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Discussion Starter · #1 ·
Hello guys I have just bought a used holley carb from ebay to restore and this is the first time I have come across the main body having some threads that are damaged. The main body is a standard 600 holley main body 4 barrel 80457 and the normal 12-24 thread size. Now my question is I watched a video by BLP on youtube on how you can fix this with there kit but I don't want to spend a fortune on a kit and I do have a tap kit and the proper drill sizes and stuff and also I have a perma coil 12-24 thread repair kit I got years back just for this occasion but I guess I never noticed they have different length coils. Mine are only .200 long which I don't think will be long enough for the fix.
Can anyone out there by using a bottoming tap to thread for the helicoil which I have the proper tap size for the helicoil but I don't know what length of 12-24 coils I would need. I see a common size like 1.0 then 1.5 etc and I don't know what would be correct. Can anyone who has done this fix before let me know and also I saw a video by jegs and they did not use a countersink bit like BLP did in there video and is that really necessary? I have a drill press but Jegs in there video just used a tiny hand drill to drill out the old threads.

This main body is aluminum and the threads are not all stripped out but some threads did come out on the bolts as the carb looked nice and clean on the outside but wow what it looked like inside was horrible. The accelerator pump was as stiff as a dead body and the spring was sticky and rusted from old gas and never saw one like that bad before. This will be a new lesson for me to learn but I don't want to ruin it as I paid a hundred bucks for this carb and they listed it as not damaged and just needed a refresh. Wow that was way off the description part.
Thanks guys.
 

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Discussion Starter · #3 ·
The kit I have is parma coil 1208-102, I looked up some info and it says the coil inserts are .324 but when I take one out of the box it only measures only .200. So my question is does that .324 mean the length when its stretched out and threaded in the hole?
 

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The special tap you use to thread the hole will spread out the Helicoil in it’s threads to give you the resulting #12 thread for the bowl screw. So yes the Helicoil will get longer as you wind it in the new threaded hole.
 

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Discussion Starter · #6 ·
Well I measured and the bolt sticks out about .350 before being torqued measuring the bowl length that sticks out from the end of the metering block lined up with the fuel bowl, and just for the record I received it that way and was not my doing. I have a hand held torque driver used for guns and stuff that I use and always torque them to 25 inch pounds and after ten plus years working on holley carbs I have never not once stripped a bolt thread in the main body.

Whoever owned it before me was the Gorilla finger person. I always just go wrist tight and am very careful when I tighten them down if I don't use my torque driver. Quick fuel in there literature stated those specs. In my rebuild manual they state even more torque but for me over the years 25 inch pounds has been plenty and I always recheck after a few heat cycles. So on the coils when they say .324 is that the length of the coil stretched out then or before? Sorry this is my first time messing with these things and I know there are different lengths. For my Perma coil kit I have they measure like I said .200 out of the package even before being installed and don't know how long they would be after going inside. Also there is a 32457 stamped on the back of my kit container.

Any tips how to successfully do this without messing it up? I would hate to damage it and be out of the amount it would cost for a main body replacement. Thanks guys for your help so far.
 

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Discussion Starter · #8 ·
I kind of understand of what you mean. In order to have enough thread engagement of a fastener you want a minimum amount of at least the full 1 size of the thread pitch to 1 and a half at the most. I will give it a try and see how it goes. Thanks again
Eric
 

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Discussion Starter · #13 ·
Hello guys thanks for all that information. I think I am understanding a lot more and once again in my ten plus years here you guys have pulled through for me and have given me some more education on something I knew about but had never done before and this will be a first for me and hopefully it will go well and I don't mess it up even though it seems pretty straight forward.

The first time I popped out my loose boosters in a main body and bought a screw in booster kit from all carbs I messed up the first time but have been successful on that since then minus this weekend but that is another more detailed deal on that one. I will get it apart and start on it today.

I am getting the understanding now of this stuff and saw a video on how the stacking of coils can be done as well so props also on you ericnova72 and also I would list everyone else's names on here but the list is long and a thumbs up to everyone and a like to everybody since the new system does not let me do it. I think the one coil will be plenty just like you guys said as the bolt does not go in very far and don't know if I could fit two in there as I can't remember how far it goes down. I think it would not be deep enough for two.

I will get to it this weekend and see how it goes. I guess I have to mess up my shop again lol. Fingers crossed.
 

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If the casting has room you can deepen the hole at the same time you do the repair, so that it will accept two inserts stacked.

Standard machinist practice is thread engagement 1x fastener diameter in hard metals(mild steel and harder), while soft metals lke aluminum and brass then 1.5x to 2x fastener diameter is used.
 

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Discussion Starter · #15 ·
The main body is aluminum but I would not know how far to drill down to fit two inserts inside the thing and the inserts are the 1.5 diameter thread pitch for one insert. The inserts state on the back of the package as .324 which would engage 1 and a half threads with one coil inserted so I would assume that would be good enough to hold in the main body as the bolts don't go in to much further then that then maybe about .050 at the most after its been tightened up.

