Another OMC 4.3 Vortec upgrade

[marada1]

OK I'm gonna throw out the 5.7 idea and upgrade my 4.3 to vortec instead. I already have a set of Vortec heads (automotive). Now considering Edelbrock Performer intake and 600 cfm carb (1409). Anybody with experience or thoughts on these Edelbrocks vs stock GM?
Is a gain of 45-50 hp pretty close to accurate?
Right now my engine is turning the max RPM of 4600 at WOT with a 19 pitch prop. I also run a 21 (when not pulling skiers) that I'm turning 4000 RPMs at WOT. 2mph faster by the on-board speedo (not very accurate I know).
Can I get closer to 4600 running the 21 with this upgrade?
Thanks

 

[John_S]

Re: Another OMC 4.3 Vortec upgrade

Carb is easy to work on, and Edelbrock sells a 4.3L kit for it. Out of the box, it is tuned for a SB V8. You can probably easily find out what jets and rods are in the 4.3 kit, and just make sure they are part of their performance tuning kit. That way, if you had to tweak further, you have the extra rods/jets.

The performer intake is probably a good match. If you boat in salt or brackish water and raw water cooled, you would want to find a bronze water jacket lined, marine version.

As far as a hp guestimate, just look at Mercs current 4.3L MPI, and take about 10hp off. This should be a reasonable, at prop, hp estimate.

 

[marada1]

Re: Another OMC 4.3 Vortec upgrade

Thanks John,
Any thoughts on the ability to swing the 21 prop with the extra 50 hp?

 

[Bondo]

Re: Another OMC 4.3 Vortec upgrade

Thanks John,
Any thoughts on the ability to swing the 21 prop with the extra 50 hp?

Ayuh,....... Should be No Problem.................

 

[marada1]

Re: Another OMC 4.3 Vortec upgrade

Hey Bond-o,
I was reading some previous threads. Did you do this same upgrade? Please give me the results.
Thanks

 

[marada1]

Re: Another OMC 4.3 Vortec upgrade

Do the Vortec heads require different pushrods? Any other changes required? Valve covers maybe?