Hello All, I need some help with my cam timing. I have a Clay Smith 274 112* cam from Classic Inlines. This is fitted in a 250 which will be turbo charged. I also have a new stock timing set from Mustang Unlimited.
This is my first time degreeing a cam and it’s not as easy as I thought it was going to be!
I’ve calculated that the lobe centres of this cam should be In 112* ATDC and Ex 112* BTDC. CI recommends installing 4* advanced, so that should make it In 108* ATDC and Ex 116* BTDC. Is this correct?
I installed the cam straight up with the timing dots aligned. I measured/calculated the lobe centres to be In 116* ATDC and Ex 108* BTDC. So by my calculations the cam is 4* from straight up and 8* retarded from the recommended position.
I tried moving the cam around one tooth and measured again. This time I measured In 100* ATDC: 8* advanced over the recommendation (12* adv over straight up).
So which would be better for a turbo engine, 4* retarded or 12* advanced? Has anybody else had similar problems? If so, what have you done to correct this?
There isn’t (as far as I know) an adjustable timing set for the 250. The only other option I can see is to take the cam sprocket to the machine shop and get them to make me a new keyway, that is 4* advanced to give me 8* at the crank and therefore get the In at 108*. What do you think of this idea?
Any help is gratefully received!
Thanks
Nathan
This is my first time degreeing a cam and it’s not as easy as I thought it was going to be!
I’ve calculated that the lobe centres of this cam should be In 112* ATDC and Ex 112* BTDC. CI recommends installing 4* advanced, so that should make it In 108* ATDC and Ex 116* BTDC. Is this correct?
I installed the cam straight up with the timing dots aligned. I measured/calculated the lobe centres to be In 116* ATDC and Ex 108* BTDC. So by my calculations the cam is 4* from straight up and 8* retarded from the recommended position.
I tried moving the cam around one tooth and measured again. This time I measured In 100* ATDC: 8* advanced over the recommendation (12* adv over straight up).
So which would be better for a turbo engine, 4* retarded or 12* advanced? Has anybody else had similar problems? If so, what have you done to correct this?
There isn’t (as far as I know) an adjustable timing set for the 250. The only other option I can see is to take the cam sprocket to the machine shop and get them to make me a new keyway, that is 4* advanced to give me 8* at the crank and therefore get the In at 108*. What do you think of this idea?
Any help is gratefully received!
Thanks
Nathan