Merc SC525 cam
 

What cam did the Merc SC525 run???

I have a 7.4 with a b&m 174 and she is out for winter and to get properly setup for the blower and i figured i might as well do a cam change if i can get some more HP out of her.

Is there a better cam to be runnign than the one that wa sin eth sc525?

I am running CMI headers and custom tailpipes taht will be pretty much dry except for some H2O mixxing right before the tips at the transom. (fully dry with H2O exitting seperate from eth exhaust was just to damn loud!!!)


Also i am running a dominator 1050 I think it was SUPER rich last year (only ran it for maybe an hour so i didn't get good test time) What wodl be the proper setup for this carb for my engine (i bought it with teh blower and it was supposedly refferenced to the blower adn engine setup)?

Puder,

Did you do any ignition upgrades? I found that what I thought was rich condition, was cured immediately by adding an MSD box to the merc V6 module...

mmmm well i do have 2 msd brain boxxes just chillin somewhere in my garage....

I have a thunderbolt 4 witha 24* v-6 module

how do i hook up the MSD with the tbolt4? I bough the brain boxxes about a year ago thinking i was goign to use them on a project boat that never happened. I weas goign to run the full MSD setup.

I tihnk i am runnign rich fora few reasons. The plugs looked funky after only and hour. After installing a blower and teh new carb I saw little if any gains and my exhuast was running SUPER hot. My tailpipe were totally dry (no h20 mix) and they got so hot at one point they were glowing a tad. It was night when i ran it so i could see them glowing.

You would hook them up like the points style diagram in the MSD literature. Basically, the two wires from the thunderbolt module that go to the coil now, would go to the MSD box instead and the MSD box would connect to the coil. It only acts as an ignition amplifier. Also, you would need to remove any other wires that currently go to the coil. They go to misc places. The MSD box is the only thing that connects to the coil. I can send you the MSD wiring diagram if you need it.

My new motor would foul the plugs in 2 miles of running on a new set of plugs. Not just a little fouled either! Not just at WOT either, 2500rpm. This never happened on any other engines I have ran. I kept chasing down carb issues, but they were new Nickerson units. Couldn't see how they could be that far off. Him either. Finally pulled the motor and put on the dyno. Should do that at all COSTS!!!! Added the MSD box and the torque instantly gained 30 lbs. Tweaked from 30 to 32 degrees of timing and gained 60 hp. All told we found ~75hp in an hour! Also saw what the hp and torque curve looked like (different than I thought it would be for the cam I was using) and realized that I had made a mistake changing to 1.36 gears (ears are burnin). The motor made it's max power at 5900rpm instead of 5500 like I thought it would.

Ate up all summer doing this. GO TO THE DYNO!!

Wouldn't hurt to send your carb to someone who knows what they are doing. If it is a old Nickerson unit, get the stamped number off of it and give him a call. He can look it up and give you advise.

if you could e-mail me the wiring diamgram I would be super appreciative.

My coidl is lookign kind of old and funky shodul i replace it with the msd one? And is there a specific marine version i should get or will a car one work fine?

The MSD box is actually spec'd to use with certain coils. It puts a much higher primary voltage on the coil. I just happen to have a new MSD blaster coil still in the package. Made a mistake and ended up with an extra a long time ago. You pay shipping and it's yours. I'll also look through the manual to see exactly what you would do with any extra wires on the coil. What year is your engine package originally? What model MSD box do you have?

puder, the Merc 525sc cam is Crane #132561. Its a flat tappet with 228/236 duration and .530/.551 lift on a 114 lobe separation.

MSD 6M-2

brainboxxes. I would gladly take that blaster coil off your hands.

my address is
71 buckram road,
Locust Valley NY 11560

what is your address?

I'll get it out today. I took a look at my seloc manual schematics and it looks like you would simply lift all the purple wires off the coil as well as gray ones, how ever many, (keeping them together) and connect them to the input of the MSD box. Then the MSD box output goes to the coil. One of the grey wires is for the tach. Many other things (sensors) might use an additional purple to get ignition 12v power from the key. I had to go through this some time back with the engine on the stand and completely took the wiring harness apart to see what was going on. Many changes since the harness oriningally came on a 7.4L with knock module. That's why I can't exactly say how many other wires will be on the coil, but they all stay together and act as an input to the MSD box. BTW, my MSD instructions are for a 6AL. They might just be the same though, but I forgot to bring them in. I'l post tomorrow what the hookup is.

I Don't think you will have a rev limiter with the 6M2 box and the Merc V6 module.....

Have you thought about having your motor dyno'd? It's very informative to be there asking questions and learning what works and why. It also helps to know exactly what the motor is capable of and where rpm wise when the motor gets back in the boat.

You have a message.

Puder check your email

I hope this helps

Puder,

Lift all the purple wires off the positive of the coil and attach them to the red wire of the MSD. Lift all the grey wires off the negative of the coil and attach them to the white wire of the MSD. Connect the orange wire of the MSD to the coil Positive and the black wire of the MSD to the negative of the coil. These should be the only wires on the coil. Then there are two heavier gauge wires, red and black, comming out of the MSD. They go to the battery and the additional magnetic pickup pigtail from the MSD is not used.

Now you will still have the same advance curve as before, but instead of the ignition module pulling down on the negative of the coil and inductively storing energy and releasing to the secondary, the MSD will internally charge a capacitor to 400v and apply it to the coil when the spark is needed. This will result in more energy and more voltage to the plug.

