In short driver's side back most bolt on the exhaust manifold/header flange was all messed up and I forgot all about it while I had the motor out of the car. Wish I would have remembered because none of this crap would have happened if I had thought about it. Went to reinstall the headers and couldn't get the bolt to catch and that's when I remembered. Anyways it's in a pretty tight spot. Thankfully the steering column and the Z bar are out but it's still pretty tight. Purchased a cheap right angle drill from Harbor Freight. That was probably my biggest mistake. The damned thing doesn't have any guts at all and probably is the root of the installation issue. Anyways fought with it to get the hole drilled and tapped for a 3/8 insert. Got the insert in and was just cleaning up everything with a 3/8 tap and the damned thing broke off inside the hole (deep)....

Thankfully I managed to break the tap up with a punch and some luck but I'm willing to bet getting another helicoil in there isn't gonna happen. I chewed the threads up pretty good in the parent material getting that tap broken up and out of there. I was considering using an oversized timesert this go around but I am slightly worried about the thickness of the casting in and around the exhaust flange. Any real reason for concern or am I just being paranoid?

Motor in question is a mid 70's 454 out of either a C20 or C30 truck with peanut port heads. Yeah, I could pull the heads and definitely do it a performance favor, but I just want to get the damned thing running at this point.

 

Whew, there for a moment I thought someone had made a really poor choice in tires and tore the car up.


Okay, at this point it all becomes a pain in the *** and you have a choice to make. If you ever thought about new heads then now is the time. Swapping heads is a day job. So is just pulling the head and redoing the job on a bench. Worst case is you have to take it to a machine shop. I understand if you don't want to buy new heads now, but, at least, pull the head and do the job right.

 

Could you run another 3/8 tap in there and clean it up enough to get a stud installed in that hole? You have a bottom tap? If you have a sacrificial taper tap you can just grind off most of the taper to make it a bottom tap.
If you can get even a few threads for a stud to grab onto it probably will do the job. Then just don't torque it down super tight, use a little high temp silicone on the gasket at that location to help make the seal good. I've done stuff like that and had it hold indefinitely.

 

That could work...rethread it VERY slowly with tapping oil! and if it doesn't..........

 

My bottom tap is what broke off. Wish I could just retap like you said but I don’t have any faith in that working given how crewed up it is. I have a set of thread chasers too. Ran a chaser down it and it definitely isn’t a snug/proper fit. It threads/kinda but there is about 3/8” wobble at the end of the chase. I would be more willing to bet that it will pull out vs not given how loose the chase is.

Thinking of picking up this kit with a 3/8-16 and .5” deep inserts. http://www.timesert.com/html/bigsert.html As I mentioned I’m alittle worried about punching through to the water jacket given I have to drill it larger but as I mentioned on my first post maybe I’m being paranoid.

 

How about running a 7/16" tap in there? I would not want to drill larger either, at least if I could avoid it. then use a 7/16" stud with 3/8 sticking out kinda like this. Just one of course.

 

Shazam! Me too! I was wondering, haven't seem car recaps in a coon's age. Agree, either way, do Something now.

 

I broke a bolt off in a printing press one day, by the time I got out the threads were shot. I had some industrial steel-laden epoxy in the shop, so I filled the hole with it and drilled and tapped it next morning, it never got loose or broke again. I got the stuff from a bolt company here in town, the big box stores don't have anything like this stuff. I also bought some aluminum-laden epoxy from them to fill two 1-1/2" holes in my pool deck, that was 15 years ago.....still there. There's also a company called "Lawson Products", they sell some pretty good stuff too.

 

Norfolk? I've used some great epoxy which may've migrated from a navy yard

 

If I'm reading this correctly, OP was trying to tap the hole for a threaded insert? The Helicoil tap is different thread diameter and pitch than a standard 3/8" tap. You'l need to get another kit for the tap. When I use a tap, I use plenty of oil, tap 1/4 turn, back out 1/2 turn to clear the chips. If you put too much side load on a tap, it will break.If the hole isn't too far gone, the helicoil should fit and lock into place after knocking off the tank. There shouldn't be that much stress on that hole with the other 7 being good.

 

I used a similar insert to fix an exhaust stud on an aluminum head F-150 (in the truck). I had about 2” between the head and the frame to get it done. My Harbor Frieght right angle drill with a custom modified drill bit got it done, along with a wrench slowly turning a tap, but my lord, what a PITA. I wish you luck.

 

 

Something like this? I used it for rifle bedding way back when: https://itwperformancepolymers.com/p...steel-putty-a/

 

A question I have about the epoxies is how will they handle the the temperature cycling. If they expand differently than iron/steel they could come loose. Note, I'm just mentioning it as a concern since I don't have the stuff sitting here to see it's specifications. But the examples here, a printing press and rifle don't see the temperatures that an exhaust port experiences.

Also, I know an idiot dealer mechanic snapped off several tranny pan bolts on a Ford Windstar I had and then used epoxy hold them in. Needless to say, it didn't. The original bolts were metric, 6 mm diam, 1 mm pitch. My solution - I used 1/4-24 bolts without tapping. In metric a 1/4-24 translates to 6.35 mm diam, .945 mm pitch. I figured since the tranny is aluminum the 6.35 mm thread would bite into whatever remained of the stripped threads and the .945 pitch was close enough to 1 mm to follow them for the half inch or so length of the screw. Worked like a champ. Which brings up the question, is there a metric bolt with a diameter between where you are and where would have to be to put in the next step on an SAE bolt or insert? Might be easier to install with less risk of cutting into something you want to avoid.

 

That plus this might be an option. I mean after all this bolt is not used for for structural support of anything. It just has to seal the exhaust port to the header/manifold.

 

The link I shared has the TDS - and yeah, it won’t work. Thermal capacity 250* F.

https://itwperformancepolymers.com/w...y-a_062919.pdf

 

Dig through here and see if you can find something
https://www.mcmaster.com/

check through here...
https://www.mcmaster.com/metal-epoxy-for-engines/

Can you tap it metric next size up?
Metal epoxy weld a stud in?

 

I have done that many times,pipes, bolts, screws.