1904 question

M

maunster

New member
Hi...I have a 1904 carb in my 67 s800. I have rebuilt this thing...hmmmm....I don't know 50 times, and read about every piece of literature about it. I've got it close...so very close, I replaced the main well with a refurbished one from either mayben or kennedy, I cant remember who was redoing them. It's running great aside from one tiny quirk I just can't figure out.

When the engine's under load it runs like a top...but if a were to be in nuetral and throttle it to, I don't know, maybe 1000-1200 (just guessing) I start to get a sputtering misfire thing going on. The same will happen if I'm cruisin in the neighborhood in at the top of 2nd gear....as soon as I stomp on it, it gets as solid as a rock. any thoughts???
 
I should probably also just clarify that I can go from a complete stop to a typical 45 mph and hold that speed with no sputtering/misfire at all. It just happens in the previously stated circumstances.
 
Sounds like your accel pump and nozzle squirter are functioning properly. The carb is still transitioning between idle and primary circuits at @ 1200 revs. Double check your float level, check your idle air mixture setting and see what kind of vacuum the intake is pulling at idle with a gauge. Are you running an engine driven pump or an electrical? Have you measured fuel pressure upstream of the carb? Have you verified that your point gap or better yet your dwell is within spec? Spark plugs and plug wires in good condition?
 
scoutboy74 said:
sounds like your accel pump and nozzle squirter are functioning properly. The carb is still transitioning between idle and primary circuits at @ 1200 revs. Double check your float level, check your idle air mixture setting and see what kind of vacuum the intake is pulling at idle with a gauge.
Click to expand...

2x the fuel level. Also the accel plunger needs to be starting up the nose a bit at idle. You don't want the plunger fully on the flat of the pump cam. There should be a slight angle between the flat on the cam and the plunger.
The opposite can also be a problem. Too much pump to early. You May want to try it by lowering the angle if you already have it up on the nose a bit.. The adjustment is made by bending the crook in the link between the plastic cam and the throttle arm. Remove the link to bend it as you are likely to break the plastic arm other wise.
 
Hey thanks for the help! I think I need to recheck the float level. Quick question...how do you guys set it up accurately? I did it by eye..so that May be an issue. I'll check the cam angle on the pump...I not sure if that has an issue as the problem only arises when a steady rpm is held. But you know better than I so I will double check :thumbsup:

also, I should add, I was toying with it last night and noticed that if I take the vacuum advance off the dist. The problem decreases quite a bit.
So I have a couple thoughts:
1. End play is too great
2. Worn bushings
3. Mech. Advance springs need adjusting

I've tested vacuum and the advance unit operation and they seem to be fine. Could it be that the mech. Advance is advancing too great and the vacuum is pulling it just a bit too far? I don't know...I'm kind of shooting in the dark....just a thought. Let me know what you think, thanks!
 
Could possibly be ignition. Tough to tell by words alone.
We have to assume the items other then the carb were solid.
I forget thes measurment but the kit should have come with something.
Said you could get it to run rough out of gear. Do that and look for black smoke. Of you don't see it, I would look into the ignition stuff you suspect.
 
You must log in or register to reply here.
Back
Top