4.3 to 5.0 swap

[ozmatt]

Hi,

So it's been a year since my '91 volvo penta 4.3l got salt water in it and needs replacing and I have been researching suitable replacement engines.

I have a complete 5.0 chev/mercruiser with all accessories of the same era (late 80's) ready to go and from what I have read in other threads this engine should mate up to the SP-C outdrive. Is this correct?

Ideally I would have just put another 4.3 in but I am yet to see one come up for sale at a reasonable price in Australia.

I understand that the mounts have to move back about 3" and that the gear ratios will be different (however the jump from 262 to 305 can be sorted by a bigger pitch prop).

Is there anything else I should be aware of... Summer is creeping up and I am sick of seeing the boat out of water.

If I can get a firm "YES it will match up" then i'll book it in for the swap today!

cheers

 

[Bondo]

Re: 4.3 to 5.0 swap

I have a complete 5.0 chev/mercruiser with all accessories of the same era (late 80's) ready to go and from what I have read in other threads this engine should mate up to the SP-C outdrive. Is this correct?

Nope,... Not really... The only thing shared by Merc, 'n Volvo is the basic Long Block...
Everything else is Very different...

 

[TilliamWe]

Re: 4.3 to 5.0 swap

...
I understand that the mounts have to move back about 3" and that the gear ratios will be different (however the jump from 262 to 305 can be sorted by a bigger pitch prop)...

What Bond-o says, plus, the front motor mounts will need to move Forward, by about 4 inches. Or you'll need to custom fabricate new mounts to bolt to the block.
Yes, you could solve the gear ratio "issue" with a higher pitch prop, provided the 5.0 is really making more power than the 4.3.

 

[kewlkatdady]

Re: 4.3 to 5.0 swap

Something to consider... as I did recently when deciding to figure out whether to "upgrade" from my water logged 4.3 to a 5.0.

I opted to upgrade to a new 4.3 and move from a 2bbl carb to a 4bbl carb...

This is "suppose" to get the HP up to around 220-225 for the 4.3L.

That about what a stock 5.0 with put out, but the 4.3 is lighter....


So power to weight ratio popped into mind and made the 4.3 the better choice in my opinion.

Plus its much easier going back with what was there as opposed to the conversion.

 

[ozmatt]

Re: 4.3 to 5.0 swap

Sorry I meant move the mounts forward.

Bond-O.. when you say "everything else is very different" are you just referring to all the bolt ons? The 5.0 I have has everything, starter, carb, intake, exhaust manifolds, flywheel, etc etc and I don't plan on trying to swap over any of the 4.3 parts.

I would love to just get a 4.3 but they seem to be as rare as hens teeth here (Australia), and I have not seen one come up for sale for a very long time.

I have seen a few complete engines being sold online that say "Mercruiser style, direct replacement for volvo penta, omc, mercruiser" These engines look exactly the same as the 5.0 I have, so what is stopping these "mercruiser style chev engines" replacing a volvo engine and mating to a volvo outdrive?

Would I have trouble with this?
http://cgi.ebay.com.au/MERCRUISER-S...AU_Boat_Parts_Accessories&hash=item255689ea3e

thankyou for your time, really just want to get the boat back running

 

[Dakota47]

Re: 4.3 to 5.0 swap

Should bolt right up. if you buy it tell them its to replace a 1991 Volvo Penta 4.3 V-6 ..

 

[Lou C]

Re: 4.3 to 5.0 swap

Other than having to move the engine mounts foward, the other thing is the exhaust system. You need for the V-8 manifolds to mate with the Y pipe that was used with your V-6. Now if the Volvo used the same Y pipe for the 6 and 8, then you could use Volvo manifolds and risers to make sure they mate up right. But if the Y pipes are different in how they angle up, then there could be a problem in mating them up. Drive ratio is the other issue, that may be solvable with prop pitch but it's hard to say. When I do re-power my old FW, I would be temped to put in a 5.7 with a 4 bbl but I'd have to change a lot of stuff, by that time I may just convert the Cobra over to a Merc or a Volvo depending on price and availability. Lots cheaper to stick with the 4.3 and with a 4bbl it has good power and is very economical.....