THEBRAD

iTrader: (3)

i have a 2000 trans am. what is stock compression? i just bought 241 heads and im having them shaved .040". what will my new compression be and what is the cc on these new heads before and after the shaving? whats the cc on the stock 00 heads?

socmguy

iTrader: (18)

Your stock heads *are* 241 castings... stock CR is 10.1:1

THEBRAD

iTrader: (3)

i didnt think the 241 castings were on the 00 just 01-02

Lt1Porsche

iTrader: (6)

He bought a set of 241 castings. But wanted to know the specs on what he has versus the specs of a set of 241's shaved .040.

Beaflag VonRathburg

iTrader: (176)

.040 / .007 = 5.7142857142857142857142857142857cc.

66.67cc - 5.7142857142857142857142857142857 = 60.955714285714285714285714285715 aproximately = 61cc.

I got right around 11.11:1 with a .052 compressed head gasket and .006 out of the hole. I'm not sure on the head gasket bore diameter, but I used 3.910 which I'm pretty sure is right, but not 100%.

THEBRAD

iTrader: (3)

wow those r a lot of number u wrote down there, sure u got em all right lol. but really though, sweet thanks a lot. thats pretty much exactly what i wanted to know

DONAIMIAN

iTrader: (18)

A rule of thumb is that .007=1cc, and 241's were the stock heads for the 01-02 cars.

Beaflag VonRathburg

iTrader: (176)

I just copied and pasted from the calculator and yes, they should be correct.

GuitsBoy

iTrader: (4)

Actually, 241's started mid year 2000, so its a crap hoot weather he had those stock. Either way, 61cc looks about right to me. Thats what I came up with when I milled my heads .040, although my pistons are flycut and I lose some compression.

dmiz0420

iTrader: (8)

its pretty easy to look at your heads and see if they have a 241 staring at ya....

would take care of the speculation....

Beaflag VonRathburg

iTrader: (176)

Yeah, really. Just look at the top front of the passenger's side head and see what number is on it.

Bo White

iTrader: (59)

Also keep in mind that when you mill .040" off the head you need .040" shorter pushrods.

THEBRAD

iTrader: (3)

cool cool

02blackbeauty19

iTrader: (22)

My AFR heads are milled to 59cc. I havent put them on yet but I am about to have LG install them and flycut for the G5X3. How come I have never heard of people having to get shorter pushrods? I have the pushrods that come in the Comp 921 kit.

Bo White

iTrader: (59)

Most pushrods are only availible in .025" increments, if its milled less than .025 just run the ones you have. If you mill a head X amount you also move the rocker X amount closer to the cam.

Dragkid1917

iTrader: (2)

Never thought of the pushrod thing, do you think milling the heads .040 and with a .616/.620 lift will clear? I wanna get some new rockers too, and the pushrods are the 7.4 cromoly's. I dont know how there gunna fit now.... but... about the clearence... anyone?....

GuitsBoy

iTrader: (4)

Find out what the base circle of the cam is.

The base circle on my cam is 1.450 vs stock 1.550, so its .100 smaller diameter, or .050. Stock PRs are 7.380 vs aftermarket 7.400 for a difference of .020 longer. The mill is .040. Not sure what yoru gasket is, but lets assume its a .045 down from a stock .053 for a difference of .008 tighter.

-.050
+.020
+.040
+.008

This totals out to +.018 over stock length. Hydraulic lifters should be able to absorb this extra length fairly easily, but as you can see, dropping to 7.375 pushrods would bring you closer to stock spec at .007 under.

Personally im running my pushrods at .012 over, and iv very happy with the setup.