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Discussion Starter · #1 ·
Hello guys I have another question here and I read somewhere before someone doing this and can't find anything doing different google searches. I have a 600 Holley vacuum secondary I am working on and it had an electric choke on it and I am putting a manual choke on it and I know when doing the kits they give a lead ball to stick into the vacuum hole to close it up so as to not have a vacuum leak since your not going to be using an electric choke.

I am going to a manual choke on this but I don't want to take away the ability of being able to use an electric choke in the future in case if it ends up in someone else's hands then I want to be able to put it back as an electric choke if wanted. My thing is I don't like using the sticky cardboard cover that comes in the rebuild kits as over time I have seen them fall off and cause a hidden vacuum leak that is hard to find at first.

I don't want to stick the lead ball in there and I have heard of folks tapping it with threads and putting an allen cup screw into it to seal it up instead. My question is what size would I be able to tap that hole and has anyone done this before as I have a tap set and a drill bit gauge set to do everything with. I tried like I did before and used some RTV gasket maker over the hole but its the JB weld brand this time and for some reason sitting in my house at room temperature for 24 hours it did not fully cure and was still soft underneath and only cured over the top but not the bottom. I was able to take my paper towel and wipe it off with very little force.

I need to get this thing running by this weekend so I have my wheels going again as I just cleaned out my carb and put some new gaskets on it and took my electric choke off of it to go manual which is what I recently had on the previous carb that was on it but it was sold to a gentlemen who needed one for his ride. I used gasket maker on it but it might have been a different brand but I don't know as it worked. I just want to be able to keep it being able to go either way and not permanently take away the electric choke option.

Tapping it for threads and being able to use an allen cup screw would be excellent and I could then take it back out if ever going electric again. Hope to hear from someone who has maybe done this mod before and give advice on what thread size would work without having to drill the hole if I don't need to and just tap it with the size it already is Just looking for a better way to seal up that hole with it still being able to be used as a manual or an electric choke.

Thanks everyone.
 

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Discussion Starter · #3 ·
I know there is a paper gasket but like I stated before they don't stick on there very long in my experience and they end up falling off and then cause a vacuum leak and many times its not that easy to find when you spray carb cleaner around your carb as it sits behind the choke linkage. That is why I asked if anyone had done the tapping and putting in a allen cup screw before and or something similar as to make it a better solution and not have to worry about the cheap gasket that eventually falls off after a while.
 

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Discussion Starter · #5 ·
Well you must have been lucky because I have had it fall off on me before after a short time and the surface was cleaned. Maybe I can find a bulk of them somewhere or if I were to just glue a cut your own gasket piece what would you recommend for a glue that would hold it on there to keep it simple?

Thanks for the heads up on your experience. If it worked for you is should work for me if I can get something to just stick. Thanks for sharing.
 

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Discussion Starter · #7 ·
Well I guess we will have to give it a try if I can't get my gasket maker to cure. I am trying it again as that is what I did the last time and it worked like a charm for several years with no problems on two different carbs. I will use it with some gasket tack for extra insurance.
 

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Have you thought about using a Golf T. Ya push it in and cut it off with a tiny amount left sticking out so you can grab it later and pull it right back out. Worse case would be using a small wood screw to get the piece out.. Just throwing that out there. I use to keep a handful in the tool box for blocking all kinds of lines... :cool:
 

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Discussion Starter · #9 ·
Rip VW I thought about something like that the other day but not a Golf T but I did think something that I could poke in there and that is something I might try and give it a try. Heck I could cut a small enough chunk off and put some sealant on it and press it in and leave enough out to grab if I want to take it out. Thanks for the idea.
 

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Discussion Starter · #11 ·
That is what I would like to do is use a set screw and make it look good and work good as well but I would not know what size would work best that is a common size such as an 8/32 or so without having to drill out a big size hole and end up ruining the main body on that part and create a seal problem if went back to electric. Something close to the current hole size which I have yet to measure maybe will give me an idea come to think of it. I have tons of 6/32 and 8/32 brass allen set screws on hand that I use for idle feed restrictors.
 

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Find the size of the hole by inserting a drill bit that fits snuggly into it and use the appropriate drill/tap.

6-32 tap uses a #36 bit (7/64 is close, slightly larger but will work))

8-32 uses a #29 bit (9/64 is close, slightly larger but will work)
 

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Discussion Starter · #14 ·
Well I checked and a 22 drill bit is about the tightest fit with some resistance and according to my drill guide chart I can use a 21 drill bit which is not much difference in size to a 21 and tap it for a 10-32 set screw or even a regular machine screw will fit since it sits down enough and would have enough clearance for the head. I will tap it and then put a tiny set screw in and be done with it.
 

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Discussion Starter · #15 ·
Well guys I tapped it and put in a 10-32 set screw and its sealed up nice and good and can be put back to the normal function if I choose to use an electric choke again in the future. Thanks guys for your help and stuff much appreciated.
 
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