Repaired 8N stalling when trying to open up the throttle (yes, me again)

[Egon]

To make spark testing easier one of these are a great help.

http://www.denlorstools.com/shop/images/LIS26900.jpg

 

[Soundguy]

remember.. fire order is 1-2-4-3 so 34 is easy to mix up.

if no change in rpm.. then those cyls are not fireing.

pull wire off and hold close and see if it jump gap and fires cyl. if so.. plug may be fouled.

swap in new plougs nad see if ti helps.

if not. pull those plugs and roll engine over and do a 'thumb' compression test.

might have stuck valves.

 

[Soundguy]

remember.. fire order is 1-2-4-3 so 34 is easy to mix up.

if no change in rpm.. then those cyls are not fireing.

pull wire off and hold close and see if it jump gap and fires cyl. if so.. plug may be fouled.

swap in new plougs nad see if ti helps.

if not. pull those plugs and roll engine over and do a 'thumb' compression test.

might have stuck valves.

 

[PorkChopsMmm]

I think the carb is my main issue. Here is why...

OK, something must have been amiss last night because when I checked removing the plug wires again there was a definite change when 3 and 4 were removed. I did a thumb compression check and all cylinders had strong push and pull.

For the heck of it I pulled the 4 spark plugs and found that 1, 3, and 4 were blackened while 2 looked relatively clean. I replaced these year old Autolite 437's with new ones, properly gapped to 0.025.

At first this sounded better and stronger, but then I noticed one of the mounting studs was loose on the carb. From my previous thread, the threaded portion on the right hand side stud on the carb itself was partially stripped out. To remedy this I bought a longer stud and torqued it down last year. It looks like the threads finally gave out sometime in the past few months and there appeared to be a vacuum leak there. So I brought the carb in the house and used some QuikSteel to permanently afix the stud. That allowed me to torque the bolt down on the carb, but problems still remain.

Sooo.... using the manual and carb guides on the internet if I turn in both the idle air and the main mixture screw, and then back out a turn, that should bring me to baseline. It still runs just as crappy as it has recently at 3/4 to full idle. If I start backing out the screws many turns then it slowly starts to sound better, but I get some backfiring. Not to rehash old memories, but I had issues last year with getting this carb to take to "normal" 8N carb adjustments even after 2 full rebuilds. Any other advice? I foresee another carb rebuild in my future.

 

[Oldtractorfixer]

I know you've been over all this but the way it started still sounds like either a restricted fuel flow (bad filter, junk in tank, pinched line, etc.) or weak spark. Back to basics. Really doesn't sound like gov, it just controls throttle on the carb. Could be a vacuum leak at the intake I suppose. Does this have an advance mechanisim in the mag/distributor? That could do it. Try checking timing with a light. Probably not much help but some things to think about.

 

[Soundguy]

1 turn on the main won't get you much.

here's the deal. i start with about 1.5 turns out ont he main.. and usually expect to end up closer to 2 turns. that is a fuel needle.. out to enrich.

the small needle / idle needle is an air needle. IN to enrich, OUT to lean

I think the carb is my main issue. Here is why...

OK, something must have been amiss last night because when I checked removing the plug wires again there was a definite change when 3 and 4 were removed. I did a thumb compression check and all cylinders had strong push and pull.

For the heck of it I pulled the 4 spark plugs and found that 1, 3, and 4 were blackened while 2 looked relatively clean. I replaced these year old Autolite 437's with new ones, properly gapped to 0.025.

At first this sounded better and stronger, but then I noticed one of the mounting studs was loose on the carb. From my previous thread, the threaded portion on the right hand side stud on the carb itself was partially stripped out. To remedy this I bought a longer stud and torqued it down last year. It looks like the threads finally gave out sometime in the past few months and there appeared to be a vacuum leak there. So I brought the carb in the house and used some QuikSteel to permanently afix the stud. That allowed me to torque the bolt down on the carb, but problems still remain.

Sooo.... using the manual and carb guides on the internet if I turn in both the idle air and the main mixture screw, and then back out a turn, that should bring me to baseline. It still runs just as crappy as it has recently at 3/4 to full idle. If I start backing out the screws many turns then it slowly starts to sound better, but I get some backfiring. Not to rehash old memories, but I had issues last year with getting this carb to take to "normal" 8N carb adjustments even after 2 full rebuilds. Any other advice? I foresee another carb rebuild in my future.

 

[PorkChopsMmm]

This may be the dumbest question ever posted, but are these full 360 degree turns or 90 degree turns of the wrist?

 

[Soundguy]

wrist?

the head of each needle is a circle.. there are 360' in each FULL turn.

 

[PorkChopsMmm]

Thanks SG. Will try tonight. My snow plow guy just told me he is going to raise the price for plowing my 1/2 mile dirt road. I need to get this baby running.

 

[murphy1244]

This may be the dumbest question ever posted, but are these full 360 degree turns or 90 degree turns of the wrist?

Oh Lordy.