[Healeys] Thread size on 29D Engine.

Blue Healey bluehealey at gmail.com
Mon May 30 13:03:42 MDT 2011


Many thanks for the prompt response Bob.
I had a suspicion it might be a coarse thread. So glad I asked.
This list is just the best............
 _____________________________________________
(______________ Alan Bromfield _______________)
      (______ \____1957-BN4____/ _______)
          (_________________________)
         http://tinyurl.com/healeyforum



-----Original Message-----
From: Bob Haskell [mailto:rchaskell at earthlink.net] 
Sent: 30 May 2011 19:05
To: Alan Bromfield; healeys at autox.team.net
Subject: Re: [Healeys] Thread size on 29D Engine.

Alan,

5/16-18, 5/8" long with a copper sealing washer.  If you need to chase the
threads with a tap, fill the flutes of the tap with grease to catch the
swarf.

Cheers,

Bob Haskell
AHCA 3000 Mk I registrar
http://www.ciahc.org/registry_3000mk1.php

On 05/30/2011 01:22 PM, Alan Bromfield wrote:
> Team.
> I have fitted my BN4 project with a 29D engine that has been subtly 
> upgraded to a spec that is similar to the BJ8.  The engine was fired 
> up for the first time last weekend and all initial checks seem ok.  
> Unfortunately I have this afternoon traced what appeared to be an oil 
> leak to a couple of tapped holes on the generator side of the engine 
> that are open to the crankcase.  I don't know if this is common to all 
> 29D engines but there is a flat mounting face that would accomodate a 
> mechanical fuel pump in other roles.  The two mounting bolt holes (for 
> a pump) are drilled and tapped but strangely the square window for the 
> actuating arm doesn't exist - solid casting.  Why the holes were drilled
and tapped beats me.
>
> My question is, what thread form would these tapped holes be?  It is 
> tricky to get to see down there and I can't get a 5/16-24 UNF bolt 
> started into the tapped holes.  A 1/4 bolt drops in and hardly touches 
> the sides.  It may just be paint in the threaded holes that is preventing
the bolt starting.
> My worry is, If I chase this through with a UNF tap only to discover I 
> should be using 5/16-18 UNC I could wreck the threads.
>
> Paint peelings and perhaps cast iron swarf into the crankcase is a 
> secondary worry.  I wish I'd noticed this while the engine was out of the
car.
>
> Thanks.............


More information about the Healeys mailing list