ding56

I have a c4 with stock gears, think 2.73 or close to that. What rpm range they consider "low" when they say the cam should make good low end torque.

Yea before the light total timing was really high but now that it's correct there is no performance difference.

Grind number is fs xe 256h-10
Comp cam part number is 31-234-3.

Thanks

Tim

Gun Jam

according to the card it should be timed more towards torque than peak Hp. I expected to see a range closer to 2000 to 6500.

It could be a gear combo that is giving issue....what was the grind number on the previous cam?

barnett468

that cam starts to falls on its face at around 4800 rpm . . i have probably used 20 of them.

ding56

I don't know anything about the old cam. The guy I bought the car from said he thought aprevious owner has done some engines work but not sure what. I could not decipher any numbers on it.

I might need to do rear gears, thinking about 3.25 so the revs aren't too high on the freeway.

Tim

Gun Jam

Yeah thats what the card seems to indicate so it should be making good low end performance...or its low end performance should be where it preforms best and thats what the general description claims.

But if we dont know much about the original cam then I suppose that makes comparing the two quite tough.

-Gun

barnett468

yes, so i looked at his specs again and it is a reproduction of a stock 64 thru 72 289 and 302.

an original cam would have this marking



.

ding56

Yup that's what the markings I found on the cam I took out are. Did I go backwards with the new cam?

Tim

barnett468

ok, that is a stock cam, if you want more bottom end and only rev it to 3500, you need the xe250h as i previously mentioned if you keep the same gears.

the duration @ .050" on the stock cam s less than the ex256 cam

ding56

But should the xe256 give me less get up and go than the stock one? I'm trying to figure out if there is a problem with the install or tune or just I'd the cam I installed is a step back. All the research I did said that with stock head and valves the 256 should of improved my performance and that's why I'm confused.

Thanks,

Tim

barnett468

the term "improves performance" is a bit misleading . . i cant tell you if you installed it one tooth off and its hard to describe the difference in power between the two, but you can order the xe250h from summit then take your timing cover off and if you installed the xe256h one tooth retarded, just fix it and return the xe250h.

if you installed it 1 tooth off in the retard direction, it would be a total pig off the line and might have a big flat spot when you hit the gas.