The Stovebolt Site Forums The Parking Lot Big Bolts 1954 GMC 630 ?'s

There are shop manuals on eBay from time to time. Inside of glove box has engine, trans, rear axle and ratio. The 426 is within the largest series of GMC 6 cyl. engines. 318? 426, 477, 503. Many interchangeable parts on largest ones. Cylinders are separate from block, as is head separate from cylinders as is common. Several different carbs., manifolds, depending on COE or conventional. Later 503's had .437 valves, early had .375, don't know break, 426 may be all .375. Engine SN should start with 426xxx, etc., stamped on left side of block, very rear, close to firewall, difficult to read.

Plugs are common GM of that vintage. Cannot observe timing mark on flywheel because peep hole covered by tin cover which cannot be turned, left rear, high on block, next to firewall. Put wood stick or such in #1 spark plug hole, turn engine 'tail compression comes out to find TDC, put marks on harmonic balancer.

Distributor drive not like normal GMC, offset drive under base of distributor, works fine, though.

Make sure to oil valve stems, tap with rubber hammer or 2 x 4 piece of wood to make no valves are rusted, prevent bent pushrods. If find a bent one, be gentle. Parts are rare.

Ed