Aq171A DOHC manifold ideas?-gctid349919

[Guest]

Greetings all from a former lurker. I just bought a 1984 Trophy 2260 that has a replacement Volvo Aq171A DOHC engine with a cracked exhaust manifold. The learning curve just spiked upward! $1700! I'm use to a freshwater cooled Mercruiser manifold; how often do the raw water manifold need replacing? Has anyone tried using the automotive (street rodding) Yoshifab adapter plate-(which the rodders use to adapt a 16 valve head exhaust to the 8 valve version to in order to utilize it's factory cast iron manifold/header)-then using the log style, Aq151, manifold? My concern in trying is the high riser the stock DOHC manifold has vs the lower profile of the other four banger manifolds. Back to my Mercruiser roots...they have exhaust shutters and plus "add on" risers, Volvos, not so. How so? Thanks

[2850Bounty]

Looks like this is p/n 855503 and is unique to the AQ171.

Also looks like it was manufactured between the years of 1987 and 1989 only, so this is probably a dealer item.

I seem to recall that there were several issues with the twin cam heads so it may be less expensive to replace the cylinder head with a single OHC.

I looked at KeyPart, nothing there.

Have you tried Go2Marine.com?

[Guest]

If you are looking to get the boat going, sell the AQ171 engine for parts(they are worth alot if the head casting, crank and rods are any good), and see if you can get a AQ131, AQ145, or AQ151 sohc motor. It will drop in with minimal fuss and parts are cheap and common.

I have seen another 2270 with a 3.0L merc swap from drive to motor, but that is a transom rework and a step backwards in my opinion.

The width doesn't allow for a V-motor without serious mods to the deck and a new doghouse, and the hull is a semi-displacement anyway and isn't stable over ~20mph. These were made to cruise 14-17 knots @ 3-4mpg, good economy for a boat this size, and they cut thru chop and handle the rough sea's pretty well.