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Replace 2000 Volvo Penta 4.3L with 1988 OMC 4.3L

Eternal Noob

New member
A tree fell on our 1988 bowrider a few weeks ago and totaled it. The 4.3L OMC Cobra seems to be fine. I found a very nice 2000 boat with a Volvo Penta SX 4.3L with a cracked block from freeze damage. I have not seen it in person but from the pics the engines look almost identical. The owner only says it is an SX, no other info on the model or serial. What problems will I run into putting my 1988 OMC 4.3 in front of the 2000 SX drive? I know there will be boat wiring, hose, etc. issues, but I think I can handle those. I need to know if there is any difference in the block, exhaust system, engine coupler, flywheel, etc. that will cause a major problem. I will be using everything possible from the old motor, so carb vs. fuel injection and ignition system differences should not be an issue. I am concerned about the shift and throttle cables. My motor is 2BBL carb and boat is EFI, and I have read the SX does not use a rear shift cable like the Cobra. I am going to visit the 2000 boat tomorrow and will get more details on the motor and drive. Also, in case there is a major problem with the engine swap, would it be possible to replace the outdrive with my Cobra if it became necessary? I have read enough about VP outdrives to know I don't want to do that unless I have to, but it would be nice to have the option. I understand Cobra and Mercruiser use the same transom cutout, but have seen conflicting info on whether the SX is the same. Thanks!
 
Ayuh,...... The '88 is pre-Vortec, 'n the '00 is Vortec, so you'll need to use most of the dressings from the Volvo, on yer older OMC short block,.....

The intake bolt pattern changed when the heads changed in 1996,.....
 
Well the exhaust manifolds from the Volvo will fit for sure because that's what I used on my '88 OMC to replace the old batwings. The '88 has a mechanical fuel pump, and different intake, it can be either a 4bbl Quadrajet or a 2bbl Rochester, you will have to adapt the bracket for the throttle linkage because the brackets are different between the vortec and pre vortec due to the spacing and angle of the bolts on the intake manifold. The main thing is if you can use the same coupler, even if the flywheels are different.
 
That's great news so far. I am pretty sure I will be buying this boat tomorrow. If so, I will update the thread as the project progresses. I have been lurking on boating forums for a few years now, that is one reason the '88 Cobra is still running strong. Many thanks to the contributors and moderators. This and other boating forums are the best source of info out there.
 
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