Liberator21

I want to upgrade the cam in my 383 stroker.
I currently have the Comp XM262H, and was considering the XM270H. The 262 pulls great, but falls on it's face at 4600- 4700 rpm. I called Comp's tech line, and got a guy who seemed to know boats (says he has a 27' formula with twin SBC's). He says stay away from the 270 because with the stock center rise manifolds, I'll have reversion issues. He recommended I go with an XE268H. Says he built a number of SBC's for boats, and that was his cam of choice. Says it performed well. Any comments on this? Anyone use that cam?
Other recommendations? I've heard good and bad about that cam. I've also heard that's the most common cam they push for the small block. A roller setup is not in the budget at this time. The engine has 9.5:1 cr, and a dual plane intake with a Q-jet.

blkhorse

iTrader: (1)

I have the xm270 in a 355,9.5cr,performer,vortec heads,quadrajet with stock center manifolds(thru hull) and am more than happy with it.pulls strong to 5300 and have not noticed any reversion,I even spend a decent amount of time idling(love the sound)

Liberator21

That sounds about where I want to be!
What boat/prop, and what kind of speeds are you seeing?

blkhorse

iTrader: (1)

89 baja sport 220 with a 21p quicksilver, at midrange it will blow out,have 23p mirage plus to try.have'nt chk'd gps yet but speedo reads 63 so about 58?

Liberator21

That sounds about right. I have a 21' Liberator (Heavy Boat), and at about 4600rpm (which is all I can get with this cam), I'm doing 56~57mph GPS.
That's with a 21 inch Viper prop (OMC). How does it feel at cruising speeds, and how is it when you're idling around the dock? The XM262 is so mild, that you can't even tell there's any kind of cam in there. Even at a 700rpm idle. That's why I was surprised when the Comp tech guy told me to stay away from the 270. I didn't think there would be that big of a difference. I've heard that there are issues with the XE series of cams wiping out lobes because of the aggressive profile, and that makes me nervous to go that route, even though he recommended it. If you're happy with that cam, and it's not causing you any problems, I might go with that. How long have you been using it?

blkhorse

iTrader: (1)

I have about 40 hrs on it,around the docks it sounds great ,nice lope with idle around 750(not too aggressive).I cruise at 3000 to 3200 can't remember speed,but going from that to wot(if prop don't blow out) it goes like a raped ape.I feel I made the right choice ,overall throttle response is excellent

Liberator21

OK,
I usually set my idle at around 700, and the shift assist module pulls it down to 400 when going into or out of gear. That's only for a second though, so it shouldn't affect anything. Your cruise rpm is the same as me.
My main worry was reversion, and once this thing is back in the boat, the last thing I want to do is have to change a cam! It sounds like you're not having any of reversion issues. Your oil is clean I assume. I appreciate all the info. It's really going to help me make my choice. Thanks. I just wonder if anyone else has any opinion or feedback on these cams?

Paul

SB

iTrader: (1)

Where we or he getting mixed up with the XE vs XM ?
XE's are ground on a 110LSA, and XM's on a 112LSA.

BTW: Call Comp 3-4 times and see how many different answers you get. Not to totally knock them, but I call big cam companies once in a while with a certain combo just to play like a reg person and a handful of times I've gotten answers with 10 degrees or so difference within the same company. Some ask more questions, some don't. Some know more than others.

A restauraunt with 10 chef's is going to be more inconsistent than a restaurant with 1-2 Chef's.

fstboater

They should be able to open up the cams centerline to 114 if the want to sell it as a more marine friendly grind I have tried the cam hot lines with little luck most just read to you off a screen.

Full Force

iTrader: (5)

I just did heads and cam on my boat,I have mixed feelings about the results,you guys seem like you know about small blocks,I would love to get opinions here.
For now I reused my short block,280 hrs,very well kept and clean,I have dart sportsmanII heads with 64 cc chambers,cam is crane 114 lca 212/[email protected] with.446/.459 lift with an edelbrock rpm dual plane and 650 holley DP,timing and jetting seem close.
I have a 88 chris craft 245 limited last season with stock engine with only intake and carb mods I got 50 gps with 21 mirage at 41-4200 rpm,46 with a 19 P mirage,now I get 50 with 19P and not sure on 21 yet,I had a vibration start as soon as I started planing with the mirage,I let out and put the 19 back to finish the weekend,I did not want to break anything yet,long weekend!! I will try to find out what the vibration was this weekend.? I thought I may have gotten a tad more,it for sure planes alot better but I hear people going faster than me with stock motors!! boat empty is supposed to be 3800 pounds.

The only thing I did not totally check is enough fuel at the top end,I need to continue plug monitoring to see if they can get darker,pretty light right now,can a (new ) stock pump flow enough?