390 FE motor side clutch pivot bracket bolt size and thread?

[brushwolf]

Installing a 390 and 4 speed in a 61 Galaxie convertible. Car was an automatic from the factory, so it had no z bar in its previous life. Also the 69 390 I am using was an automatic so it never had clutch brackets on it before.

But the bolt holes for the motor side clutch bracket are in the block. (It had no threaded inserts on the frame side for clutch bracket either, but the holes were there. That problem has been resolved).

I am having problems getting any bolts to thread in the engine in the factory clutch bracket holes. 5/16" bolts are too small it appears. I can push a fine thread 5/16" bolt all the way in the holes.

Are they 3/8" bolts. Tried several, but the bolts seem too big. Fine thread bolts will not even start, coarse thread bolts turn in about 3/4" turn and stop). And are they coarse or fine thread? Or did some of the 390's have untapped holes in the block if they had automatics,so neither until they are tapped?
 
I can tap them if required (which I should have done prior to installing the motor) but want to make sure I have the correct thread before attempting that.

Or if there are definitely threads on the 69 blocks, but there is rust on the previously unused 50+ year open threads then I want to use the right tap.

Thanks

[brushwolf]

Never mind. They are 3/8" coarse tapped holes. Paint at the outer edge and rust further in leading to clean threads the last 1/3rd of tap run. All 4 flutes on my tap were full. All good now. Glad my son decided not to put left exhaust manifold on until the clutch linkage was all bolted up.

[59meteor]

Glad you got it figured out, I have yet to see a FE block that did not have the 2 bolt holes in the rear block bulkhead already threaded. Over the years , Ford used several different style Z bar pivot brackets, for various applications, not sure what a 61 needs. Also some full sized cars in the 60s do not use a block mounted pivot, as they had bellhousings with a pivot ball mounted to the side. Not sure if a 61 had that configuration or not. Also interesting that your frame side pivot bracket holes were not tapped. I have converted several older Fords from factory automatic to 4 speeds, including my current 59 2 door sedan, which was originally a 332 2 speed automatic, and my cars always had the holes threaded, although usually clogged up with dirt and gunk. Maybe some assembly plants put threads or threaded inserts in every frame, and some didn`t.