Hello all i have been degreeing my new cam for the last 3 days. Between being very **** and checking timing wheel alignment and finding TDC i think that i may have a problem, in less i am totally misinformed by the cam card. There are several specs as far as when the valves on intake and exhaust open/close. Now on the bottom of the card it says @.050... then lists the specsof intake opening at 3 degrees BTDC. This spec is dead on. Now when i cycle through the rest of the specs it seems that they are off by approx. 2-3 degrees. Is this normal? Thed cam a have is a crane energizer 272 dur .454 intake .454 exhaust. If anyone can help me out i would GREATLY appreciate it. Thanks, Bob

 

Are you using a solid or hyd lifter to check the specs? A hyd lifter will compress slightly and give inaccurate readings.

2-3* is nothing to worry about as far as duration, but it can make a world of difference when talking LSA or ICA.

What do the peak lifts read compared to the card?

 

Make sure that if you move the engine backwards you go back to far and then forward to the lift you want. Otherwise the slack in the timing drive can cause your readings to be off.

 

I am using the outer rim on an hydraulic lifter, and resetting the dial indicator every time to make sure its at 0. Yes, the lift specifications are dead on. Now that you mention it I think that it may be slack in the cam drive that may be giving me inaccurate readings. So 2-3 deg. difference in duration is nothing to worry about? My lifts on the card say .454 intake and .454 exhaust.
I think another thing that is confusing me is the spec on the cam card for the valves CLOSING @ .050'' lift. These specs measured when the intake/exhaust are at .050" on the closing stroke right? I was thinking that it could also be .050" AFTER the max lift is achieved. This is the first gear drive timing set that i have ever used and let me tell you, it is a b***h, especially with the idler gear attached to the cover, every time i pull the cover off I have to make sure that I didnt let the cam rotate on tooth to far in one direction. Usually i just line up the timing marks on the chain gears then check the specs with the wheel and dial indicators and it has been ok. Thanks for the input, i am very wary of putting this motor together, installing it in the car and causing engine damage or having the motor be a dog because the cam is off. -Bob

 

If you were .05 after max lift you would be way more than 2-3 degrees off. The key thing to look at went you degree the cam is the lsa. Measure the one in your engine against the cam card. Do you know if you cam was ground with advance in it already or not? Its possible to install it to far advanced.

 

Another thing that can cause minute inaccuracies like that is not having the dial indicator EXACTLY inline with the lifter. I'm guessing that since you're using the outer edge you're fairly close, but every little bit makes a big difference.

Kinda like having the sights on a rifle off 1/32" can be off by 32" 100 yds away.

Plus another thing is how a flat cam is ground. As you probably know, the rear edge of each lobe (toward the back of the engine) is higher than the front. I doubt they're all exactly the same. Even cam manufactures have production tolerances they allow for.

I know it sounds like it shouldn't make that big of a difference but add that to not having the dial indicator in perfect alignment with the lifter, then figure in lifter-to-bore clearance, cam-to-cam bearing clearance, etc. etc. and 2-3* is minute. I wouldn't worry about it.