Just wondering if anyone know the difference between these 2 cams or have used either one. I am looking for one of these for my 454 with 781's. Specs on both are appx 230/230 .520/.520 on a 110LSA. Also anything similar in Lunati?

-Joe

The 274 is a dual pattern cam. Is the 280H the magnum cam? If so Comp cams said the 274 is better. That's their word though.

i run the xtreme 274h in a 454. it is supposedly newer technology and a more agressive profile. if you are serious about the most performance for the $ i would consider a solid camshaft. any questions about the 274 feel free to ask . mike

The 280H will run better with higher compression and is a little better on parts. The XE line closes the valves earlier to build more cylinder pressure. What CR do you have?

I am assuming I have 9.1 at most as I have flat topped pistons and 781's. I didnot build the motor myself so I have no clue exactly where I am at. Iknow I am severly over-cammed now as I cannot pass the emission test after I had a speed shop try to dial it in. I had 120psi cranking compression with this huge cam. Once again I am looking to go to a smaller cam as thing thing is just a dog down low until you hit about 50, then she pulls like a bi***. Also I got a reading of about 10hg vacuum at idle.

The only thing I can add is, that the 274 does make a little noise, I am told it's due to the agressive ramp design slamming the valves shut...

I havn't really ran mine enough to comment on the performance, seems strong, but I still need to change my rear end gears from 3:23 - to 3:73 because of the new M-20....

You may actually be down closer to 8.0/1 CR. I would look even smaller something like a XE268. Also, you may need a wider LSA like a 112LSA. Look at the smaller marine cams or the truck cams.

Thanks guys!

Originally posted by GRN69CHV:
You may actually be down closer to 8.0/1 CR. I would look even smaller something like a XE268. Also, you may need a wider LSA like a 112LSA. Look at the smaller marine cams or the truck cams. ..What Joe said.
8 to 1 is about right.A great cam for a low compression 454 is the Crane 272H
I've run it before in stock 1974 454 with 049's..ran pretty good with an M20 and 3.31's
Specs are .515 lift on intake/exhaust,216 @ .050 110 LSA

I'm running the xe 274 and really like low end.Ive got 175psi cranking pressure trw 2399 pistons,oval ports. I just wish I had more top end. Don't want to lose any on the bottom so for now im keep'n the 274.

If it's a flat-top piston motor, it's about 8 to 1 CR.!!!

No bigger then a CC 268HE and to me a 260HE would be better yet, imho..

I know you can run a 280 Magnum in it, but it JUST won't be right!! DCR will be way off!!!!!

pdq67

Back again, a CC 280 Magnum cam will create a 6.29 DCR in an 8 to 1 CR., 454 motor!!!

I used "Boost Calculator" and put in 4.28" bore, 4.0" stroke, 8.0 to 1 CR., 6.135" long rod and intake valve closing = 66 degrees, 0 for boost and finally 600 feet elevation which is about mine is here in central Missouri.

pdq67

pdq67,
Please help me! I kinda understand DRC, but where should it be on an 8:1 or 9:1 compression motor?