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YmeHP
07-27-2008, 03:40 PM
Hello, I've got a 89' Donzi Z-22 w/ a SBC and Volvo outdrive. The stock OMC outdrive was replaced by a previous owner as hole is there for the original controls and just outside the hull, transom? is a OMC part but the outdrive itself I was told is a Volvo. Anyways on to my problem, How many RPM's at full throttle should I be turning with this boat? I currently only turn around 3700 @ WOT. If im on the gas for a period of 30-60 seconds the boat falls flat on this face and sometimes even backfires, maybe a fuel problem. Where should I begin to investigate; fuel filter, fuel pump, timing, spark plugs, or dist. etc? Any thoughts, and also any recommendations on a good prop?

onesubdrvr
07-27-2008, 04:14 PM
Hello, I've got a 89' Donzi Z-22 w/ a SBC and Volvo outdrive. The stock OMC outdrive was replaced by a previous owner as hole is there for the original controls and just outside the hull, transom? is a OMC part but the outdrive itself I was told is a Volvo. Anyways on to my problem, How many RPM's at full throttle should I be turning with this boat? I currently only turn around 3700 @ WOT. If im on the gas for a period of 30-60 seconds the boat falls flat on this face and sometimes even backfires, maybe a fuel problem. Where should I begin to investigate; fuel filter, fuel pump, timing, spark plugs, or dist. etc? Any thoughts, and also any recommendations on a good prop?
Check all the stuff you've mentioned. Be diligent on the timing. Was the engine recently rebuilt?

When I rebuilt the engine on my Ragazza, it ran GREAT on the muffs, so I took it out, and gave me many of the same symptoms you mention. Turns out that I was 180* out on my distributer. Removed, re-installed correctly, ran like a champ from then out out. So I'd start with the electrical stuff. Plugs are easy to pull and check, timing is easy, etc.

What kind of carb?

For a good all around prop for normal power, I'd look at a Turbo I, probably 20" or 21" pitch for a stock set-up.

Best luck, and keep us informed with what you find out. It's good information for all.

Wayne

joseph m. hahnl
07-27-2008, 05:07 PM
Hello, I've got a 89' Donzi Z-22 w/ a SBC and Volvo outdrive. The stock OMC outdrive was replaced by a previous owner as hole is there for the original controls and just outside the hull, transom? is a OMC part but the outdrive itself I was told is a Volvo. Anyways on to my problem, How many RPM's at full throttle should I be turning with this boat? I currently only turn around 3700 @ WOT. If im on the gas for a period of 30-60 seconds the boat falls flat on this face and sometimes even backfires, maybe a fuel problem. Where should I begin to investigate; fuel filter, fuel pump, timing, spark plugs, or dist. etc? Any thoughts, and also any recommendations on a good prop?

Backfiring thru the carb or the exhaust ?

YmeHP
07-28-2008, 06:50 PM
Backfiring thru the carb or the exhaust ?


I'm guessing through the exhaust. However, I never opened the hatch to investigate any further at the time. I plan on checking the timing, changing the plugs, and install a new fuel filter tmw. Another question, what do you guys recommend for plugs? I've got an extra set of NGK V-Power 8's in the tool box, are these applicable? Also, what should the motor be properly timed at?

YmeHP
08-03-2008, 07:53 PM
Ok, thus far i've tried sparkplugs, fuel filter, and new gas. Where should I look next? What should timing be on the 350 and at what RPM, what are some rough numbers on compression, and any recommended props?