I run single plane on mine 540ci tall decks 650 hp...bottom and mid range is fine

The 741 cam is an excellent cam, but it doesnt make its best until approximately 6500 rpm. Here is the dyno sheet on my 540. Its a Dart Big M block, Brodix bb-2x heads and a custom ground cam from Competition Cams. Notice the power at 5300 rpm. When I talked to the Comp people, I told them that I wanted to have peek HP and torque at around 5000 to 5300 RPM with a max rpm at 5500.

Rehr & Morrison did the dyno and I dont believe any numbers were fudged as I had done to me from a prievous well known motor builder that claimed his dyno said the his motor was making 631 HP. I ran my boat and it went 1 mph faster than it did with my original 454 motor. We pulled the new motor out and put it on the dyno...2 different dynos. The motor made 535 HP on one dyno and 537 on the other...no where near the 631 that was claimed.

The 741 is almost the same as the 502-525HP EFI cam. The only difference is the lsa. On the 741 it's 112 degrees, 525 is 114 degrees. The 525 will have slightly better idle but not much. With the 990 heads and 540 ci., it should make peak power at 5400 or so. Using larger port aluminum heads will make the power peak at higher rpm's. Overall the 741 is about the best cam you could put in this engine. The 731 isn't a bad choice either. It would idle very smooth, peak at 5000 but be down about 50 hp from the 741.

That's a potent engine! Could you tell us what carb and intake you used and can you post cam specs? Thanks, I'm curious for my 548's with AFR 335 CNC's Good bsfc also.

Im running lightning headers!. What cam was the Mercury Racing Bulldog originaly came with.? Intake and heads? and what makes it down to only 470 propHP ? just to compare why it is so easy to make op to 600HP

if you look at dyno runs on the single plan vs the air gap you see the #'s on the air gap are stronger thru the mid 6000 range before the single pulls ahead, and the torque is never as good..and thats what marine power is all about

I have never seen that actually happen, but if you have, then you have.

Maybe it was the cam, or the heads o the way it was set up.

Good information to know.

Had friend just get off of the dyno 540 with the 741 cam, ZZ502 heads (originally a ZZ502) dart single plane. peak torque 660TQ @ 3800, 600HP @ 5200 and then started started to fall. The heads were only chamber ported to raise CC's for new pistons.

540 - AFR 305's, Victor manifold, 1050 Dominator, 1" hvh spacer, jessell shaft rockers, RM Builder cam. pump gas with all accessories and wet exhaust. I asked for a 4800 peak tq, 6000 peak hp, and that is what I got. Bob Madera is the man: 585-654-8583. My 540's power fell of extremely quickly at 5000rpm with an dual plane air gap manifold on the dyno.

The carb is a single Holley Dominator 1050 and the intake is a Merlin single plane, portr matched and blended under the carb. Cam specs are .244/258 duration with .651/646 lift and 112 lobe centers hydraulic roller Comp Custom grind. The heads are mildly tricked Brodix bb-2x by Rehr & Morrison.