milled 915

Posted By: moretork03

milled 915 - 07/08/11 07:48 PM

what is the least cc's you can get to by milling the 915 head

Posted By: R/T1968R/T

Re: milled 915 - 07/08/11 09:26 PM

I have a set thats milled .060. I cant remember the ccs, but it has to be in the low 70s at least. Im sure you can take it down more, but milling the intake face and lining everything up begins to get tricky.

Posted By: ademon

Re: milled 915 - 07/09/11 06:12 AM

Quote:

I have a set thats milled .060. I cant remember the ccs, but it has to be in the low 70s at least. Im sure you can take it down more, but milling the intake face and lining everything up begins to get tricky.

and expensive, i have a set that are just milled to clean they came in at 80cc, with valves that are not concaved i bet they would be right around 78cc

Posted By: oldman

Re: milled 915 - 07/10/11 05:30 AM

It will also depends on what pistons you have ,you can check what you have now with clay put your clay on top of piston and bolt on head turn over and measure also you can adjust a little with different head gasket thickness, but as stated you'll have to mill the intake ,I have noticed that even some heads, that have just been surfaced makes it hard to bolt up some of the new aluminum intakes.

Posted By: DaytonaTurbo

Re: milled 915 - 07/10/11 06:12 AM

I've heard of some guys cutting .100-.120 off 452's to really cut their chambers down to size for use on smogger low-cr big blocks. The problems are like said, getting the intake and valley tray to line up, valvetrain geometry becomes an issue because you really need shorter pushrods by that point and lastly by that much milling the heads become very crack prone.

Posted By: MLR426

Re: milled 915 - 07/11/11 02:57 AM

Quote:

I've heard of some guys cutting .100-.120 off 452's to really cut their chambers down to size for use on smogger low-cr big blocks. The problems are like said, getting the intake and valley tray to line up, valvetrain geometry becomes an issue because you really need shorter pushrods by that point and lastly by that much milling the heads become very crack prone.

I'ved milled some 100 to 125 thous. You will have to cut the intake runner side of the head to straighten up the intake alignment and cut the intake runner part of the gasket off the valley pan and use paper gaskets and silacone to seal the valley pan and intake,thats not an issue. Mostly used this way to jump compression on any combo. Haven't seen any cracks on heads milled this way although special care should be taken when torqueing heads down, at least a 4 step method until you get to the final torque so their is no extra stress on the castings.

logan426

Posted By: moretork03

Re: milled 915 - 07/11/11 04:21 AM

i wonder if there is a way to tell how much my heads were cut? trying to determine how much compression was gained, its matched with a TM7 intake

Posted By: DaytonaTurbo

Re: milled 915 - 07/11/11 04:40 AM

Quote:

i wonder if there is a way to tell how much my heads were cut? trying to determine how much compression was gained, its matched with a TM7 intake

If you CC the heads there's a formula to figure out how much they've been milled. I think the head thickness can also be measured but I don't know what the spec is.

Posted By: JohnRR

Re: milled 915 - 07/11/11 04:41 AM

Quote:

I've heard of some guys cutting .100-.120 off 452's to really cut their chambers down to size for use on smogger low-cr big blocks. The problems are like said, getting the intake and valley tray to line up, valvetrain geometry becomes an issue because you really need shorter pushrods by that point and lastly by that much milling the heads become very crack prone.

You almost have that correct, valvetrain geometry is not affected by milling the deck surface of the heads. One can mill the deck surface all they want , the rocker to valve geometry NEVER changes, the only thing that changes is pushrod length.

If this were something that had rocker attachment like a smallblock chevy then yes you will change the valvetrain geometry if you don't get a shorter pushrod.

Posted By: JohnRR

Re: milled 915 - 07/11/11 04:43 AM

Quote:

i wonder if there is a way to tell how much my heads were cut? trying to determine how much compression was gained, its matched with a TM7 intake

Measure the head bolt boss under the exhaust manifold mounting surfacing , factory they seem to come in right about 1.000