zero deck

[comstocb]

Is it safe to say that for optimum performance, one would want to have a zero deck height block and that the combustion chamber completely determones CR? My reading on here is leading me to believe that the best burn of A/F mixture is acheived when the entire contents are compressed into the chamber and there is no space left between the top of the compression stroke and the head. Thoughts?

Brian

[Mb125]

This is true but you have to have some clearence between the head and piston depending on connecting rod and RPM. With an efficient combustion chamber less timing lead is required such as BBC pro stock type heads with that chamber design you only need 16-22 degrees. Make compression adjustments by dishing the piston.

[flynbrian]

My engine is a true Zero Deck with KB Pistons in it...We took .044"-.046" off each side from the stock height to get true zero. My head gasket is the only thing between the top of the pistons and the 72cc "E" heads. I have reworked stock rods.
The gaskets are rather thin too...from ROL. One side of the engine required about .002" more than the other side...I guess it was lax factory tolerance. My car runs good on 93-94 octane...I will put Oct. booster in it in the hot weather for insurance. My engine seems to like alot of timing....But the distributor is funky...A unknown swapmeet unit with a new Pertronix unit in it....I need to replace it with a good one.

[OldGoat]

Zero decking will give you an engine that is less prone to detonation. Your quench area (squish) should be about .040, or if you subscribe to the "Groove" theory, about .060.

Somender-Singh.com http://somender-singh.com/

[comstocb]

OldGoat, Forgive my ignorance but I would imagine the squish area as being the thickness of the head gasket installed and torqued? What is the groove theory?

[Mb125]

These grooves or channels or passages after ignition direct the flame front to cause multipoint ignition during the combustion cycle resulting in the following distinct advantages over existing designs in practice. First, quicker and complete clean burn combustion; second, lower operating temperatures due to the higher flame velocities; third, enhanced torque and power through the entire range resulting in better fuel economy with lower Emissions; and fourth, smoother engine operation through the entire range enhancing engine life.

Is someone reinventing the wheel again

[OldGoat]

Constocb, the quench area is the area above the piston and head at TDC. If you did not zero deck the block, you would have the gasket thickness and the area from the deck to the top of the piston. On the average Poncho, that could be an extra .025+ inch. Add that to the head gasket thickness (.039-.060) and you could have .085 quench or more.

You want to have as much quench as you can get. Small quench=better burn, more efficient. To achieve this there are alot of steps to go through. You have to have most of your parts selected, pistons, cam, rods, ect., and assemble, meassure everything, and degree the cam to get proper clearances to know what to take off of the block/heads.

[flynbrian]

Thats true Goatman, I had to have every single piece beforehand and everything had to be assembled into every hole then checked side to side and end to end then the block set up on the machine and cut according to the findings. The piston to valve clearance had to be checked, the benefit was I could use the stock length pushrods instead of .100" over length with my Edelbrock heads. The Intake manifold had to be machined in order to fit right too....It sucks because I cant just bolt on any intake and go....The guy who machined my engine really knows his stuff. He even suprised me on stuff I didn't even think about. But in the end I own a screamer of a 406.

It's definately a big job, but, like you said, worth it in the end. :ax

[Mb125]

Should we all cut some grooves with a wiz wheel in our combustion chambers. Thay crazy person that wrote that article should go back to his 7-11 and just make sure the coffe is fresh

Originally Posted by Mb125

Should we all cut some grooves with a wiz wheel in our combustion chambers. Thay crazy person that wrote that article should go back to his 7-11 and just make sure the coffe is fresh

Or make sure someone's not taking a whiz in the coffee.

[INJUNTOM]

my 455's pistons sit .005 out of the block...

[INJUNTOM]

Originally Posted by flynbrian

Thats true Goatman, I had to have every single piece beforehand and everything had to be assembled into every hole then checked side to side and end to end then the block set up on the machine and cut according to the findings. The piston to valve clearance had to be checked, the benefit was I could use the stock length pushrods instead of .100" over length with my Edelbrock heads. The Intake manifold had to be machined in order to fit right too....It sucks because I cant just bolt on any intake and go....The guy who machined my engine really knows his stuff. He even suprised me on stuff I didn't even think about. But in the end I own a screamer of a 406.

if your engine machinist had milled the intake surface of the heads instead of the intake manifold, you would have been able to use any intake manifold.

if you ever have the heads off, you may want to do that to them

[flynbrian]

Good Idea, I never thought of that...I have a torker two Single plane intake because I have always had better performance out of single planes and it's the only one that easily clears the hood. I think even the Performer RPM two plane is too tall.
I had a Victor on my last car and it was awesome...But it had the hood clearance. I saw a new Victor for my Pontiac...The speedshop I grew up around has been trying to get me to buy one...Its looks like a foot tall just looking at it. Impressive but maybe I will get another hood in a few years so I can try it.

[OldGoat]

"You want to have as much quench as you can get. Small quench=better burn, more efficient."

Goatman, can you splain yourself. How is it that you want the largest quench, and yet small quench=better burn etc?

[INJUNTOM]

Originally Posted by flynbrian

Good Idea, I never thought of that...I have a torker two Single plane intake because I have always had better performance out of single planes and it's the only one that easily clears the hood. I think even the Performer RPM two plane is too tall.
I had a Victor on my last car and it was awesome...But it had the hood clearance. I saw a new Victor for my Pontiac...The speedshop I grew up around has been trying to get me to buy one...Its looks like a foot tall just looking at it. Impressive but maybe I will get another hood in a few years so I can try it.

Holley Street Dominator is fairly low for a single plane...it is supposed to even work with 2nd gen shakers, and still fit up well.

Originally Posted by OldGoat

"You want to have as much quench as you can get. Small quench=better burn, more efficient."

Goatman, can you splain yourself. How is it that you want the largest quench, and yet small quench=better burn etc?

I meant small quench. Got cornfused.

[OldGoat]

I new that.