MEANGREEN231

Well guys, after rebuilding both my SBC's one is acting up with only a few outings on it. I was cruising along at about 3,800rpms came up to a no wake pulled back on the sticks and the port motor tapped out. Got it restarted no problem, but you give it a little throttle under load and it just dies again. Idle sounds a little odd too, rev it up in neutral and the sound clears up, but then back at idle it sounds almost like a muscled up Harley.... When I first went out yesterday, when she was cold I had a little popping through the carb and driveability issues, once warmed up it seemed ok. Anyways, I am thinking a wiped out a cam lobe or two, three....whatcha think? Broke them both in for 25min at 2k-2,5k then changed the oil right away.

Other motor runs out like a top and pulls to 5,400, with no second thoughts. If the cam is wiped I think I am going to upgrade both motors to the XM270H or XM290H as I think the cams I dropped in were not what the doctor ordered anyway. I am wondering if the 290h will be too much and I will lose all my low end.

Twin sbcs
K&N 14x3.5 filters
edelbrock 1410 carbs
edelbrock performer air gap manifolds
RHS aluminum 64cc heads, factory 4 eyebrow pistons
comp 1.5 full roller rockers
edelbrock hardended +.100 push rods
224/224 @.050 282/282 advertised 465/465 cams with 114LSA
I run rotella oil with edelbrock zinc additive, and 93 octane pump gas.

Thanks, for any input

JJONES

Check for water in the float bowls

Griff

It could be any of several things causing your issues. Assuming its cam lobes right off the bat without checking the basics first is a stretch.

It could be as simple as water in the fuel.

dereknkathy

pull valve covers and idle engine. a little messy, but any gone lobes will be easy to spot.

mach1magnum

if the cam lobes have problems i would think you would hear some ticking coming from valve lash?

dereknkathy

sometimes not. the base circle is still there, just the lobe wiped off. and if exhaust is gone, it'll open just enough to idle, but blow fire back into intake at any load.

MEANGREEN231

If it was bad fuel I am pretty certain both motors would be having the same issue, as they share same fuel tank. I wish it was that easy though, so would the bank account!

As soon as my next days off come around, i am going to start pulling the top end apart, and see what is going on. Do you have any thoughts on the other cams I am looking at as replacements? Or maybe isky or howards cams of a similar profile. I heard isky does all grinds in house, so to me sounds like a better quality as who knows where comp has there production shelf came machined.

MEANGREEN231

Thats what I thought too, but between the thru hulls and the fact that the rockers dont always chatter loudly due to a bad lobe or two, I think I just missed the early warning signs.

CC230

I would check carb and ignition before going too deep. Hope it's something simple, bad wire or something.

picklenjim

Second that. I would seriously doubt it is a camshaft problem. Make sure everything ignition wise is cool, plugs, wires, cap, rotor, timing. Then check out the carb. A lean condition, for what ever reason it might be, will give you popping through the carb.