Madmax

What kind of symtoms will a flat lobe on a cam cause? I'm kinda worried I might have one. Also, it's a roller cam, do these go bad very often? Thanks.!

Drew

Usually have trouble with a lifter that can cause cam wear as far as roller cams. Are you running a hydraulic roller or solid and what kind of trouble are you having. Noise or backfire through intake or other problem. How many hrs on parts. Cam profile and spring rate have a big factor in wear. Just my .02 I am no expert.

Madmax

It's a fresh hyd roller cam that i just put in. Seems to have a miss at all speeds, but no backfiring. Compression on all cylinders is good. I'm thinking more ignition problem now..... I'll letcha know. It's a weird one mainly because it's got a new cap, rotor, wires, plugs, and didn't start doing this till I put the new cam in.

HiPerf2000

iTrader: (2)

If the lobe flattened, there should be signs of the lost metal in your oil / oil filter.

Madmax

mmmm good idea about the filter, i'll check that also. Didn't think of that one. My hope is that it's some kinda ignition problem. It's a Thunderbolt 5 settup, anything that goes frequently wrong with these, or is it usually a go/no go settup? Anybody have luck with the MSD settups? I've seriously thought about converting because the Thunderbolt 5 settup is impossible to get a big cam to idle nice with since you can't advance it...

Turbojack

What MSD box are you using? I had the digital box & have ended up throwing in trash due to problems it has caused me.

On cam going flat.
Remove valve covers, pull kill switch & have someone crank engine over on starter. (Either hook up water hose so you do not burn out water pump or remove belt for water pump beforae starting this.) Watch rocker arms. if one is not going down as far as the others than you have a problem. If everthing looks good than probably this is not your problem.

blue thunder

A vacuum gauge reading would be perfect for diagnosing your symptoms. A valve issue will show up clearly. I think you probably have a simple but elusive ignition problem though.

Good luck... and btw where do you run your boat? The Cedar River doesn't support much more than a tube from what I remember.

BT (born and raise in Waterloo, Ia.)

jpclear

Pops back thru carb when goosed. (I think I know her) --- Jer

excaleagle42

i had a lobe go bad due to a stuck exhaust valve. like jp clear said, mine was popping back through the carb at any rpm over 3400. you may want to double check your wires to make sure the firing order is correct. and the wires are seperated well too. hopefully it's something that simple but easily overlooked.