fixing stripped carb bolt hole on intake

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mshred

mshred

The Green Manalishi
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hey guys,

it seems that i have stripped the threads on my rpm air gap manifold by tightening down too much on the carb bolts. There is now a vacuum leak there (rear passenger side bolt) since i cant get it tight. Does anyone have any suggestions of how i can fix this without taking the manifold off? should i tap it a size larger? tap it the same size to hopefully clean it up? maybe fill it in with some JB weld and re-tap it to the same size?

any suggestions are appreciated....i should have known better when tightening down on aluminum

thanks!
Matthew
 
Just put a Heli-coil in it . The kit is like $30.00 . Or , Mcmaster-carr.com has inserts available , just drill and tap to the next size and screw in the insert , I think they are only a couple bucks plus shipping . Or, make your own insert from threaded rod two sizes larger .
 
you have a few options.....you could drill and tap to a size bigger....and if need be you can drill out the holes of the carb to match a larger bolt size..

you can JB weld as you mentioned and drill it....although I don't suggest it.

you could have someone who is good with welding aluminum weld the holes closed and then redrill to the proper size.

OR what I would do......I would drill the holes larger,tap them and run some heely coils in which would let you maintain the original bolt size that the holes in your carb are already sized for.

thats just a few options,hope that helps a bit
 
damraider said:
Just put a Heli-coil in it . The kit is like $30.00 . Or , Mcmaster-carr.com has inserts available , just drill and tap to the next size and screw in the insert , I think they are only a couple bucks plus shipping . Or, make your own insert from threaded rod two sizes larger .
Click to expand...

is that my only option is to sleeve it? if i was to retap it the same size or go a few sizes bigger it wouldnt work?
 
DusterDude72 said:
you have a few options.....you could drill and tap to a size bigger....and if need be you can drill out the holes of the carb to match a larger bolt size..

you can JB weld as you mentioned and drill it....although I don't suggest it.

you could have someone who is good with welding aluminum weld the holes closed and then redrill to the proper size.

OR what I would do......I would drill the holes larger,tap them and run some heely coils in which would let you maintain the original bolt size that the holes in your carb are already sized for.

thats just a few options,hope that helps a bit
Click to expand...

just saw this now...im not familiar with helicoils? what are they? would the only benefit to using them be that i can use the same size bolt, because i dont mind having to go a size up or two with the bolt as thats no issue
 
there just like a threaded coil on the outside that screw into your threaded hole and on the inside is a different diameter thread.

its pretty much a hollow bolt with a threaded inside that you can thread a bolt into
 
1000 ways to skin a cat .... all the ideas will work and get you what you want . I would just drill and tap for an insert and make my own , that would take all of about 20 min and you get to use the same wrench on all four bolts .....
 
hey guys,

i checked out my carb base plate and if will fit a 5/16 bolt with no drilling...so keeping that in mind, id like to use a 5/16 bolt

now the threads that are screwed are 1/4"...what drill bit size would i have to use before i can use my 5/16" tap to thread it? its something id like to fix right now instead of having to order a part for it

thanks!
Matthew
 
i know this might be a no brainer, but nobody knows what size drill bit i need?
 
When you get done, use studs if you can, it'll avoid creating the same problem all over again.
 
Hadahemi said:
When you get done, use studs if you can, it'll avoid creating the same problem all over again.
Click to expand...


just finished up now drilling and tapping for 3/8" bolt there...and the idea of studs makes very good sense! i will definatly do that

thanks everyone!
 
if you dont care what it looks like a self tapping sheet metal bolt will get you going. The kind with the notch at the end of the threads

bucket9.gif
 
Heli-coils were used in every threaded hole when I built satellites at JPL. I know rocket scientists tend to over think everything....but they do make the threaded holes in aluminum a lot stronger...especially for those who drink multiple red bulls while bolting down their carbs....make sure to put some sort of covering over the card opening on the intake.
 
Yep, I like helicoils, used one for the first time on my manifold and it took maybe 10 minutes tops after I got the right drill bit. They aren't cheap though so if you can save the cash I can't argue with that!
 
Helicoil is the only way to go. As you tighten up the bolt the helicoil expands slightly into the surrounding aluminum and the threads can't pull out. If you tapped it out to the next size, there is still the chance that they could pull out again. You can get the kit at NAPA and it includes the correct size drill, tap, installation tool, and 4 to 6 inserts. If it were me I'd helicoil all 4 holes and go with studs.
 
like i said in my previous posts, its been fixed with a regular drill and tap...thanks though
 
Recently I rebuilt a motor for my 1944 Willys jeep. I had a few broken studs in the block and we replaced them all with Heli coils. They work great and I will never try anything else, they really beat and easy out if you break it in there then your screwed.

My jeep 134ci 4 banger bored .060 over=P~

29319_1408720389540_1578387732_30984467_1396890_n.jpg
 
I've got a heli coil (NAPA branded) set for the Holley fuel bowl screws....no need to ask why I bought the set...that would just be mean. Moral of the story is without the little gasket that goes on the screw...the screw can bottom out and cause agony. Anyone need a slightly used heli-coil set for fuel screws?
 
edbux said:
I've got a heli coil (NAPA branded) set for the Holley fuel bowl screws....no need to ask why I bought the set...that would just be mean. Moral of the story is without the little gasket that goes on the screw...the screw can bottom out and cause agony. Anyone need a slightly used heli-coil set for fuel screws?
Click to expand...

Hang on to it, you never know when you will need it again and they are not cheap.
 
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