440 with 915 heads? Going for quench

Posted By: VoodooCLD

440 with 915 heads? Going for quench - 03/29/12 10:10 PM

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

Posted By: jjl

Re: 440 with 915 heads? Going for quench - 03/29/12 11:49 PM

The deck probably won't be square,and easy way to find piston to deck height is to install 1 piston and rod assembly in each corner and see what needs to be milled.So you gain two things zero deck and square.Chamber size will vary,the last set I did with 2.14 1.81 valves and milled was 77.cc.

Posted By: VoodooCLD

Re: 440 with 915 heads? Going for quench - 03/30/12 12:17 AM

Ok that makes sense. Do you think i can get away running that high compression with iron heads on pump gas?

Posted By: RUNCHARGER

Re: 440 with 915 heads? Going for quench - 03/30/12 01:34 AM

I vote to mock it up. If indeed those pistons will sit .020 to .030 in the hole there's no need to spend money decking the block and dealing with all the intake fitment issues that may cause. I ran some 915's on a 440 with Ross pistons at -.030 and it ran like a bear on pump gas with a .528 mechanical cam.

Sheldon

Posted By: Cab_Burge

Re: 440 with 915 heads? Going for quench - 03/30/12 01:45 AM

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

Posted By: Dr-Dave2

Re: 440 with 915 heads? Going for quench - 03/30/12 02:05 AM

L2355F is Flat top 4 valve relief 6 pac replacement piston

Posted By: BSB67

Re: 440 with 915 heads? Going for quench - 03/30/12 02:56 AM

You'll probably be above 10.5 and will likely not run on pump gas unless you have a very large cam, IMO. My 10.3 CR 440 with 915 was not even close with pump gas, but the cam was fairly small.

Posted By: 1968RR

Re: 440 with 915 heads? Going for quench - 03/30/12 03:07 AM

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?

Posted By: R/T1968R/T

Re: 440 with 915 heads? Going for quench - 03/30/12 02:47 PM

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

Posted By: JohnRR

Re: 440 with 915 heads? Going for quench - 03/30/12 02:56 PM

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.

Posted By: JohnRR

Re: 440 with 915 heads? Going for quench - 03/30/12 03:01 PM

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 ...

Posted By: DARTH V8Я

Re: 440 with 915 heads? Going for quench - 03/30/12 03:07 PM

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..

Posted By: 1968RR

Re: 440 with 915 heads? Going for quench - 03/30/12 03:58 PM

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).

Posted By: VoodooCLD

Re: 440 with 915 heads? Going for quench - 03/31/12 05:32 PM

I bought a bunch of parts off a guy, and got those brand new pistons with it. I have a 69 block thats .030 over with some surface rust on the cylinders. I also have a 74 block thats standard. I think i'm just gonna drop them both off, and have them try to use the 69 block first (its in worse shape with quite a bit of rust) and if i have to, have them use the 74 block. I'm pretty sure the 915 heads have the smaller exhaust valve. Although its weird becuase i have the old valves (they are the bigger valve, but don't sit as flush as the proper intake valve) and i also have brand new 2.14 intake and 1.81 exhaust. I would have to have the heads worked to get the new valves to fit. I have a set of 906's that are pretty ready to run as well as some 452 with slighty burnt exhaust valves.

Think i'll probably just build the short block, run the 906 heads. Then sell the 915's, and pick up some aluminum heads down the road.