BB head milling limits?

[dtpolk]

Can big block heads be milled .050" safely, and if so, how much to mill the intake? Thanks!

[passing you]

yes and .0123 from the intake side for every .010 off the chamber side.
Also, mill .0042 per 1cc

[63Fury]

Originally Posted by passing you

yes and .0123 from the intake side for every .010 off the chamber side.
Also, mill .0042 per 1cc

I seen a set of 906 milled 0.100 but it was ugly, the guy ended up having to mill the top of the block so the valley pan would sit low enough.

The 1cc = 0.0042 is for open chamber heads, I think closed chamber heads ar like 0.0070 for 1cc

[passing you]

Originally Posted by 63Fury

I seen a set of 906 milled 0.100 but it was ugly, the guy ended up having to mill the top of the block so the valley pan would sit low enough.

The 1cc = 0.0042 is for open chamber heads, I think closed chamber heads ar like 0.0070 for 1cc

For closed chamber heads it's .0062 for every cc

If the valley pan hangs in bottom of the ports a lil grind it like a gasket match.

[dave5711]

keep in mind, that even at .050 off the heads, your stock pushrods are unlikely to work.

You'll need to make a set up yourself. That's the cheapest option anyway. Buy a set of stock aftermarket pushrods. The ball ends acan usually be removed, so pull on end off, and shorten the pushrod, then put it back in. Stockers are solid, so you can't do it with them.

Adjustable valve gear is an expensive alternative, and will likely not compensate enough, leaving you with expensive valve gear, and a set of shorter pushrods.

[passing you]

If they came stock with .019 steel head gasket then milling .050 will be like milling .030 with a .039 thick felpro keep in mind...

[dtpolk]

??? Why on earth would I mill a head, then use a thicker gasket? If the stock pushrods are solid, can they be machined shorter?

[Paul Precht]

You can use rocker arm shims. If you cut the heads .060" and are using the same type of gasket use about a .030" shim. With a wire gauge you should have around .030"to .040" lifter preload between the plunger and the clip, Paul.

[DartGT66]

I have machined the stock pushrods shorter, it works. They are pretty hard, had to grind them.

[passing you]

Originally Posted by dtpolk

??? Why on earth would I mill a head, then use a thicker gasket? If the stock pushrods are solid, can they be machined shorter?

you never said what head gaskets you were gonna use and the .039 felpros are the common replacements be it perma-torque or race....

'If needed' just buck up and buy the right length pushrods.

[bulldog426]

instead of spending all that money to get the heads milled, and the block decked, and all that, by time you spend all that money you can just buy a good set of aftermarket pistons and get the same compression, that's what i figured out when i built my bigblock, with all the money i would've spent milling, and decking, for around the same money actually less money buying high compression pistons were cheaper....

[Von]

Yes you can mill them .050, but keep in mind they will crack, maybe today, maybe tomorrow, but eventually they will.

I wouldnt use rocker shims under any circumstances either.

[bulldog426]

just get some aftermarket pistons to up the compression, that way you don't have to worry with cracking heads, different lenght pushrods, rockerarm shims, all that extra stuff, which in the long run can hurt the engine, such as heads cracking...

[passing you]

Originally Posted by Von

Yes you can mill them .050, but keep in mind they will crack, maybe today, maybe tomorrow, but eventually they will.

I wouldnt use rocker shims under any circumstances either.

anything has the possibility of cracking given the right environment, I don't think he'll have problem.jmo

but shims?

explain.

[Von]

Ask the guys who put shims under their shafts and broke their pedestals off. I doubt that they will run shims again.

As far as head milling, my comments came from a very well respected Mopar head porter. Soo, my mind is made up.

[DartGT66]

I have used shims too, without any problems. If doing things on budget or according to your own will, you sometimes have to go through under the fence. Milling is usually not the optimal way to increase CR, and after you have fixed everything involved it may actually even cost more than getting hte correct pistons. But sometimes you just have to do those things, and very often they even work.

[passing you]

Originally Posted by Von

Ask the guys who put shims under their shafts and broke their pedestals off. I doubt that they will run shims again.

As far as head milling, my comments came from a very well respected Mopar head porter. Soo, my mind is made up.

I'd be looking at the pedestal.........cause it was probably cracked to begin with.

as for respected head porters, most say different stuff then 1 another and a lot are scared to hit water.......oh yeah and mostly do chevy crap and we all know chevys are thin, just look, even with all there head bolt glory when thrown on the mill there are always high spots at the bolt holes.

consider the source, your respected head porter.

[dtpolk]

Original poster. Well, I'm not opposed to using different pistons, but I'm now thinking about keeping the open chamber heads that were on the engine (they are in very good shape). But after checking a few websites I can't seem to find a piston that will give good quench with the open chambers. Also, I'm...well, I'm poor, and can't really afford new pistons. Can anyone suggest a piston (I've heard about running .020" 440 pistons) and does this forum have a 'for sale' section?

[passing you]

what are your concerns that drive this quest for quench?

[passing you]

If your trying just to raise the compression some then don't worry quench distance.
How far in the hole are the pistons now?

If this is a rebuild then just get quench dome pistons from KB and prepare to mill the quench pads after the heads are cc'd, cc matched and chamber depth checked then figure head gasket thickness into the mix and go from there depending upon how deep the chambers are on the shallow side.

I know... were all broke but a silk purse out of a sows ear?

[Paul Precht]

Quench is a marketing term and buzz word that Keith Black used to sell thousands of pistons. A lot of stereo/hi fi people are obsessed with Monster Cable which has been proven in blind tests to be worth nothing. Quench may be worth a little but there are so many things that people overlook that are more important, Paul.

[bulldog426]

http://store.summitracing.com/partde...D&autoview=sku try them pistons they will give you plenty of compression