replace 85 4.3 to 99 4.3 vortec ? ?

[JERRY J]

I was given a 99 4.3 Vortec with 20 hrs on a dyno. (new motor)...

Can I, without too much difficulty, change out my 85 4.3 that has a cracked block ?
The boat is an 85 Four Winns with less than 100 total hours...
(thanks Son-in-law.. "I got ALL the water out" )....

!st thing I noticed was -- '85 is SAE, and the '99 is metric...

I do appreciate any and all help......
Jerry Jeup......

 

[Bondo]

Re: replace 85 4.3 to 99 4.3 vortec ? ?

Ayuh,... It should go smoothly,...
The only fitment issue Might be the flywheel/coupler...
The crankshaft bolt pattern changed between those years....

 

[JERRY J]

Re: replace 85 4.3 to 99 4.3 vortec ? ?

Bond-o;

Thanks so much for your response. So far, I have not run into any problems..
I did notice, before starting, that the flywheel bolt pattern was different...


Bubba ;

It is a prototype engine, run on the dyno at various speeds, was not run for 20 hours straight.. I do appreciate your concern, and have pulled the oil pan and checked bearings and crank... Changed crank bearings, just because....... and the crank journals look great.......

I will post any pitfalls as I go......

Thanks again.......

 

[mylesm260]

Re: replace 85 4.3 to 99 4.3 vortec ? ?

I Went through the same thing, let me share some of the problems I ran into.

Old engine had a smaller flywheel, 12 1/2 inches vs 14 or something like that.
as a result, I needed a new coupler and a new starter.

Vortec Intake manifolds are different. you will need to get yourself a new intake manifold.

Brackets and belts. Newer vortecs run serpentine belts, your older 4.3 will be running V belts. You will have a hard time with pulleys, water pump, alternator, power steering, etc..

The differences in power output will actually surprise you... my boat performs much much better with the newer vortec than it ever did with the old odd-fire v6.