jaroot

Does anyone have any experience with the Comp XM276HR (08-418-8) marine roller in a 350? I am at the point where my motor has seriously outgrown the XM264HR, plus i would really like those extra ponies . I'm interested in the idling and throttle response (under load) charactaristics, particularly the idling portion since i run a sterndrive (alpha SS) and don't want to have to idle this thing @ 1000 rpm in gear. Kinda tough on gears and clutch dogs...

I have plenty of cylinder head (too much in reality) - 220 cc Pro-Action , intake (rpm airgap), carb (650 vac sec holley), exhaust (imco), ignition (MSD) and compression (9.4:1) to handle this camshaft easily and am not against spinning 5500...

Thanks in advance for the help.

J

BAD-HABIT

I am running the XM-270HR. I have some lope to it but not as much as I'd like If I had to do it all over again I would go with the 276. I idle at 750 without too much of a problem. Id call Comp cams. You probally can get yours re-ground for less than what a new one would cost. Ive heard that they can custom grind any cam if you want. I think Dennis Moore mentioned it once....

BH

traviss

I haven't ran that cam. But I did put your setup through the program dyno 2000. Like you said you know the heads are a little larger then needed, you might just have to rev the motor up a little higher to get the power wanted. I was told by tyler crockett for my 383 not to use heads bigger then 210cc. With your current setup it makes around 370 hp at 5000 rpm and 445 lbs of trq at 3500. Now if you switched to the 276 cam it would make around 403 hp at 5500 rpm and 443 lbs of trq at 4000 rpm. These numbers just give you a idea of what your working with. So with this cam it would be propped to spin 5500 rpm minimum. Right now I run a crane roller cam 234/242. .575/.595 lift on a 112 LSA. I only need to spin this 5500-5600 rpm to max hp. This is in my 383, AFR heads, victor jr intake, 10.8:1 CR, 750 holley with EMI exhaust and a alpha drive. My motor idles at about 800 rpm and makes those big block guys think twice You can probably put that 276 cam with springs to match, change to a single plane intake, slap on a 750 holley and spin it at 5500. You will probabvly be happy with that. There are a few other small block guys here that can help you too, wette vette runs a wild 355 He'll convince you to run a solid roller cam and spin it to the moon




Travis

jaroot

Thanks for the replies guys.

Yep i use desktop dyno and back my motors and my customers motors up on the dyno from time to time... generally fairly close for peak hp.. little flighty in the mid to low range torque (and hp) numbers.

your desktop numbers come out bout the same as mine.. 370 - 375 hp @ 5000 - 5200 and the 276 shoots me to about 408 @ 5500... modeling with small tube headers with mufflers.

currently my camshaft is @ -4 from straight up and that's where i'd put the 276 also. i generally don't run under 3000 rpm anyway so i can afford to drop some low end torque.

i run an alpha SS on the back of the little donzi and we're just thinking about that 80 mark... i am spinning my current setup @ 5500 which helps alleviate some of the strain from all that torque on the drive by cresting the peak and being on the downturn.

5500 is max continuous for me anyway since i do not have a 4 bolt, steel crank, balanced assy in the bottom end...

just want to keep it turn key and managable yet make some respectable oomph with sleeper qualities (fits under the hatch)... looks like the motor is gonna have to come out for a new paint scheme and some "improvements"

thanks again

Root