73 Chrysler 35hp running rough w/harmonic surge. Help

ArmorLite

Recruit
Joined
May 30, 2009
Messages
1
Hey everyone, thanks for taking my question. I have a 1973 wards/chrysler 35hp on a 14' wards fiberglass hull, 600 pounds dry wieght. Engine hard to start when cold, but choke selonoid is missing so that solves that problem. Easy to start once its warmed up though.

Once running and warmed up at idle, it will chatter (like a single misfire) and the engine will jerk slightly (like the kill button was pushed for a split second) then it will resume normal operation for a few seconds, the repeat the misfire. At mid throttle the engine will run slightly rough and send a constant vibration thru the whole boat. at WOT under load the engine has a slow throttle response and has a harmonic surge once it gets up to speed, like 2 guitars playing the same note thought slightly out of tune with one another,(whum whum whum) about once every second. The boat will not plane out.

Max RPM is only 2100 at WOT in gear. Carb is clean, new fuel and tank, new spark plugs and both appear to be firing normally now although it had a dead no2 plug when I got the boat, impeller working fine pumping plenty of water. Timing advance appears to be working normally with no signs of tampering or previous adjustment.

I'm thinking

Bad points or weak condensers
Cracked points wires near the stator assy.
spark plug wires leaking
Coils leaking
Other cracked ignition wire causing intermitent break
Low compression in one cyl. (please no)

Anyone have any suggestions as to the most likely candidate or other ideas?

Thanks
 
Top