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 
Carb question - Where to buy welch plugs - or do you say welsh
Posted by: keitho64 ()
Date: December 27, 2020 10:46AM

I had posted this on a different thresd but I feel it makes more sense to start a new one. If you want some of the background about why I am doing this, check here. [corvaircenter.com]

I took the advice of the experts and pulled off two carbs to see what I could find. This time I took out all the welch plugs. What I found were passages with a lot of gunk in them. After a lot of soaking, working with mechanics wire and an assortment of small round wire brushes, I was able to clean out all the passages.

I also found on one carb the vent tube was plugged and I could not get air through it. Using the same tools as above I was able to clean it all up. I included two pictures of the tube, one at the top and one at the bottom.

It appears all passages are clear so I will reassemble them and try again before going the EFI route. I am still leaning heavily toward EFI but I hate to be beat by something like a carburetor.

I will add that I have a fuel filter at the tank before the pump and one in the engine compartment along with the bronze filters on the carb inlet. My assumption is the plugs have never been removed before.

I may be able to reuse the smaller ones but the two larger ones in the picture below will need to be replaced. If my measurements are correct one is 3/8 and the other is 1/4. The other 4 look to be 3/16.

This brings me to my question, do any of you have recommendations for what to use as welch plugs? or are they welsh plug?? Is it possible to thread the hole and install set screws?

Keith
64 Monza Convert 110 4-speed
69 911T (IROC Clone)
"Horizontally Opposed"
05 GTO 6-speed (Gotta have a V8)
Chicago Burbs; the Anti-Dragon... 11 turns in 318 miles



Edited 1 time(s). Last edit at 12/27/2020 10:50AM by keitho64.

Attachments:


Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: MattNall ()
Date: December 27, 2020 11:06AM

I would go to your local NAPA....they should have an assortment.

I checked ebay. WELCH is the correct name.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: 66vairman ()
Date: December 27, 2020 11:30AM

Keith - In your picture I see the 66 type idle mixture hole near the idle mixture transition slot. The 66 carburetor idle mixture mixture circuit, per Bob Helt's book, was revised to allow a more consistent mixture (and leaner) to reduce idle emissions AND promote a smoother idle. Works great when the carburetor was new, but if corroded it's not practical to fix.

A fellow in our club at one time had the "welch" plugs and we swapped favors. He pulled all the plugs and cleaned the passages on my 66 carburetor. He noted the passages were "rough" due to corrosion. After installing the carburetor it STILL had the same issue of NOT holding a steady idle speed!!

Just theory, but per the carburetor diagrams that extra hole in the idle mixture circuit was to ensure a constant air fuel emulsion to the idle jet. It required a change to the cluster idle port sizes AND SMOOTH internal channels. Once the channels are corroded (you picture shows corrosion) the carburetor WILL NOT work even if cleaned. I suppose the passages could be drilled out smooth, but then the change in diameter would affect the flow characteristics.

Bottom line --- I've had two "corroded" 66 carburetors I junked and replaced them with 65 bases that are more tolerant of corrosion.

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: MonzaJPD61 ()
Date: December 27, 2020 11:42AM

[www.carburetor-parts.com]



Edited 3 time(s). Last edit at 12/27/2020 07:19PM by MattNall.

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: MonzaJPD61 ()
Date: December 27, 2020 06:33PM

Matt, the link doesn't work

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: MattNall ()
Date: December 27, 2020 07:20PM

try it again

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: Frank DuVal ()
Date: December 27, 2020 07:42PM

Maybe here also. Lots to choose from. I also bought lead balls (shot) for holes in other carburetors.

[quadrajetparts.com]

Frank DuVal

Fredericksburg, VA

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: JimBrandberg ()
Date: December 30, 2020 05:11AM

In my mind for many years I've been thinking "welsh plug" when looking at 66 transmissions.
It will be interesting to see if I can adapt to "welch plug". They say writing it down helps cement in your brain. I wonder if typing it down is the same thing.

When I entered "welsh plug" in a Google search it said "did you mean welch plug?"

Mirriam-Webster had this to say at the bottom:

"Comments on welch"

"What made you want to look up welch? Please tell us where you read or heard it (including the quote, if possible)."

I didn't bite.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: joelsplace ()
Date: December 30, 2020 12:53PM

I'm with you Jim. I'm also confused since I've always associated the term with cup type plugs such as freeze plugs. Does it cover any kind of metal plug? Most of the carburetor plugs are not cup plugs.

Joel
Northlake, TX
5 Ultravans, 116 Corvairs and counting...

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: Frank DuVal ()
Date: December 30, 2020 07:06PM

Welch plug is a think disk. It can be used to seal many different holes in things, typically holes for cores in castings.

So, you can find them in holes in cast blocks, to get the core sand/form out, and in carburetor castings, to seal machined holes, like:

[www.youtube.com]

I have not seen them in Rochester HVs, though.

Cup plugs are not by definition Welch plugs. But they can also seal core or machined holes. So can lead balls.... if the hole is deeper than its diameter.winking smiley

Frank DuVal

Fredericksburg, VA

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: keitho64 ()
Date: December 30, 2020 08:38PM

I checked Quadrajet parts that was referenced. They do have the right sizes and I am ordering them.

