330 to 525 swap opportunity
 

Hi all,
I have a friend that is putting in new 525 blocks in his boat.
I could get one of his old 525s for 2500$ canadian. (engine in runing condition)
To put you in perspective, in my area, a used 500 carbed motor with a cracked piston is for sale as is at 4.5k$

My boat currently has a 454 carbed engine.(non mag)
I would be receiving the 525 as a longblock.
From my research these are 502 bbc's, so im guessing mechanically it will bolt up in the same space as my 454? if not this might be deal breaker.
The heads are my next concern, are my current imco powerflow manifolds compatible. is the mercury intake the only fit?

In a perfect world i am looking at a engine/head refresh, performance intake, stand alone ecu with supporting mods. Am i dreaming?

If the 525 still has the Edelbrock Mercury aluminum heads your exhaust wont bolt up, its a propitiatory bolt pattern designed around the CMI headers

It does have the original heads, i was looking into this and found that stainless marine offers a jig kit to drill and tap the correct bolt pattern, im guessing the machine shop doing the head refresh could handle such work. 750usd for the jig + labor still cheaper then cmi headers and exhaust. Still a setback tough.

Find a cheaper way to get (reliable) 195hp out of your 330..... You can always recoup some from selling the jig

How many hours are on the 525's ? your 2,500 equates to around 1,950 usd ......if so thats cheap for a gen 6 525 long block

Any competent machine shop should be able to drill and tap the heads without much more than the header gasket. You may even find a jig here on OSO.

I had to relocate the exhaust holes on my transom and the analog gauges will not work without new wiring harness. Those were the main problems I had when swapping out my 496 for a 525.

Isn't the cooling system plumbing different on the 525 head with a coolant passage at end vs the 330 if he's using his accessories? I assume this has to do with the closed cooling set up on the 525.

I doubt the long block will include the heat ex changer ? you can install freeze plugs in the heads to block the coolant passages

When I replaced my CMI's with Stainless Marine exhaust, SM loaned the jig to the shop doing the install.

The 330hp 454 and 502 525EFI should have same transom holes, right ? As far as I know the 525 heads from Edelbrock have stock location exhaust ports.

yes same, I didnt understand that post ether , no raised exhaust ports on the 525,600,700 heads

The Edelbrock heads still have the proprietary bolt pattern. I had to relocate my exhaust tips because I switched to the headers that came with the 525.

Thank you for all your input guys, i called the shop doing the engine swap in my buddys boat. The mechanic tried to discourage me saying it wont fit and nothing is the same, he did confirm its a good old 502 bbc, that the heads are different and water passage on the heads are different. He also told me it would cost over 4000$ in parts alone to get the heads rebuilt... i didnt check into this yet but for 4000$ seem allot for valves/springs/rockers. He said hel sell it to me but he aint gonna start fixing my stuff if it doesnt work out. If you know of places to shop for these kind of items lmk.


This is wat im hoping for, my friend assure me the shop hes referring me to has 3d cnc machines and this would be a joke for them.

this is something i was told by the mechanic thats swaping the engines, water pâssages are different he said; ''you will never make it work'' where his words :D

this is also a great option if it come down to it.

engine is over 500 hours

The mechanic is not being truthful IMO or he just doesnt know , Im running the same long blocks with no exchanger, 2 freeze plugs and its done, at 500 hrs Id replace the lifters also if you move forward.

My guess is he just doesnt want any backlash from selling a worn engine to a guy thats trying to rig up an older boat. He just sold 2 525s for my budys 38 hustler, he could give a rats ass about my 2500$ for a longblock haha. He is a reputable mechanic and pretty much the only performance boat shop in the area.

at that price, he probably wants the motors himself...

I was thinking the same thing ^^^^^^^^

Where are you located?
 

where are you located I can help answer your questions

That mechanic is not being honest with you. You can buy brand new heads for under 4k. He's blowing stem up your a$$ so he can buy the long blocks. Buy them and have them looked at by a reputable engine builder if you thinks it's needed. Otherwise plug the required passages as said above, stuff them in , and go have fun.