Bad Habit Bird

iTrader: (12)

I am going to be rebuilding the stock bottom end of an LT1 here soon and was curious about how much can be milled off of the stock heads and still have a good amount of piston to valve clearance when using an LT4 Hotcam?

Formula_LT1

iTrader: (2)

I'm running a larger cam than a hot cam and my heads have been milled .030

It also depends on the head gasket thickness also. Felpro gaskets are like .038 or something like that? Thats what I used, no problems so far.

Bad Habit Bird

iTrader: (12)

What kind of times are you getting with your car? This is the first LT1 I have had so I don't know what to expect from a mild heads/cam/stalled auto.

the_merv

iTrader: (88)

That's alot..30 thousanths, sure it's not .003... I got mine milled 6 thousanths(.006) and I'm running the Felpro 1074's. They are .039 thickness. I have smaller relief Pistons and the Hotcam, haven't had a problem. I am estimating mid 12's with my setup, and that is with Port-matched Heads, stock Stall.

Bad Habit Bird

iTrader: (12)

I milled my heads on my LS1 Formula .035 a few years ago and never had any problems.

Formula_LT1

iTrader: (2)

No .030

Formula_LT1

iTrader: (2)

I haven't been to the track this year. There all closed in my area this time of year. Its making more power than with my previous cam and I ran an 8.06 in the 1/8 on a 1.83 60ft.

moserman

iTrader: (7)

someone mark me if im wrong, but isnt the piston to valve clearance supposed to be .010?

FANTA-Z

iTrader: (16)

I had my heads milled around .030 running Felpro 1074s (.039 thick), and zero decked block with no issues. It was pretty high compression but still ran on 93 octane with no knock.

96capricemgr

iTrader: (1)

PTV clearance is more in valve timing than lift.
Also you would be better off to deck the block to get compression up because by doing that you improve quench.

To get the same compression increase from milling the heads as you could decking the block you will have to remove MUCH more material and would not be improving quench atall.

Now if by "rebuilding" you mean a rering/rebearing but no machining you can still get well up over 11:1 with a thin gasket and reasonable head milling. I am at about 11.5 with a .026 gasket and 53cc heads, the heads were milled .032 BUT the chambers have also been reworked so if your chambers are as cast you would not need to remove that much material from the head surface to make the chamber that small.
Going to want to run some DCR calculations too so you know how much static will actually work with the HOT cam.

Bad Habit Bird

iTrader: (12)

How much would you guess could be safely decked off of the block while keeping the stock pistons/rods and using the hotcam?

96capricemgr

iTrader: (1)

You would have too measure your shortblock but deck height is usually around .025.

If you get the deck height down too .010 and use a .029 b-body head gasket you could have about 11.6 and a decent .039 quench height, like I said though run some DCR calculations and make sure that is OK with the HOT cam. Guys routinely run more compression than this but usually on different cams.

Bad Habit Bird

iTrader: (12)

I have been trying to figure it out but I'm not sure if I have the correct information for getting the correct numbers. What all information do I need about the hotcam? Do you know of a good online calculator?

Thanks