Why plane your intakes w/ milled heads???

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TXDart said:
Standard formula is .0048 milled from head=1cc, and for every .0048 off the head,you need to remove .0095 from the intake side

Thanks 70aarcuda,I did not think of cutting the intake face of the head...My AirGap Manifold will remain stock now on my 318 build with J heads.
Martin
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The correct amount to mill the heads is:

For every .010" you mill the block side of the head you need to mill .0095" from the intake side of the head. I usually mill any SBM heads .020 on the block side and .019" on the intake side. Cleans everything up nice and I can run any intake I want without machining it. The end gaskets will still work with up to .040 milled heads and an untouched intake manifold. Magneflux any heads before you put any money in them though.
 
Somebody else saw that,too!
Thanks brother!
Now taking that further...
How many machinists are actually going to be "that" accurate!
We're talking half a thousandth! Which pretty much says equal amount on both surfaces...Unless we're talking big cuts...
As someone mentioned...Planning, and knowing your starting reference...
Engine already together, or purchased already built heads, one might say "my manifold doesn't fit, whaaaa", and machine manifold.
Planning a build you might say " I'm going to take .019" off manifold surface of head because I'm taking .020" off my heads to begin with"...
My useless opinion, I'd rather be able to try a different intake without having to machine it, and it only fitting my engine...
 
Mill the heads intake face.

If you mill the intake....u end up with a ''one off'' intke that will only fit that combo of parts.

There is no angle change either, so the guy saying that better rethink that bs real quick..

Most street performance intakes with the exception of the victor stuff, you CAN also mill the front and rear end rails..

I have milled J heads down from 72cc to 59cc's...and then milled the necessitated amount from the heads intake face side and have NEVER had any sealing issue with the intake or valve cover cause THE ANGLE DOES NOT CHANGE!!

Angle milling the heads, now thats a diff story and YOU WILL have to then do some corrective milling between BOTH intake manifold and intake face of heads in order to not create sealing issues....but then you also have to make wedge type washers to keep the bolts loaded against the manifold correctly.
 
mopar373 said:
rather than mill a head that far, that you would have not enough threads left on the intake side is foolish. you would do better to get a better piston for the job. do it right or don't do it! Al
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Really, you'll make better power and cleaner burn losing chamber and then learning where to add some shape than stuffing a piston into the chamber and hurting the flame. . . .

I guess doing it right is harder than taking the easy way out to gain compression. . .
 
I recently pieced together a mild 318 on a budget.
I had 65thou milled off the heads and then dummied it up to figure out how much to shave off the intake.
Don't worry,it was just a Performer I scored free so I didn't mind ruining it for future use.
Anyway,I had already done some light,cleanup porting including raising the port roofs.
The std intake pretty well port matched to the raised port milled heads but with a big valley gap.
I reckoned with a struggle I could get the manifold to bolt down and I was right.
The big valley gap I used the cork gasket whereas normally I'd delete the cork and just use a bead of sealant.
I did also have to file the edge of the MP alloy rocker covers to clear the manifold ports but on the whole it all fit together tight but very nice.
 
1wild&crazyguy said:
i would think milling would shorten the end gaps, and not milling enough would have the covers hitting the intake. jmo
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Milling the heads will not change the physical width of the valley as you haven't touched the block's deck surface, so the end gaps will stay the same. Milling the heads shortens them, bringing the covers into contact with the intake.

Of course, port and bolt alignment will be off.
 
On my current motor, I had the heads intake surface milled so I can swap intakes at will....because I have a hard time leaving well enough alone:D.
 
MoparAnglia said:
Milling the heads will not change the physical width of the valley as you haven't touched the block's deck surface, so the end gaps will stay the same. Milling the heads shortens them, bringing the covers into contact with the intake.

Of course, port and bolt alignment will be off.
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U missed what i said....maybe i wasnt clear.....and i didnt say ''width''

and yes it does change the end seal gap when you mill, ill post a pic of my ld340 manifold that 'I' milled...along with the heads and theres now barely an 1/8 of an inch gap as opposed to the 1/4 + it before.

when the intak is not milled enough...it sits high and the cover will hit.


when u mill the head or intake...it lowers the port window placement toward the block of that head and or intake.
 
1wild&crazyguy said:
U missed what i said....maybe i wasnt clear.....and i didnt say ''width''

and yes it does change the end seal gap when you mill, ill post a pic of my ld340 manifold that 'I' milled...along with the heads and theres now barely an 1/8 of an inch gap as opposed to the 1/4 + it before.

when the intak is not milled enough...it sits high and the cover will hit.


when u mill the head or intake...it lowers the port window placement toward the block of that head and or intake.
Click to expand...

No, you were clear enough but nqkjw was talking about milling heads but not the intake. However milling the heads effectively narrows the valley width as the intake isn't perpendicular to the deck. So he was right... Yes the port window on the head moves down with milling hence my comment about the port and bolt alignment.
 
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