.96 valves I have not located any. Where can I buy some.

Thanks Greg

If not too late, you can always upsize to a Chevy 2.02 valve. Have your machinist compare specs vs. the 1.96 valve.

[PONTIAC LARRY]

Originally Posted by footjoy

So if it is 7.5 what will I do with this K2801 cam that I just got. It says 9.0 compression.

If you are up for the cam swap the heads are easy to change then. Any good local deal cheap on a small valve head from 68-78 off a 350 would range from 78-80 cc 68-70 , up to 93 cc 71-78 and still get you at least in the 8+ :1 range closer to 9:1 it would make the difference and run well with the 2801. Just lose the 98-101 cc chamber 400 heads save em for a 455. Years back I did a 2801 on 400 that had crap pistons in a 76 TA for my brother in law, but swapped to 1970 #11 heads rated 8.8:1 I think. So it might have been 8.2 actual and it only had single exhaust but that THING RAN REAL WELL for what it was

[SD455DJ]

Originally Posted by PONTIAC LARRY

If you are up for the cam swap the heads are easy to change then. Any good local deal cheap on a small valve head from 68-78 off a 350 would range from 78-80 cc 68-70 , up to 93 cc 71-78 and still get you at least in the 8+ :1 range closer to 9:1 it would make the difference and run well with the 2801. Just lose the 98-101 cc chamber 400 heads save em for a 455. Years back I did a 2801 on 400 that had crap pistons in a 76 TA for my brother in law, but swapped to 1970 #11 heads rated 8.8:1 I think. So it might have been 8.2 actual and it only had single exhaust but that THING RAN REAL WELL for what it was

Good points Larry. The #15 heads Greg has actually measured at 87 cc's, so his compression is in the high 8's on a .030 over 400. I think the 2801 cam is a good choice for his combination.

Dennis