Re: 440 with 915 heads? Going for quench
[Re: VoodooCLD]
#1205935
03/29/12 09:45 PM
03/29/12 09:45 PM
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Joined: Aug 2003
Posts: 43,257 Bend,OR USA
Cab_Burge
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I Win
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Posts: 43,257
Bend,OR USA
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What is that piston, flat top with no valve reliefs, six pak piston with four valve reliefs or the high compression piston with the small dome? If they are the small dome high compression pistons be very careful on how much compression the motor will have with the iron heads I have built a lot of stock stroke 440 motors with iron heads, both open and close chamber heads, 9.6 to 1 is the most I'll use on the compression ratio for a pump gas motor BTW, 500 HP and 540 + ft. lbs torque is not hard to make with a stock stroke, 9.5 to 1 comp. ratio iron headed 440
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 440 with 915 heads? Going for quench
[Re: BSB67]
#1205938
03/29/12 11:07 PM
03/29/12 11:07 PM
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Joined: Nov 2005
Posts: 1,943 San Angelo, Texas, U.S.A.
1968RR
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San Angelo, Texas, U.S.A.
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In my opinion, the whole pump-gas question depends on the cam duration. I run a 440 with Indy SRs (72 cc chambers) and the Keith Black forged flat tops (two valve reliefs) on pump gas with no problem. Of course, I also run Comp's XE295HL cam, and that helps. Are the chamber sizes of the two versions of the 915s different? If so, which version do you have?
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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Re: 440 with 915 heads? Going for quench
[Re: VoodooCLD]
#1205939
03/30/12 10:47 AM
03/30/12 10:47 AM
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Joined: Oct 2007
Posts: 736 New York
R/T1968R/T
super stock
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super stock
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New York
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I have run that exact combo many times. I found those pistons to be between .022-.025 in the hole. with a .020 steel shim gasket your looking at about 10.3 Static compression. The important thing is your Dynamic compression. If you can keep it low enough (8.0) with quench it should be ok. camshaft selection is important. Try this calculator http://www.projectpontiac.com/ppsite15/compression-ratio-calculator
Last edited by R/T1968R/T; 03/30/12 10:50 AM.
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Re: 440 with 915 heads? Going for quench
[Re: 1968RR]
#1205940
03/30/12 10:56 AM
03/30/12 10:56 AM
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Joined: Jan 2003
Posts: 75,080 U.S.S.A.
JohnRR
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Quote:
In my opinion, the whole pump-gas question depends on the cam duration. I run a 440 with Indy SRs (72 cc chambers) and the Keith Black forged flat tops (two valve reliefs) on pump gas with no problem. Of course, I also run Comp's XE295HL cam, and that helps. Are the chamber sizes of the two versions of the 915s different? If so, which version do you have?
ppppssssstttt , Indy SR's are ALUMINIUM , of course you can run it on pump gas .
915's all have the same chamber size.
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Re: 440 with 915 heads? Going for quench
[Re: VoodooCLD]
#1205941
03/30/12 11:01 AM
03/30/12 11:01 AM
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Joined: Jan 2003
Posts: 75,080 U.S.S.A.
JohnRR
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I Win
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Quote:
So i'm about to build a 440. I have a 69 block with steel crank, and a brand new set of .060 over trw 2355 pistons. I've read that the pistons are about .020 in the hole if the deck isn't cut. Everyone says to deck the block to get a zero deck piston, but whats the point? Why wouldn't i just get a steel .020 head gasket (compressed thickness) and get my optimum .040 quench that way while running 915 head? are these set ups basically the same? any pros, cons?
If i did run this set up, do you think i'd be able to run on pump gas? They are iron heads, and i believe the pistons would give it a compression ratio in the tens with the 915 heads.
any help/experience would be great
Ok , now that I have that out of the way ....
What is the chamber CC of the heads? You need to know that. You don't need to zero deck the pistons, but it would be a very good idea to at least have the block squared, cut the least amount to accomplish that.
Does the block need to go .060 ? The bigger the bore the higher the compression is going to be.
Once you have the specs and figure out the compression you can contact someone like board member fast68plymouth or Dan at Performance Only to spec you a cam for your combo that will help you build a pump gas engine with what you have ... assuming it's not 11.0 ...
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Re: 440 with 915 heads? Going for quench
[Re: JohnRR]
#1205942
03/30/12 11:07 AM
03/30/12 11:07 AM
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Joined: Nov 2011
Posts: 2,154 Its a TRAP!
DARTH V8Я
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Oh No!! I just had a moron attack!
Joined: Nov 2011
Posts: 2,154
Its a TRAP!
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And for chits and giggles, cc more then one chamber. You'll be like wtf is going on here So open up the other chambers to match the largest one. But yah at the very least square the block, however much that takes off. Then after cc'ing the heads, you can choose gaskets, etc..
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Re: 440 with 915 heads? Going for quench
[Re: JohnRR]
#1205943
03/30/12 11:58 AM
03/30/12 11:58 AM
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Joined: Nov 2005
Posts: 1,943 San Angelo, Texas, U.S.A.
1968RR
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top fuel
Joined: Nov 2005
Posts: 1,943
San Angelo, Texas, U.S.A.
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Quote:
Quote:
In my opinion, the whole pump-gas question depends on the cam duration. I run a 440 with Indy SRs (72 cc chambers) and the Keith Black forged flat tops (two valve reliefs) on pump gas with no problem. Of course, I also run Comp's XE295HL cam, and that helps. Are the chamber sizes of the two versions of the 915s different? If so, which version do you have?
ppppssssstttt , Indy SR's are ALUMINIUM , of course you can run it on pump gas .
915's all have the same chamber size.
Agreed, but I you would think that the difference in chamber sizes between the 915s and SRs (about 6 or 7 cc) should more than compensate for any differences in thermal expansion. And even though most SRs are aluminum (including mine), Indy did offer iron SR sets (at least for a while).
"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson
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