Sisson choke mounting bolts question

[viningben]

Hey all,

I am new to this site and forum... I have a '48 D24 with a Sisson auto choke, recently while trying to troubleshoot rough idle and running issues. I found that the 2 bolts that hold down the automatic choke had broken off. I have read about drilling a re-tapping the studs, but what I don't know is if the studs thread into the exhaust manifold or if they were braised or welded on originally. From what I can see the bolts broke off flush and I cannot tell see if there are any marks from where they were to begin with. Really just stuck trying to figure out how best to repair this so I can get my D24 back on the road, a y help would be great.

ben

  

[_shel_ny]

Pretty sure they were threaded in. You may be able to see where they were if you sand or wire brush the area vigorously.  If found, you could then tap, or braze on new studs. The exact positioning is not that critical. The solenoid (sisson choke) grounds through the stud.

 

 

 

EDIT: reduce  pic size

Edited April 19, 2014 by shel_ny

[desoto1939]

Here is a real quick fix use the modern style hose clap the screw type and then clamp the choke down onto the top of the manifold.  All you need to do is hold it in place so it does not move also you will need a heat gasket between the manifold and the coke.

 

I think the rods were just brazed onto the manifold.

 

Rich Hartung

Desoto1939@aol.com

[Tom Skinner]

They are threaded in.

I would send a picture but I can't figure that out on here anymore.

I went to a good Mom and Pop Hardware Store in Charlotte NC in the Auto section and found 2 Studs.

Drill and tap them in - don't worry the waste goes straight out the exhaust manifold/tail pipe.

Then use little star washers with the nuts to hold it (Sisson Choke) in place. Don't forget the gasket.

Tom

[viningben]

Thanks every one I am currently wire brushing the broken stud area and center punched one to attempt to drill it out.  Hope and easy out will be able to back it out if i can get a good bite.

 

 

Ben

[Don Coatney]

Might help to drill it out with a left handed drill bit

[viningben]

Does any one know how far in or deep the threads go? do they go all the way threw? i just dont want to drill to far.

[Plymouthy Adams]

a left handed drill bit could well do the trick but I would not count on it unless I had gone through at least three cherry red heat cycles prior to the drilling attempt..steel bolts/studs in cast iron are usually easier to extract once heated a few times.

[Don Coatney]

Here is a real quick fix use the modern style hose clap the screw type and then clamp the choke down onto the top of the manifold.  All you need to do is hold it in place so it does not move also you will need a heat gasket between the manifold and the coke.

 

I think the rods were just brazed onto the manifold.

 

Rich Hartung

Desoto1939@aol.com

Curious how many points would be deducted at a judged event for the use of a screw clamp to make this repair?

[DJ194950]

I drilled out two differant manifolds for Sisson type  chokes. The first I tried 1/4+ and tapped them. With the choke and gasket I only had a couple of threads actually holding the choke on. Not enough threads. Redrilled enough and tapped again to use a 5/8"  long bolts. Fine.

On the second one tried to do the same and ended up drilling one all the way through, but did Not cause and problems at all.

Do not use grade 8 bolts! Too hard to drill  if needed in the future. Grade 5 max. Also a little antisieze will increase your chances if removal needed.

 

Just drill straight as possible and maybe have a helper with a good eye check on you. Do not hurry! 

 

Best of luck,

 

Doug

Edited April 19, 2014 by DJ194950

[_shel_ny]

Original nuts were brass, or some such material. When I have removed them at a salvage yard I have split them with a chisel to avoid breaking the stud. Moto tool with a cutting wheel in my garage.

[DJ194950]

I like  that  observation!

Then if possible find a short enough stainless steel stud and use a brass nut. I guess a grade 5 stud will work.

Mine never had the electic-Sisson chokes installed -factory/dealer. Just did my best guess at home with what I had.

 

Doug

[desoto1939]

Curious how many points would be deducted at a judged event for the use of a screw clamp to make this repair?

Don>  I do not have an answer for that question, but knowin ghte judges they might take a couple of points off.

 

Rich Hartung

[TodFitch]

I like  that  observation!

Then if possible find a short enough stainless steel stud and use a brass nut. I guess a grade 5 stud will work.

Mine never had the electic-Sisson chokes installed -factory/dealer. Just did my best guess at home with what I had.

 

Doug

Grade 5 is way overkill. You are looking at needing ounces of holding force not pounds.

 

Stainless on the stud and brass on the nut are a good idea to resist high temperature corrosion issues though.

[viningben]

I ended up drilling both studs all the way out and re-tapped them 1/4 20. I like the idea of SS all thread with brass nuts will go ahead and do that. As far as the pad underneath I found some GARLOCK gasket material and am going to cut it to size. Does it matted how much I put down 1/4" or 1/8"? Will SS studs with brass nuts conduct enough to act as a ground for the solenoid? 

 

And on a really side note: Can anyone recommend a good paint/body shop in the Houston Tx area for my D24 so once my engine/mechanical rebuild is complete i can get her in for a great paint job?

 

Ben

[Plymouthy Adams]

Garlock is a very good gasket material...as for body paint....check with your local car scene at cuises etc and see who the locals recommend...even the parts houses are usually a good source for "who does it" folks

[Tones52]

After an advance search & going through several threads, I still need help. What is the bolt size for the Sisson choke’s mounting bolts on a ‘52 Plymouth? 
 

I was able to remove mine after days of PB Blaster & some good tapping to break them loose. They’re pretty crusty.  I've been to the more well stocked Ace hardware stores & not finding the same size. I’m guessing it’s a 12-24 mounting bolt. Any help is appreciated. Thanks in advance.

[Dodgeb4ya]

They originally are studs with nuts mounting the Sisson choke unit.

The original studs are 1/4" X 20 tpi at the end that threads into the exhaust manifold.

The other exposed end of the stud retaining the Sisson choke unit has 1/4" X 28 tpi.

Overall length of this original factory stud is about 3/4".

Use what you want to retain the choke unit. Screws, bolts etc.

I always use the correct studs.

 

[Tones52]

Thank you DodgeB4ya. At the hardware store they have the display that you can measure your nuts or bolts against and mine were smaller in diameter to the 1/4 ones. I do see in the manual that studs were used though. Could be the PO changed them. If I find matching bolts or other solution, I’ll add it here. ?

 

[Dodgeb4ya]

The stud part # is 657047.

All those choke units are mounted for many years with the same size studs?

See line 14-64-3

Edited November 16, 2021 by Dodgeb4ya
Add photo

[Bryan]

My father disconnected his and had a manual choke.  Just did the same you had..went to take it off, both bolts broke, but I snapped the manifold in half anyway.  One end was already cracked.

[Tones52]

Bryan, going to a manual choke set up is my back up plan if all else fails. Well as it turned out the mounting bolts for my Sisson are 12-24. I’m curious if other 51 or 52 Plymouths are the same? So I cut the gasket for mine and hooked up the linkage. Next will be attaching the wire from the starter.

[Tom Skinner]

I used the stud part, Bolt or Stud you are good to go.