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SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: mattlockwood ()
Date: December 06, 2020 02:57PM

Thought I’d add an item to check on the hesitation at low idle issue:

My hesitation had the characteristics of a bad vacuum advance circuit, either the diaphragm or the line, but both checked out. I knew (hoped) it couldn’t be the accel pumps since I just rebuilt the carbs.... I checked everything: timing, plugs, points, changed the condenser, fuel line, fuel pump,etc etc.

Turns out, it was the advance plate on the distributor. I had disassembled and cleaned it all up, but- there is a small hold down wire under tension at the base of the spring underneath the cam lubricator... when I removed it and cleaned it and reinstalled, it must’ve skipped up a couple coils on the spring. This allowed the entire advance plate to sort of jar itself out of position in the vertical plane every time the vacuum advance moved the plate.

I reinstalled and secured that tension wire, and it fixed the problem.

------------------------------------------
1970 VW Bus- converted to a 110hp w/a PG. Now with electronic ignition!
Kansas City, Mo



Edited 2 time(s). Last edit at 12/06/2020 03:06PM by mattlockwood.

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: American Mel ()
Date: December 06, 2020 03:03PM

thumbs up

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WA. state, 1 mile south of the Canadian border, I am not at the end of the world, but you can see it from here.

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: cnicol ()
Date: December 06, 2020 03:38PM

I won't, umm, hesitate to put that in the database. Good sleuthing.smileys with beer

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: Seth Emerson ()
Date: December 06, 2020 06:40PM

Nice finding!

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: chris ()
Date: December 06, 2020 07:35PM

Nice work Matt!

'66 Monza coupe
4 speed
140hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: Brizo ()
Date: December 07, 2020 07:54AM

Timing / dwell "jump" due to a worn breaker plate pivot has been a common problem with Corvair distributors forever. That wire preload spring insures the plate stays against the pin even if the plate hole is worn and its often missing so I keep a piece of .047 music wire on hand to make a stronger replacement spring. A drop of oil on the pivot pin any time the cap is off is a good idea.

Dan Brizendine, Circle City Corvairs
'64 8 door Greenbrier, +.060, stroked 186 ci.140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: GMB ()
Date: December 27, 2020 07:09AM

I am dealing with deceleration issues/jerky deceleration. Going thru the distributor, I noticed this wire/spring is missing with a great deal slop in the assembly. Pulled a spare point plate and installed it. Took the car out, and it runs much better.

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: Frank DuVal ()
Date: December 27, 2020 08:22PM

It is possible to rebuild that points plate. I have done several. Takes a small length of 1/4" steel tubing (fuel line) to make a bushing for that pivot pin.

Smitty used to just braze the hole in the plate, drill to size and reassemble.

I got the fuel line bushing idea from Jack Dempsey, long time Corvair mechanic in Maryland. Most Corvair owners in the mid-Atlantic in the 80/90s have lots of Jack stories!eye popping smiley

Putting a wire braid between the moveable plate and the distributor case also solves some irregular running issues.winking smiley

Frank DuVal

Fredericksburg, VA

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: mattlockwood ()
Date: December 29, 2020 08:43PM

Frank DuVal Wrote:
-------------------------------------------------------
> It is possible to rebuild that points plate. I have done several. Takes a small length of 1/4" steel tubing (fuel line) to make a bushing for that pivot pin.
>
> Putting a wire braid between the moveable plate and the distributor case also solves some irregular running issues.winking smiley

Frank- can you clarify where the bushing goes? Does it replace the spring at the pivot point?

Interesting point about the braided line.... vw distributors have that braided line, I believe as a ground...

------------------------------------------
1970 VW Bus- converted to a 110hp w/a PG. Now with electronic ignition!
Kansas City, Mo

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Re: SOLVED: Hesitation at low idle , not accelerator pumps
Posted by: vairmech ()
Date: December 30, 2020 05:03AM

Actually I use a piece of brass tubing.

The bushing goes inside the pivoting plate over the stud. There are many different ways to hold the bushing, I solder mine in place.
Then you add a ground wire soldered to the pivot plate and the base leaving a bit of extra so the plate can move and not bend the ground wire but rather roll it. Sound complicated but just takes common sense.

I generally have 2-3 ready to go and for sale @ $50 ea.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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