Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
vacuum modulator question
Posted by: thumper477 ()
Date: September 12, 2018 12:57PM

I have heard that the reproduction modulators are not holding up.Am I better to put a new repop one on or a tested used one?

Options: ReplyQuote
Re: vacuum modulator question
Posted by: isucorvair ()
Date: September 12, 2018 01:20PM

I have repros on my 3 PGs with no issues to report. All 3 cars have been driven significantly (or raced) with the repros as well - probably 10k or more on one of them, alone.


Eric P.
DeWitt, IA

Options: ReplyQuote
Re: vacuum modulator question
Posted by: GWLee ()
Date: September 12, 2018 01:37PM

While I don't have as many miles on mine as Eric, I have ran mine 3,000 miles or so, and it seems to be fine. Ymmv

Lee Adkins

A Cave Man car
1960 2dr Coupe with pg
Color Tasco Turq.
With Ermine white top.

Catlettsburg,
In the Beautiful state of
North/East KY!

Not the best pic, but the only I had from then, 1997!

2016!

Options: ReplyQuote
Re: vacuum modulator question
Posted by: thumper477 ()
Date: September 12, 2018 01:40PM

Cool,thanks for the feedback!

Options: ReplyQuote
Re: vacuum modulator question
Posted by: JimBrandberg ()
Date: September 13, 2018 05:43AM

I would get one from Clarks or other Corvair vendor, I think the local auto parts will sell you one for a big car powerglide. While it will fit, it may not have the same vacuum characteristics in how it operates.
It could be another one of those things where a good used is better than a new Chinese. I'm so fed up with half of the new crap these days.

Jim Brandberg
Isanti, MN
CorvairRepair.com

Options: ReplyQuote
Re: vacuum modulator question
Posted by: thumper477 ()
Date: September 13, 2018 05:48AM

I went through my pile of used powerglides and found a newish one.Too old to be a repop but too new looking to be 50 years old.I vacuum tested it and it held for 1 hour.Customer wanted me to overhaul his engine due to it smoking out the tailpipe.I will hate to disappoint him to tell him a ruptured vac mod diaphram was the cause and the engine is fine.

Options: ReplyQuote
Re: vacuum modulator question
Posted by: Brizo ()
Date: September 14, 2018 11:06AM

JimBrandberg Wrote:
-------------------------------------------------------
> I would get one from Clarks or other Corvair
> vendor, I think the local auto parts will sell you
> one for a big car powerglide. While it will fit,
> it may not have the same vacuum characteristics in
> how it operates.
> It could be another one of those things where a
> good used is better than a new Chinese. I'm so fed
> up with half of the new crap these days.

NAPA has the regular big car modulator and also an adjustable version so you can tune the shifting just how you like it. The hole in the threaded area has to be drilled out to fit over the Corvair valve but the vacuum characteristics are the same. I just installed one this week, about the 10th I've done.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

Options: ReplyQuote
Re: vacuum modulator question
Posted by: American Mel ()
Date: September 14, 2018 08:06PM

Have also done the adjustable NAPA one.
Works fine! thumbs up

.
-----------------------------------------------
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.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

Options: ReplyQuote
Re: vacuum modulator question
Posted by: vacman ()
Date: September 18, 2018 02:18AM

Can you tell me what this vacuum modulator does and where is it located? I seem to be having a vacuum problem and wonder if this is it. The car runs fine, in neutral you can rev the engine up, put it in gear, will not go more than 5 or 10 miles an hour. I put a vacuum gauge at the vacuum advance, only showing 10 pounds. Thank you

Options: ReplyQuote
Re: vacuum modulator question
Posted by: joelsplace ()
Date: September 18, 2018 01:56PM

It varies fluid pressure in the transmission based on engine load. It is located on the passenger side of the transmission just forward of the dipstick. The distributor is ported vacuum so you shouldn't see anything there when you hook up a gauge unless you are driving the car.

Options: ReplyQuote


Sorry, only registered users may post in this forum.
This forum powered by Phorum.