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AQ 231 salling and not reving under load

T

The PM

New member
Hi new to this forum but there seems to be a lot of sensible posters here

Quick history I am a city and guilds mechanic been around boats all my life but don’t do mechanics every day

I am trying to help out a friend who has every one and their uncle, and now me, work on the boat

it is fitted with twin Volvo Penta Aq 231 the have been retro fitted with electronic ignition and the times have been checked, i think the engines have been rebuilt ant some time but no one can confirm that they have been fitted with service replacement Rochester quadajet carbs. both have volvo penta duo prop out drives

compression tests have been done and all pots show at least 140 psi
Both are completely independent electrics fuel etc

i have two problems
if i set the tick over to the recommended 750 rpm the engines stall after two or three seconds.**to stop this happening*the tick over needs to be at least 1100 rpm.

Second

once out at sea the boat powers up both engines fine but they both hit a wall at 2750 rpm and the boat (Sealiner) hits a speed of 14knots and wont quite step up

both engines run smoothly at tick over and rev freely when in neutral

Its doing my head in but there has to be an answer, I love a challenge
Thanks
 
A common problem with simply installing the Pertronix kit, is that the kit alone does ZERO for the distributor's advancing system.... and/or to correct any distributor shaft wear that may be causing an irratic dwell. Yes Dwell!

The Pertronix Hall Effect system still requires a consistant distance from the magnetic unit and sensor unit.
Any deviation here, will essentially affect dwell angle, just as though it was still using contact points.

The other issue may be in the cam weight return spring system.

Given that these are older, I'd pull each distributor and have them tested on a distributor machine.

Bushings can be replaced, and the advancing system and curve can be re-calibrated.

.
 
Last edited:
Hi Thanks for the replies i will work through the suggestions and re post when we find the solution

Part of the problem is that so many people have worked on it, and changed bits like fuel filters etc. i know there is at least one new distributor fitted

Thanks again for taking the time to make suggestions.
 
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