502 Cam Help
 

I went through my engine this winter to freshen it up and i used a cloyes billet roller.When it came time to degree the cam at straight up it was at 110* centerline. the specs call for it to be at 116* so thats where i dialed it in. It seems that i lost about 300-400 rpm. I saw where someone says to run it at 110*.Anyway i've lost about 6mph and the rpms. My biggest problem is I had houston prop to redo my prop and now I don't know where the hell i'm at. I think my cam is where my rpms went , can anyone shed any light.? I dont want to mess with the prop until I know my cams dialed in. Please help a brothe out!

Re: 502 Cam Help
 

You may have more low end were you are now, but you will gain up top at 110°. I don't know anything about the cam you are using, but I have read here on OSO that guys are running some cams at like 106°.

Re: 502 Cam Help
 

Ive always run mine at 106. Im trying one of them at 110 this year to see if there is any noticable diff.

Re: 502 Cam Help
 

Kennyo,
Are you running the factory 502 MPI cam #12551622
224*/224* @ .050
.483/.483 Lift
Bob

Re: 502 Cam Help
 

Alot of people get confused using centerline method when degreeing camshafts in. Lobe seperation and lobe centerline are 2 different things. Also with asymetrical camshafts, degreeing by centerline method can throw you way off since "A" cams have different opening and closing flanks and ramps. Crane has an EXCELLENT step by step instruction on the duration method of degreeing by using the open and closing events. Good reading.

I would venture to say your cam is well retarded.

Chris

Re: 502 Cam Help
 

I appreciate your time on this. It is a stock 97 gen 6 502 mpi cam. My engine builder looked it up and it said to install it at 116* centerline. I installed the crank key at 0 and it came up at 110*so we moved it to the next keyway ( I don't remember which way is - or +) and it moved up to 116-117* centerline. I'm guessing i retarded the hell out of it. I'm running a procharger and a 30p 4 bl. I'm not concerned about low end because I take off easy anyway. Since then i've lost a lot of top end rpm. and about 6 mph. Obviously that not gonna work! your input would be greatly appreciated. Thanks, Ken

Re: 502 Cam Help
 

If it is the cam I referenced, the specs are:
ICL 109* ATDC
ECL 122* BTDC
LSA 115.5*
The cam is ground 6.5* advanced for a very specific purpose and should not be retarded to a "straight up" position.
If the cam is degreed via the ICL method @ 116* ATDC you have effectively retarded the cam 7*. In an artificially aspirated motor the late EVC will further aggravate the problem. This cam needs to be @ 109* ICL.
Bob