No, I am not a total retard when it comes to cams, but would like to know if anybody has looked into how much a cam will retard when a double roller chain has been stretched.

 

I have seen much mentioned on how these stretch so I just assumed people have degreed again after running one for awhile.

 

I've seen 10° (crank) and more, on those cheap "truck roller" POSs.

 

After 50k miles, I replaced the cloyes $20 special on my 305 HO. Picked up 3/10's and 2mph in the 1/4 on a mid/low 14sec car. I checked the timing before and after and it changed 3 or 4 degrees. I have never gone to the trouble of degreeing a worn out one, but after 50k miles this one had some slop. I definetely got my $20 worth!

 

So that was about 3 to 4 after about 50,000 on a cheapie?

Obviously cheap is not a way to go with a chain. Do those that cost 3 times more and up hold up better or is the roller chain just a stretcher?

 

how much of a pain is it to install one of the gear drive systems instead?

any more parasitic loss or is the stable timing worth it even if it does give a little more drag?

 

Lo-tec, the loss in performance you saw was due to fluctuations in timing? Retarding the cam that amount would not cause the loss, am I correct?

 

It's not due to fluctuations in timing, but the change in cam timing. Retarding the cam shifts the power band higher, and advancing it shifts it lower. It's not something you just feel one day, it took 50K miles to stretch that much. For a reference, most off the shelf street cams have 4 deg. of advance ground into them.

 

I just thought 3/10ths was a lot for a little shift in timing. A mid 14s engine might see 5, maybe 10 ftlb loss somewhere in the lower rpms. Does that sound right?

 

3 or 4 degrees is not a little shift in cam timing. If you were to advance a cam that made good power to 5500 by an extra 4 degrees, it would probably crap out before 5000, and retarding it an extra 4 degrees would move the power band up to 6000. These #'s are a rough guess, but you get the idea.

Edit:

I stuck a free low mile 90 factory roller 350 in the car (305 was getting tired). Put in a crane TPI cam because it would work with the factory roller setup. .452" I .465"E on a 112 LSA ground 5 degrees advanced. When I degreed the cam it was 6 degrees advanced, which I left as close enough. This was with a dual plane and a CC Q-jet. The midrange torque was incredible, but it crapped at about 5K rpms (which would be good for a TPI). I retarded the cam 3 degrees, and it shifted the power band up about 500 rpm, and picked up 3/10 and 2mph in the quarter.