525SC Rebuild Recomendations
 

Rebuilding the power plant in my project and need some OSO advice from those who've been down this road.

Goal: 500-575HP, where I can run my Bravo 1 and keep it together for more than 2-3 seasons at a time, I'd like to make this thing as bullet proof as possible and get 300-500 hours out of the rebuild. Not super concerned with how fast I can push the boat, it's a 75mph boat with the Orig 525SC set up and that is plenty fast enough for me as it'll be used mostly on the river with occasional western US lake trips, some skiing & wakeboarding.

Current Set up: 94 -27' Warlock world class, Weiand 177 with super chiller over driven at 2.15:1, stock 88 rectangle heads, Brand New Set of Hardin Marine Orig replacement manifolds (420-901180-MER) with orig Gill E-top, through transom, original manifold water ports seem to be ok (if not I can weld it up and machine it), 12" K planes, external power steering, Bravo 1 outdrive, 26P 4 blade Bravo prop. (let me know if I missed something).


I have the block stripped and it's time to send it out for machine work but I need/want a plan before I start having work done and I could use your help Griff & Mild Thunder


I've done a lot of reading and have gathered a few recommendations so far, here's what I think I have, take me to school please:
-I have water damage in 2&8 and will most likely need to go 30 over, so that means new pistons & rings, if a power hone (CK10) can't clean it up or it'd be out of spec.
-If it needs a bore, probably just do the speedpro OEM +30 on the pistons
-Not sure on the rings someone said Total Seal AP top & Napier 2nd?
-The motor came un-ran with a mystery cam, so I'll need to buy a new cam, I can go Orig, Crane 132561 ($260), OR is there a better one for my application (I think roller might be out at over 1K for the switch as I'm not sure if that money is better invested in heads or roller)?
-Heads have been redone but I'm not sure what's been done or how good of a job they did, so most likely Redo the heads or get new ones depending on price (Young Performance quoted $1,800 for the full boat and all the new parts on the OEMs)
-If I stay 88, replace valve springs with ISKY 8005-A, and new 10*retainers & Locks
-If I stay 88, replace head bolts with ARP bolts, which ones/part numbers?
-Replace head gaskets with Cometic MLS 40 Head Gaskets
-Replace the rod bolts with ARP, which bolts fit the original rods or is there a better option to keep them together?
-Has Orig Merc TB IV, with a MSD blaster coil & a 6L box (not sure if I should run the 6L box?)
-Has original Distributor & cap, should I get a new one, if so which one?


Other Misc things I need to address:
-Like to get a stainless manifold riser set up as the cast one is in pretty bad condition
-Need to replace raw water pump, maybe with a stainless one, hardin, CP, do they make just a stainless intake and use the OEM plastic housing?
-Mechanical fuel pump needs to be rebuilt, who has the best parts?
-Need a fuel/water pump pulley, is this the same as the power steering pulley? Can I just get a black one and paint it Merc Racing Blue?
-Need a sea strainer or sand strainer for the Super chiller as it has no filter on it now
-Need a new harmonic balancer, dyco was mentioned?
-Need new oil pan, go with billet or just stamped steel so things can escape if needed :)?
-Need new Windage tray, solid or screened?
-Should I get a new oil pump & pick up, or is stock sufficient?
-Does this motor need a billet timing cover to help it from flexing or does stamped steel do the job?
-Need new timing gear & chain, what is a good set?


Let me know if you need more info.

Thanks
MoHav

Do a cam or aftermarket heads, doing both will put you up there...

For reference I am just finishing a build... 454 motor with a 731 cam and AK heads, .030 over and went to 8.5:1... 525sc blower should be a little over 600 hp,

Delete

If I did Dart iron eagle heads which ones should I look at, 345?

Making 575hp will be pretty easy.

For your power goal and budget, I'd just keep the 088 heads.
Bump the compression ratio up to about 8.25:1
Go with a roller cam. An off the shelf Crane 168731 will work well. That's what I put in mine.
I would send the blower off to be inspected and rebuilt. I've heard very good things about DMPE Inc. / Home page
As long as the TB IV distributor is working well, I'd keep using it.
I assume you are still running the Merc timing advance module and using the rev limiter on the 6al. I'd keep using them also.

If I keep the 88 heads like you've suggested and upgrade the cam instead what do I need to do to the heads and what parts do I need to put in them? Valves, springs, locks & retainers, head bolts, machine work etc? If that's the case I'm still dropping $1k to 1.8k to try to make them right in addition to the cam upgrades.

If I do one or the other, is it better to run the less expensive flat tappet set up and dump the money in to better heads like some iron eagles or brodix bb2s or put the money in to the cam and run the stock heads with spring, retainer, lock, arp bolts upgrades only?

