CLASS RACER FORUM - View Single Post - Hemi piston pop-up

HankN · 10-31-2019, 09:24 AM

In a 426 street Hemi for stock the pop-up on piston from deck is 0.536” and gasket is told to be 0.018” and dome cc should be max 88.3 cc.
As I got it this motors it is not allowed to adjust the pop-up if a thicker head gasket, as in a wedge.
I has use steel heads and use the MP steel gaskets before.
Reason I ask is I like to use aluminium heads now on this combo ( who is practically dead horse with steel heads in A/SA ) and use Cometic’s MLS gaskets.
This are sold at 0.027, so from 0.018” diff is 0.009”.
Is there news on this today, if so I let pop-up be another 0.009” when I deck my new MP block.
Keep posted.

I waited 5 years on this block now. Mopar has not sold them in years and to get here was not a easy one.
But at #297 LBS it’s heavy but with aluminium heads it will be ok in AA/SA and not that front heavy.
I had the topic’s up last summer on oil pan who I see many use 8Q but after calling NHRA they told me oil pans who is numbered is legal, so not the 8Q.
On use big bore cam tunnel I got to know it’ been legal for years in babbit bearings, but as I has contacted Pat C at NHRA he told me for several years it’s not Ok in stock eliminator.
If one read the rule book it’s not permitted.
So how is it ?
Has it ever been checked at a NHRA race ?

10-31-2019, 09:24 AM	#1
HankN Junior Member Join Date: Jul 2019 Posts: 18 Likes: 0 Liked 3 Times in 3 Posts	Hemi piston pop-up In a 426 street Hemi for stock the pop-up on piston from deck is 0.536” and gasket is told to be 0.018” and dome cc should be max 88.3 cc. As I got it this motors it is not allowed to adjust the pop-up if a thicker head gasket, as in a wedge. I has use steel heads and use the MP steel gaskets before. Reason I ask is I like to use aluminium heads now on this combo ( who is practically dead horse with steel heads in A/SA ) and use Cometic’s MLS gaskets. This are sold at 0.027, so from 0.018” diff is 0.009”. Is there news on this today, if so I let pop-up be another 0.009” when I deck my new MP block. Keep posted. I waited 5 years on this block now. Mopar has not sold them in years and to get here was not a easy one. But at #297 LBS it’s heavy but with aluminium heads it will be ok in AA/SA and not that front heavy. I had the topic’s up last summer on oil pan who I see many use 8Q but after calling NHRA they told me oil pans who is numbered is legal, so not the 8Q. On use big bore cam tunnel I got to know it’ been legal for years in babbit bearings, but as I has contacted Pat C at NHRA he told me for several years it’s not Ok in stock eliminator. If one read the rule book it’s not permitted. So how is it ? Has it ever been checked at a NHRA race ? Last edited by HankN; 10-31-2019 at 05:43 PM.