Welch Plugs

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Welch plugs (core plugs) are circular discs that fit into, and seal the casting and machining holes in the Engine block, Cylinder Head and Transmission.

Terminology

The Welch plug was originally designed circa 1910 by the Welch brothers at the Welch Motor Car Company of Pontiac, Michigan. You may hear them incorrectly called "welsh plugs". See Patent No 1058210

They are often called "freeze plugs" because if the engine coolant freezes they'll be pushed out of the casting. However, the purpose is not necessarily to solve freezing problems but rather to seal the holes left by the casting or machining process. Those that are designed for freezing safety are called "expansion plugs".

Set

Sets are for the engine block only (does not include the Cylinder Head plugs).

PLUG-WELCH 
44Ø CAM bore, rear
50Ø CORE block, rear
35Ø CORE (3) block, side

DORMAN 557-031 A12 & A13 engines

MAFCO 437 120Y 1969-1972 (http://www.mafcobell.co.uk)

MAFCO 438 1972-1980

MAFCO 441 Sunny 140Y 1980-1982 (L14)

above may be for L14 engine???
PB210 (140Y in South Africa) - L14 engine
11021-21000 PLUG-welch [6 total, 40 mm]
* (3) right side
* (2) left side
* (1) rear
cylinder head
* 00933-13500 PLUG-welch, 35 -7410
* 00322-13000 PLUG-welch, 30 -7410
* 11048-73403 PLUG-blind (2) 7411

Cylinder Head

One Welch Plug:

• 00933-14000 PLUG-WELCH (1) head, rear [reportedly 40 mm]

Engine Block

B110

Five Welch Plugs

* 11019-32200 PLUG-WELCH 44Ø CAM BEARING (1) block, rear (44.425 Ø) [1-3/4 inch]
* 00933-15000 PLUG-WELCH 50Ø CORE HOLE (1) block, rear prev. 01648-00084

* 00933-13500 PLUG-WELCH 35Ø CORE HOLE (3) block, right side 
 
* 35mm brass core-plugs

B120

35 mm Expansion Plug 00933-13500/11021-E3000/00933-1351A
Nominal Dia.: 35.21mm
Steel
Height: 0.380"

プラグ (35mm - 3 required)
7510-8506 00933-13500
8506-8706 11021-E3000 [11021E]
8706-     00933-1351A

Cam bore plug
11019-32200 44 mm -8506
01648-00191       8506-

Transmission

Three Welch Plugs

• 00933-11400 PLUG-WELCH TRANSMISSION CASE (2) inside bell, northwest of mainshaft
• 32102-18000 PLUG-WELCH TRANSMISSION CASE (1) inside bell, below mainshaft

  Can be seen in photo, just below throwout bearing

  

Removal and installation

Removal: tap one edge with a punch or chisel, then grab it with vice-grips and wiggle it out.

To install, fit squarely into bore, and tap gently and evenly into place. No sealer is used.