575sci ate a cam lobe....
 

Well, my 575 decided to eat a cam lobe... so.... I am doing a complete overhaul on it and have some questions...

First: Is it better to use a flat tappet cam again or hydraulic roller?

Second: Pending no damage to the lower internals, I was just going to replace the bearings, balance, re-ring, hone, ect, and re-asseble. What else should I be doing? I plan on rebuilding the heads too. The motor has 270 hours on it.

Third: Any upgrades to do while i'm in there?

Thanks

Todd

Hydraulic roller would be better but there is more work and expense to set one up, about 4 times the price of a flat tappet.

Have the crank journals polished and inspected to be sure it don't need to be ground.

Should be no need to do any balancing.

Being a 575 I would think it already has several upgrades, however the skys the limit. It just depends on how much you want to spend.

Do you plan on doing both of them???????

If not, you need to stick with the stock cam. You can make more power with a roller cam and that would be the way to go if you are doing both engines. You will also need to have the ecm's recalibrated and they should probably done on a dyno unless you can find a builder with a specific combo.

I recenetly rebuilt a pair of 575's . That is exactly why we decided not to switch to roller cams. It was impossible to duplicate the flat tappet cam to a roller. You can duplicate the lift and duration but not the ramps. The concern was the vacuum signal would be different, requiring the ECU to be re-programmed on a dyno. Once the heads were apart, we found most of the valves needed to be scrapped. Most were tuliped. A new set of Manley inconel exhaust and stainless intakes were installed, along with new springs, retainers and 10* locks. BTW... Mercury used 7* locks!! WTF!!

If you find you need some stock pistons, I have 16 of them available. We took the blocks .030 over to get fresh bores.

Thanks for the input guys....
As for right now, I plan on fixing motor, then pulling the good motor and going through that one as well this winter. It all depends how quickly I get moving. Last night I was ready to work all night to get it pull out but this morning I am slowly loosing my enthusiasm... So... We'll see... lol

I had a head gasket starting to let go on mine
a couple years ago, they had around 388 hours on them,
ran great otherwise.

I pulled them out, was planning to just do the top ends,
but found out the heads were cracked around the ex. valve seats.

That changed everything....I really couldnt see spending
good money on GM heads.

I got a hold of Dean Gellner, (he's done several 575 upgrades) I had him build me a set of Dart Iron Eagle heads,
his custom hyd roller cam, lifters timing chain and ECM upgrade that he uses in his recipie.

I had the block honed, decked, ringed and bearinged it.

They run great, probably picked up 4 to 5 mph,
idles good, they dont load up any more

Deans # is 216-398-8500

Since it sounds like you are doing both motors, I would do the cam upgrade, raise the compression to 8.5/8.75, reprogram the ECUs and raise the rev limiter to 5800.
There is also horsepower to be found by raising the boost from 4 PSI to 6. Just change your snout pulley from the 4" to 3.5". All this can be done and safely run on pump 93.
Your heads should be upgraded with the springs from the cam kit, and sent off to a machine shop for clean up and setting spring heights.
With more boost, these motors also like intercooling.
Eric Betty (EB Marine) has a ECU curve that should be close for this setup. I would bring one motor down to run on the dyno, and then duplicate that curve on the other ECU. Or you could dyno them both. EBM can handle your entire project.
We've done what you are doing (and more) to several 575s.
The good news is there is plenty left. The 575 is a well built, very undertuned motor from the factory.
Let me know if you need Eric's #.
Regards,
Steve

hydraulic roller, .030 over, .010 deck, a clean on the heads, Chiller and 3.5" pulley=704HP and climbing (rev imited at 5350) with stock ECUs. Fuel map is good. Figure I'd have to replace fuel system if I raised the limiter so I didn't. The engines have run great for 3 years.

Engine does not load up while idling through the cut for an hour. Not much soot on the back either.

This year I sent the injectors out for a check. Everything seemed fine, just being safe. 1 didn't flow at idle and flowed 15% more at WOT. The others flowed about 5% more after cleaning.

No noticable changes afterwards.

If the heads are in good shape, then i'd re-use them. If they arent, i wouldnt spend the money too go thru them fully. For not that much more, you can go to a better head. I'd go to some aluminum darts and bump compression to 8.5.

