what should be my checklist if i am interested in changing my EFI over to a carb setup?

i have a 99 502 with 230 hours. I am interested in making around 600hp.

I have cheap access to a whipple for a carb setup -- hence my thoughts on just switching over to a carb setup.

does any of the internals of the engine need to change?

distributor?

i know i need new intake and obviously a carb to go with this.

just trying to get a real world idea on what this would cost me.

intake and carb i'm guessing 1200???

can i sell my EFI setup? whats it worth?

thanks guys!

just trying to brainstorm here

Your EFI setup is worth about a 1000 on ebay.

The Whipple should come with an intake with intercooler built in. If not I don't know that I would change over to it.


Also you should pull heads and get a good single angle valve job done, switch over to PC seals for the valves and install fel-pro LMS head gaskets with studs for best reliability. Carb should be an 825 that is boost referenced. Expect 550-600 hp at 6 lbs boost.

Might want to add a different cam while in there to guarntee the 600hp.

thanks for the info -- i also have stock exhaust -- will that hurt a lot?

As long as the stock exhaust goes out thru the transom, you will be okay. Could you get more power with better exhaust-sure, but not necessary. If it goes thru the prop I would say do not change to the blower.

yes it is thru hull.... i'm surprised more people haven't chimed in with their experiences on this conversion. i've heard of a lot doing it.

i'd really like to know what the gotcha's are.

I would also not upgrade the cam if you are going to run stock exhaust. Too much of a chance for reversion.

I don't think any engine builder would use stock exhaust if building a motor. There are several problems associated with stock exhaust in a modified motor. If I were installing a blower I would at minimum add exhaust and head work like good rockers and minimal valve job. Not because it would make more power but because it might even last all summer.

Replace head gaskets, valves and springs at the minimum.

It sounds as if you're making lots of changes and there is a lot to consider. Perhaps upgrading to a better breathing exhaust system MAY not be absolutely necessary, but you will only bennifit from it so, I would really think twice about it---especially in light of any reversion!---and especially with a stock cam or the wrong cam. An aftermarket exhaust manifold system would obviously breath better and give more HP over the stock Merc stuff---especially with a blower it needs to breath! Stainless Marine, Dana, or GIL system would be adaquate....preferably with a ONE PIECE tailpipe that goes all the way through the hull/out the transom.

Do youself a favor and call "RMBuiler"/Bob Madara of Marine Kinetics in N.Y. (585) 564-8583. He will take all your components into consideration and make sure you have the correct combination for your application and he will pick the correct cam for you. Bob is a stand up guy with years of experience, very intelligent and has helped a ton of people on here. Have fun.

thanks for the advice -- i'm trying to do this as inexpensively as i can. the only reason i'm thinking of going the whipple is because i have easy(read cheap) access to one.

other wise i'd probably go the tyler crocket route or a pro-charger.

i figure i can do the whipple and most of the work myself -- and only spend about 2 grand -- that is a whole lot less than the 7grand it would take for crocket or a rebuild.

trust me -- i wish i wasn't working with limited funds -- but it is what it is.