RPMS with a 540
 

Guys,

I'm having a strange problem with my 540s...

It seems that no matter what props we try, the most I can get out of these motors is 5000 rpms... I've gone from 26 all the way up to 30" Bravo I propellers and cannot get these motors to turn...

I have Weiand Team G manifolds with Barry Grant 1050 carbs and Gil exhaust. Do you guys think headers and smaller carbs would help me breathe better and get more rpms?

how about rejetting the carbs.??? I think we are jetted pretty fat right now but I dunno...the guys at the shop have some ideas, but I thought I'd post here as well...

Any thoughts?

Turning some RPM
 

What camshafts are you running? Lift, Duration, Lobe Separation Angle, Intake Lobe Centerline?
Sincerely
Dennis Moore
FAMILY AND PERFORMANCE BOATING MAGAZINE

You're out of cam.....what heads are you running?

Sean, did you buy these motors new or rebuilt? I don't mean to start any trouble but it seems you have been having too many issues for new or rebuilt motors. Hope you get it straightened out so you can post some #'s for us. I don't think we will be bringing the boat out East anymore this season, but a Claudio's run always gets my attention!:D

Sean,
Just a thought, but what are you running for fuel supply?
Maybe you are running out of gas, when you get into big cubes having enough fuel supply is critical!
Also, ignition, timing, or rev limiter?

What do the plugs look like? I bet they are looking lean. I agree with TomR, 540's like alot of fuel. A friend of mine is fighting this same gremlin with his 540. He is finally going to upgrade his fuel system, too bad he is doing it at the end of the season, at least it is for us in the North East.:(

i got a go with the latter of comments, fuel supply is running out, had that problem along time ago, when i built some 496's come to find out that the fuel system was plumbed wrong in series with electric pumps. (that way from cigarette) changed a tee fitting and picked up about 500 rpm's.

have you tried to trim up until the prop blows out. still no change in R's would be the rev limiter.

i forgot to add, a capacitive discharge ignition with rev limiter can be affected by the wires being too close to other wires no matter what your limiter is set at.

I had the MSD digital control box in my boat. Motor woud scream up to 4K but after that would fall on face. I then changed to the old analog box & motor went to 5650. I had called MSD & they said exactly what ex42 is saying. Only with the analog system I had the extention cable installed with wire going over every other wire in boat & it worked. Digital box mounted next to distributer & no high RPM's. MSD said their digital box was not bad. I am now running the 6L box (not sure of complete part # ) & motor now raps up