They seem to be in good shape. My plan is to have the heads completely gone through. Both engines are ready so I once I get this one apart and rebuilt, the other one will be pulled down. Definetly going roller... from the talks of it... I think we can make it happen. Not really looking for more power, just something that will get me by for the next few years. Then again... we are sooooo close to the triple digits mark....sigh.....

Well, here's un update...

I have gotten the block all the way down to pretty much bare nothing. Pulled the cam and it was definetly bad. The lifter that was on the bad lobe is about .100" shorter lol. Took a look at the cam bearings and they showed excessive wear as well so I called a friend of mine and we popped the old ones out and pressed new ones in. Prior to doing that, obviously we had to remove the crank and when we did, we inspected the rod and main bearings. All the rod bearings looked good except for the set that was directly below the failed lifter/lobe. That set have some metal go through but no damaged to the rod. The mains looked ok but I will be replacing those as well. Hopefully when the heads are done being rebuild (2 weeks or so), it wont be much longer till this motor is back up and running. Going to start the tear down on the other mill this week.... oh, the joy lol....

**UPDATE**

After I tore down the first motor, I decided to sample the oil to see what the zinc and phos numbers were.... SURPRISING!!!

In my hurt motor, the zinc number was 617. I run the Valvoline VR1 20w50.... or I did. There web site says they have extremely high zinc content. This is not high. Also, according to there site, the number should be upwards of double that. I highly recommend anyone running this stuff stop... especially those running flat tappets. I won't be running the flat's anymore but very disappointed in my findings....

Triple digits:drink::drink::drink:

Ch!t BIG Daddy that aint no good :eek: sounds like your well on your way and good luck ...:drink:

What cam did you go with Todd?

I got ahold of several shops but finally settled on a custom grind from RMBuilder (Bob Madara). I ended up throwing away the flat tappets and going full hydraulic roller along with some remapped ECM's... we should be around the 653 HP range prior to the super chillers. Supposedly those add 100HP... but let's say 75HP. So, when the builds complete, we should be pumping just over 725HP on each mill. I'm excited but trying not to goto fast and forget something. Got the first set of heads back from Jimmy Valako tonight after a full rebuild along with some light porting. The boat ran great before and now I cant wait to see what she does.... stay tuned...

Way to go on going with one of bob's cams. Should be a sweet setup!

Yeah, even from speaking with Bob on the phone, the technical service he gave was incredible. He seems very keen on building these cams and I'm sure it will rock! So far I am VERY impressed with him!!! Stellar Rep!

**UPDATE**
Cams are in, new timing chains/gears installed, heads on and torqued. Degreeing cam's tonight, hope to get pushrod lengths dialed in yet this week then get the valvetrain all buttoned up. Could be a couple weeks till we are dumping them back in the boat but I do see us doing a early november run... damn.... never thought I'd be wearing my snowmobile suit on the boat lol.... pics will follow once the project is complete.

You made a wise choice in dealing with Bob (rmbuilder). You're in good hands!

I couldn't agree with you more! Bob has been a pleasure to work with and has a vast knowledge of much more than just cams... I could chat this guys ear off for hours but all you others would never see your product lol! Bob, hats off to you, very pleased with the service... And will continue to use you for future builds at my shop!!!

**UPDATE**
Well, the reflashed ECM's should be arriving today along with the pushrods. The plan is to get the motors fully assembled this weekend and get them re-install into the boat this coming week. From that point, I'll fire them up on the hose, make sure all is well, throw the drives on and its off the lake for the shake down run. Just prior to the cam letting go, I bought a Go Pro HD camera and I think I'll try it out... Engine hatch will still be off when we hit the lake so maybe it will be a backside view...I dunno.... Anyway, just wanted to update anyone following the build up... Once she is complete, I will post up some pics of the teardown and rebuild...

nice read.... thanks for the insight

its off the lake for the shake down run.


know the feeling BIG Daddy we did the Lake in Nov last year 41 degree Air & 56 degree water :eek: good luck and hope she warms up 4 ya there saying 29 degrees 2 nite :eek:

Yeah, it will be a slower run that what were used to but more for piece of mind knowing that she's being put away soundly... I hate having to wait until spring to find out I have some problems still plus we are thinking of heading south in February so she needs to running smooth.