mopower

OK cam garus , I'm looking for some advice for a pair of 540s. Last years cams turned out to SUCK big time per Comp's suggestion. Had 700 hp and torque all over 6000 rpm. Told them it's a boat and max out at 5/5500 rpm. Their head engineer now sez my present cams are too big.
Had 3371/3372 Comp Cams with 647 In/ex lift. 254/247 @.050 and 111*sep.
Now suggests 3376/3377 with 612 In/ex lift. 240/250 @.050 and 112* sep.

These are 540 Merlins with rectangular Merlin iron heads. CR 9.75:1

Thanks

Monty

I used Crane 741 hyd rollers (234/242, .610"/.632", 112) for 698hp@5600 and peak 683tq@ 4600 on my 9:1 540's. This cam is popular and gets recommended alot, but it helped me meet my power goals and it idles smooth and strong at 850rpm.

mopower

Thanks. That's what I'm looking for...real life , not a salesman. My others would die when you put them in gear or if you set the idle in gear , when you went to neutral they would be idling 15/1600

KNOT-RIGHT

I use the 741 here myself normaly asperated.
They idle at 800 and pull well past 5400.

Just did complete overhauls for installation of blowers.
keeping the same cams.

Great cam for my use.

Just my 02
Gerry

blue thunder

Mo, did you ask them about advancing the cam to bring the torque band down? Can you use pump up lifters to help the idle quality. Or are you just done with these cams and going to the 741s?

Dave

mopower

Well Dave , I think I'm just done with these cams. These engines would have made some bad azz 1/4 milers , but in a boat they really sucked . The torque and hp was so high they topped out at 4700 with 28" Bravos If I went back to my 25 Mirages and spun they 62/6400 rpm they probably would have run like a raped ape. I gotta get a printout from the dyno , but if I remember correctly around 46/4700 rpms I only had around 425 hp.Most HP500s in 35' boats have 28" Bravos on the rev limiters. The vacuum at an idle was only4" and when you put them in gear and the r's dropped the vacuum went right down the chitter. So it wouldn't pull fuel and die. open the idle screws three full turns was a help , but kick it up to 1200 or so in a no wake zone and vacuum went to12/13 inches and I was fouling plugs
The power band of these were just plane toooo high.

PatriYacht

I'm running Crane 651 cams in my 540's. They have .630 lift, 246 int 254 ex @ .050. They idle easy at 800, no stalling or plug fouling. This may be the result of fairly high compression 9.5 and 16 deg. initial timing and MSD. You may be right about the power peak being too high to use in a marine engine. I may have the engines dyno'd this winter as they're out of the boat now anyway.

Cord

I have a 741 in my 540 engine. Very happy with it. I have 10" of vacuum at idle.

blue thunder

I see your position Mopwer. I think I've heard the crane 741 cam is good in a boat.... just kidding guys, what better recommendation could you get on a cam to switch to then from the guys above?

Just make sure you have attained correct problem definition as the cams. That kind of disappointment once is one thing, twice is a killer. I'd hate to see you spend all the $ on cam changes to get the same result, then find something else unrelated was the problem.

Good luck,

Dave

mopower

[QUOTE I'd hate to see you spend all the $ on cam changes to get the same result, then find something else unrelated was the problem. [/B][/QUOTE]

Not half as much as I would
Tomorrow morning I'm tearing it apart. I'm gonna check comp. and leakdown one more time first , then check the cam postion. (make sure it's in right). If so , then order the new cams. But I do share your feelings exactly.
Last summer I spent unnecessary money on this problem that didn't work , like different ignition modules and new flame arrestors.