From what I think I've read, doing a cam upgrade without going through the heads is only asking for trouble, as these heads have notoriously weak springs and possibly other issues?

Thanks


I'll check on the advance module, everything else yes

You'll need new head bolts, springs, retainers and locks and seals the same as you'd you'd need with a flat tappet cam.
No way to determine what else the heads might need until they are inspected at machine shop.
The biggest cost factor will be if they need new valves. All new valves will add about $800.

You can't just buy a set of aftermarket heads complete and expect to bolt them on. The machining tolerances are not good enough and they would need to be torn down and checked. Several people have found that out the hard way.

Stock 525SC valve springs are not notoriously weak. They do loose pressure over time and hours, but the stock cam is not very big and does not overly stress them.

I made 572hp@5600 with the following setup.

Stock crank and rods
TRW 2399 pistons
Crane 134561 cam with recommended springs
stock 088 heads
525sc blower setup
I have over 100 trouble free hours on it. Im very happy.

79formula's recipe is exactly what you need to do what you said you wanted.

ARP rod bolts are great, and I would use them if you plan to run 5600, but you WILL need to have the big ends resized if you change rod bolts.
Stock crank is fine. If it looks great, then use it. Set your bearing clearances for 40wt oil.
Stock oil pump size is fine - if you plan to run WOT for longer distances, upgrade the oil cooler (one with a t stat on it).
Stamped pan is also fine, your choice - but you did mention a budget..
Louvered tray is adequate.
Crane 731 is a h-roller. You already said you didn't want that expense and if you are honoring a budget you don't have to go roller.
The 134561 cam is a great cam, but may result in water reversion around the docks - check with others running this cam...
Also, the springs recommended for that cam are on the high side of what you want to run on a flat tappet with 1.7:1 rockers... You will have to probably run a lighter set of springs during break in (a flat tappet cam HAS to be run-in, preferably on a test stand, with proper break in oil before you can expect it to last at all). Those springs are 354# over the nose, and I'm leery about breaking in ANY flat tappet cam with more than 325 and I PREFER staying under 305 ish.. You could always break it in with the outer springs, and then add the inner springs and run a second cycle on the stand.
OR you could drop to a 134241 cam and use the recommended springs - that combo would go a long way towards reducing reversion AND those springs would give good service at a 5600 rpm limit. It's your choice, but somebody needs to give you things to consider.
DEGREE your cam, don't trust the markings -
If the heads arent rotted out in the water jackets, then just check for cracks and measure the seat width. If the seats sealing width is overly wide, then the seats will need recut. Exhaust seat width is okay to be a little fat for a blower motor. Check stem clearance. If that's all good then add springs matched to the cam. Check locks for wear on the stems, and if the lock area is questionable on the stems, replace those valves. New retainers and locks for sure. Mid-grade is fine. Comp mid-grade works great in sub 6k rpm. Be sure to set up the installed height to spec.

MC

Thank you 79 & MC, some good info.
I have been looking at comp cams as their rollers are bigger, .82" ( I think that's better? & Not sure if they use needles or solid bushings) And their 1/2 to 2/3 the cost of crane for all of the parts, so a retrofit roller might be an option if I can find a good set up for $1,200 all in BUT so far I can't find a comp retrofit roller grind comparable to the 731 or 741, any suggestions?

Also, 79 do you mean you where running a 134551 (553/571 and 110*lsa)? I can't find a 134561 and the 134571 rpm seems to high. Also your L2399 Pistons where domes?

Which brings up another question, what is the best way to raise the compression to 8.25:1 to 8.5:1 in this motor? Go from dished Pistons to flat tops, or domes, deck the head, run thinner gaskets??? I'm sure some of these have their down sides, so what's the best way to bump it up on the 525sc running the 177 at 115% over driven?

Do they make a dished piston with a lowered wrist pin to raise the compression?

Thanks for the help

JE SRP -3cc dome pistons should do the trick to get the compression ratio close to 8.25

From your response Griff, I'm assuming the best way to raise compression is increasing dome volume or piston height?

Here is JE's SRP pistons, I'm starting at 4.25" +.030" but what is the compression height & the stroke so I can pick the right one?

Thanks

Anybody have any experience or opinions on Comp's 11-409-8 (224/[email protected]", 537/547, 113* LSA) with a -3CC domed piston at8.25-8.5:1?

Or would it be better to have comp custom grind something like a 731/741?