I stopped at a few parts stores and hardware stores today. I thought I may dons something locally. I found set screws that I could use if I tapped the openings. Do any of you think this would work?

Keith
64 Monza Convert 110 4-speed
69 911T (IROC Clone)
"Horizontally Opposed"
05 GTO 6-speed (Gotta have a V8)
Chicago Burbs; the Anti-Dragon... 11 turns in 318 miles

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: RobertC ()
Date: December 31, 2020 12:30AM

keitho64 Wrote:
-------------------------------------------------------
> I found set screws that I could use if I tapped the openings. Do any of you think this would work?

I would assume so. What type?

I used socket head screws (short) to plug the vacuum advance port hole on carbs. Way too long ago, cannot remember which Loctite was used.

OOPs, forgot to add that you need to make sure the set screw does not interfere (flow) with the passage you are plugging.

Seth Emerson used one to cover the hole drilled when he relocates jets - at least he did a few decades ago. This replaces the GM welch plug that covers the hole that GM used to drill the port for the PEV valve in 65 / 66 carb fuel bowl.



Edited 2 time(s). Last edit at 12/31/2020 12:35AM by RobertC.

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: JimBrandberg ()
Date: December 31, 2020 05:06AM

I've been using a 15/16 "frost plug" to fill the hole left by the mechanical fuel pump. Would this be considered a "welch plug"? Maybe more of a "cup plug" since it is about a 1/4" deep cup. I'm curious to have one come back in a year or two to see what is in the cup, fan belt fuzz or oil or ...? I should look up the Dorman # to see what they call it.

I'm also interested in getting plugs for our Rochesters. The big assortment from the carburetor guy looks intriguing but it seems folly to have a lot of different sizes on hand if only a few are needed. I'd sure be interested in easy ordering information with correct sizes rather than figuring it out on my own.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: 66vairman ()
Date: December 31, 2020 09:53AM

JimBrandberg Wrote:
-------------------------------------------------------
> I've been using a 15/16 "frost plug" to fill the hole left by the mechanical fuel pump. Would this be considered a "welch plug"? Maybe more of a "cup plug" since it is about a 1/4" deep cup. I'm curious to have one come back in a year or two to see what is in the cup, fan belt fuzz or oil or ...? I should look up the Dorman # to see what they call it.
>
> I'm also interested in getting plugs for our Rochesters. The big assortment from the carburetor guy looks intriguing but it seems folly to have a lot of different sizes on hand if only a few are needed. I'd sure be interested in easy ordering information with correct sizes rather than figuring it out on my own.

Franks link to Quadrajetparts (thanks Frank) has a lengthy list and it appears you can buy individual sizes without purchasing a "kit". That said I have no idea what dimension the "plug" sizes refer to. Hole in carburetor?

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: JimBrandberg ()
Date: January 01, 2021 07:28AM

Yes I would certainly appreciate more information on what to buy please.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: keitho64 ()
Date: January 01, 2021 04:18PM

I ordered some various sizes today from Quadrajet Parts. Once they are in I will share my findings with all of you. Fingers crossed this will work. I should have everything next week. Thanks!

Keith
64 Monza Convert 110 4-speed
69 911T (IROC Clone)
"Horizontally Opposed"
05 GTO 6-speed (Gotta have a V8)
Chicago Burbs; the Anti-Dragon... 11 turns in 318 miles

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: joelsplace ()
Date: January 01, 2021 04:36PM

Keith, that will really help out. Thanks!

Joel
Northlake, TX
5 Ultravans, 116 Corvairs and counting...

Options: ReplyQuote
Re: Carb question - Where to buy welch plugs - or do you say welsh
Posted by: keitho64 ()
Date: February 28, 2021 12:39PM

Well it has been a while since I updated this thread. I picked up a few different size plugs from Quadrejet Parts but in the end none of the fit right.

I tried making a mold out of wood, melted lead from fishing weights and poured them into the mold. It worked OK but not great. Maybe if I made the mold out of steel it would have worked better.

In the end I tapped the 4 small passages with 8-32 and installed 4 set screws.

In the one passage by the ported and fill vacuum hookups I tapped them to 5/16-24 and installed a set screw. I did have to drill them out just a little to tap them.

On the large passage by the idle jet I tapped it 7/16-20. I could not find a set screw so I just made my own.

I covered all the threads with black RTV and screwed them in. I was thinking I may cover the small ones with JB weld. I saw the thread about leaking gas and I want to make sure mine are secure so I do not run into that issue.

I did find many of the passages in the carb were very gummed up. I soaked them for quite a while and was able to clean them out.

My car is still in storage for winter so it will be at least another month before I can test this. I have quite a few old carbs so I figured this was worth a shot. I’ll let you know what I find out.

Keith
64 Monza Convert 110 4-speed
69 911T (IROC Clone)
"Horizontally Opposed"
05 GTO 6-speed (Gotta have a V8)
Chicago Burbs; the Anti-Dragon... 11 turns in 318 miles

Attachments:


Options: ReplyQuote


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