Hi guys,
I'm yanking the engine from my '81 for a new set of pistons and cam.  I've suspected for 2 years that the engine did not have the compression ratio I asked for (10:1), and this was confirmed when I removed the heads and found a .039 gasket and a .045 deck height.  The shop had installed "general rebuild) pistons with .020 less deck height than standard, which would typically be used to not raise the compression on a "stock" motor when they deck the block .020.  Being a Vette, where the VIN on the pad may be of significance at some point, I asked them to not deck the block...  The result: 9.1 static compression ratio, aluminum heads which lower the effective CR even further, a Lunati Voodoo 60102 cam and a nowhere near an ideal .040 quench.  Pretty unimpressive performance :-(

So... my plan is below.  I'd appreciate any feedback, especially from guys with or who have built similar combos.  I plan to run 92/93 octane gas and want to get the absolute most power I can out of the compression ratio without getting into detonation.  Also, this is not a daily driver - mostly just weekends and evening drives, so "daily driveability" is less important to me than the ability to rampage down a country road, but I do need enough vacuum, to operate the headlights and power brakes acceptably.

Anyway, here is my parts plan:
- Leave block undecked (.025 deck height)
- .015 steel shim gasket
- Edlebrock E-tec 170 heads, plus I plan to mill them .020 to get them down from 64cc to 61cc
- Keith Black KB-120 pistons, hypereutectic, 7cc piston head volume (valve reliefs)
- Comp cams Magnum 282 solid lifter cam (CC lists the vacuum as "marginal" with this cam)
- Comp cams full roller rockers, 1/6 ratio
- 180 degree thermostat
- 2000 RPM stall converter
- THM 350 tranny
- Factory 2.88 rear end
- If I must to eliminate detonation, I figure I will add a cold air intake and retard the timing a little...

This computes out to a static CR of 10.5:1, which Comp Cams says is the max for this cam with aluminum heads.  I've looked for rules-of-thumb for max DYNAMIC compression ratio, but everything I've read does not state whether they are talking about iron or aluminum heads, so I don't trust the numbers, as that should be almost a full point difference. 

Also, I don't plan to take the the strip, so I was planning on sticking with the rear end gearing at least until I rebuild the rear end, when I may replace with 3.55 gears.

Thoughts?
Thanks for your time with this long-winded post!

hmmmm those numbers seem vaguely familliar. I'm no engine builder but that seems pretty close to what I got in mine. I went a little different route and I just put the stock L-82 in a corner and got another motor. I was worried about running pump gas also but the builder said it wouldn't be an issue with the new engine. On their dyno which was "very conservitive", it was 400HP 426ftlbs trq, on 110 sunoco gas, I can give you specifics if you like but the numbers were real consistant throughout the range.

In my opinion the expense of milling the head for only 3cc is not worth it.The performance gain will be marginal. Plus the Edlebrock heads run pretty good right out of the box. If you mill the heads you may have to mill the intake also to align the bolt holes. I had my BBC block milled .03 and the heads .005 and there was no way my intake was going to line up. I had to have my machine shop mill about .07 off the intake to get the holes to line up. Be sure they do the ends also not just the runner side.
I have Desktop Dyno 2000 and I will run some of your numbers to see what I can come up with. If you have the flow numbers for the Edelbrock heads forward them to me.
Also get a good set of ceramic coated headers(helps with the under hood temps and the flow). The 3.55 is ok if you are going with a four speed auto w/overdrive otherwise you will be taching about 3500 or so at 75. I have 3:73 with a th-400 and it runs 4000 at 75. I put in a 700r4 and now it tachs 2800 at the same speed.Still a little high but alot better on the engine.custom762007-12-28 18:05:25

Looks like the head gasket I planned to use wouldn't work well for aluminum heads on an iron block, so I've juggled the parts plan to try and keep CR and quench close to ideal for 92/93 octane gas.  Here's the updated plan:

- Leave block undecked (.025 deck height)
- .026 composite (steel/graphite) gasket
- Edlebrock E-tec 170 heads (NOT milling them)
- Keith Black claimer pistons, UEM-9902HC020-8, hypereutectic, 5cc piston head volume (2 valve reliefs) and .005 higher deck height than standard
- Comp cams Magnum 282 solid lifter cam (CC lists the vacuum as "marginal" with this cam)
- Comp cams full roller rockers, 1/6 ratio
- 180 degree thermostat
- 2000 RPM stall converter
- THM 350 tranny
- Factory 2.88 rear end

According to calculator on Keith  Black site, it should result in 10.25:1 CR.  Quench will be .046.

Phil, if you wouldn't mind running the numbers for me, That would be awesome!  Here are the flow numbers for the heads:

lift/intake/exhaust
.1 /64/54
.2/130/104
.3/186/140
.4/220/169
.5/232/183
.6/238/190

Thanks!

Any other opinions?

 I have a zz4 short block, bored .30 over,Edelbrock performer 64 cc heads, crane  med lift, cam,headers, weiand intake, edelbrock carb,, she dynoed at 410 hp, runs good on pump gas, but the m22 and 410 rear really give it the wow factor, I think if I were you I may just start fresh with a differant block, piston set up,,and Id make sure to change the rear gear,,good luck, rd

I agree with guys about the rear end ratio. You'll want to change out those highway gears if your looking for a nice strong launch off the line.

 I also agree with the team here regarding the tear ratio. I had a 4 bolt 350 with a comp cams 280H at 10:1 with 3.36 gears in a 69 Chevelle. FELL ON IT"S FACE!! Bumped up to 3.90s and it felt like someone slipped a big blick under the hood!

Here is what I came up with for your combination. This is with small header tubes with mufflers and a 660 cfm carb. Comp cams asks that headers,stall converter,and some rear gears be used with this particular cam to get the best results.
Definatly a nice torque curve
RPM   HP   TQ
2000 133 349
2500 172 361
3000 212 372
3500 263 394
4000 311 408
4500 355 414
5000 387 406
5500 405 387
6000 405 354
6500 389 314
7000 364 273

Thanks a lot, Phil.  Your "dyno" curve looks a lot like the one for the example buildup in Lingenfelter's book, which increases my comfort level.  I should have mentioned that I'm also running headers, although they are not optimally sized for low-end torque - I have hooker sidepipes, so the primaries are 1-7/8.   The reason I was looking at this cam with this combo is that Lingenfelter uses it in the example build ups in his small block chevy book and he touts the wide power band.  Even though it is a fairly big street cam and will have some lope (a plus in my book) it looks like it will produce enough torque by 2K RPM to get my car moving pretty well, and my 2K RPM converter gets me into the 2500 range really quickly.  I know it won't be the optimal setup for the 2.88 gears, but I'm building the engine with the assumption that I will probably go to 3.55 gears when I rebuild the rear end next winter. 

Anyone have additional thoughts?

John,