Thanks

Delete

Yes, a piston change is the best way to change the CR in any significant way.
The 139477 has the same comp distance as the stock L2453 pistons
https://www.summitracing.com/parts/srp-139477-8
https://www.summitracing.com/parts/slp-l2453f30

If youre replacing pistons, i would go with an actual blower piston. Where the top ring is down further, better pins, etc. JE makes a forced induction flat top piston off the shelf for your application.

I wouldnt bother with arp rod bolts. By the time you get done rebuilding/resizing those rods, with new bolts, youll be at almost the cost of a set of brand Eagle/scat H beams, or for a few bucks more, some molnar rods. And youll have a much better rod with a floating pin rather than a press fit. Ebay the old rods to some car guy who thinks the GM dimple rods were the best thing since sliced bread for 100 bucks.

the cam 79formula posted, works well in this combo.

upgrade the stock balancer. Powerbond makes a nice unit thats affordable.

if staying flat tappet, get the crower cam saver lifters with the oiling groove.

check the rear bearings in the blower , the seals leak and fuel gets in the rear oil reservoir.

Get a good valve job done on the heads. Worn guides lead to valves that dont seal well or transfer heat well. Inconel or not, they need to seal or they will burn.

a 30 deg backcut on the intake valves is cheap, and picks up a good amoubt of airflow at lower lifts

I thought the pink rods were the cat's Azzz

buddy i work with freaked out when i told him I gave a set of them away. He was like "those rods are amazing!" ...good rod , but cmon

If I stick with dished blower Pistons, I'll have to get a piston with a raised compression height or do I need to get a longer rod to increase the the comp to 8.25-8.5?

Which model of powerbond damper do you recommend?

https://www.summitracing.com/parts/pbb-pb1018ss

A blower piston doesnt have to be dished. You dont increase compression by installing a longer rod. Rod length is determined by stroke and block height. You can use a 6.385 rod if you wanted to , in your build, but that would require a piston with a shorter compression height. Slightly better rod angle, but nothing thats gonna really matter. The stock 6.135 rod works fine. Now, if you ever thought down the road, you might install a 4.25 crank, the 6.385 rods would be able to be reused.

but anyhow, stock stroke, stock rod length, this piston would fit , and is a forced induction piston.

http://www.jepistons.com/Products/257980.aspx

Thanks MT, I have a powerbond PB1018SS on the way and the blocks in the truck to get dropped at the machine shop.

I've read a couple threads about bearing clearances, should I follow the Mercruiser book or is there suggested bearing clearances for the rods, mains, and cam?

Also I called JE and according to them the SRP 139477 and the JE 257980 are physically the same, both flat tops with a -3CC relief for the intake valve BUT the 257980 has different forge bosses and is made from 2618 alloy instead of 4032 alloy which I was told is much more brittle and won't hold up to detonation as well so they recommended the 257980 over the 139477, I wonder if the $400 price difference had anything to do with it.

I wouldnt get wound up in shooting for tight bearing clearances or anything. .0025-.0027 rods, .003 -.0035 mains, works.

Same goes for the pistons and rings. A set of plasma moly speed pro file fit rings will work fine, or the JE plasma moly file fits. I have around 140 hours on my short 468 short blocks mike tkach put together for me with speed pro plasma molys. Over 800hp, was running 9lbs boost . 6200rpm. Cylinder walls look like the day they were honed , and zero oil consumption between oil changes.

if buying new rods, i would opt for the arp2000 bolt upgrade.

i would have the line bore checked and honed if need be.

the bbc bottom end is stout. If the machine work, assembly, and oiling is good, they last. The valvetrain and tune is where main focus needs to be. Proper setup is key.

Im blown away by the work ive seen lately on cylinder heads. Ive seen several sets of cylinder heads from boat engines that have had half ass work done on them by professional shops. The main one that I noticed, is these heads all came in with no spring locators , or cups. Some had nothing at all under the springs, some had thin non hardened valve spring shims directly below the spring! The best valve spring in the world isnt very good when they are wobbling around, nor is metal shavings being sent thru the engine a good thing .

The other is mismatched hardware. Springs come in all different od and id. You need the hardware to match the springs. Having a locator with a .670 or .680 O.D, and a spring with a .740 ID , is no good. Valvespring setup is just as if not more important than the material they are made of.

I'm in the same boat as you...no pun intended lol...rebuilding my 525 currently...the machine shop I chose told me 700 hp should be an easy target with my setup....bored .030 dart heads ported eagle rods JE pistons roller cam and rockers with the 256 blower at 6-7 lbs intercooled....I'm not sure that i'll get 700 easily but we shall see...

BTW if you're looking for a blower upgrade...I posted my 256 for sale in the swap shop as I'm leaning more towards the 6-71 I have sitting at my house....just a thought

Good luck!!

