zero deck and open chambers?
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Junior User
Joined: May 2002
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zero deck and open chambers?
Just wondered if it would be better to zero-deck the block and use dished pistons, or just surface the heads/deck flat and use badger flat-tops. What are the advantages/disadvantages as far as detonation in a polished, open chamber 400 head with all other things (CR, fuel type, elevation, etc.) being equal?
Thanks much!
Thanks much!
Posting Guru
Joined: Mar 2002
Posts: 2,070
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From: Boise, Idaho
zero deck and open chambers?
[updated:LAST EDITED ON 20-Nov-02 AT 02:07 AM (EST)]I can't think of any advantage of zero-decking with open chamber heads. The main reason for zero-decking a block is to produce quench and open chamber heads have little or no quench.
It takes some doing to try to create some quench in a 400 cubic inch engine with 4" bores. The attempt to use the Oz Cleveland heads on 400's is regularly flogged on this forum and I haven't yet heard of a way to get compression down and quench up. It would take a piston with a sizeable dish with a shape that matched the shape of the combustion chamber.
A few years ago piston companies made 'reverse dome' pistons with D shaped dishes that matched up to quench chambers pretty good, but you don't see them any more.
It takes some doing to try to create some quench in a 400 cubic inch engine with 4" bores. The attempt to use the Oz Cleveland heads on 400's is regularly flogged on this forum and I haven't yet heard of a way to get compression down and quench up. It would take a piston with a sizeable dish with a shape that matched the shape of the combustion chamber.
A few years ago piston companies made 'reverse dome' pistons with D shaped dishes that matched up to quench chambers pretty good, but you don't see them any more.
Posting Legend
Joined: Sep 2001
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zero deck and open chambers?
Ditto...
No quench possible with open chambers.
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No quench possible with open chambers.
Thanks for using FTE!
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Senior User
Joined: Jan 2002
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From: Green River USA
zero deck and open chambers?
The optimum (and most expensive) solution is to buy custom pistons from a name-brand company (JE) with a custom compression height that brings the piston to zero-deck. Then have them cut a reverse-dome (just tell them to use the shape of the 351C 4-bbl head) to get your compression down and use the aussie heads. Although expensive (600 for a set of custom slugs) that would be massive gains. If you do choose this route, keep in mind that clevelands are high lift engines and bringing the pistons to zero deck will require special attention to valve clearance. This will be even more necessary if you are using a radical profile or a roller cam. It's not the cheap way, but it's definitely the best way.
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Junior User
Joined: May 2002
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zero deck and open chambers?
Thanks all! Jdawg, I think I read a post that you were using that crane powermax hyd. roller cam in your engine. Is it running yet, and how do you like it? From what I have been reading, our engines like shorter duration and lots of lift.
As for me, I am sticking with a fairly cheap, moderate rebuild. Can't afford 500 HP, but 350-400 with stock heads ported and polished should be no problem. I guess I am just going to go with the badger flat tops and mill/deck to get me up to about 9.5:1.
Thanks again.
As for me, I am sticking with a fairly cheap, moderate rebuild. Can't afford 500 HP, but 350-400 with stock heads ported and polished should be no problem. I guess I am just going to go with the badger flat tops and mill/deck to get me up to about 9.5:1.
Thanks again.
Lead Driver
Joined: Nov 2000
Posts: 6,640
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From: Albuquerque
zero deck and open chambers?
The dished pistons probably don't add much "quench" effect but what they do is eliminate the cylinder from the combustion area. If you use flat top at 9 to 1 they will set well down in the cylinder and cause preignition problems.
