Ok, I bought a rebuilt short block 87 350 chevy (roller cam) motor. I assume this means L98. I just wanted a L98 block with the crank and pistons already assembled and the bolt holes for the spider to hold the lifters down and the ones to hold the cam in in front.

Anyway I pull the cam out so I can put my comp cams XR269HR-12 part number 08-502-8 in and start to compare them. They look nothing alike at all. The one I pulled out looks bigger. The backside of the lobes is much thicker. It looks like while the valves are closed the factory cam will have the valve train .200 inches higher. I don't understand how these can be so dramatically different. I cannot find anything on the factory cam that looks like a part number. Only thing is 155-cpc-bc-16 between the non-existant fuel pump lobe and the first one on the cam. Also the actual shaft has a square pattern that gives it a disco ball effect. Is that what an L98 cam looks like?

Question is, is the one I pulled out an L98 cam or did they stick a flat tappet in there by chance? What other things can I look for to verify what I pulled out of this thing?

 

Yup, that's pretty typical...

Aftermarket cams will always have higher lobe lift than factory cams. But think about how an engine is built for a minute: lobe lift is the difference between the tip of the lobe and the back side. But, to get more and more lift, you can't keep making the tip taller, because if you did, they wouldn't be able to go through the cam bearings during installation; instead, you make the back side (base circle, if you will) smaller, which also increases the difference. So a high lift cam always looks small, because the lobe tip is essentially the same height no matter what the lift is. That's also whay as you increase cam lift, you have to increase push rod length: the base circle keeps getting smaller and smaller.

Who knows what that other cam is, for that matter who cares. It makes no difference if you're not going to use it. You can measure it with a micrometer and get some idea of its lift if it really has you curious. Just put what you want in it. Don't forget, if you want to use the factory's idiotic roller Frankenstein, you have to have that big stupid spider thing in there to retain their moronic lifters; otherwise you can use what all the rest of us had been using before the factory re-invented that wheel and made it triangular, which is what is now referred to as "retrofit" roller lifters. THey're joinrd together in pairs per cylinder by a link bar to prevent them from turning. One way or another, they have to be held in place.

 

Thanks RB83L69, I understand the world a little better now. You have put my mind at ease. I guess I could have noticed that both cams lobes at full lift were almost as high as the journals on the cam. I am pulling a 305 HO motor from my 87 z28 so I will be re-using the spider from that motor. Thanks again for your help!