Cams
 

I have two sets of those cams for sale cheep if any one is intersted.:p :cool:

Brad's right, I have a MSD 6AL with the Tbolt IV and this is how it's wired. Iknow its a 6AL, but tell me how my motor notices the diffrence?

if i wanted more power what woudl be teh "next step up" in cams? I hav enever selected a new before so this is new teritory...

ANy help and input would be appreciated.

FYI the engeine started at a 330hp gen IV 7.4 so i have teh cast crank and such. Would a hotter cam and teh blowe rbe TOO much? I figure i would be safe with the sc525 cam becasue merc used a similar setup but used a tame cam for reliabilty. Input please!!!!

I was also thinkign abotu adding roller rockers. Now i have teh stock stamped rockers. With the sc525 cam would I have to use them? If i don't HAVE to use them woudl it be a good idea or worth soem HP if i did?

Puder, the roller rockers are a very good idea. The blower is to small to support more camshaft, stay with the 525SC selection. You will likely only see idle improvements with the MSD amplifier, typically engines of your combination don't benefit from the amplifier. The coil upgrade is always a good idea.

thanks for the quick replies.

Bruce maybe you can help me out with carb setup too. I have been told mydom 1050 is too big for this setup. I think it might be. I didn;t get much test time last season but when it ran i saw very little performance gain. Even afetr an hour (at most) my new plugs were already funky and looked pretty fouled.

I bought the blower and carb from a member here who had it on a 454 mag and said it (carb) was referenced to the blower. I still think i am runnign SUPER rich. If i was runngin very rich I would assume my performance woudl begreatly hindered BUT would running very rich also cause very high exhuast? I am runngin CMIs with water jackts and such. But i have custom tailpipes. Last season they were setup fully dru with no H2O mix at all and no water jacket on the pipe from eth headers to the tips. BUT at one point they got so hot they were glowing (at night). Woudl runngin rich cause this? A buddy of mien though if i was blowing unburt fuel out of my heads that mayeb it was burning in the pipes and causing the heat. (just his theory).

In any event. what would be the proper setup for this carb? I was thiknkign i might run it on a dyno but i wanted to get it close before going to a dyno. Oh yeah right now it has teh stock cam and large performance oval heads.

Thanks,
puder

Puder,
Bruce did a complete go over on my 1050 Dominator. Boost referenced it as well. It is a totally different animal now. Runs and idles great! The carb work alone has been the best money I spent on my boat since I bought it a few yrs ago.

Puder, I remember your custom exhaust tailpipe story, it truely brought tears to my eyes with the description of glowing red pipes and single wall tubing. :D The dominator is a good selection for your blower application, the 525SC uses it. That said the dominator series should be tuned by someone that at a minimum, knows what air bleeds, emulsion tubes, squirter nozzles and throttle blades have in common. If you don't know what these components do, don't screw with your carburetor, it will likely get worse. Most shops that dyno engines will calibrate the carburetor as part of the dyno process. Ask around, there are many good shops in your area. I'd suggest you have your engine dynoed, they can correct your carburetor issues at the same time. DanL can give you some unbiased input on dyno facilities, he has probably used them all at one time or another. :D

I've got to type faster!! I start my reply and two people have posted before I'm through. US1 Beekboat, THANKS for the kind words. We still on to dyno your monster Tuesday? All is now well in dyno repair world, it will be re-calibrated on Monday. :D

Bruce,
Yes, planned on Tue from your message. I will call you Mon while at work to double check that your up and running.
Thanks
Jerry

bruce thanks for the info. I will throw dan an e-mail. He set my brother up with a good mechanic for his (POS in my opinion)lotus. (you didn't heae me say that :D) The damn thign was all f-ed up 9k to get her running right again!!!!

So teh 1050 dom and the new cam should be ok huh? As for making more power she needs a dyno run huh. Just get her back in shape put teh blower back on and let teh dyno tech take care of setup? I have never done a dyno run before so what do i need to know?

As for my tailpipes. I am converting them to wet pipes. I have few option to do this. IO might just put plain old H2O dumps in in eth last 4-6 inches and dump a hell of alot of wate rin them to cool and cut eth noise some. Its just too loud. If i am dumping H2) into them an dteh engine is runngin normal will i need to put full on water jackets on? I'm not to worried abotu reversion becasue of teh way i am putting the dumps in. I will post a sketch of the deisgn of them. If the dumps idea doesn't work i am goign to put full on jackets on with dump ports drilled into the inner pipe so the wate rwill flow from the jackets into the main pipe and mix. It going to be tougher to make this but it will cool better.

opinions on that woudl be appreaciated.

i posted the pics on my website they are bigger than allowed here.


Opinions please.

Jacketed Version Sketch

Non-Jacketed Version Sketch

one more question. What should my water temp be around for this engine? What about oil temps?

actually i have a ****load of new questions!!!!

bruce is it cool if i call monday to ask you a bunch of questions? If so please e-mail me with your number. [email protected]
thanks

Puder, do those pics show the actual design needed with the tailpipes above the headers?

yep my exhaust tipsa re above the rub rail withe manifodl i had 4" spacers between the manifolds and risers. So i needed tailpipes with 2 angles in them. The CMI exits angle down. So the first piece is short and connect the tailpipes and has abotu a 45* turn. The middel part about 10" long is where the (jackets would go) get connecteed to the third piece on about a 30* angle to connect to the tips.

My only other option was to glass existing exhuast tips holes and put the tip in lower so i could use standard tailpipes.
Or get super expensive custim height headers.