350 pistons choice ( street )
March 3rd, 2021, 02:27 PM
#1
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Join Date: Jul 2008
Location: st-jean baptiste quebec,canada
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350 pistons choice ( street )
Dint rebuild an Olds 350 for a while, and my old catalogs dont show the reality ......
the car is a 1970 Rallye 350 , 4speed muncie ,with 3:42 posi rear end .....
the car is pristine but the engine is really tired ( 50 years lots of mileage and been rebuild with .030 over pistons about 22 years ago .....
I want to achieve a final compression ratio of around 9.5 to 1 ....... customer does not want to run on 94 gas
I used to fiind quite some pistons choices for 455 s ,,,,but for a 350 pretty rare !
W-31 pistons are flat top but achieve 10,5 CR with the code 6 (64cc) heads , too high
the regular 70 pistons yield ( as per GM ) 10.25 CR
Not many choices either in cast or forged .....
Maybe ill go for deep dish ( 8,5 CR ) and shave the block & heads to attain 9,5 CR
I know ill have to go for adjustable valves ( studs, plates & rockers )
unless someone knows about new pistons that gives better CR for our intentions
any inputs on this ?
thanks
Dan
the car is a 1970 Rallye 350 , 4speed muncie ,with 3:42 posi rear end .....
the car is pristine but the engine is really tired ( 50 years lots of mileage and been rebuild with .030 over pistons about 22 years ago .....
I want to achieve a final compression ratio of around 9.5 to 1 ....... customer does not want to run on 94 gas
I used to fiind quite some pistons choices for 455 s ,,,,but for a 350 pretty rare !
W-31 pistons are flat top but achieve 10,5 CR with the code 6 (64cc) heads , too high
the regular 70 pistons yield ( as per GM ) 10.25 CR
Not many choices either in cast or forged .....
Maybe ill go for deep dish ( 8,5 CR ) and shave the block & heads to attain 9,5 CR
I know ill have to go for adjustable valves ( studs, plates & rockers )
unless someone knows about new pistons that gives better CR for our intentions
any inputs on this ?
thanks
Dan
March 3rd, 2021, 04:15 PM
#3
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Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 9,004
The Mahle 10cc dish forged pistons with 1mm ring packs Cutlassefi brought to the market will give you exactly what you want. They are available up to a 4.155" bore I believe, so whatever oversize needed will be available.
March 3rd, 2021, 04:18 PM
#4
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Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 14,121
Agreed, 64cc is the NHRA minimum spec and not the actual volume. In several polls, most folks reported 66-70cc, with the majority being on the upper end.
As for pistons, there are several options - check with cutlassefi as said above.
As for pistons, there are several options - check with cutlassefi as said above.
March 4th, 2021, 02:17 PM
#6
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Join Date: Jul 2008
Location: st-jean baptiste quebec,canada
Posts: 10
looks like those Mahle NO 197815300 are the ones to go for...... 9,5 CR , forged .040 over ( engine at .030 over already )
thanks for the reference !
combined with the Comp cam : XE 262 H or XE268H ,,,,,,should give great results !
thanks for the reference !
combined with the Comp cam : XE 262 H or XE268H ,,,,,,should give great results !
March 4th, 2021, 05:00 PM
#7
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Join Date: Nov 2008
Location: Central Fl
Posts: 7,888
I can get those at a real competitive price too. Let me know. Hope this helps.
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