1972 20' Volvo straight 6 - original? Advice?

[CRSeacraft]

Hello,

I'm a Shamrock guy (www.fishtheclassic.net)- I have a 1980 20' walkthru - but I have the opportunity to purchase a 1972 20' Seacraft with a volvo straight 6 (with 3 carbs) mated to a volvo 280 outdrive. She runs and shifts great but I know these Volvo's are old and parts are expensive and hard to come by. Do you think this engine is original? Would it be hard to convert to an inline mercruiser in the future? Any advice is appreciated since I'm a newb Thanks!

[Fr. Frank]

The 280 Volvo sterndrive is a reliable performer. It is not designed for high-performance, but for reliability.

I'm going to presume that if the I6 cyl. engine is original, you have the AQ170A or AQ170B VP system. it is the 181 ci GM block, which came in 170, and 160 hp versions. 170 hp was the most common, I think. The engine is pretty strong, and infinitely rebuildable. It is not, however, very economical. It's a good motor, just not a great motor.

Conversion to a Mercury inline 4 cyl. is pretty easy from a Volvo AQ170 w/ inline 6.

The Volvo-Penta brochure is here: Volvo Penta out of production

[CRSeacraft]

Fr. Frank,

Thanks for the reply. I'm an auto mechanic which is why I like inboards and I/Os better than outboards but I'm not real familiar with volvos. I do know that I looked up the price for an exhaust/intake manifold which is dealer-only and it was like $2500! I'm assuming these should be replaced every 5-6 years like the ones on a v-6 or v-8? I guess when the manifold goes I'd just swap to a GM inline 4 like you suggested - It'd be cheaper and only have one carb to deal with

[spareparts]

I have never seen one of these set ups personally, but assuming it is the GM 250 cu inch I-6, you can use a number of aftermarket manifolds rather than go back with Volvo, you may have to modify the exhaust a bit to make it work, and maybe some cooling mods too, but it shouldn't be too bad. If the carbs start giving you trouble, you could change to the mercruiser 165 set up with a single 2bbl rochester. Or even use the mercruiser manifold without the carb adapter plate and bolt a Q-jet on it like they did on the 292(200 hp) Mercuisers. Putting an I-4 in there might not give you the torque you're after. The drive itself should hold up under most power options. If there is room in the boat, a v6/8 could be a swap option, keeep an eye out for a ragged out late 70's, early 80's bayliner(they used Volvo drives) that has a good engine/drive for a complete swap out, they can be found cheap. All the aquamatic drives had the same hole in the transom. Changing over to a merc or latemodel Volvo would require redoing the transom

[CRSeacraft]

Thanks for the info Spareparts. I was hoping the triple-carb manifold set-up could be replaced with a mercruiser single in the future. The owner prior to the latest had the boat for 15+ years and was meticulous about maintenance. The motor looks beautiful and the drive operates and shifts with no noise or bump going in and out of gear. Only problems seem cosmetic (definitely needs a repaint in and out) and a small 1'x1' soft spot in the floor where the leaning post was originally mounted. Still don't know if I want to make her my next project but hanging around on this site is sure pushing me in that direction