My issues

TCap

TCap

Member
Hi everyone, been working on the "A" and finally got her running great…but I started to notice at the last two start ups she popped/snap right as she fired up. Not a big bang but a pop or snap, like a loud spark type noise or small backfire from carb. I checked the timing and its dead on. She also doesn't start right away, takes a few crank attempts and more choke than it use to. But she runs well and Idles great. So that's issue #1. Issue #2 is I also noticed a slight hesitation when giving her gas. So I had her idling in the driveway with the spark advanced and the idle about three notches down and I could hear the hesitation/miss rather than a steady high idle. Think I will pull the carb off and clean it out. And now Issue #3, I checked my plugs and they are black. I'd clean them run the car a couple of times and check again…still black. Running rich, but don't know why. Adjustment on carb (zenith) is 1.5 turns open. Gav is at 1/4 when running, 1/2 to 3/4 turn at cold start, plugs are new and gapped at .035, points on dist. are at .020 -.022. Running out of ideas, would really like to get some new thoughts on these issues, I'd appreciate it. Thanks!
 
You want to "proportionate" your advance to match your engine speed. Run at full retard at idle (or maybe down a notch or two) and only when out on the road start moving the advance forward by pulling down matching engine speed to advance.

This is an action done better actually by the Model B distributor with it's centrifugal advance weights.

You may have a sticky valve - or a valve seat that needs "dressing up" with some cloverleaf. You may be attempting to compensate for loss of power by running the carb a little rich - which it will do but doesn't give you a clean burn.

Not a badly operated thing though. I.e. not your fault. You're adjusting the operation based on your sense of operation - but some other mechanical issue is keeping you from optimal performance (and fuel efficiency.)

Joe K
 
put a set of flow tested renners jets in it, and also make sure your throttle shaft is tight //not sucking air//float level set to specs... i always change out both when going through an old carb. what plugs are you running? maybe you need a hotter heat range and on a properly tuned carb youll need to open the GAV more when starting cold maybe another 1/2 turn then back to 1/4...
one or more of these things shouls straighrten it out
 
Thanks for the info guys, I'm running 3X champion plugs. Carb is a new old style zenith from snyders. The starting issue is the problem that's bothering me the most. Would jets be an issue here?
 
TCap said:
Thanks for the info guys, I'm running 3X champion plugs. Carb is a new old style zenith from snyders. The starting issue is the problem that's bothering me the most. Would jets be an issue here?
Click to expand...

Possibly. Mitch//Pa may have the best solution to the over-fueled condition. Starting may be an issue of float chamber level?

OBTW, both of these (jets and float level) are common issues with aftermarket carbs - and easily addressed.

Joe K
 
first thing check your points have had this happen more than you think the rubbing block does ware a tiny bit of grease will make them last longer
 
Hi everyone,

I started on the list of items to check that were suggested. I checked all the point gaps and made sure they were to spec., tightened the manifold bolts (they were only torqued to 40 ft. lbs.) have them at 45 now. Checked and cleaned both battery cables. Just pulled the bottom of the carb off last night and found some rust at the bottom of the bowl, very little but it's there. I'll clean out the carb and may buy a fuel shut off valve screen for the gas tank as this is the second time I've found rust in the carb bowl.
 
TCap said:
Hi everyone,

I started on the list of items to check that were suggested. I checked all the point gaps and made sure they were to spec., tightened the manifold bolts (they were only torqued to 40 ft. lbs.) have them at 45 now. Checked and cleaned both battery cables. Just pulled the bottom of the carb off last night and found some rust at the bottom of the bowl, very little but it's there. I'll clean out the carb and may buy a fuel shut off valve screen for the gas tank as this is the second time I've found rust in the carb bowl.
Click to expand...
Tcap,
You shouldn't find rust flakes in the carb bowl, IF you have that fine wire screen in the front of the carb body.
Bill W.
 
Hi Bill, This is what I found in the carb bowl. It's not much but it's there.
 

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Hi Guys, wanted to update you on where I'm at. So I cleaned out the carb and had more rust dust come out. Put it back on and she ran better, no pop at startup. Will be installing the gas valve screen to help with the rust. I still think she can run better, so hotter plugs might be next and maybe new jets for the carb. But over all everything looks good and I had her out on the road on Sunday for a short run. Thanks for all of your help!
 
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