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OK. How many cc's will i lose milling my 915 heads .050.
Here is a chart that gives you an estimate. Its pretty close. I milled mine .030 and lost about 7cc according to the chart it will be about 10.4 cc with open chamber heads
To use the chart divide the amount to be milled by the number in the chart. Or if you have a particular amount of ccs you want to reduce multiply the amount you want to remove by the number in the chart for example say you have 70cc and you want 65 do 5x.0048=.024 that's how much you need to remove. Or close to it. I'm sure there is a better way out there but that's how is did mine. I wanted to remove 6ccs which was .288 so I just did .030 and it came out to around 7ccs
.040 should be enough to make the average 915 about 63-64cc
And .040 probably will not require the intake to be milled. Although it's possible.
At .040 I'd mill the intake side .038 to keep everything in the right relationship.
Thanks everyone. I'm trying to come in at 60 cc so I will go .050 and that should get me close. Yes I will shave the intake side .0475. Heads do have SS valves that are flat on the bottom so that should help a little. Thanks again.
Mine are 59.8
you should remove 10.3ccs with a .050 in. cut if you dont touch the chambers, assuming a 4 in. bore in the chamber.
What the quote on that mill job? I got a set that needs a clean up and may as well get it to where I want it, as well as the intake.
It cost more the more u have them milled. Simply because they have to make more passes to take more off. The intake side is another charge. Same goes with it. Kim
Some shops want 200.00 to mill an intake.
I had my SpeedMaster heads milled .031 and the intake milled I’m guessing .050-.060. It was outta wack b4 I had the heads milled. I never asked him. I traded parts to him so I only know what my parts were worth. Notice how far the bolts are outta wack. Kim View attachment 1715767036 View attachment 1715767037 View attachment 1715767038 View attachment 1715767039 View attachment 1715767042
My porter charged me $175.00 Canadian to mill mine .005. Kim
The more passes..the more money. 80 bucks for a your basic .003 off a pair of heads. One pass each.
My machine shop can cut up to .020 a pass, so figure it out from there. Then I cut the intake side to keep everything in the right relationship. Evidently there is a wide spread on milling costs per machine shop. I never tried to cheap out on performance builds. You have to do what it takes at your level.
If this is a fresh build, why not leave the heads and intake alone and just use other pistons. Just spit balling
Heads always "warp" a bit so while you are milling them flat again, I just would go the whole .020. Then mill the intake side .019 to keep the head surfaces in the right relationship to each other. You only have to do this once as they don't "move" much after all those years and thermal cycles. I never mill an intake manifold, unless it is out of spec. I still have High Performance blocks from 273's, a 318 Magnum, and 340's that will clean up with a hone, so I will reuse the pistons in those blocks. Those engines are not compression challenged, so I do not feel the need to add the extra expense of boring and pistons. I assume the OP is keeping his short block as is or is just freshening up the motor.
I don't see a problem, that's not far out.. Sure they are not in the exact centre of the hole but they look like they have been easily started and port matching will need to be done. But if they are all like that the inlet will still bolt down properly. If only 3/4 of the thread was visible through the hole, now that would be a problem and the intake would need to be machined.
The bolt angle is way off also. It’s a .040 over 340. TRW pistons. Speedmaster heads. Howard’s cam. Balance rotating assambly. Kim View attachment 1715774110
It took .030 to make the intake fit. The angle was off also. Kim