Degreed my "stock" 88 GT cam - Surprising results!

[tmoss]

I have my engine down to do a new timing chain, GT40P heads and Explorer intake, so I degreed in the stock cam after putting the Cloyes double roller in. I was VERY surprised at the results - so surprised I re-did it to make sure I did not make a mistake. Look at these actual cam measurements and the Ford specifications for both the early and later GT cam specs. Anyone else ever check theres early GT cams and find this?????????????????

 

[89MustangGX]

I've heard that factory cams can vary wildly from one ot the other, that's why I never paid much attention to the specs. This also explains why there are some people who collect and spec out factory cams, and why some others have custom cams ground into the factory specs...so all in all, I'm not really THAT surprised.

 

[tmoss]

The split duration with the exhaust side long duration is what surprised me. May work well with the P heads. I'm considering using the 4° retard key to get advance from 6.5° back to 2.5°. I'll also probably do the .050" lift durations too as those numbers were recorded when I saw .0005" of movement on the dial indicator.

 

[89MustangGX]

The split duration with the exhaust side long duration is what surprised me. May work well with the P heads. I'm considering using the 4° retard key to get advance from 6.5° back to 2.5°. I'll also probably do the .050" lift durations too as those numbers were recorded when I saw .0005" of movement on the dial indicator.

I don't know as much about cams as I'd like to, but I know that retarding the stock pieces 4 degrees is a pretty common thing -- so I'd say you're definitely on the right track. It's too bad there's no chance of just seeing on a dyno how much of a difference retarding (or advancing) the cam makes...

 

[Ranchero5.0]

May even explain why some factory cars run soo much harder than others...

Still seems like a 'weak' profile.

Jamie

 

[90mustangGT]

Those numbers are pretty far from each other. I wonder if ford did this on purpose due to the intake and exaust flow differences between different runners in the intake and exaust or was it just some very messed up machining practices? That makes me wonder how far other FMS cams are out? Maby I should do this to my B cam, if I had a degreeing kit and knew how to use it.

 

[tmoss]

90mustangGT - if you laready have a dial indictor on a magnetic base, you can get a degree whell from summit for like $27-28. This is all you need, but you will have to tear the front of the engine down.

The exhuast duration is too far off to be a simple machining tolreance variance it seems. Odd that it's the exact mirror of the 89+ cam too.

 

[IndyBlk5.0]

did you get your car running with all your new parts yet tom?

 

[tmoss]

did you get your car running with all your new parts yet tom?

No, reassembly is starting now

 

[90mustangGT]

90mustangGT - if you laready have a dial indictor on a magnetic base, you can get a degree whell from summit for like $27-28. This is all you need, but you will have to tear the front of the engine down.

The exhuast duration is too far off to be a simple machining tolreance variance it seems. Odd that it's the exact mirror of the 89+ cam too.

I can get a hold of the magnetic dial indicatior, if I can't maby I should buy one, I have needed one before. This could be interesting. If my cam is that far off, it's comming out.

 

[tmoss]

I resurrected this post to let you guys know about some problems with the way I did it the first time and how to avoid these mistakes yourself. I used one of my lifters the first time and took it apart, inverted the plunger to make it solid like I had seen mentioned before and took my first set of mesurements. Well, that was a mistake. As it turns out, the plunger was not exactly seated and square giving and unparallel surface to read from. Not only that, but my dial indicator stem has a half-round surface on the face of the stem and the inverted lifter has a similar surface - all this led to inaccurate and non-repeatable results. I finally used the small flat area at the edge of the lifter body to get solid repeatable results. The first readings and these are very different as you can see from the attachment here.................the results are still surprising but the split duration in favor of the exhaust is gone and total duration at .0005" (I verified my first .005" duration numbers) is higher than I expected - took tem from .0005" just to see waht the #s were. Duration @ .050" lift is more than I thought it would be and the ICL,ECL and LSA are less than I expected. That's OK though because the cam has excellent vacuum which my SD EEC needs.