Questions about the Mercury Racing 525
 

For some of you Merc repair shops...
The Mercury Racing 525 has been out for a few years now and are out of warranty. This being the case I am starting to get a few customers with this engine asking about freshening the heads. While reading all the mass hysteria in the racing and general discussion forums concerning the DQ of a SuperV Fountain, I noticed a statement in there about Mercury Racing never planes or decks their heads, they are always replaced. Do I need to tell my customers that the Merc Racing 525 heads can not be resurfaced? If this is indeed true, and Merc Racing replaces all 525 heads, what happens to all those old heads? Can they be bought somewhere? If a certified shop pulls the head for whatever reason under warranty, and the head surface had any minor imperfection, did Merc Racing warranty the head?
If they were still using the 525 in Factory racing, I'm thinkin that would make a factory rebuild close to $10k. Ouch!

Re: Questions about the Mercury Racing 525
 

you cant surface them for class racing. if the customer is not a racer surface em and do a valve job.

Re: Questions about the Mercury Racing 525
 

If it's ok for the average customer, but not the racers?
What does Merc Racing do with the heads that come off of the race motors? Can they be bought as used heads?

Re: Questions about the Mercury Racing 525
 

surfacing the heads raises the compression and along with that HP slightly too. in spec class racing that would be an advantage over the guy running them right out of the box. not sure what they do with all the take off's.

Re: Questions about the Mercury Racing 525
 

Stupid rule. The other point in this kind of class with factory motors is to keep racing affordable. Having to buy 2 sets of aluminum heads when a simple resurface will do the job doesn't make sence. Sbi allows it.

Re: Questions about the Mercury Racing 525
 

I thought the 525 heads were Alum Edelbrock's ??????


Surfacing a head .005-.010 will not make if any HP .Unless ya really cut them and zero the deck,thin head gasket etc :rolleyes:

Most heads that need resurfacing dont need much takeing off.


Being a closed cooling systen the heads aught to be in real good shape!!!!

I have 1 new in the box 525 head, not in love with it willing to sell or trade.

They are Edelbrock heads marked up 1000%.

This is true but have better parts, comp guide plates, ARP studs. think comp springs and retainers.

Has odd Ex bolt pattern.

Would post pics if i could figure it out.

Be careful where you buy new heads. I believe Merc heads for the 525 have a special exhaust bolt pattern.

Is that why we are screwed with CMI only headers?

Edelbrock will not talk about that head at all, the tech line only said it was private label and is not the same as any of their heads. Hinted that ports may be moved to customers request. Who knows but a new one from Mercury is about 2k list. CRAZY

I was going to get a 2nd head and build a new motor but Innovation marine talked me into doing a full CNC on my heads and intake to achieve the power lever I was looking for cheaper.

Just to be clear, the heads are designed per Mercury specs, Edelbrock is the mfg but they are not the same as Edelbrocks big block heads. The runners are very different with the Mercury Racing head vs a standard Edelbrock head. They also have different exhaust bolt pattern and the water passage and boss on the front of the head.

Very different head than any Edie head that I have seen. All the sharp edges are stress relieved and the bowls are hand blended. Very nice head.

what about the 525 long blocks you can get thru bam marine,,,there about 10K,with a good return,,,has anybody ever used them,,,and where are they rebuilt at,mercury racing???

Are these Merc-Racing long blocks? Or GM 500/502 crate engines?

4 top exhaust bolts were moved back about 3/8th's of an inch.heads can be drilled and tapped for a stand bbc pattern.
as far as ports,exhaust ports are nicer,intakes look really close.guess i'll break out the inside calipers and check.
Heads can be decked.We've fixed alot of them for leaking exhaust(water).Just need 2 more heads and I'll be putting some on my boat.

Mecury has a seperate division for the remanufacturing. They are the ones that make the 383 and 357 engines and the rest of the Mercury reman & CPO stuff. The remanufactured 525 longblocks come from them. So --- done by part of Mercury but not done by Mercury racing. Like most of the consumer product they have a 1 year factory warranty.

s30,
Can you elaberate on the "4 top exhaust bolts were moved back about 3/8th's of an inch.heads can be drilled and tapped for a stand bbc pattern" What exhaust did you use after this mod? Do you have any pics you could post?
Thanks,
Dean

Dustin
Have you tried Dart's head with Mercury 525/600/700 Header and coolant flanges?
Thanks
Steve

bam are the long blocks sealed also

when Merc rebuilds your 525, they give you all the old parts back

I've seen waterslinger's 525 head, it's brand new. Here are some pics.

