5 replies to this topic

[andrewdjackson]

I have a 1965 850 and have an issue with it hesitating only when cruising, most notably around 20-30mph. The hesitation seems to be regular.

The car ticks over lovely no hesitation. It accelerates well and appears not to be hesitating at higher speeds (40+). I have a good spark on all cylinders, have changed the plugs, ht leads, dizzy cap, rotor arm, points and condenser. Dwell is rock solid around 61 at idle, rising to 63/64 when revved. Timing reads around 7/8 and is steady. Dizzy shaft doesn’t have much lateral movement and easily rotates and returns when turned by hand.
So I’m a bit stumped what to check next. TIA

Edited by andrewdjackson, 24 June 2024 - 09:49 PM.

[Chris1275gt]

I’d check the piston in the carburettor is clean and not sticking just to discount it and the oil in the dash pot.

[Spider]

It sounds like it's running lean at cruise.

Worn throttle shaft ?

[Lplus]

I have a 1965 850 and have an issue with it hesitating only when cruising, most notably around 20-30mph. The hesitation seems to be regular.

The car ticks over lovely no hesitation. It accelerates well and appears not to be hesitating at higher speeds (40+). I have a good spark on all cylinders, have changed the plugs, ht leads, dizzy cap, rotor arm, points and condenser. Dwell is rock solid around 61 at idle, rising to 63/64 when revved. Timing reads around 7/8 and is steady. Dizzy shaft doesn’t have much lateral movement and easily rotates and returns when turned by hand.
So I’m a bit stumped what to check next. TIA

When you say it seems to be regular, do you mean it feels like just 1 cylinder is misfiring regularly?

[andrewdjackson]

I’d check the piston in the carburettor is clean and not sticking just to discount it and the oil in the dash pot.

Thanks Chris, I need to check the carb but I did check the dash pot.

[andrewdjackson]

 

I have a 1965 850 and have an issue with it hesitating only when cruising, most notably around 20-30mph. The hesitation seems to be regular.

The car ticks over lovely no hesitation. It accelerates well and appears not to be hesitating at higher speeds (40+). I have a good spark on all cylinders, have changed the plugs, ht leads, dizzy cap, rotor arm, points and condenser. Dwell is rock solid around 61 at idle, rising to 63/64 when revved. Timing reads around 7/8 and is steady. Dizzy shaft doesn’t have much lateral movement and easily rotates and returns when turned by hand.
So I’m a bit stumped what to check next. TIA

When you say it seems to be regular, do you mean it feels like just 1 cylinder is misfiring regularly?

 

Perhaps, but it's quite subtle and when I stop and check if I have a spark on all cylinders and check the burn on the plugs it all looks good. Once I accelerate to a higher speed it seems to go away, of course it could still be there but there's enough momentum that it's not noticeable.