[Healeys] Motor Mout Bolts

[Perry]

OK I got confused on this exchanged.  Regarding the UNF threads, my info shows the 3/8 (major diameter) UNF bolt as having 24 threads per inch. The exchange mentioned 20 TPI
Perry

From: Michael Salter
Subject: Re: [Healeys] Motor Mout Bolts

"So, now I can run a 3/8 - 20 UNF tap through the hole to clean it up. So, I take it all threaded holes in the engine bay are UNF."
I think that may be a stretch Mike ... I know, for example, that the nuts welded into the frame for the battery hold down rods changed from BSF to UNF as C.#156839. I would bet that there are other instances of this.
I would always recommend checking your parts book for the correct thread for your car before running a tap through any.

M

On Sun, May 10, 2020 at 12:50 PM Michael MacLean <rrengineer.mike at att.net> wrote:
The only reason I asked this question in the first place was because a 3/8" UNF bolt screwed into all eight holes for a few threads and stopped.  Because it was the same in all eight holes I did not want to force it.  So, now I can run a 3/8 - 20 UNF tap through the hole to clean it up. So, I take it all threaded holes in the engine bay are UNF.  Certainly simplifies it.
Mike MacLean
On Sun, May 10, 2020 at 8:51 AM, Curtis Arndt
<cnaarndt at gmail.com> wrote:
They are UNF on my BN1 built 11 Jan. '55.  If they ever were BSF, it was very early in BN1 production. 

On Sat, May 9, 2020, 16:54 Perry via Healeys <healeys at autox.team.net> wrote:
Michael
There was a slow switch from BSF to UNF fasteners used and threads on some parts starting about mid 1954 through the end of 1955 at several locations on the 100. However I can not speak to the engine mount to chassis fasteners. 
Its one of those areas of the car that if I ended up with damage to the welded nut threads that could not be cleaned up with a tap I would do what was necessary to secure the engine mount short of replacing the welded nut. 
Perry
 
From: Michael MacLean

 
Are the bolts that fasten the motor mounts to the frame different threads between the BN1 and the BN2?
Mike MacLean

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