I have a Pro Drive that I have been working on over the last couple of years. Last year I added a muffler, modded my stock carb, added a cam, modified stock intake, had some head work done and added stainless valves(stock size). I just had my heads worked on again. I had new larger SS Valves installed, they bored out the existing seats with new larger seats installed, and added roller rockers.

I do not have the boat back so I have not run ti yet, but my WOT out of water RPM's are now at 4490. I originally had it set at 4250-4300. What would be the appropriate setting on motor with these mods? As you may be able to tell from this post, I am learning about these engines, so your input is appreciated!

I know 4250 is the standard answer. Thoughts?

If your valve springs are shimmed then 4500-4600- the stock connecting rods are your next point of failure.

Thank you Gary. I will probably just leave it where it is then, and see how it goes. Not sure where she is going to turn under load yet. I may adjust it down a little after I run it, but we will see. The springs are not shimmed, but I have dual springs installed. I forgot to mention that. I am finished with the mods now. I may add the Mikuni, but that is going to depend on how she runs. Not sure if I want that hassle though...

Newton,
Did you have Sid work on your engine? Did the last guy do what you paid him to do?

David- Not yet. Sid has had a hard time getting the Mikuni, but he has them in stock now. From what I hear, the head work turned out really nice. Tim, Steve's buddy reassembled the motor, and he was really impressed with the work. I am picking it up this Sunday. Steve said the motor is running really smooth, and just sounds really tight. I found out during this process my intake was shot. I had two broken bolts and three cracks/holes in it!! I have no idea how this happened, but this could have explained some of my problems... Tim also re-wired my fuel pump to turn on with oil pressure gauge rather than the key. This will keep the FP from turning on every time I turn on the key. It will kick in only when there is oil pressure (when I am running or try to start the motor).

I haven't been out scouting yet. I have been slammed. Looks like I am going down to Broadmore for the opening, and then probably over to "Kissimmee" to wrap it up. What about you? Gainesville? I will let you know if I get on them.

I would set it at 4250.......I WOULD NOT be turning an engine with stock connecting rods 4500-4600 rpm!!!

he keeps the push rods stock.

I ran my last motor at 4500 RPM for over a 130 hours with stock connecting rods but not much over that.

You are right- I wasn't thinking. Hmm- maybe I am not finished with the mods.... Are most guys who have gone this far replacing the connecting rod's? And I guess my original question still holds though, as this seems to be my weak link today, at what RPM range do they begin to fail? Thx.

And last question- Assuming I change the connecting rods, then I would assume the push rods become my weakest link. When do the push rods begin to fail? This is actually very helpful, so thank you for the info!

why not just run a bigger prop? Your speed will go up and your RPMS will go back down to where they were. Maybe mud motors are different, but I'm a big bass fisherman and we keep the RPMS where we want them by changing the size of our prop.

In the 5000 rpm range.

Thx guys. i appreciate the info!! Connecting rods may be in my future...

My advice to you......leave it alone! Leave it just the way you have it and be happy!

probably good advice!