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Is this advance to compensate for timing chain stretch?Quote:
As has been stated, cam grinders will grind in a little advance when they manufacture the camshaft.
What I'm trying to get at is, when you install a new cam in a street motor and you want it "straight up" would you give it some advance knowing the chain will stretch? or Install it "straight up" knowing that the grinder has allowed for this?
Install the cam on the centerline advised on the timing card that comes with the cam. The guys who grind these sticks know more than we do. If you need to alter the cam very much from the straight-up point on the cam card, then you probably have stuck the wrong grind cam in the motor.
I'm with Tech. When I buy a cam, I fill out the tech data completely and accurately, and go with the manufacturer's recomendation. On race or hot street engines, I usually wind up calling Comp Cams, giving them all the information about the engine and the rest of the car and have one custom ground.... Yeah, I know I spend a bit more for a cam, but when it's installed in the engine I know it's the right one. Used to play with a lot of cams, cam settings and everything else on the dyno. Discovered it's really tought, as in almost impossible, to out engineer the engineer's!!!!!
PS---Notice I said talk to the Cam Company Tech's, not some dummy working the phone bank at Jeg's!!!!!
When I've put motors together that's what I've done.....follow the manufacturer's recomendations, it generally works out best that way.
But the question remains unanswered....
Is this (built in) advance to compensate for timing chain stretch?
Let's say you were going to build two idendical motors....with one minor difference. One uses a timing chain and the other uses a gear drive.
Would you install the cam the same way? Or would it be different?
Hmmm. not really a question for me seeing as how I would never put a gear drive in an engine. If I used anything other then a chain, it would be a belt drive....Quote:
Originally Posted by ceh383
In answer to your question, there is minimal stretch on quality double roller chains, doubt you could see the difference on a dyno....
In Denny W's post above, there is a pic apparently decribing the positive stop method of finding TDC. I seem to recall some expert(s) writing to find true TDC, use a dial indicator, and note on the degree wheel wheel where .010 BTDC was, and .010 ATDC, and TDC would be the in between point.
They said, if I remember correctly, that using the equivalent of the positive stop method could give an error of several degrees.
Sure dont mean to be an ass here, just trying to learn. I have been doing a lot of reading trying to get ready for my try at degreeing a cam, coming soon.
A dial indicator would be more accurate then a positive stop. Unless you are actually going to change the cam setting, the positive stop is probably plenty accurate for just checking the actual specs against the cam card......
Another post stated...
So, if using a chain would you compensate for this?Quote:
As much as 8 degree's.
At it's worse it could mean 30 less hp.
No. Use a dial indicator to get absolute TDC. A positive stop bolt is little more then a WAG. If it's the right cam for the engine you won't need to change a thing on the advance. If it's the wrong cam, no amount of advance degree change is going to make it right. A quality double roller timing chain and gears will be dead on. Trying to compensate for something you can't measure is over thinking the whole operation.