500efi rebuilds
 

So a good friend and I pick up a couple merc 500efis for a decent price. So now were on the hunt for a decent set of heads and cam package for these things to make them run decent. Not shootin for the moon power wise but if we can make it to the 6's and not break the bank we'd both be pretty happy!!

Any OSO recommendations for a top end from someone??

2 502's bored .030 over about ready to go back together!

Thanks!!

where are you located? Frank at FU marine can do it, but to get into the 6's you will need the bigger throttle bodies and such, i have 2 complete intake systems with with injectors for sale as well, going to have to tune the computer as well.

Thats pretty much what i was planning along with a full aftermarket fuel system and bigger injectors.

im shootin for 600... for now, then ill have a nice platform to throw some boost at it later

Im in SoCal. I was trying to find the parts to make the factory 500 TB a monoblade, i can machine the body myself but no luck.

What do you have for sale?

A non modified 500 EFI TB can make 630hp with the correct components, Ive done it in full marine trim with CMI sweepers, get out your big boy check book.....

you can easily turn the 500 tbs into 525 mono blades if you have machining capabilitys. You can buy replacement 525 blades from merc for about 42$each. Big problem is you will need to buy 525 fas as the flange will be gone at that point BUT the 500 fas kill hp, the 525s cost virtually no hp in my dyno testing, Smitty

if i could do it myself and save some $$$ and make some extra HP im all for it. But im not gonna spend 5-600 on a TB for a few HP just to turn around and rip it off when i slap a whipple on this thing next year.

I think ill get by just fine with what i got. Thanks for the input!!

thats the thing about it, it isnt cheap and if you are going to whipple it no sense in doing it, i was at 640, and i had the ASM monoblade, bigger injectors, bigger fuel pump, etc and it ran great on 87 octane, what i have for sale is upper and lower manifolds, ASM throttle bodies, injectors and fuel rails. its for the guy that wants to go to 640 hp and run it for a few years.

What/whos heads and cam are you running? And what size injectors?

I started with AFR 305s, 741 cam with a firing order switch, 55lb high impedance injectors and tune. do not use the stock 500 efi fuel system, you will lean it out and do lots of damage.. if you are interested in all the stuff i have i had it listed for 2500 per set.

To the OP, I have a pair of Vortech Superchargers for 500EFI if you're interested in going that route vs. Whipple.

Offshore, would you be willing to sell just your mono blade throttle bodies? Also, were your intakes honed out at all, or stock? Just curious as my 500's already have upgraded fuel system and cam with firing order switch. Im basically just planning ahead for when its time to do top ends, only have 200hrs on full rebuilds. Thinking a good set of heads and mono blade TB's and I should make some good reliable power.

id rather sell it all as a set

I looked into rebuild/upgrade of my HP500EFI's a while ago and ATECO looked pretty good. There should be a thread here if you search for "ATECO HP500EFI". Haven't pulled the trigger yet. Don't know if they still offer the package but it claimed dynoed results in excess of 600 hp, as I recall. Without force-feeding.

in reality the 500 efi with some tuning could make 530-540hp so their claim of 125hp gain is some what miss leading, and to get 635hp through the stock TB and intake is almost impossible.