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stownsend

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I’m after a bit of help…

Some history, I had a VP 260 (AQ151 with 290 SP-A leg) in a 16 ft speed boat. Took this engine and installed it into a 23 ft cabin cruiser (Invader 2200).

I serviced / overhauled the engine, new head gasket; seals etc… spark plugs and leads, coil, alternator, etc, cleaned and rebuilt the crabs (twin solex) I replaced the timing belt, checked and rechecked the timing several times (all the notices line up as per the VP workshop manuals and Solec manual), she idles fine but under load I can’t get anymore than 1500 to 2000 rpm. If I rev her out of gear she revs fine, any ideas?

Could my timing be out by a couple of tooth on the top pulley, and she is just off when the valves open?

Fuel starvation / carbs issue?

Wrong prop ?

Any help will be much appreciated as I’m going round in circles!

Cheers

Stu
 
stownsend said:
Some history, I had a VP 260 (AQ151 with 290 SP-A leg) in a 16 ft speed boat. Took this engine and installed it into a 23 ft cabin cruiser (Invader 2200).

she idles fine but under load I can’t get anymore than 1500 to 2000 rpm. If I rev her out of gear she revs fine, any ideas?
Click to expand...
There is some conflicting info here..... the AQ 260 is a GM V-8.
I'll assume that you are asking about the AQ151, and I'll assume that you are geared correctly (2.15:1), and have explored several different propellers!

Begin by strobing your timing marks with a timing light set in "Standard" mode!
Refer to your OEM manual for both BASE advance and TAT (total advance timing).
The timing belt must be phased correctly!

If you can set BASE as per OEM specs....., and if you see a somewhat linear progressive ignition advance (as you increase RPM to OEM limit specs), then move on to other items.
If not, then you very likely have an ignition issue...... possibly within the distributor itself!

Not reaching TAT will prevent power....., yet with NO Load, the engine will still rev up!

An incorrect gear ratio, and/or incorrect prop will also prevent you from reaching WOT RPM while under load.
 
Last edited:
thanks for the info, i'll see if i can sort out a timing gun, i'm doing the testing when tied up on the pontoon, would that have any impact ?
 
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