I don't want to end up messing this thing up and end up with another main body ruined for another reason because of drilling error on my side. I would think putting in a second one would not do much as the problem is I would not know how long each coil would be stacked and the elongated length would be and don't know how far I could actually drill in. I took a measurement but I forgot how far the factory hole goes down. I think but I can be wrong that the one coil insert should be good enough to hold at least it in that form would or should be stronger then what it was before anything was done but I am no expert on this stuff.
 

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A quick visual way to see how much length the installed coil has is count the threads on the tap....the coil inserts are 6 coils /threads long.

Or just use the thread pitch mathematically...at 24 threads per inch it is .042" per thread/coil. 6 x .042" = .252"
Your single insert installed will fill a depth of .250":cool:
 

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Discussion Starter · #17 ·
Ericnova72 you are the man. Like the emoji at the end of your quote are your cool. In your honest opinion do you think the one insert will hold up good in the aluminum body? All the holley repair kits out there just use the one coil and I have heard many have used them and they have never had any failures with just one insert.

Sorry but I am a rookie with all this stuff you guys have shared with me and have only heard only certain things here and there over the years. I am ready to take a crack at this thing and get it done and fixed and over with so I can get it put together. Thanks for your math formula I will add that to my notes that many of you have given me over the years to keep for my binder full of information you all have shared me with over the years. I keep a library of info of what I have learned from you and many others on here. Thanks again
Eric
 

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Yeah, for the load it should take one insert should be fine.
Making 2 fit would just be insurance if the bolts show they could use it. Just off memory it seems like 8 threads was the ideal length to contact all of the bolt, but I'm not positive on that.
 

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Discussion Starter · #19 ·
Well guys I am back with an update. I swear I am cursed with the carb I bought used from ebay. I have never done a helicoil repair before and was not about to start since I could my drill press was not the right size for adjustment since its only an 8 inch size but anyways I brought my main body up to my Fathers house which he has a big size high quality drill press and the main body was drilled out just fine but the parmacoil brand insert kit must be junk compared to the Helicoil brand as we got the first 4 holes just fine with the inserts and then on the last four the insert tool was starting to receive damage on the insert tool and it must have been soft metal as it started to mess up the threads on the insert tool and it would wobble since the beginning and my Dad who has worked for over 40 plus years said he has never seen a helicoil type insert go this bad.

He then took the coil and machined down an actual holley fuel bolt screw and cut a notch in it to screw the inserts in and the insert would just push out once you tried to install the dang thing and I have so far got six out of 8 and have two more to go before its fixed. The drilling and tapping was spot on but that was about as far as we got before trouble happened. My Father made sure his dripp press was straight on what they call as sweep of the drill press so everything was right on square.

We tapped it and it came out perfect but the coils just seemed to just be cheap and to think the permacoil is made in the U.S.A and the tool by the time after we did four coil inserts was all but done and he had to grind it down to make a new notch so it would catch the tang to screw in the coil and he also did countersink the hole as well as he worked as a machine worker for many years and knows his stuff and he said they said just screw in like a regular screw but the coils would just push out when trying to do so but the tap would go right in just fine so I guess the coils and the insert tool are not up to par with the Hecoil brand name for quality.

I have two more holes to get fixed then I am done with of a curse of a carb I have never had so many problems with before with over ten plus years of dealing with Holley carbs this a lesson for me to learn that is for sure. I just wanted to let everyone to know how I am coming along. I am going to buy a actual Helocoil brand kit and have the better quality tools needed if this comes up in the future.

Uugh what a week for bad luck for carburetor stuff.
 

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Discussion Starter · #20 ·
One last update here and I forgot to mention my Father took a file to the insert tool and after just putting in four coils the threads were starting to round off the insert tool and yet everything was straight and good. The first two coils went in excellent then after that they were starting to wobble on the insert tool and not staying tight when trying to screw the coils in. He drilled the hole size first then did a tiny countersink then tapped the holes. The tap goes through all the new threads for the coils fine.

The insert tool when he took a file to the side to see how strong of a material it was he hardly put any force on it and the insert tool just had a heck of a mark in it so he said it was too soft of a material and he said he was so baffled and never saw any coil not want to go in like that. When he tried to insert them in just starting off they would want to push out so easy it was not funny. Went through all twelve just to get 6 holes done. He has done this his whole life for forty plus years and never had this happen before. So now I have to buy another kit but this time I need to get a better quality install insert tool but I wish they sold it separate though.

I can't seem to find one for a 12-24 by itself. Thanks guys so far for all your tips. At least one thing out of this he is giving me his nice big size drill press so he has an excuse to buy a new one that is more modern and he just put a new motor on his current one so a good deal for me. Thanks all

I will let you all know the final outcome when hopefully I can get it the last two fixed.
 
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