Piston help!

[parpart]

Has anyone tried Sealed Power/ Speed Pro H535-CP pistons in a stock stroke 460, 30 over, with Edelbrock 75cc Perf. RPM heads (part# 60679)? I am ready to build and am worried about clearance issues.

[techinspector1]

It wouldn't matter if everybody on this board had used those pistons and those heads. It's still a one-on-one set of circumstances every time you screw a motor together. Follow the instructions given by the "Camfather" and you'll be fine.....
http://www.iskycams.com/camshaft.php

[parpart]

What do you think of the build as a whole?:1975 30 over 460, Edel 75cc heads, H535CP pistons for about 10.5 to 1, FMS roller rockers, Comp Cams 34-250-4 cam- 584/588 lift, dur. @.05 is 240/246; Ford Powertrain Applications custom headers, Perf. RPM manifold w/ 870 Holley (elec choke), MSD 6AL w/ MSD vac. adv. distributor. Transmission to be built next week which includes a 2800rpm stall conv., 3.89 gears for street and some strip (Lewistown MT and Minot ND), my original 2.50 or new 3.00's for the highway and interstate. This is all going into 1977 Tbird that I've already swapped over to a 460 some years ago.

[techinspector1]

What do you think of the build as a whole?:1975 30 over 460, Edel 75cc heads, H535CP pistons for about 10.5 to 1, FMS roller rockers, Comp Cams 34-250-4 cam- 584/588 lift, dur. @.05 is 240/246; Ford Powertrain Applications custom headers, Perf. RPM manifold w/ 870 Holley (elec choke), MSD 6AL w/ MSD vac. adv. distributor. Transmission to be built next week which includes a 2800rpm stall conv., 3.89 gears for street and some strip (Lewistown MT and Minot ND), my original 2.50 or new 3.00's for the highway and interstate. This is all going into 1977 Tbird that I've already swapped over to a 460 some years ago.

60679 heads?

[parpart]

Yep, 60679. I bought them in about 2003-4 to do this build, but put them on the back burner due to time working on the oil rigs. But now I'm ready- all I need are 3/8" custom length pushrods (Smith Brothers?), new deeper front sump oil pan and a water pump. I happened to run into a test stand for the break-in and tuning. Couldn't have been luckier. Also, do you know where I can get cast aluminium valve covers, lower than Ford Racing covers, that will clear roller rockers?

[techinspector1]

Piston compression height is 1.752", rod length is 6.605", stroke radius is 1.925", so the stack is 10.282" (or thereabouts, measure it yourself). The block deck height of a '68 - '71 block is 10.300", for a '72 -up it is 10.320", so cut the decks to a new block deck height of about 10.285". This will result in a piston deck height of 0.003". Using the 7314 Edelbrock head gasket that compresses to 0.048" will result in a squish of 0.051". Measure all the pieces and shoot for this squish.

955 cc's in the cylinder
75 cc's in the chamber
4.2 cc's in the piston
0.7 cc's in the piston deck
12.5 cc's in the gasket
1,047.4 total cc's divided by 92.4 cc's = 11.33:1 static compression ratio

Before we go any further, do you have E85 at the pumps up there?

[parpart]

No sir, I don't believe I've ever seen it here. Boy, 11+ comp ratio is not what I was after. Wanted "just streetable", maybe mix a bit of race gas. What are you thinking? I want to learn by doing this right. Is there a 30 over piston that you would recommend to give 10.5 to 1, maybe better suited?

[parpart]

You guessed right also. I have the "Edelbrock Head Set" for the entire top end.

[techinspector1]

Couple of ways to go. You could change the heads for #60669, 95cc and get a 9.5:1 SCR with the pistons you have. You'd have to come back some on the cam. Or you could change pistons to, for instance, Keith Black #206 hypereutectics that would yield 10.15:1 SCR. You still might want to come back a little on the cam. I'll run a DynoSim for you and see what the motor wants....
http://www.summitracing.com/parts/UEM-KB206-030/
These pistons are manufactured with a taller compression height than the H535CP pistons, so the stack works out like this....
piston 1.772", rod 6.605", stroke radius 1.925", for a stack of 10.302". Cut a '72-up block from 10.320" to 10.304" for a squish of 0.050" with the 0.048" head gasket. The earlier block should not need to be cut at all and would result in a squish of 0.046". This should be ok with a hyper piston as they are fairly tight fitting in the bore and would not have much piston rock on the pin. Fit pistons to bore with 0.002" (two thousandths) to 0.0025" (two and a half thousandths) piston to wall clearance. Gap top ring at 0.029" (twenty-nine thousandths) and second ring at 0.018" (eighteen thousandths).

[parpart]

I thought I'd researched this as well as I could! I could not find any info on the pistons except for the listing in my old 2005 P.A.W. catalog (its at my house in Glendive) which said w/ 77cc: 10.4? comp ratio. I'm going off top of my head, so don't quote me, but I know I'm close. Gonna try find their site, look for info and I'll be back. My machinist ordered the pistons for me and pressed them on.

[techinspector1]

OK, Edelbrock 60679 heads, KB 206+030 pistons, RPM intake, 850/870 carb, large tube headers through the mufflers, 10.15:1 SCR, 0.050" squish and CompCams 288BR8 (34-711-9) solid roller tappet retrofit cam and roller lifters, stock ratio rockers. This is a puller and mud race cam, but it makes the most power in this motor. I don't know what springs are in the Edelbrock heads, but they may need a change to run this cam.
http://www.compcams.com/Cam_Specs/Ca...csid=1032&sb=0
RPM HP TQ
2000 176 463
2500 227 477
3000 290 507
3500 371 557
4000 453 595
4500 530 618
5000 586 616
5500 621 593
6000 632 553
6500 619 500
Peak volumetric efficiency 98.2% @5500
Peak BMEP 200.0 @4500
The motor wanted more cam even with less SCR. Motor makes 500+ ft/lbs of torque from 2800 to 6500.

[parpart]

That sounds good. I am going to look at the parts you listed and choose carefully! Here is all that I found so far on my current pistons:

CID
72.cc
73.5cc
77.cc
92.cc
97.cc

H535CP30
466
10.81 w/ 72cc
10.66 w/73.5cc
10.33 w/77cc
9.14 w/ 92 cc
8.81 w/ 97cc


Talk again soon I hope.