Im going to replace the magnum 280H in my 388 [230 @.050, .480" lift] with a solid flat tappet. I've always been a comp cams man until I found out about ultradyne :D Anyways looking for a comparison of the xs274s vs a comparable Ud grind. The specs for the 274 are 274/280* duration with 236/242 @.050 and .501/.510" lift. Also the lash is .016 and the LSA is 110*. Just about perfect as I don't want my intake lift to be over .510" max [vortecs start stalling too much any higher] What do you guys think?

As far as I know, and that aint so far, the only two UD/Lunati lobes that sport under .500 lift are the 272/282 which spec at 238/248 ).050. A bit bigger.

Look here at Lunati's site,

http://www.holley.com/HiOctn/ProdLine/Products/IEC/IECC/Chevy4.html

I believe the grind numbers with the "U" are Harold's Ultradyne cams.

Im not real good at comparing cams yet, so bare with me please smile.gif I know solid cams duration is comparable to a 10* higher rated hydro flat tappet, correct? I want to shift at 6500rpm. For a 388cid motor, I would think this would be about 235* @.050 with a hydro cam, so I should be looking for about a 245* flat tappet?

I ran the xs282s10 in my 385...shifted at 6500..chipped it at 6800

Bored & Stroked,

I always allow about 8° more at .050 to compare hydraulic and solid cams.
I use .525" gross lift, .500" net, lift cams in Vortec-headed engines, with no problem.
A custom cam I can make is the Lunati 01-UF80-UF77-10-A01. This cam is 267/271 at .020, 239/243 at .050, .510/.520 gross valve lift, .494/.504 net valve lift, and 110 LSA, in at 106 ICL. At .200 this cam is 150/154. The CC XE274S is 147/153, according to their catalog.
Valve lash on both cams is .016"/.016"
Last year CarCraft had a dyno test of a 383 with 195 AFR heads and a CC 294S. The CC 294S is 248 at .050, 154 at .200, and .525 valve lift. Westech, the dyno company, claimed 540 BHP out of this combo. YYYooaahh!!

UDHarold

BTW, if you're not in a big hurry and can wait 2 months, I'll have some real replies to the XE stuff.......

The SB UD276/284F10 has a net lift around .500.
It's .518/.530 gross w/.026 lash or less if you want. I'm putting one in a 10.8-1 383 w/ vortec heads. Hopefully will fire it up this weekend. Can post the results next week.

UDH posted a while back that his TL cams need about 6 deg added to them to compare them to the .026 lash cams. So the 267 is comparable to a 273 .026 lash cam. Slightly smaller than the 276/284. The XS cams are rated at .015 IIRC, so with the listed lash compensation, they are about 2 degs bigger than listed. I figured all this out for doing DCR calcs.
Regardless, the 276/284 is a little bigger than the other two cams. And more aggressive than the XS cam.