540 Cams???
 

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

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.

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:eek:

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

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

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:hothead: . 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:eek: 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:hothead:
The power band of these were just plane toooo high.

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.

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

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

[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:hothead:
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.

I don't know about you Cal, but I'm think there may be a lot of rpm and speed lost in my rigging and hull. I've had a similiar result to yours (last year) and have been wondering if I may be hitting a wall due to X dimension and other issues. Audacity used to speak of that often and I think he may be very correct. Have you considered these things? I know the one rigging related change I made last year to spinning the props in made a huge difference in hull attitude.

Food for thought........ ;)

Dave

Hmmm:confused: Point well taken. But the boat (Formula 272) did exactly what it was expected to do with the 330's and would run with the best of them. I did hear of a guy on here that reversed his props(same boat as mine) and claimed to pickup 3 to 4 mph:eek:
I'd talk longer but I'm at work and have a problem at the moment...really gotta go
Cal

OK Blue I'm back. Everthings cool.
Now like I was going to say. The boat did 68/69 gps with 330s. These 540s @ 46/4700 rpms on the dyno were doing 425/450 hp. That gained me 7 to 8 mph. Just about right for a 200hp gain. I was going to try my old 25 Mirages toward the end of the season just for the hell of it but didn't have the heart to twist the engines that high:o. I do believe there's ALOT more speed to be gotten out of this. Just have to get my power band down to a reasonable level. I had 700ft lb torque in the high 5000s and 700 hp @ 6200
Anything will go faster given Mopower:D :D

My last boat was a 21'FourWinns Liberator with a 625hp 540 and could easily bury the 80mph speedo. That one my torque peaked around 710 ft lb@3700 and 625hp @ 5200. No gps back then. That was quite a handful:crazy: You could be doing 50 and it could still plaster you in the seat. Only trouble it was a Ford

I would really like to know what the OSO knowledge base thinks the result would be to Mopower's situation if he advanced cam timing 4* and used pump up lifters. Would the advance bring his torque band down into the low to mid 5k range and would the pump up lifters fix his low vacuum at idle problem? At 4" of vacuum the power valve was likely opening. I think these two changes may have a good result.

Other than that Mopower, my boat was a pig with the props spinning out. Probably due to hook in the hull. Spinning in gave me a good 4mph and made the boat loosen up. What was your boats attitude last year at WOT and trimmed... bow high, low or in between and managable?

Dave

Dave,
I didn't get to it today as planned , but I think my cams are in at +4.
At 77mph and trimmed slightly over center it was quite well behaved. It held the bow up with no porpoising. That was turning out , with 28" Bravo ones.

Cal

Sounds good Mopower. I run a set of 27p mirages plus props. Would have been nice to give them a try on yours last year. Maybe next year we can get together on the Chesepeake and do some prop testing. That is unless you are spinning 32p props by then :cool:

Dave

Mo,

My personal opinion is that I believe those Comp cams of 247*/254* are too big for a 540 inch marine engine. The following info I have laid out is something I believe might help you in your decision when it comes to making a cam selection.

I had some Crower hyd roller cams 236*/244* on 114* lobes in my naturally aspirated 540's that are almost identical to the Crane 741 cam and they worked very well. In fact, the Crower cams I had were a hair milder. The Crane 741 usually comes with 112* lobe seps which is fine. My Crowers idled at about 800rpm in neutral and with 160* thermostats and Crane Hi-6M ignition box and MSD crank trigger fire it idled down as low as 550-600rpm in gear. Those cams made for very smooth shifting and manuvering around the docks, wind, water currents and boat traffic. In my 8000lb+ (dry) 32' A/T I was able to turn a pair of lab finished 32" Bravo One 4-blades to 5600rpm. Hope this helps a little.

Mark

Kaama, havent seen your name in a while. Good to hear from you.

Blue - I nix the pump-down lifters. Old tech. Band-aid.
They are only helpful to increase engine vacuum at idle to near-idle. This was a plus in overcammed street cars that wanted an erratic idle but didnt have enough vacuum to operate power brakes. Modern cam profiles should provide acceptable idle qualities if matched to the correct build spec and compression. Contrary to street talk, pump-down lifters do not have enough pump down effect above 2000 rpm to provide for any torque increases worth considering. If their orifices were sized large enough to provide for that, they would be hammering the entire valvetrain to an early demise.

+4 to +6 is advised, but many cams these days are ground with the advance built in.

When I was about 25, I specced a roller cam for a really hot stage 3 440 Chrysler with a race-tuned 6 pack setup (yeah, I know, but friend was a 6 pack nut and did not want to go dominator - although the 6 pack setup was 1100 cfm so it wasnt hurting for flow). This was in a B body Coronet.

I thought about it and picked a .710 [email protected] on 105.
It was the baddest sounding thing you have ever heard (it was a race gas 13:1 motor). Idled at an angry 1500rpm.

Launching at 3500, it STILL had a NOTICEABLE soft spot and a steep power peak. Pulled hard thru 7600, but not like I had expected it to.

Realized the mistake and sent it back.
Reground it to .660 and [email protected] on 108.
Car became a monster.
Now idled at 1100 and sounded ALMOST as good.

Same car now runs a 535 inch hemi with aluminum indy heads and twin 700 Carters on a crossram. Built right and touches 900hp thru full exhaust (race gas motor again). I left the cam choice to a Hemi expert even though I have made and fixed a thousand mistakes since the 440 cam episode so many years back.

Too big of a cam in a boat is much worse than too big in a car. Just turns it into a soft turd.

Thanks Kaama , I think it's to big too. And so did my engine guy, but I believe it was James at Comp insisted it would be ok because "it's a 540 and should be able to handle it" WRONG:hothead:
Comps head engineer sez it's too big too, now:rolleyes: . Well thanks for yoour advice:mad: Talk about being a day late and a dollar short. Not to mention one lousy boating reason with a number of embarrassing moments try to dock with engines that didn't want to idle and a tide that woulldn't quit:o
Your #'s and the Crane 741 look a whole lot better. Something new will be ordered this week. Just have to get the power band down and the idle vacuum up and all shoud be good;)
And Mc. Your right , it is a turd:(