I think ive found the cam for the 383, comp xe274h. But, Im still kinda concerned about the bsae circle. But even on comp's spec card for the 274 on their site, it doesnt say how big the base circle is. U think it wud be ok as far as clearences go, or do I need one that specifically says "small base circle"? Or is there another cam I shud go with all together?

 

Take a caliper and measure where the yellow lines are in the picture I have included (I marked all 3). I do not know Comp's base off hand but I don't forsee any real issues.

 

I don't understand the picture above. That just seems to be measuring the core. The base circle numbers are not always published and it's important to those who are stroking a SBC.

I ask around also until I found someone to tell me. I called Comp Cams and the measurements that they gave me were WRONG!

When I finally got the cam I just measured it. It's the diameter of the cam lobe without the lobe. In other words, measure on each side of the lobe 90° from the highest point.

 

What SMasterson did, will get you close, with any cam likely to be "streetable". Probably within .015" or so. But that has little or no meaning for most cams; only billet rollers are ground as a "base circle" plus lift.

In order to make a cam "bigger", they don't make the tip of the lobe "taller"; it's already as tall as it can go, and still allow the cam to go through the bearings to install it. What they do, is to make the back side of the lobe "shorter". Which means, the "bigger" your cam, the "smaller" the base circle becomes.

A stock XE274 fits into a stock 400 just fine. Guess how I know that. I don't know what you're putting it in; but if it's a motor with any stock stroke and the rods to go with it, it'll fit fine. If you're stroking something, it will depend entirely on what rods you use, what hardware is in them, and how they're prepped.

 

its goin in a 383, and right now im lookin into the eagle stroker kit from summit. it cost more than the powerhouse one, but Im also taking into consideration integrity over money. Id much rather build the bottom end once with good reliable parts rather than build it up twice due to faulty parts. But either way, ill probably be goin with the stock 5.7" rod length.

 

phone comp and ask what the part number is for the small base circle version of the cam you want before you order it.It'll probably cost ya a few more bucks for the cam.the other option is getting the rods clearanced to clear the cam.Might want to see whats more costly?