Irocss85

iTrader: (1)

how much would miling my 853 heads .030 lower the CC volume of the chamber?

how much if milled .015?

also, how have you cleaned the deck of your block to use cometic gaskets? Im assuming you used something plastic to avoid gouging the alum. surface? any other gaskets out there that are good and .040"?

Ive heard some horror stories about the cometics, and am not sold on them because of that.

Long Beach

iTrader: (51)

If i remember right for every .07 you mill you will loose 1cc. So stock 853 heads are 67 or 66 chambers so if you mill .015 that will put you close to 65. But with those gaskets that should put you close to 62cc. That should give you close to 11:0 compression. Not 100% sure about this and im not an expert by any means the reason i know a little about it is i just had a set of 853 milled that i installed and i was asking the same questions that you are. Good Luck

Long Beach

iTrader: (51)

Also do those heads have the notch in them. If so you have to use composit graphite gaskets or they will leak. I ended up using gm 12498543 they were $40 and i havent had any problems. I milled my heads the same as you did but with stock gaskets though.

Irocss85

iTrader: (1)

aha, what notch? i wasnt aware of the diff. heads requiring the older style gaskets? what thickness was the GM gasket you used?

if I mill .030, will the intake still seal right? I know on the old schook SBC's at some point milling the heads you had to mill the intake to match the angle's. ET performance says they mill .030 typically off these heads.
thanks in advance
chris

Long Beach

iTrader: (51)

On your heads is there a notch on the flat side that you would mill? It looks like a little rectange block that is in the head just below the chamber. You can mill to .030 but be carefull how big of a cam you are planning to run because you might have to flycut the pistons. I cant remember the thickness off hand but it is somewhere in the .053 - .055 thickness. Some of the 853's had the notch and the later years did not. If you dont have it then use the mls gaskets they are a good gasket. But i have the graphite ones and the notch and dont have any problems.

transAm-98

iTrader: (1)

I believe you are only supposed to use the graphites for thos 853's. What I was told is that the old heads have to use the old gaskets, but the newer heads can use any gaskets.

Irocss85

iTrader: (1)

well I do have to fly cut anyways. now just trying to maximize SCR/DCR since I have to flycut and mill heads anyways. I'll look for the notch tomorrow, and ask ETP about the gaskets.

anyone know of other gaskets (maybe felpro?) that offer thinner then stock thickness?

Long Beach

iTrader: (51)

I also have a part number for some fel pro gakets #004923 compressed thickness of .041. I did not use these ones but this is the number that i got to match these heads with the notch. Maybe you can use these but if your heads dont have the notch you can use most mls gaskets. Good luck

Irocss85

iTrader: (1)

perfect. thanks