Stewart

I think the 6-71 is the way to go, the 256 is just a small step above the 177. If I do a blower upgrade I think that's the route I'm going unless you're letting your 256 go for a good price.

What cam & rollers are you putting in?

I feel its a decent price for what it is...if I didn't already have the 6-71 I would use it without question but I got a good deal on it so just trying to get my money back out of it....not sure on cam specs as they are ground off...I bought the heads and cam lightly used from a guy which came off of a Keith Eickert built motor and from what I'm told he uses comp blanks and makes his own cams out of them...the lifters are comp and the rockers are crane golds...I also have a used set off crane golds I could sell cheap if you're interested...surprisingly my 525 already had them on it when I pulled it apart...I'm open to offers on that blower btw....the chiller and blower/intake are like a 9 out of 10 as far as condition...they are literally close to new

Stewart

oh I do have a few specs on the cam that I found...just off of the guys word I bought it from he said its 245 int 255 ext and 635 lift...not sure on duration or anything so the machine shop is going to check specs for sure before it leaves their shop to make sure it will work well for me

Stewart

thats alot of duration for a 454 based supercharged engine assuming its a hydraulic.

the 6-71 would be a much better choice if you want to make over 700hp.

Ok took my parts in for machining and the manifold landings on one of the 88 heads is pretty eaten up and since I'm looking at dropping $815 in labor in to them and another $340 to TRY and clean up the landings, I think it be better off looking for replacement heads.

So I'm thinking it's best to either pick up already done after market heads in the ball park of $1100 or get either a pair of Merlin 345 or iron eagle 345 and go through those instead.

IF I do the rebuild option, what's a better head the Merlin 345 or the iron eagle 345?

P.S. I can get a good set of 1-043b Merlin cores for $300?

Thanks

345's are way too big.
I'd look at these in the 320cc version. https://www.offshoreonly.com/classif...ds-o72091.html

Merlin iron heads dont flow much better than your heads in stock form. Griffs right, the 345s are too big.

the engine quest 320s griff put the link to, would work very well. The 308 iron eagle is a nice head as well.

Too big you say, I know the stocks are 320cc

So I understand, how this would affect the performance; if I go to a set of 345 with 2.25 valves with a crane 731 roller with 8-8.5:1 comp how would the motor run or what would change that you say there way to big?

Just trying to understand why.

Thanks

Icdedppl and I have had a set of dart 345 iron eagles on the flow bench. They come with 2.30 valves. The EQ 320, flowed more cfm from .200, to .800 lift. Same bench, same fixture, same operator. Not a ton more, but again, larger port, larger valve, and flowing less

theres a good argument that one might opt for more airflow with a postive displacement blower , and not worry as much about port velocity . However, in this case, the bigger head doesnt flow more air, and doesnt have more velocity.

the dart 345 is a great head. Just wouldnt be my choice on a 454 build. Now, if you told me you wanted to turn 7000rpm with a 871-1071 on top, maybe.

downside to the larger port, larger valve, can also affect idle quality. Intake reversion is more pronounced with a larger valve, and slower moving port. Even though a larger valve can help pass more air into the cylinder, it also allows more air to be passed back up into the intake at idle.

the darts if i recall, are around 650 per head bare, the EQ around 450 per head bare. So, 1300 vs 900 for a set. 400 bucks is 400 bucks, and could be put towards valves , springs, etc. Both are great heads, and much better than a world products Merlin iron casting out of the box. At least the older merlins ive seen. The combustion chamber was horrible on them. Maybe they improved that in recent years , but the last set i saw, not so good

Duplicate

I updated my post and maybe it got missed, the Merlin's are 1-043 castings, off a Mercury ( I think a 502). From my research there 345 but I'm not 100%

Here's the kicker I can be in the Merlin's $1,150 completely rebuilt with high performance valve job, Manley severe duty valves 2.25 intake and 1.88 exhaust and isky springs. So $1,000 less than the EQ'with parts, would you still go for the engine quests?

heres what the chamber looks like on my buddys merlins. Check out the blend from the valve seat to the chamber. The ridges in the throat from the seat were huge. Tonight i can post up what they flowed before and after some work.

thats a good buy though, if they have severe duty intakes with extreme duty exhaust. The extreme duty are inconel valves from manley, which you want with a marine supercharged build. https://cimg0.ibsrv.net/gimg/www.off...b9ace067f0.jpg

Yes if you could put up some numbers that would be great. Again I'm not shooting for big hp numbers just a solid strong runner.

If I went with a different cam or cam specs using the 1-043 (345?) Heads would that help with the reversion, maybe less duration?