remltr

iTrader: (4)

Another question guys!
I have an Eagle forged 383 set up from CNC Motorsports
3.75 stroke
5.7 H-beams
ARP L-19 12 pt. cap screws
The block I'm using is a 2-bolt but I am planning on installing splayed caps,so the block will be line bored bringing the crank centerline that much higher in the block. I called comp about the 280 XFI and they said they could do it in a small base circle. They stated that the small base circle is 1.050. How can I determine if this would be enough clearance. I don't want to spend the extra money on a grind just to have it not fit. Should I just get a standard grind cam,install it and check clearances to see if I need this cam in a small base circle?

sofakingdom

iTrader: (1)

Only way to know for sure, is to mock it up and check. You have to use the cam you're checking for, because some other cam may have very different lobes (duh).

However, given that your rods have capscrews rather than bolts and nuts, your odds are better than some.

On the other hand, Comp charges like $25 for a custom grind. Seems like a VERY TINY price to pay for the added security toward a trouble-free build.

However, if you get a custom grind, I'd strongly recommend having it ground on a .900" circle, and more importantly, on a billet core instead of a cast core. Billet cores are much less likely to have the typical roller cam failure of "tracking". Plus, the even smaller base circle you can get with the better material pretty much guarantees a fit. It'll cost a bit more still (probably close to $100 more than the off-the-shelf product), but avoids the possibility of either having to buy another cam, or do more machine work, or of having problems that damage other parts and require spending money on those.

The problem of course being, sure you can buy a std cam and hope for the best, and maybe it will work and maybe it won't; but then how much is it going to cost you if it doesn't? Did you REALLY "save" anything by trying to dodge the expense on the front end? Sometimes it's actually cheaper to spend money than to "save" it, in the long run; and sometimes the "long run" isn't very "long" at all.

Align-boring usually only moves the crank upwards by a few thousandths; .010" or so. Not a large effect on the issue at hand.

remltr

iTrader: (4)

Thanks for the info sofa. I was under the impression that all hyd.roller cams were ground on billet cores.. I'm using stock gm roller lifters. With a .900 base circle would I need a "taller" lifter(would the lifter decend too far into the boss) or can I go with a longer pushrod. Also can you explain "tracking"? Thanks again!

sofakingdom

iTrader: (1)

Longer push rod.

Tracking = where the lifter makes a track in the cam lobe; the roller equivalent of a flat tappet cam "rolling" or "flattening" lobes

No all rollers are DEFINITELY NOT billet. Here's a cast roller and a billet roller to look at. Note that this cast one is an off-the-shelf Comp XRxxxHR series (I forget which one) and the billet is a custom grind on a .900" base circle for solids.

Sonix

iTrader: (1)

the one on the shop towels being the cast one right?
the other one is so shiny, i'm gonna assume it's billet.

remltr

iTrader: (4)

Well, I finally spoke with a tech at comp. I told him about my build and he assured me that this cam on a 1.050 base circle will give me the clearance I need with the eagle 3.75 crank, h-beams and the arp l-19 cap screws. I asked him about a billet core on a .900 base circle. He told me that if I went with a .900 base circle that I would need new longer lifters because on the 900, the lifters would fall too far into the bosses. I was surprised that this cam in a cast core in the 1.050 base circle was $312 and $330 for billet. I was advised that I didn't need this grind in billet, the cast is good on a 1.050 base circle. He sounded very confident in his advice and if there is a mistake that they can take back a custom grind if HE makes a mistake. He also stated that he does these type of stroker cams 3-4 times a day! Anyway, the cam is on order, block is on its way to the machine shop Thanks for the advice guys, hopefully this wont be a $312 dollar lesson