Exhaust bolt hole repair
 

Found out that one exhaust bolt in my block will not tighten. It threads in and will almost snug BUT will not tighten. Any preference as to a Heili-Coil or a “Thread-Cert”? OR any other suggested fix?? I am leaning towards the “threadsert” method.

Re: Exhaust bolt hole repair
 

Are you 100% certain you are utilizing the correct size bolts? Remember the forward most threaded holes are larger than the rearward four.

I've never been a big fan of HeliCoils but have found a few instances where they served appropriately.

Re: Exhaust bolt hole repair
 

Mike
The other two end bolts and the one on top, all three are 3/8-16 tightened nicely. After getting it back from the machine shop I cleaned ALL the bolt holes with carb cleaner & a thread cleaner (not a tap) and made sure ALL the threaded holes were clean and straight. It will start to pull the lock washer flat BUT not quite!!!

Re: Exhaust bolt hole repair
 

Just to be doubly sure - the two front bolt holes are 7/16 - 14, not 3/8 16. Easy mistake to make!

Re: Exhaust bolt hole repair
 

Mike/Bored&Stroked
Why yes they are, I was fooled as one of the 3/8 bolts held tightly for some odd reason, the other did not. Thanks for my oversite.
What a maroon and rookie mistake!!

Re: Exhaust bolt hole repair
 

I think every one of us has done that at one point in our "flathead careers!". The larger front bolts were because they needed additional clamping force for the cross-over pipe that went from side-to-side on stock exhausts.

Re: Exhaust bolt hole repair
 

Also, I've seen guys HELICOIL them back to 3/8 NC - thinking they were stripped. I always get a kick out of that when I see it. :D

Re: Exhaust bolt hole repair
 

That explains the Heli-coils in a block I got with a 4" crank I wanted. (package deal)

Re: Exhaust bolt hole repair
 

How can this happen?:confused: The factory bolts have different head sizes for cripes sake.:eek:

Re: Exhaust bolt hole repair
 

What do you mean? Using the smaller exhaust bolts for the front two?

Re: Exhaust bolt hole repair
 

When you remove the bolts, you need two different size wrenches. It should be obvious that the bolts also have different thread sizes.

Re: Exhaust bolt hole repair
 

It's one thing when you have all the parts and pieces and I can lay everything out in order and by parts off the motor for sure. Different "sometimes" when you didn't take it apart, what parts you do have were sent by someone else who disassembled the "old" motor in Poland deciding what to send OR send what they had for the replacement block and you don't have ANY of the fasteners........NONE of them!!! I'd also like to say I build flatheads on a regular basis BUT I don't!!!! It's been at least 8-10 years since I have built one OR since I have had to mess with the exhaust manifolds or that area and I damn sure wish I could remember every single nuance of them, BUT I can't, to your dismay Tubman!!! Again, rookie mistake on my part.....Once it happened, I remembered it AFTER THE FACT!!!!

Re: Exhaust bolt hole repair
 

Not every block comes with the exhaust manifolds installed or the bolts. Think bare block.

It's a mistake that I'm sure more than a few people have made. Those unfamiliar with the front crossover stock exhaust set up, it's not what you normally encounter on any other motor. All part of the learning curve.

Re: Exhaust bolt hole repair
 

Robert,

Go easy on yourself, man. Very easy mistake to make; especially like you say, if it's been a few years you have one apart.

Honestly, first thing I do is scrap the stock exhaust, so I'm always dealing with a header or something else than the stock set up.

Re: Exhaust bolt hole repair
 

Thank Tim, it's all good here!!!!!

Re: Exhaust bolt hole repair
 

I guess I've just been working on these old boiler too long!:D

Re: Exhaust bolt hole repair
 

Saw this on Hagerty. Maybe it will help someone the next time.

https://www.hagerty.com/media/mainte...a96c94ccdf8583

Re: Exhaust bolt hole repair
 

I always thought those two front big bolt are for hanging the engine vertically in the factory perhaps gaining several inches = thousand engines minus inch's means more engines on the line....don't make sense big bolt for a tin pipe...............

Re: Exhaust bolt hole repair
 

I agree.