430 exhaust manifold woes

In order to pass inspection for plates, I have to remove and replace/repair the drivers side exhaust manifold it as it's cracked above the heat riser valve. I gave the top row of bolts a try to see what I was dealing with and as one would expect, nothing budged. The lower bolts are hard to reach as the upper control arm is kinda in the way. Taking the heads off would be one way to deal with it on the bench, but it's a gently driven 86,000. mi engine that runs real well with good oil pressure. Once removed, there is a shop that welds cast metal and can repair the crack. I would love some advice as to my next move. The car has other issues to deal with to pass inspection, but this is the most pressing.

Gary, 68 Wildcat

would it be possible to JB Weld it, at least until it clears inspection?

or have they identified the exhaust leak already and are requiring a full repair?

No possibility of temporary repair. They chastised me for traces of muffler cement (not permitted) from the previous owner. I tried some of the manifold bolts and they won't budge.
One slim possibility remains, the crack is visible facing outwards above the heat riser and a welding shop that does cast metal might be able to weld it in place, but they need to see the car. They did not sound optimistic on the phone about being able to do it. None of the muffler shops or garages around here want to tackle the job.

Gary

welding cast is tough because the welding process itself is a heat treatment of the cast iron.

which hardens ( and makes more brittle ) the cast iron which is exposed directly to the arc. it ALSO changes the expansion characteristics of that *particular* part of the casting. so what winds up happening is that you have to be VERY careful not to over heat the cast or the simple cooling process will actually cause the part to break.


i see that there are guys doing this now:
https://www.youtube.com/watch?v=K85MH9Z5FPU



I tried some of the manifold bolts and they won't budge.



have you tried heating them? i know it's much preferable to work on a cool exhaust, but it's sounding like we're down to last options.

you're really going to need to be able to take the manifolds off if you ever do a rebuild or want to put headers on.

i know a trick being used on newer cars is the manufacturer is using an extra long bolt, like +2" over length, and then sleeve the bolt with a steel tube that spaces it out to the head of the bolt. that keeps the bolt head away from the massive heat cycle of the manifold and keeps it from getting frozen to the manifold.

Thanks Bob for the reply. I have 12 months from the date of the inspection to affect repairs so If the welding shop can't fix the manifold in situ, then I'm going to change direction and concentrate on getting the gas tank rebuilt with a new filler neck grafted on. This way I'll be able to store the car till spring without it emitting fumes. In the spring, I will re assess as I do want to rebuild the engine with an upgraded cam, intake, carb and headers eventually, so the timeline for the engine rebuild may have to be moved up. I had hoped to wait, but I think removing the engine and taking the plunge would make more sense in the long run compared to farting around with these seized bolts. Heating the top row of bolts is simple enough, but the bottom bolts would be very difficult to reach. I have an appointment to see the welder today, so we will see what happens. I'm a retired mechanic after turning wrenches for 43 years and I'm still going thru shop withdrawal (closed the business in Vancouver in 2016 and moved to Montreal). No longer having access to hoists and torches etc. has been quite a transition.


Gary

Success! The welder was able to fix the crack in the manifold and when we restarted the car the noise was reduced 50%. I did learn a host of new French swearwords as a red hot blob of welding rod fell into his shirt and he ran around trying to get undressed as quickly as possible. On closer inspection, the remaining exhaust leak is caused by a worn out shaft in the heat riser directly below the repair. I can now remove the heat riser, cut out the flap and shaft and weld it up and reinstall. The car will only ever be summer driven, so I see no need for the heat riser in that case. One step closer to getting my certification for plates!!!!!

Gary

excellent.


closed the business in Vancouver in 2016 and moved to Montreal


hah.

i think you're going to enjoy winter. :D

also, the French are noticeably less organized about how they build and maintain their streets than Ontario is. Toronto may have traffic every bit as absurd as Montreal does, but at least they've made an effort to build the roads to handle some of it.

We have done one winter already and it didn't kill us. My wife won't drive here and likens it to driving in Peru where she spent a year. No regrets however. Great Smoked meat and Bagels!

Gary