1968 Merc 500 Stalling / Restrictors?

[twinx1649]

Hi,
I have a Merc 500S, 1968 model, that I believe the restrictors need to be serviced. When cold, the motor stalls when I put it in gear. If I do manage to get it to catch when I drop it in gear, it runs great until I let it idle a long period (approximately 5-10 minutes) which is when it starts to run rough and stall (acts like it's flooded). If I am running the boat and shut it off for 10 minutes it will start up and run fine when put in gear. Any longer than that and it stalls when dropped into gear.

Am I on the right track here? The Serial No. is 2306763. Does anyone know if the restrictors are still available for this motor?

Thanks for any help.
Jim Mc.

 

[Laddies]

Re: 1968 Merc 500 Stalling / Restrictors?

The 500 had no restrictors, you need to check the carbs and the carbon in the dist cap.

 

[quicktach]

Re: 1968 Merc 500 Stalling / Restrictors?

Probably starving. Check filters, gas tank vent...carb cleaning and set up. Possibly link & sync next. When throttle advanced, does carb plate open more and continue as throttle is advanced ?

 

[twinx1649]

Re: 1968 Merc 500 Stalling / Restrictors?

Thanks for the advice. First off, I did a tune-up including an overhaul of the entire fuel system. No smoking gun, everything looked great. Here is a clue; with the idle adjustment screw all the way in, the idle is still very low. I expected it to increase enough to allow it to catch when I put it in gear. I asked about the restrictors only because a outboard mechanic suggested it.

Thanks,
Jim Mc.

 

[Laddies]

Re: 1968 Merc 500 Stalling / Restrictors?

If your timing is right and the engine is just idling slow, back in the day it was a common problem and was normally repaired with a longer screw in the idle plate or the lock nut was moved to the front of the plate, I think the plastic cap on the tip of the screw was drilled to deep, letting the advance arm retard the engine to much. If you are going to time the engine you could also lenghten the rod between the advance arm and dist plate but then the timing must be reset.