Milling 452 heads

[m79ded]

I would like to find out how much can 452 heads be safely milled?
I need to cut them to achieve proper quench, but not sure how much is a safe limit, I am concerned about going too thin and cracking or damaging heads.

I have kb184 pistons which have a quench dome of .140============ The piston is .087 in the hole that leaves .053 above the deck then minus the .039 head gasket (Or any other recommendations on head gaskets) that will leave .014 above the deck. I would like to achieve about a .035 quench so that would mean with a open chamber head that has a recess of aprox .110 it would mean i would have to cut around .060

Any ideas would be helpful and would a combination of decking the block lets say .015 and using thinner gaskets do the trick???


Thanks

 

[Nacho-RT74]

use metallic headgaskets.

no prob on cut that ammount on heads though. just take in mind the heads intake face won't align perfect with intake, so will need to be cut too.

as far I recall, for each 0.010 of head surface intake head face must be cut 0.012 too... or something like that. Not really important if is just a shave over the head surface ( or head gasket thickness change ), but bigger cuts will require to note that

 

[Cranky]

Yup, use the factory style steel shim gaskets. They come in right around .020 thick and go from there. Most shops don't like to mill much from heads and usually take enough to clean them up....plus it will change how the intake sits on them too but I've taken .040 to .050 before without any problems. Do a mock up on the intake before milling it or the intake side of the head.

 

[Nacho-RT74]

 

[Badvert65]

You should be very careful milling the heads. One thing you haven't mentioned is valve clearance. Things will get tight with high top pistons, especially if you have oversize valves. I have always shot for zero deck and flat top pistons.

 

[Supershafts]

Then you see your machinist and fly cut the pistons for the needed room.

I would Definitely make the other alteration to the intake side of the head and not the intake manifold.

 

[Garys1969RR]

Use the steel shim head gasket, then you will only need to mill the heads and/or block a total of around .040". I once built a 440 using the KB quench dome pistons, and had to cut the heads about .030 to get to .035" dome to head clearance. It worked great!

 

[Cranky]

As for that chart, I always do a mockup before cutting anything. In a perfect world, the chart is right......but.....

 

[m79ded]

Use the steel shim head gasket, then you will only need to mill the heads and/or block a total of around .040". I once built a 440 using the KB quench dome pistons, and had to cut the heads about .030 to get to .035" dome to head clearance. It worked great!

Thanks for the input. I'm wondering since you did a 440 quench motor did it really make a significant difference? my 440 is almost all street with manifolds and TQ carb and Iron intake

 

[Garys1969RR]

Thanks for the input. I'm wondering since you did a 440 quench motor did it really make a significant difference? my 440 is almost all street with manifolds and TQ carb and Iron intake

Yes, I felt it did help. The engine had a factory iron intake, stock cam, and headers. Its difficult to tell how much difference the quench dome made, because I haven't had a non quench motor to compare it to. It would sputter and miss on regular fuel, but premium worked great!

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I now have a 451 with 915 heads and 13 to 1 C/R. .035" quench with dome pistons. It runs really good with alot of low end torque, plus good top end power. And I have to use a blend of race fuel, premium, and E 85 for it to run well. I have never been able to get a really strong running big block unless I run alot of C/R. Others have with good cyl head airflow, but not me. So I go with alot of C/R and use Hi Octane fuel. I am at 5600 feet, and that makes a big difference as to what you can get away with, as far as hi C/R goes.

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I am now using a blend of 3 gal 91 octane premium, 2 gal of 100 octane Sunoco, and 1 gal of 105 octane E 85. Gets me about 96 or 97 octane, I believe. The engine runs great on this ratio, and it averages out to about $5 a gallon.