MSD

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downsr said:
Looking back the pcv system was affecting my idle circuit
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I'd look a this next. The idle can 'hunt' when the PCV close-down level is too close to idle vacuum.

Measure the idle vacuum cold and then as it warms up and see what you have. It could easily be a PCV valve that is open to cruise opening at cold idle and then closing down to idle flow level as the vacuum comes up a bit with warming up, and thus effecting idle in the carb, with the carb being set wrong at cold idle to compensate for the cruise PCV flow it is seeing then. It may not be the only issue, but that needs to be checked.

What PCV do you have, OP? (Assuming you have one....)
 
nm9stheham said:
I'd look a this next. The idle can 'hunt' when the PCV close-down level is too close to idle vacuum.

Measure the idle vacuum cold and then as it warms up and see what you have. It could easily be a PCV valve that is open to cruise opening at cold idle and then closing down to idle flow level as the vacuum comes up a bit with warming up, and thus effecting idle in the carb, with the carb being set wrong at cold idle to compensate for the cruise PCV flow it is seeing then. It may not be the only issue, but that needs to be checked.

What PCV do you have, OP? (Assuming you have one....)
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Might be on to something, just installed this 1930-2008 All Makes All Models Parts | DF1700 | Dual Flow Adjustable PCV Valve | Classic Industries
 
Measure your cold idle vacuum and set the transition point between cruise and idle flows 4-6 inches below that. With the unusually large overlap of that cam (large for that duration), I'd expect a lowish idle vacuum. Looking at the description of how to set this thing on the M/E Wagner site, it looks like you can just put in 1 of 2 springs to set this point; it looks like the screws are there to set the 2 different flow amounts.

Once that is sorted, then I'd be looking at the secondary throttle stop screw setting as another cause for this idle hunting. If too large, then the secondary progressives can be exposed and coming into the picture when they shouldn't. Are your main idle mixture screws really responsive to set idle smoothness when you adjust them, or do they not have much effect? If they are not very responsive, this is an indication that fuel is being fed in on the secondary side.

I'd doublecheck the carb float settings too. This whole deal can be a combination of things, so it can be a sequence of things to get settled down.
 
nm9stheham said:
Measure your cold idle vacuum and set the transition point between cruise and idle flows 4-6 inches below that. With the unusually large overlap of that cam (large for that duration), I'd expect a lowish idle vacuum. Looking at the description of how to set this thing on the M/E Wagner site, it looks like you can just put in 1 of 2 springs to set this point; it looks like the screws are there to set the 2 different flow amounts.

Once that is sorted, then I'd be looking at the secondary throttle stop screw setting as another cause for this idle hunting. If too large, then the secondary progressives can be exposed and coming into the picture when they shouldn't. Are your main idle mixture screws really responsive to set idle smoothness when you adjust them, or do they not have much effect? If they are not very responsive, this is an indication that fuel is being fed in on the secondary side.

I'd doublecheck the carb float settings too. This whole deal can be a combination of things, so it can be a sequence of things to get settled down.
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Carb has 4 corner idle. 80803 0414
 
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nm9stheham said:
Measure your cold idle vacuum and set the transition point between cruise and idle flows 4-6 inches below that. With the unusually large overlap of that cam (large for that duration), I'd expect a lowish idle vacuum. Looking at the description of how to set this thing on the M/E Wagner site, it looks like you can just put in 1 of 2 springs to set this point; it looks like the screws are there to set the 2 different flow amounts.

Once that is sorted, then I'd be looking at the secondary throttle stop screw setting as another cause for this idle hunting. If too large, then the secondary progressives can be exposed and coming into the picture when they shouldn't. Are your main idle mixture screws really responsive to set idle smoothness when you adjust them, or do they not have much effect? If they are not very responsive, this is an indication that fuel is being fed in on the secondary side.

I'd doublecheck the carb float settings too. This whole deal can be a combination of things, so it can be a sequence of things to get settled down.
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All four corners respond to settings, idle mixture screws...
 
Update, installed a 16 Degree bushing, set initial at 25 degrees. All in at 41 Degree. I will see how it does....
 
Update, got tune worked out, Idle stays right where I set it now. I think it was in the end a combination of a few things. The timing curve, and the secondaries on the carb, Carb. has four corner idle, and It seems the rear ventures were open a little too far. Runs awesome now. As always THANKS for ALL input. :thankyou::thankyou:
 
Mopar Tim said:
Update, got tune worked out, Idle stays right where I set it now. I think it was in the end a combination of a few things. The timing curve, and the secondaries on the carb, Carb. has four corner idle, and It seems the rear ventures were open a little too far. Runs awesome now. As always THANKS for ALL input. :thankyou::thankyou:
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Good to hear Tim!!!!
 
Pull a plug and see where the line is on the ground strap. Should be right at the bend. If closer to the bottom too much timing, closer to the tip. To little. My 410 x heads likes 34 total.
 
Why? Don't really know, but believe it has to do with the overall combustion chamber temp. I learned a bunch about how to read plugs on the 4secondsflat fbo site. As crazy as it sounds sb mopars also tend to have small triangle like patterns out near the tip of the ground strap. Not sure why, but intersting. Definitely worth going to the site and reading thier tech archives.
 
furrystump said:
Why? Don't really know, but believe it has to do with the overall combustion chamber temp. I learned a bunch about how to read plugs on the 4secondsflat fbo site. As crazy as it sounds sb mopars also tend to have small triangle like patterns out near the tip of the ground strap. Not sure why, but intersting. Definitely worth going to the site and reading thier tech archives.
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:thumbsup::thankyou:
 
The only time I think it won't be a good estimate of the timing is if you are running a WAY to hot plug. It won't show a line, but you will see other evidence of heat. Like too many threads on the plug showing heat discoloration.
 
nm9stheham said:
And we have another new member in the Secondary Stop Screw Club LOL. Glad you got it all good!
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Well in all fairness, this carb has a stop screw you adjust just like the front. It has four corner idle and four mixture screws. NOT the one you have to remove carb to get to. You can idle off just the rear if you wanted to.
 
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