500 to 525
 

I have a set of carb 500s and would like to do some upgrades. I have a set of 525 efi setups with ( pcm, sensors, coil packs, injector harnesses and upper and lower intakes. My question is if I bought some 525 heads or dart pro 1 heads would it be a pretty simple swap or are the the block different. Sorry if this question has been asked befor.

Blocks are the same. Heads and cams and all electronics are different.

and you can do better than the stock 525 heads, I think they were edlebrocks, but the exhaust mounting holes are in different places so then you have to mess with that.... Since you will have to have the ecm reprogramed, I would decide on who you want to do that and ask if they have a head/cam recipe for you thats proven and he has a base program for.

I have all the sensors and harness off the 525 plus the ECU. I was thinking about the dart pro 1 heads. And as for cam I might as well change why I am in there. Any cam suggestions

My suggestion is to talk to whoever you are going to have program it before you buy stuff....

That is my understanding as well, Whipple, Precision and maybe a couple more

The 525 is a "sealed" race motor... Im willing to bet there are a few more people that can tweak the ecm than we know about...... :party-smiley-004:

I was more wondering if it was an easy swap. I didn't know how differnt the block was from 525 from 500 . Since I had all the stuff. So aside from the heads and cam how differnt is the block and internals.

So it should all swap pretty easy if I buy heads and cams.

The 525EFI cam is a really good unit.

What he said * REmember the 525 is a really good motor and pretty damn durable, plus it usually made well over 525hp. avoid the 525 headers though,Im sure there is something comparable to the heads out there.

We use the 525: system with great results. Dustin Whipple does our tuning. You should be able to use your stock heads, the intake is the limiting factor.

OP has a carb 500 not 500EFI, does that make a difference to do a " bolt on" 525 EFI conversion?

As said before. Strongly recommend checking with Mark at precision or Eddie young. Intake and injectors are a huge limiting factor to these engines. Save yourself time and money and listen to what they say and what packages they have made work.

The 525 head is made for Merc by Edelbrock, really nothing special. The head off a hp500 carb is really pretty close. If he is going to keep it close to stock they should work ok. He will have to make a few spacers to get his belts to align because of the crank target wheel. Unless he has the newer version with it under the timing cover.

Stock 525EFI cam will work well.
525EFI's are 525hp at the prop and dyno in the 560-570hp.

I agree with talking to Young Perf or Precision Marine before you buy parts. They may have a parts list for a similar build and have a PCM tune ready.