I sure wish this thread would have popped up last year before I dropped a bunch of coin on a custom cam setup. It's got my attention and making me second guess if what I have is worth a chit or not. Lucky for me I haven't fired it up or put it in the boat yet, maybe I need to do a little more homework before I go any further.

If you have a custom lobe and it hasn't been spun on a spintron putting it in your motor and running it is a crap shoot.

One thing that adds to this is that at 4400 rpm, the engine is working at or near peak torque. This is about as hard as you can be on an engine...peak torque, full load, max cyl pressure and really pushing anything that isn't just right.

Sometimes you can tell right off the bat, just based on the specs. Other times the specs look good, and you won't know until you try it. Essentially your engine becomes the spintron machine, on your dollar. Roll the dice.

Absolutely. The engine that rattled the tie bars off the lifters was in a guide boat. The rpm history showed the majority of the engine hours were between 3200 and 3400 rpm. Obviously there was something in that rpm range that was causing issues. The heads were hurt, and you could see the heat wasn't getting out like it should. That engine has over 700 hours on it now with a shelf cam. I just recently took apart another one, that was almost an identical build and it had popped the tie bar off one pair, and was about to lose another. I put it back together with a take out 500 efi cam and it's working well. Made a bit more power then the original cam too.

Good thread

Thanks guys

The best cam is going to be junk if all the supporting cast members aren't in the show. I'd love to see the geometry on some of these engines that have valve train problems and the cam is being blamed. Spring selection and set up can be really critical from some of these builds and the geometry on some of these after market rockers really sucks. We're fixing that. ;) .
3/8 x .080 wall pushrods aren't going to cut it either on most of these builds.

The Crower backset rockers take care of the issues on the intake valve for the BBC AFR, or shaft rockers. Of course the heads need a bit of clearancing around the pushrods when the geometry is correct, even with a 3/8 rod. The thinnest wall I've used on an NA build is a .096 Manton. But in reality, they shouldn't be required for some of the milder builds. I've got a pretty good handle on geometry at this stage.

I see the morel lifter name getting tossed around on this thread. Just had a set put in our 500's. They seem to be the company of choice by many of the top builders. Not just in the marine world but also the car game.

i don,t know about the higher hp engines from merc but every 502 based merc engine i have worked on has a 3/8 .080 wall pushrod.correct me if i am wrong about that.