Profile Picture

High dome pistons

Posted By Jack Groat 6 Years Ago
You don't have permission to rate!
Author
Message
Jack Groat
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)

Group: Forum Members
Last Active: 2 Months Ago
Posts: 137, Visits: 1.4K
I am looking for pistons with rings (.03 or .04 over) for a 292 rebuild.  I would like about 10:1 compression when finished.  I want to run available premium pump gas.  All the ones I have found so far are flat tops.  I would like to find some high domes to get to my chosen compression ratio.  I plan on buying Mummert aluminum heads.  Any suggestions where I can find some??
NoShortcuts
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)Supercharged (3.0K reputation)

Group: Forum Members
Last Active: Last Year
Posts: 1.4K, Visits: 179.6K
Jack.  John Mummert is offering a forged piston with a 10cc dome.  Click the link below for a chart John has on his web site that indicates the static compression ratio that will be yielded with various bore and stroke combinations used with different cylinder heads.

http://www.ford-y-block.com/forgpiststk.htm

Hope this helps!  Smile 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York
charliemccraney
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)Supercharged (9.7K reputation)

Group: Moderators
Last Active: Yesterday
Posts: 6.0K, Visits: 379.1K
Mummert had domed pistons at one time.  If he doesn't then they will probably have to be custom ordered.


Lawrenceville, GA
Ted
Posted 6 Years Ago
View Quick Profile
Co-Administrator

Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)

Group: Administrators
Last Active: 2 days ago
Posts: 7.2K, Visits: 202.6K
Keep in mind that the Mummert aluminum heads have smaller combustion chambers than the oem iron heads.  Assuming the combustion chambers of the aluminum heads are at their advertised 60cc values, they are roughly 9 cc smaller than the smallest of the iron heads.  With a 10cc dome, the compression ratio with aluminum heads becomes very unfriendly with pump gasoline.  Here’s a compression ratio workup for a +040 over 292 with flat tops and aluminum heads.


http://forums.y-blocksforever.com/uploads/images/6f70f69e-c84b-494f-94c2-4b1b.jpg 

Lorena, Texas (South of Waco)


Jack Groat
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)Supercharged (416 reputation)

Group: Forum Members
Last Active: 2 Months Ago
Posts: 137, Visits: 1.4K
Great response guys..  I talked to Mummert and he said he did not have any of the domed pistons.  But it looks like I can get close to 10:1 with flat tops and aluminum heads.
miker
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)

Group: Forum Members
Last Active: 5 days ago
Posts: 1.7K, Visits: 171.7K
I’m just going to add a comment. I’m running a stroker motor, 3.811 bore, 3.510 stroke, 320 cid. Pistons .010 down. I pulled the ported cc’d 113 heads and installed a set of Mummert’s aluminum heads. This put my combo over 10.5, and detonation on street fuel was a problem. We did a cam change to lower the dynamic ratio a bit, and with proper timing all worked out ok.

But when we pulled the heads, the pistons had a consider area with clean aluminum. Now, I don’t really know what this means, but I know a lack of flame travel has to do with the quench area. Which is a mystery to me, I just can’t seem to get my head around it.

Hopefully, someone will explain it, and I know the stroker displacement affects the compression ratio. My point is you need to look at the combustion chamber volume and shape. It’s real easy to get into detonation problems from other than just static ratio.

Ted Eaton and John Mummert were very helpfull in arriving at the new cam specs, but in retrospect I should have probably cut and rebalanced the pistons.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ
Ted
Posted 6 Years Ago
View Quick Profile
Co-Administrator

Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)Co-Administrator (12.5K reputation)

Group: Administrators
Last Active: 2 days ago
Posts: 7.2K, Visits: 202.6K
miker (12/5/2018)
......But when we pulled the heads, the pistons had a consider area with clean aluminum. Now, I don’t really know what this means, but I know a lack of flame travel has to do with the quench area. Which is a mystery to me, I just can’t seem to get my head around it.  ......

The clean piston tops could be the result different things of which a combination of them could be at play.  Minimum quench will be one, too much piston to head clearance could be another, and fuel wash could be yet another.  If a result of being from minimal quench, then I’d not be worried about it.  Fuel wash in itself could be a result of just a rich fuel mixture, inadequate atomization of the fuel at the carb venturies, poor fuel distribution from the intake port, or a lot of camshaft overlap which is typically the result of a reduced lobe centerline and poor exhaust scavenging taking place.  Low rpms creates many of the aforementioned scenarios but a restricted exhaust system is also a player.


Lorena, Texas (South of Waco)


miker
Posted 6 Years Ago
View Quick Profile
Supercharged

Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)Supercharged (3.9K reputation)

Group: Forum Members
Last Active: 5 days ago
Posts: 1.7K, Visits: 171.7K
Thanks Ted. With the EFI, FPA headers, 2 1/2” exhaust, we were thinking minimum quench. The a/f ratios are good on the dyno and when driving. Low rpm doesn’t happen that much with me driving.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ


Reading This Topic


Site Meter