MIKELMOTORCYCLE3398

iTrader: (3)

I hAve some cnc ported 806's i got for bext to nothing dfor my budget build on my 98 TA. The flow charts from the heads are surprisingly good. 296cfm@.600. Anyway. Im running a GMPP ASA cam (please dont tell me to go bigger. Not gonna) and before I bolt on the heads i wanna mill them to bp up the compression a lil. Gonna be using stock gm gaskets btw. If milled .010 whats that give me??ect.. Looking for 10.5-11:1 if possible. Id like to mill them as much as possible before I have matching issues on the ls6 intake ect.. Please pm me with the answer if u can. I get lost on this site. Lol. Thank you

MIKELMOTORCYCLE3398

iTrader: (3)

Please pm me. Thanks
Also looking for a good used 3 bolt ASA cam

TeEnAgE pHeNoM

iTrader: (6)

If you milled the heads to 61cc that will give you 11:1 scr and around 8.32 dcr. I'm no expert on this so maybe someone could chime in a verify. You should be fine on piston to valve clearance, but again I'm no expert so I would definitely verify that and of course you should always check. If it was my car I would go 62 cc and a .040 gasket. Hope this helps.

bww3588

iTrader: (49)

What do the heads flow at low lift numbers?. You're never going to see 600 lift with that cam, so flow numbers at 600 are totally irrelevant.

MIKELMOTORCYCLE3398

iTrader: (3)

Thanks guys. And I'll have to look at the glow chart, it doesnt really matter to me what they flow really, I'm stuck with em, lol. they are comparable to the TMS cnc'd 243's flow rates. and I know they will out perform the crap stock 806's on there now. So how much do I mill them to get 11:1?? Remember I'm using stock head gaskets. If anyone has a graph showing mill comp ratios on stock 806 or 241 heads i would appreciate it Thanks for the input guys

TeEnAgE pHeNoM

iTrader: (6)

I'm not sure what heads the 805's are. If they are 66.67cc stock then you need to mill them .028-.030.

MIKELMOTORCYCLE3398

iTrader: (3)

Anyone else?

td1168

iTrader: (2)

I'm assuming you're running the stock flat top pistons with no valve reliefs. If so, with the stock GM head gaskets you need a combustion chamber volume of 60.5cc's. The guys over at TSP told me you decrease combustion chamber volume 1cc for every .006" you remove. I cc'ed my heads before milling them and after milling them. The 1cc for every .006" is right on. You need to remove 6 cc's from your heads which is .036" I'm not real familiar with the castings so you need to make sure it's safe to remove that much material and if you will have intake alignment problems. I think you'll be alright but you will have to probably go with different length pushrods. Also, you should cc them to get a baseline of where your combustion chamber volume is. The heads may have already been cut.

KCS

iTrader: (20)

Are the chambers CNC'd? In order to determine how much needs to be milled, you need to know where you're starting.

427zm

iTrader: (9)

This post is from way back, but still is a good tool. It gives you the CR by chamber size using a sock MLS gasket. It's in Pat G's sticky at the top of this section.

https://ls1tech.com/forums/advanced-...ume-vs-cr.html

MIKELMOTORCYCLE3398

iTrader: (3)

They are stock height and stock chamber cc's.

MIKELMOTORCYCLE3398

iTrader: (3)

Thanks for all the help fellas

MIKELMOTORCYCLE3398

iTrader: (3)

I think I'll go with .015 or .020 mill Gives me 10.5-10.7 comp ratio and enough clearance.

MIKELMOTORCYCLE3398

iTrader: (3)

.030 will give me 11:1. But i think thats too much and will have fitment issues

TeEnAgE pHeNoM

iTrader: (6)

If you're going to run a cam that size then you need to take advantage of compression. I would definitely go 11:1.

MIKELMOTORCYCLE3398

iTrader: (3)

Thats my plan. I should have any PTV clearance issues milling them .020 with this cam and everything else stock (pistons and head gasket) right?

TeEnAgE pHeNoM

iTrader: (6)

You shouldn't but it's always to check. You need 0.030 though.

427zm

iTrader: (9)

Also, might want to think about milling less of the heads and going with a thinner head gasket so you can add quench. This would help protect against detonation.

A.R. Shale Targa

iTrader: (2)

milled my 241s .030" with no intake fitment issues at all.....MLS gaskets

MIKELMOTORCYCLE3398

iTrader: (3)

Thanks everyone!!