What engine do I have and help me tune the carb!

[Dr. Velocity]

My brother bought a (1982, I believe) Bayliner Capri and is now running into engine problems. First of all, I believe the boat has the Volvo AQ125A 4 cylinder engine. Here are some pictures, maybe someone can tell me what's under the hood:

Also, does anyone know the operating specs of the engine (max RPM specifically)?

So here's situation. After a couple hours of fiddling with the carb (which has been rebuilt and cleaned), I still can't get the engine to run below 2000 RPM without stalling. It runs at higher RPMs just fine. The only think I can come up with is that it may need a bigger idle jet.

Now, I'm used to working with fuel injected motorcycle engines, so this carbureted Volvo engine is new to me. I've worked with carburetors before, so I understand generally what I'm doing, but with this carburetor, it's hard to understand some of the adjustments. I found a parts fiche for the carburetor here:

AQ125A Carburetor Parts Fiche

On there, it says there is an adjustment screw next to the idle jet. What exactly does this screw adjust? Also, if it is anything but tight, it vibrates out easily, so I don't see how it can be used to adjust anything.

Also, what does adjuster screw #24 adjust?

Lastly, it appears in the fiche that there is only one nozzle like the #8 nozzle. However, in my carburetor, there is a second nozzle the feeds straight out of the float bowl. What is this doing here?

I've heard rumors that with a different carburetor, you can gain around 20 extra horsepower with this engine. We may end up replacing the carburetor anyways, does anyone know where to find one or have recommendations for alternatives?

Thanks in advance for the help!

- Adam

 

[jamyers]

Re: What engine do I have and help me tune the carb!

Looking in my carb books, that looks like a Volvo Solex 44 PA1 carb. I've never worked on one, but rebuild kits are available on ebay, and they *should* tell you which screws adjust what.

http://cgi.ebay.com/ebaymotors/Mari...013QQitemZ230148301484QQrdZ1QQsspagenameZWD1V is one ebay kit.

Have you looked at Volvo Penta's website? I'll bet you can download an owner's manual, it should at least tell you which is which.

Good thread here with lots of info on that carb.

Also, I'd suggest opening the carb back up and taking another look at the insides. You mentioned that it's been rebuilt and cleaned, but from the looks of the carb top, it could use another cleaning. From what I gather, the Solex carbs are pretty easy to work on, just take your time and lay it all out in order. Use lots of spray carb cleaner to blast out the small passages, and make SURE there is NO dirt/grunge/anything inside there. With carburetors, cleanliness *is* godliness, you need to be sure that it's clean clean clean.