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I am getting ready to have my stock 462 heads redone and need to decide what cam and springs to run. The heads are bone stock and will remain so. Just a freshen up valve job for now. The block is a 71 350 out of a pickup. I believe the pistons are for that application. See pic.

I am going to "freshen" the block but plan no piston replacement, as there is very little cylinder wear.
What kind of cr is this combo going to produce and will it support a cam with "attitude" as I have read in many of the threads I searched thru ?? The car does have a PG trans and no vacuum brakes, at this time, but I plan to add them eventually. I am looking to get a package cam with springs and hydraulic lifters. I know this isn't going to be a high hp engine, but I am hoping for at least the 300 hp it originaly had and with a little lope to boot. :D I will be running the stock, original, intake with the Edelbrock carb it has now. I will be looking for a dual plane aluminum for the future. I'm just looking for a reasonably strong street cruiser, if that is possible with what I have....;)
 

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Oh come on now.......none of you engine guys wants to take this on ....:D
 

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Mitch, if the heads are stock I calculate 10.61:1. It would behoove you to get a cam to bleed off some of that CYL pressure. If you do, youll need a standard or a loose convertor. It will be a blast wi the right cam. To take advantage of the setup you have, Id spend a little more for some good heads around 68-72cc that flowed 180-200. Then that would be just as fun just more ...'streetable' :D
 

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Mitch, if the heads are stock I calculate 10.61:1. It would behoove you to get a cam to bleed off some of that CYL pressure. If you do, youll need a standard or a loose convertor. It will be a blast wi the right cam. To take advantage of the setup you have, Id spend a little more for some good heads around 68-72cc that flowed 180-200. Then that would be just as fun just more ...'streetable' :D
10.6 with those dog dish pistons ?????? I certainly didn't think they would produce that kind of cr...........:confused:
 

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well help me out here. I used flattop cause I wasnt sure how much dish those are. What cc are the heads? what gaseket are you using?
 

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Those .070 full dish pistons ain't gonna make much compression. I found a chart at trw shows 8:1 with 76cc heads, 8.8 with 64's.

If I back into it on the calculator, I get a 15cc dish. I'm not sure I'm buying that. All I have to work with it trw's compression ratio chart. When I calc the compression on standard chevy advertised combo's, the numbers I get are generally .6 lower than Chevy's ad copy. A 69 10.25:1 350 calculates to about 9.7:1.

The 462's are good heads, and are 64 cc, that will help.
Use felpro 1094 gaskets (.015, check deck ht!) to get as much compression as possible. Those gaskets are worth half a point of comp, that's huge.

Then put a cam in it. It'll run good with a short cam, 210 @ 050 or so. Do to the low compression, as you put in a bigger cam, you'll lose low end fast. You would make more upstairs tho. I woulnd't go much more than 220 or so at .050

Damn... I threw away 7 good 4" bore flat tops that woulda helped you out a lot here
 

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Discussion Starter #8
well help me out here. I used flattop cause I wasnt sure how much dish those are. What cc are the heads? what gaseket are you using?
I don't know what the spec is on the piston either.......anyone with a truck spec chart.......:D
I think pdq quotes the 462's as 64cc ??
I will use whatever gasket I need for the cam and heads. I thought a shim gasket might bring the cr up to 9 ?? They look like they would work great with a twin turbo setup............:yes:
 

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Discussion Starter #10
By that chart it should be 8.79-9.03 with a .070 dish piston. I wonder what gasket they are figuring ???
As a reference, all the 71 passenger 350's were 8.5 except the Z and vette that got a whopping 9
 

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So Jim, if I used a shim head gasket for more compression do you think your 270H cam would work in this ??
 

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assuming an .020 deck, I come up with a static comp of 9.3:1, and a DCR of 7.65:1.

When my engine was a 327, the numbers were 9.4:1 and 7.72:1
as a 383, 9.66:1, 7.99:1.

