cam shaft spec

[jchildree2]

this is a two part question. On the dyno cams are the opening and closing numbers @ .050" like the isky cams are is it off .000". I am doing a cl2 cam and the c/l is way off. It is suppose to be 112 and this is at 120. I can't remember if you move the crank gear to fix this. It is on a clone 6.5 and I have had to move the gear on some to get the cam degree in. any help would be appreciated.

 

[youngengines]

Wow, I have never had a cam off more than 1/2 degree in the centerline (like show 11.5 instead of 112). That's a lot.

 

[Gould Racing]

i'm pretty sure Dyno and most cams opening/closing numbers are @.003" tappet lift

 

[NCStratos288]

What method are you using to check your center line? Reason for asking, I was degreeing one in a few weeks back and it came up 120...and it was a mathematical error on my part... No matter where I moved the cam, my calculations were still 120... Just thinking maybe you might be making the same mistake I was...

 

[Jamie Webb]

Like NC said, double check your math and method before twisting the cam. It's odd, very odd, to be that far off. Just my opinion, but I would not move the cam gear to fix a centerline problem. I think you are asking for more trouble there. I always twist the cam, but if it's over 1 degree out, I get a new cam made (like mentioned above, that is a very rare case).

 

[Gould Racing]

don't turn the engine forward and backwards either when your degreeing your cam, with the angle cut gears it will throw your numbers off a little, turn it the same direction the whole time

 

[W5R]

don't turn the engine forward and backwards either when your degreeing your cam, with the angle cut gears it will throw your numbers off a little, turn it the same direction the whole time

This makes a big difference in the numbers you get, i learned that the hard way and ruined a cam in the process

 

[Kart43]

How did you ruin the cam?

 

[jchildree2]

thanks for the replies. the way i check c/l is I find max lift, then zero indicator, then back motor up till .150", then turn forward till i get to .050" before .000' and take the reading. then continue to turn motor forward and go to .050" after .000" and take that reading. then add the two together and divide by 2. I back motor back then bring it to where i need to get the reading and it takes the cam movement out of play. I did turn the crank gear and got every thing in match with the cam card.

 

[Kart43]

The gear is pressed on athe factory and there is a variation in it's placement.I am suprised it doesn't come up for discussion more often. The placement of this gear is as consistent as the specification of all of the other components found in these engines.

 

[W5R]

How did you ruin the cam?

put a deep scratch in both lobes, from the method i was using to twist it. Anyone with common sense knows if you take a cam like that into tech, you will be tossed, its obvious evidence of twisting the cam, no normal wear will produce those kind of marks. I have since learned to cushion the cam with something between the vice jaws and pipe wrench jaws when twisting a cam, to keep from making that same mistake again. Luckily, the cam that was ruined was a cheaper BSP2 cam. Was my first time ever trying to twist a cam though. That was the same time i learned that turning the engine both ways rather than just one direction will make the numbers vary.

 

[Kart43]

don't turn the engine forward and backwards either when your degreeing your cam, with the angle cut gears it will throw your numbers off a little, turn it the same direction the whole time

This makes a big difference in the numbers you get, i learned that the hard way and ruined a cam in the process

put a deep scratch in both lobes, from the method i was using to twist it. Anyone with common sense knows if you take a cam like that into tech, you will be tossed, its obvious evidence of twisting the cam, no normal wear will produce those kind of marks. I have since learned to cushion the cam with something between the vice jaws and pipe wrench jaws when twisting a cam, to keep from making that same mistake again. Luckily, the cam that was ruined was a cheaper BSP2 cam. Was my first time ever trying to twist a cam though. That was the same time i learned that turning the engine both ways rather than just one direction will make the numbers vary.

I thought you were saying you ruined the cam from turning it forward and backwards.

 

[W5R]

I thought you were saying you ruined the cam from turning it forward and backwards.

No i ruined the cam from twisting it using the wrong method. I was talking about the numbers varying when turning the engine forwards and backwards. I dont believe its even possible to hurt a cam turning an engine one way and the other, even if you were to do it with an electric starter hooked up wrong or something lol. Sorry for the confusing post, was half asleep when i posted originally.

basically the first time i actually tried to build an engine on my own, it involved twisting the cam, and turning the engine both directions trying to get a reading. I should have said that more clearly

 

[razorcalif08]

I would recommend the positive piston stop method of finding TDC. I use an Animal piston stop, works great. I use the stop to help hold things in place when I tighten the fw too. Just check TDC again after tightening the fw just to make sure. Some cams can have several degrees of duration at max lift making it hard to find true TDC. I bought two motors at the same time from the same supplier and cam center lines had over 4 degrees difference between them. Clone motors are like a box of chocolates.