Can I put a v8 in a 98 Tahoe powerglide

[Briansteinke]

It currently has a 4.3 merccriuser, would like to put a v8 in it. Any advice would help. Thanks in advance

 

[achris]

If you have room in front of the engine, no reason you can't go to a V8... Everything else is the same, width, height. Just 104mm longer and about 60kg heavier....

Chris.........

 

[Bt Doctur]

fab up some new front motor mounts and change the drive gear ratio

 

[Scott Danforth]

assuming you have the extra4+ inches in front

unbolt the 4.3 marine motor, bolt in the 5.7 marine motor, make new front blocks for the motor to sit on, pull drive and send off for re-gearing

 

[achris]

assuming you have the extra4+ inches in front

unbolt the 4.3 marine motor, bolt in the 5.7 marine motor, make new front blocks for the motor to sit on, pull drive and send off for re-gearing

I'd pull the drive first.

And I'm not sure it'd need a re-gear... Depending on the era of the 4.3, it may be a 1.61, in which case just a prop change may be sufficient.

Chris.........

 

[Scott06]

the guys above are right - easy swap if the engine compartment has 4" in front of the 4.3.

I did a similar repower 3 years ago on a Sea Ray 200 sport- PO had cracked the 4.3. The sea ray was offered with 5.0 so you might get lucky like me and the motor mount stringers are already there (for both V6 and V8s) and there was 4" in front of the engine already. I just had to drill new lag holes for the motor mounts and filling the old. I used an Edelbrock carb and used the factory Merc throttle bracket for a nice clean bolt in to existing Merc throttle cable.

You can swap all the accessories and wiring harness of the existing engine (assuming its carbed), saved me a bunch of $$ to buy a partial engine vs complete bobtail. Assuming you have a Tbolt 5 ignition the distributor will swap over with a new cap rotor and trigger wheel. The 4.3 ignition module will work but I think offers less advance than a 5.0 or 5.7 module. I was able to get the correct V8 one off ebay and sell the 4.3 one.

On the drive most likely you can get away with re -propping. It seemed to me the 4.3 MPI typically had (in a 19-21 ft'er) a 1.62:1 drive ratio as did the 5.0. Carbed 4.3's like mine was had a 1.82:1 drive. This kept me from dropping in a 5.7 as I didn't want to mess with the drive as the boat only had 38 hrs on it. Ultimately going from a 19" pitch to a 21" (4 blade) or 22" (3 blade) my WOT rpm is right where it should be. Most likely If I did a 5.7 I might have been on the ragged edge of making a 23" work. Again I was just trying to keep my project costs down.

 

[Bondo]

Ayuh,...... My take on the 4.3l, Vs: the 5.0l is,....

Go with the 4.3l,.... It'll make the horsepower of the 5.0l, at over 100 lbs lighter,....
A Good runnin' 4.3l, Vortec heads, tight quench, 'n a AFB carb will smoke a 5.0l Efi off the pond,.....

If yer goin' V-8,..... Go Big, or go home,..... a 350 minimum, smart money is the 383 Stroker,...

 

[Scott06]

100% - if I had to do it over again I'd do a 5.7 and just bite the bullet on the drive cost... but it works pretty darn good for what I have in it

 

[achris]

Ayuh,...... My take on the 4.3l, Vs: the 5.0l is,....

Go with the 4.3l,.... It'll make the horsepower of the 5.0l, at over 100 lbs lighter,....
A Good runnin' 4.3l, Vortec heads, tight quench, 'n a AFB carb will smoke a 5.0l Efi off the pond,.....

If yer goin' V-8,..... Go Big, or go home,..... a 350 minimum, smart money is the 383 Stroker,...

Agree. I pulled a 305 (5 Litre) from a boat and dropped my old 4.3LX in. Friend's boat.... The 4.3 uses less fuel, is lighter, and 6 knots quicker....

Chris.............