Motor ran good, 383 would ping lightly under high loads with 89 octane gas, no ping with 93.
so, yes.
 

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Harley, you better look at the pics a lil closer... Those are FULL DISH pistons!
LOL YEAAH. I was guessin flattops cause I didnt know the specs on the pistons using a.015 gasket and 62cc heads. 7cc dish. oops. I was hip-shootin anyway.

I don't know what the spec is on the piston either.......anyone with a truck spec chart.......:D
I think pdq quotes the 462's as 64cc ??
I will use whatever gasket I need for the cam and heads. I thought a shim gasket might bring the cr up to 9 ?? They look like they would work great with a twin turbo setup............:yes:
I thought they were 62. Im no engine builder tho, but respnding and getting corrected or set straight by the real engine guys is nothing to me except a learning experience. :D
 

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I don't think they are using one...

The SRP pistons in my 383, the manufacturer show -16cc. Thier's no where near as much dish as those.
Look like 1156's. 21cc dish.
 

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Discussion Starter #16
assuming an .020 deck, I come up with a static comp of 9.3:1, and a DCR of 7.65:1.

When my engine was a 327, the numbers were 9.4:1 and 7.72:1
as a 383, 9.66:1, 7.99:1.

Motor ran good, 383 would ping lightly under high loads with 89 octane gas, no ping with 93.
so, yes.
OK, but I don't know what you mean by the .020 deck. It seems like it should work OK, not ideal, but then this isn't the ideal piston either. I'm just trying to work with what I have and come up with an idea what I need for springs to get the heads done. If the .020 deck is something I can achieve with gaskets, then consider your cam kit sold. If it involves machining the block .020, that isn't in the budget.
Gotta run off to bed now. Alarm goes off at 5:30. I'll get back on here tomorrow mid-late morning.

Thanks !!!!
 

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Those pistons have a 13cc dish, and will run around 9.0-1 compression, depending on deck height and head gasket diminsions. If your heads have ever been resurfaced, they may be 62cc or less, although factory spec is 64cc's. The 270 magnum will work just fine with around 9-1 compression and have a bit of lumpiness to it.
 

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To check your deck ht, bring a piston up to TDC. Lay a machinists rule on edge, or some sort of straightedge, across the deck, then see how much feeler gauge you can fit between the straightedge and the top of the piston, at the edge where there's no dish. Make sure you check it on the pin centerline, straight fore and aft, not down toward the exhaust side or up toward the intake.

You need a minimum of .030 between the uppermost part of the piston and the flat part of the head. (or they may try to occupy the same space at the same time, this usually breaks things!)
That is your "deck ht" (how far down in the hole the piston is at TDC) PLUS the thickness of your head gasket.

.020" + .015" = .035 = just perfect.

And yes, I'd love to sell you my cam. That is the works, too, everytthing from the timing chain to the rocker arms.
 

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Discussion Starter #19
To check your deck ht, bring a piston up to TDC. Lay a machinists rule on edge, or some sort of straightedge, across the deck, then see how much feeler gauge you can fit between the straightedge and the top of the piston, at the edge where there's no dish. Make sure you check it on the pin centerline, straight fore and aft, not down toward the exhaust side or up toward the intake.

You need a minimum of .030 between the uppermost part of the piston and the flat part of the head. (or they may try to occupy the same space at the same time, this usually breaks things!)
That is your "deck ht" (how far down in the hole the piston is at TDC) PLUS the thickness of your head gasket.

.020" + .015" = .035 = just perfect.

And yes, I'd love to sell you my cam. That is the works, too, everytthing from the timing chain to the rocker arms.
OK, I just came in from the shop, but I will go back out in a little while and check the deck height. I had the heads all checked when I bought them to be sure there weren't any problems and the shop declared they were 100% bone stock and in very nice condition, so I doubt they have been resurfaced.
 

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Discussion Starter #20
Hmmmmmm.......I get .030-.032. I don't have a degree wheel, but they are all right in there. This isn't going to help, is it ??
 
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