Oil gallery plug fitting

[Llessur]

Any advice?

I'm currently rebuilding my 2500 lump and have all the necessary plugs from Chris Witor - the old ones were removed by the machine shop.

Do they go in dry? With Loctite? With RTV?

Are they supposed to be a tight fit? Do they bottom out, or do I just drive them in a certain depth and leave it at that?

The large one at the end behind the backplate feels quite tight going in - almost like it's cross-threading but Chris Witor's stuff is normally right for the job so maybe this is just how they are? Threads seem clean and in good condition.

[Alec]

Hello LLessur,

they are tapered pipe plugs (NPT I think?) and should seal dry. However I would use a modern liquid thread sealer as a belts and braces approach.
I did not follow my own advice and recently had to remove my rebuilt engine (Twice, as I blamed it on the rear oil seal which it wasn't) as the rear gallery plug behind the back plate was leaking.

Alec

[Llessur]

Thanks Alec, very helpful. I'll grab some thread sealer

Do they definitively bottom out or do they just need to be done up until tight/flush with the block etc?

[Alec]

Hello LLessur,

yes, the tapered thread just jams tight, not to a specific depth, depending on the tolerance of the tapping and the plug. So some liquid seal and screw in tight.

Alec