I'm bringing the gasket(525efi) home to take a pic of it.The standard bbc upper bolt holes are marked on it to show difference.The bottom holes are the same.
For exhaust i'll be using gils.

S30,
Thanks for the great info, can't wait to see the pic. I'm going to get with Waterslinger this weekend, hopefully, and look at his 525 head and bring a pair of the KE headers I have and compare them to bolt hole pattern on the head. Need to do this BEFORE he sells it! :)

My suggestion, just buy the Dart 525efi replacemnt head and have Dart do standard bbc exhaust holes and locations and you'll end up with a better flowing head out of the box. Raylar has done a lot of testing, research and cnc'ing upgrade work on the Merc/Edlebrock HP525efi head for our Raylar HP675efi engine and believe me it was a "booger" to get this stock head to flow what we needed. We ended up with over 405 [email protected] lift on the intake and [email protected] on the exhaust with some good "black art" rework. "most things are possible, it just takes a little more time, effort and money"


Best Regards,
Ray @ Raylar

I doubt if the long block from Reman is sealed. I'm not sure that program in still alive. Anybody know? I can find out Monday.

Well they are just Dart Pro 1's with the material added to the front for the water system and the exhaust flanges changed. So we've run many Pro 1's with plenty of success and offer far more potential than the stock heads. I'm not a big fan of "as cast" in general so the CNC finished versions are a good upgrade.

Thanks!
Steve

isn't the exhaust stud pattern same as 496?

No.

S30,
Any updates?
Thanks,
Dean

S30,
Sent you a PM.
Thanks,
Dean

S30,
Any news yet?
Thanks,
Dean

Ttt !!!!

Update
 

Was told this was a 525 head. After sending pics to Mercury racing it turns out this is the new 502 430 HP motor head. Has std BBC exhaust bolt pattern. The head is manufactured by Edelbrock, however they will not confirm what head it is. Having the intake port, exhaust port and combustion chamber CC’ed reveled this head is the Edelbrock RET port head.


Marine Duty Performer RPM 454-O & 454-R
• Heavy-duty, 1.89" Inconel exhaust valves provide added durability for marine applications
• Hard anodized black to protect the aluminum in the harsh marine environment
• Sold with valves only to allow for valve spring choices
• Match with an Edelbrock Performer RPM manifold, Performer Series 750 cfm marine carb and Performer RPM cam for proven performance
• Smaller-than-stock 11/32" valve stems promote excellent flow and lighter valve weight

Cylinder Head Specifications
Combustion chamber volume 110cc
Intake runner volume 290cc
Exhaust runner volume 110cc
Intake valve diameter 2.25"
Exhaust valve diameter 1.89"
Valve stem diameter 11/32"
Valve guides Manganese bronze
Deck thickness 9/16"
Valve spring diameter Springs Not Included
Valve spring maximum lift Springs Not Included
Rocker stud 7/16"
Guideplate Hardened steel
Pushrod diameter 3/8"
Valve angle 26°
Exhaust port location Stock
Spark plug fitment 14mm x 3/4 reach, gasket seat
Made In USA



Technical Notes: Match with Edelbrock head gasket sets. Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using. Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat.

Description Bare (Single) Complete (Single)
Marine-Duty Performer RPM 454-0 Oval Port (110 combusion chamber) N/A 61459*
Marine-Duty Performer RPM 454-R Rect. Port (118 combustion chamber) N/A 61559*
Notes: Valve springs not included. Please consult your camshaft manufacturer when selecting springs to match your camshaft.


Flow Numbers as tested by Edelbrock's SuperFlo SF-1020 flow bench @ 28" H2O
#61459
Valve Lift .100" .200" .300" .400" .500" .600" .700"
Intake 73 143 208 251 284 299 -
Exhaust 71 128 153 178 200 218 -