OMC Stringer Conversion questions

Author: William B. Arnold

27 Jun 99

David Petersen wrote:

> > I read a message posted about converting an old OMC to a Volvo-Penta that you had commented on. You had mentioned that you had converted an OMC to a Volvo-Penta. Which drive leg did you have before the conversion? What drive> leg did you go to in Volvo? I have an OMC 800 1981 with a 4.3L and am sick> of repairing it. I want to switch to a Volvo-Penta. Is there a manufacturer> of a conversion plate or something for the transom shield cutout? Can I even do it with a boot in there now? Any links or help would be appreciated.>

> Dave in Seattle WA

Howdy there Dave,

Volvo's website is located at They list a 4.3L there on their engine packages. Also is a price list of motor and outdrive package or just the engine. You should inquire with Volvo-Penta and see if they will sell the package minus the motor. Their motors are EXPENSIVE! The outdrive package should be around $3,500. Not bad when you think of it. By the time I finished, I should have gone that direction. Next time I will, period. You spend it now or you spend it later! I originally had an OMC Electric Shift 800 drive. I converted from that to a Volov-Penta 280.

1. The transom MUST be refilled and then cut back out to fit. You can fit a Volvo or Mercruiser, it's you choice. I should have selected a tilt and trim model (280T) instead of just a tilt outdrive (280).

Here in the Chesapeake Bay there are a few shallow spots and they can sneak up on you. I hate to jump over and get my feet wet when the water is cold.

2. The 4.3L I believe uses the same bolt pattern as the small block Chevy's, if it does you are in luck. Make sure you get the outdrive with the v-8 gears. There are three different gear sets available; 2.15:1 for 4 cylinder engines turning 6,000 RPMS, 1.86:1 for other motors turning 4,000 RPMS, and the 1.61:1 for V-8 applications.

I just paid $375 for a V-P lower gear case just for the gear set, and am really thankful to say the least! The gear set would be around $510 dollars new. Sometimes it is almost cheaper in the long run to find an old boat with the outdrive on it, that is what I did originally.

3. You need to sit down and crunch the numbers and see which outdrive is more economical for you, either the Volvo-Penta or Mercruiser. If you are looking at a Bravo III then it is a toss up. Both the Bravo III and V-P's are pretty much bullet proof and fit in the same category. I place them in the same type category due to the fact both use similar type cone clutches, therefore provide a great deal in the long run as maintenance goes.

4. You can just buy a brand new Volvo-Penta SX or DP outdrive, that too is a toss up. One of the best drives ever made. Price will not be much more than a used V-P setup unless you get a deal.

5. Remember, you will have to change your shifter and steering assemblies. Steering for my 24 footer ran around $250 and the shifter came with a parts boat I bought with the V-P 280 in it, so that out rightly kept me from spending another 115 for a throttle/shifter mechanism. Cables ran around 60 for both the 18 foot throttle and 23 foot shift cable.

6. I made a steering bracket for the steering cable, a new one depending on the transom plate can run around 400, just another thing to consider.

7. The exhaust "Y" cost around $200 and the complete bell housing with flywheel, torsion plate and such ran around another $600. The little details can eat you up.

8. You will need to buy a flywheel mounted pump for the Volvo-Penta, since there is no water pump in the outdrive like OMC or Mercruiser. This will add up to another $200 by the time you are done. I bought a pulley-type, and made my own mounting bracket. There was abit of head scratching done. Mercruiser could very well be the economical choice for you. Just crunch the numbers and see what you come up with. Mercruiser parts are readily available and normally in stock and the drive is really good looking to boot. Also comparable parts are less expensive than V-P's. Mercruiser also has their set of problems too, so you will still have maintenance costs with either type. Mercruiser used the 4.3L in their setups, so there are parts available with them. A good place to visit, is a boat scrap yard and see a typical 4.3L setup. Should give you a lot of ideas to toy with.

Sorry, I have yet to find any other related information on the web regarding this subject. This info posted to this website is solely from my own experiences.