Repair exhaust bolt hole

E

ETriggs

Junior Member
I have a 48 59AB that has a stripped out bolt hole for one of the exhaust holes. What would be the best way to repair that? Helicoil?
Thanks!
 
ETriggs said:
I have a 48 59AB that has a stripped out bolt hole for one of the exhaust holes. What would be the best way to repair that? Helicoil?
Thanks!
Click to expand...
Hope that you are aware that the (2) front bolts are a bigger dia. than the (4) rear bolts.
 
^^ Yes, if it's a front one they have 7/16-14 thread if one of the others it's 3/8-16.

But if you have stripped one, I'd use a helicoil.

Mart.
 
51 MERC-CT said:
Hope that you are aware that the (2) front bolts are a bigger dia. than the (4) rear bolts.
Click to expand...

I didn’t know that! These motors came without exhaust manifolds so I didn’t get a chance to pull the bolts out. I’m in the process of making an engine stand adapter to strip down the motors and the 3/8” bolt wouldn’t hold on the front upper bolt. I assumed it was stripped. Thanks for the info! I am brand new to Flatheads, just starting to figure them out. I have 3 motors I bought in a package deal. 2 1948 59ABs and a 1942 motor.
 
Hey, great, that's what this forum is all about, sharing info and helping people. As you are new to it, don't hesitate to ask a question, it can save you a lot of grief. I've shared a lot of videos on youtube showing tearing down and rebuilding (more like putting back together) a couple of flatheads. Have a look. You might find something helpful.

Here's a link: https://www.youtube.com/user/martsrods/playlists
Crusty Flatty: https://www.youtube.com/watch?v=gUASvtBn2Xo&list=PLtwyFkFxie5jHQfN7btnhHBvLs12GnGQu
Current flatty project: https://www.youtube.com/watch?v=JGGuBujfSCo&list=PLtwyFkFxie5jFiazVylTHMrri6-8w-LBI

Mart.
 
The exhaust area of the block may be very thin. Use caution removing any material. I have seen more than one leak coolant from a bolt hole.
 
I is also very important to use the correct length bolts as most common ones are too short or too long.
 
Thanks for the info. Always learning. Were the larger 7/16-14 bolts used in the front exhaust manifold bolts of all flatheads, more specifically the early, non-vented ones? I'm asking because I have a '34 motor that I plan to work on in 2021.
 
marko39 said:
I is also very important to use the correct length bolts as most common ones are too short or too long.
Click to expand...

I bought a handful of grade 8 3/8 that are 1 inch, it seems like the center bolts need to be shorter than that. I’m using 3/16” thick angle as the mount.
 
Screw the bolt in and measure how much is sticking out. Then decuct your material thickness, take off a small amount so the bolt will not be bottomed out and make up the rest with washers.

To be honest, 3/16 doesn't sound very thick to me.

Mart.
 
ETriggs said:
I bought a handful of grade 8 3/8 that are 1 inch, it seems like the center bolts need to be shorter than that. I’m using 3/16” thick angle as the mount.
Click to expand...

If you plan to build the engine with all it's components, it will weigh around 500 lbs (depending on heads, manifold, etc). I would not hang that much weight on 3/16 angle iron - I would want a thickness of at least 1/4" - and probably 3/8" if I was making the exhaust mounted setup.
 
I picked up some 3/8” thick 2” angle to use instead of the 3/16” 3” angle. I already made the brackets in the thinner stuff, so at least I know where the bolt holes go. It appears as though the left side exhaust is 1” forward of the right side, this sound correct?
Thanks all!
 
ETriggs said:
I picked up some 3/8” thick 2” angle to use instead of the 3/16” 3” angle. I already made the brackets in the thinner stuff, so at least I know where the bolt holes go. It appears as though the left side exhaust is 1” forward of the right side, this sound correct?
Thanks all!
Click to expand...
Take a look at the relationship of two pistons and rods that are on the same rod journal and I think you will understand why one side is further forward than the other.
 
ETriggs: I used stainless bolts and also socket head cap screw bolts with plenty of anti seize on both when installing my exhaust headers. Use only flat washers. Other wise bolts may come loose. I also have used bronze bolts successfully. Good luck and take your time. Also, go with 3/8 in. angle iron.
 
51 MERC-CT said:
Take a look at the relationship of two pistons and rods that are on the same rod journal and I think you will understand why one side is further forward than the other.
Click to expand...

Yep, understood about that but I wanted to make sure my 1” difference was close. Thanks!
 
ETriggs said:
Here are the engines I’m working on. A 1941/2 engine with Fenton heads. This was close to running when I bought it. Two 1948 59ABs, one in good shape, one rusted up.

https://app.photobucket.com/u/ETriggs/a/f50c3386-0215-41a1-b7ce-3c06a917e99f
Click to expand...

The prettiest one! DD

(edited)_D27910C5_9C0C_42DD_9085_586EFB82D350.jpeg
 
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