TR2/3/3A TR3 Engine Front Sealing Block, Oil Pan Screw Size and Thread Pitch?

[PatGalvin]

Hello All
On the bottom of my TR3 engine, behind the front plate under the front main crank bearing, the aluminum Front Sealing Block has stripped threads for the hole in the bottom middle, where the oil pan fits up and screws in (one screw). Can anyone tell me the correct screw size and thread pitch? Mine had 1/4-inch-28 screw in it but it had been damaged by PO. Thanks

Pat

 

[Tim Tucker]

EDIT: Removed my mistaken memory of the oil pan screw size.

No more posting from memory. Apologies to the forum.

Tim

 

[TR3driver]

My notes indicate 5/16NC x 5/8".

Good place for a Heli-coil.

 

[martx-5]

There's another thread going on that mentions the screws in the bottom of the oil pan. There are three different ones.

100749 Sump to cylinder block
105220 Slave cylinder stay to sump and cylinder block
HU0855 Sump to front sealing block

I looked in my parts catalog, and those numbers are correct.

HU0855 is listed in the Triumph hardware catalog as being 5/16" UNC (18tpi) x 5/8" in length.

 

[PatGalvin]

Thanks Art and Randall. This is really helpful. Much appreciated. Shop had to grind it out and open it up, reweld (TIG) to fill hole, mill it flat, and retap it to 5/16-18. Was too messed up for a helicoil. PO really did a number on this block. Will be like new now.

Pat

 

[sp53]

If you are putting aluminum piece back on I would suggestnot using those little pieces of cork and go with some type of gasket fillersealer. I could never get the cork pieces to seal, perhaps because there is notpressure on them. just be careful of oozing sealant getting into the engine.

 

[DNK]

I would use

 

[TR3driver]

There's another thread going on that mentions the screws in the bottom of the oil pan. There are three different ones.

100749 Sump to cylinder block
105220 Slave cylinder stay to sump and cylinder block
HU0855 Sump to front sealing block

I looked in my parts catalog, and those numbers are correct.

HU0855 is listed in the Triumph hardware catalog as being 5/16" UNC (18tpi) x 5/8" in length.

100749 is 3/4" long. I believe the only thing 'special' about it is being fully threaded (which most bolts that size are). TRF has it cross-referenced to HU856

105220 is 1-1/4" long. (HB860) I don't know what is "special" about it, but an ordinary hardware store bolt seemed to work fine for me. Check yours to be certain the unthreaded portion can't hit the cylinder block.

 

[PatGalvin]

I would use

Thanks Don
You are the second person in a week that recommended use of this "Right Stuff" product. Do you use it to coat your paper gaskets or instead of your paper gaskets?
Pat

 

[DNK]

Used it on my oil pan gasket on the Wedge as those are hen's teeth
and might use it for more when I rebuild same

 

[DanB]

I use that stuff.

 

[trmarty]

If it's the block I am thinking of there are steel replacements for the TR6 and Spitfire engines. Does anybody make one for the TR3/4? Timely as I an in the process of rebuilding one now. Marty