AQ151 Bogs when punched

Hello All,

This is my first post, I have been reading posts for some time.

My issue is that I have a Volvo Penta AQ151 that starts fine, idles fairly smooth and seems to run ok with no load. If i push the trhottle up fact she seems to spit fuel out of the carbs and at times backfires. I have checked the timing, belt jumped a tooth and reset it. I also reset the timing to 6 degrees before TDC per the manual and she continues to act this way.

Suggestions on where to start?

Thanks in advance.

Brett

Re: AQ151 Bogs when punched

Today I sent my alternator out to be rebuilt and figured I would go through everything one more time. Looks like the timing belt slipped a notch so I reset it. I will check if the problem is solved when I get the alternators back later this week.

I am guessing I may have solved it but its too early to tell.

Brett

Re: AQ151 Bogs when punched

Did you adjust the valves properly when you replaced the head? It is not an easy/quick adjustment like a Chevy.

Re: AQ151 Bogs when punched

Don S said:

Did you adjust the valves properly when you replaced the head? It is not an easy/quick adjustment like a Chevy.

Click to expand...

Don,

Thank you for the response.

<edit> They are adjusted properly per the specfications you posted below.

I expected they were adjusted properly. I had the heads done by a shop that specializes in cylinder heads. I shipped them my cams in advance.

Thanks

Brett

Re: AQ151 Bogs when punched

It sure wouldn't hurt to check them to make sure.




Additional things to check.
Carb adjustment, are they syncronized?, timing and dwell. 62?3? is what the book gives, but I find that dwell at 62? or 63? gives best results.
Did you get the diverters under the carbs installed properly?

Re: AQ151 Bogs when punched

If the belt adjustment doesn't help.Try doing a compression test.Re check the timing.Go through the carb again.
Something to look at.J

Re: AQ151 Bogs when punched

The belt shouldn't have jumped, if it did, you need a new one. And you also need to look at all the pulleys and the tensioner.
After you sort that out, Do a compression test.
If your valves are to loose, your compression will be all over the place.
If your valves are to tight, you'll have little to no compression.

You say you reset the timing, how's the dwell? How's the rest of the ignition system for that matter? Points, cap rotor, ohm out the plug wires, and if you don't know the age of the plugs, throw a new set in.

After all that, if it all checks out. Move on to the carb. The solex carbs work fine when they are clean, but they are absolutely intolerant to any kind of debris or clogging.

Re: AQ151 Bogs when punched

Thanks for the tips guys. The belt jumping a tooth was likely my fault. I decided to try and remove the harmonic balancer (crankshaft pully) to clean and paint it, that is likely the reason the timing belt jumped a tooth. While I had it apart to check the timing I replaced the idler with a new one and will test it again in the next few days when I get my alternators back.

<edit> Valve clearance checked out ok.

I know the carburators need to be syncronized, thats one thing I have yet to address but the engine was bogging something aweful and I didnt expect the timing belt jumped...

I will report back one way or another.

Brett