spin back

[likearock]

hey i bought an airboat and rebuilt the motor and it spins back sometimes when i cut it off is it out of time or is there a special way to cut it off. it is a 4 cyl cont with holley 500. please help me on this i know it cant be good for the motor. thanks josh

 

[swampjet]

# 1 let it idle down for awhile before shuting down. # 2, Cut off fuel (if you have a electric pump) . #3 Install a anti- dieseling seliniod on the carb. hope this helps. It may be running too rich also


Bob

 

[cntry141iq]

Don't know much about aircraft motors but swampjet probably does. Check with the search engine on here or send a pm to jim he knows everything that is on here and where to find it.

 

[likearock]

where do i get an anti dieseling selonoid from napa
josh

 

[swampjet]

Yeah, they were on a lot of carbs in the 70s and 80s. Run a power wire to it to energize it when the ignition is on, set it to be the idle stop when on. Back the idle screw off to let the butterflys close all the way on when the ignition is off. And WHAMMO , youve got it! its not hard. As the man said, Trust me!

 

[swampjet]

You can probably find one in a junk yard

 

[AirAg]

With mine, I switched from 87 octane to 93 octane and then let it idle for a minute or so. This stopped the spin back on mine.

 

[Skeeter]

When you kill mags,give it full throttle.

 

[Preston]

Ive always been told this will fill the cylinders with a full charge of fuel not being ignited and will wash the oil from the cylinders. This will lead to premature ring and cylinder wear...lean it out to kill it. My 2 cents!!

 

[jim]

The only circuits that can feed at shutdown speed is the idle circuit and the acceleration circuit. By opening the throttle the velocity by the idle ports become so slow that the idle circuit cannot feed. In short, opening the throttle at very slow speeds does lean out the mixture, except for the acceleration circuit which will be short lived in this case.

Jim

 

[david johnson]

you can also try octane booster and 1 pint of marval mystery oil and this Will help,along with letting it idle down for min. or 2