Thread: Unknown cam?

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Well I guess we all come from different worlds. I am poor and have to use cheap,used parts to be able to hot rod, unlike you guys, obviously. I hoped I could find useful tips on this site, but it seems it's no different than any ricer forum out there! But for anyone that is actually interested in helping someone out, would I be able to use a lifter checking tool, placed in the lifter's place, and with a dial indicator, and degree wheel, find lobe lift,duration,etc.? Help from anyone that knows more than just " throw it away and spend some money that you don't have" would be greatly appreciated. Thanks, Dave.

I am totally offended, Ive never seen or talked about rice on this forum. I am not sure what you payed for your cam, but summit sells brand new ones for 52 dollars. You are plain taking a chance running a cam you know nothing about, you could find the valve lift by what you are wanting to try. But the duration will be a mystery. And if the cam you bought is used, is it still any good, gauged, scored, worn anywhere. Chances are you will install it and within a couple weeks or sooner it will destroy itself. Unless you bought the cam and exact lifters it was ran on, and every lifter was marked exactly to what lobe they were ran on, if not you will be buying another one anyway. Now think that if the cam is a stock cam just like or worse then the one you are replacing, thats more wasted money. I am sorry for your financial sittuation, but running used or mystery internal parts is a very risky business practice. And if my car had to sit for another month to get a new part that is the exact one I want, I am waiting, I know because ive been there before and will be there again, no rich daddy warbucks here,

If you can, place the cam in the engine. Take a solid lifter and install a dial indicator so it is touching the top of the lifter and zero the scale. Wit a degree wheel and pointer turn the cam slowly until you reach .050 lift. Record the number on the degree wheel. Continue turning until the dial indicator reaches the highest reading and record this number. Now tiurn the cam until the dial indicator comes down to .050 lift and record the reading on the degree wheel.

The degree wheel total between the two numbers will give you the duration at .050. Multiply the maximum lift number (off the dial indicator) by your rocker arm ratio to get maximum lift.

Do this for both the intake and the exhaust lobes.

To get lobe seperation angle will be a little more difficult, but basically, measure degrees of rotation between intake max valve lift and exhaust max valve lift.

Good luck.

Originally Posted by Geezer2

If you can, place the cam in the engine. Take a solid lifter and install a dial indicator so it is touching the top of the lifter and zero the scale. Wit a degree wheel and pointer turn the cam slowly until you reach .050 lift. Record the number on the degree wheel. Continue turning until the dial indicator reaches the highest reading and record this number. Now tiurn the cam until the dial indicator comes down to .050 lift and record the reading on the degree wheel.

The degree wheel total between the two numbers will give you the duration at .050. Multiply the maximum lift number (off the dial indicator) by your rocker arm ratio to get maximum lift.

Do this for both the intake and the exhaust lobes.

To get lobe seperation angle will be a little more difficult, but basically, measure degrees of rotation between intake max valve lift and exhaust max valve lift.

Good luck.

Thank you very much! I have the cam in the engine, and have removed all but no. 1 piston to reduce friction. I thought that would be the way to check it but wanted to ask someone with more experience. I can't see junking a cam with hardly any wear, which could be a good performer, simply cause I don't know it's specs. thanks again!

While I sympathize with your need for economy, I have to agree with the guys telling you to junk it. By the time you put new lifters, gaskets, and a lot of time and effort into it, the $60-$100 you save will look like peanuts. Especially if it wipes out in a week like every used cam I ever tried to re-use did. Then when you do buy a new one there's all the worry about what those grindings did to the rest of your engine. It just ain't worth it, man.

Hey Superdave:

I'm fairly new here as well and I have to say that this site has the finest technical minds you'll find anywhere. Most of them have years (some over 50 years ) of practical hot rodding and that includes a lot of engine building.

There used to be a device available called the "Cam Doctor". It was a precision measuring device coupled to a PC that indexed and reported on all aspects of a camshaft, i.e., lift, duration, lobe separation, shape, slope, etc, etc, etc. This machine is no longer made but a used one goes for $2500.

Please know that many of the guys on this site have used similar devices and are experts in the engine building field. They possess the knowledge and have paid the dues to allow them to say things like "get a new cam from Summit". We're not being jerks - however, we will respond in kind - which typically means your posts will just go unanswered.

Don't throw away an opportunity to learn from hundreds of years of combined knowledge and enjoy the collective wit and wisdom represented here.

Regards,
Glenn