what should my lift be with these 1.7's
 

I have been told that The 1.7 crane cams roller rockers moves your lift up some.
I have the x-303 cam and thats 542 lift and i was wandering waht it really is with the 1.7's that i have.
thanks.

Should be around 576lift. You have stock heads? This probably is kinda mismatched.

SKyler

The difference between 1.6 and 1.7 rockers is .30

Yours would be .572 lift.

wow, gtsr515 is wrong for once :)

the 1.7 or 1.6 is a ratio. You multiply the lobe lift by this ratio to get total lift.
Lets take for example a B-303 (mainly because its the only cam that i know the lobe lift off the top of my head) it's lobe lift is .300" multiply by 1.6 and you get the advertised .480" total lift.

If you dont know the lobe lift of a particular cam, all you need to do is take a ratio of ratios, divide the new rocker ratio by the old, then multiply by the advertised total lift. if you have 1.7's with a B-303, then (1.7/1.6)x0.480 = 0.510"

in your case, (1.7/1.6)x0.542 = 0.575875" (so Skyman is right)

I sure hope you have some serious valve relief's in your pistons.
Also i agree that that is wayyy too much for stock heads, try to keep it around .500"

fiveoh you are right on.. Its a ratio, not a straight across #. But for cams around 500 lift .30 is usually about right.

Skyler

Hey! I was wrong once before many years ago, that makes twice now, get your facts straight!:D

Regardless, that's too much lift.

hey skyman, I was talking to the guy that orrigonally owned the car when he had it running 13.00 and he said that the heads are gt40x's but when i put the 1.7's on i looked and it didnt say gt40x anywhere it just said gt , so i assumed that they are just heads from a gt mustang that have work done to them cause they flow pretty good.

And hows your new combo?

Havn't got my car back together yet, still porting the heads and intake (goes real slow).

See if the heads are aluminum or Iron. If they are iron they are probably GT40 iron heads. If they are aluminum then they are probably the GT40X.

Skyler

I believe the iron heads have 3 bars on the outside ends of the casting (near the bottom), you might be able to see them.

Could also be the GT40Y.

Am I the only one that noticed "soon to be AFR 185's" in his post?

Regardless, I can't figure out why you need such a monster cam. You don't have the engine for it, even with 185's. Not even close. What's the max lift on those AFR 185 springs? Probably gonna be doin some flycutting too.

unit- I didnt put the cam in it or the heads. It was all like it when i got it.. The only thing that I did to it was put 1.7's and crane cams hardend pushrods in it because the pushrods that were in it were way to short. When the guy had it before me he said it ran 13.0 and a 13.16 on slicks. He said that he broke two transmissions thats why he wanted to get rid of it.

If my heads were gt40 or gt40x's wouldnt it say it on the out side or under the covers. all it says under the covers its GT. And yes they are cast iron.
You guys tell me how to post a pic and ill post them , i just scanned them today.

to post a picture, all you have to do is hit the browse button inderneath the area that you type in when you reply to a post. Its titled Attach file: on the left hand side of the screen

I believe you may have GT-40's, i think all they said on the head was GT, not GT40.

here's a slightly related question:

If I have 1.6 rr's, 202/160 that flow 295/231 @.600" lift, what kind of cam can I run to get maximum lift without having to worry about piston/valve clearance issues on a 331 ci?