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MG MGB Technical - Cup or Dish type Core Plugs

Question: When should you use the cup type core plugs?

Having a leaky engine plug in the B, bought some new cup type plugs from Moss, also some dish type as spares for the A. The engine was rebuilt a couple of years ago, and I thought they had fitted cups, upon removing the old plug I saw it was a dish type. So can I use a new cup type, or does the engine need to be modified to take cup types and I should just fit another the same.

Tatty ( repeated this on the midget section as its too early and I messed up )
Tatty

Hi
When I rebuilt my engine several years ago I used the dished ones and bedded them into RED Hermatite before peening them and have had no problems since, I think the dished ones were what was originally fitted
Ron
R. Algie

Tatty. The original style was the dished plugs and they are still available from Rover. The cup type plugs I have only seen on US engines. Just helped a fellow tear down a Ford 302 with this type of plug last Sunday. The holes for the plugs were bored straight through and had no inner lip like the MG blocks do.

The hole for the core/welch/freeze plug is .270" deep from the surface of the block to the inner lip. The plate type plugs hit the inner lip and expand outwards to become a tight fit in the surrounding recess. The cup type plug would not do this and the square inner edge of the recess would not mate well with the curved outer edge of the cup plug. I will continue to use the Rover dish style plugs in my rebuilds. Les
Les Bengtson

Thanks,


Tatty.
Tatty

A long time ago, I helped with an engine rebuild on an Austin 1800. That had "cup" type core plugs as standard. I don't think that BMC themselves ever thought one was better than the other.
T J C Cuthill

Try the Dorman brand solid copper expandable plugs, 1 5/8" diameter. They work great!!
Ken Lessig

This thread was discussed on 29/05/2003

MG MGB Technical index

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