Heart Surgery (Post # 74)

It looks like the Alfatross' engine is finally getting close to completion. At this point virtually every part has been cleaned, inspected, refinished, polished, checked, and double-checked. The pistons, rods, valves, valve guides and springs, bearings, timing chains, and cam sprockets were replaced. Reassembly is under way. I'll let DeWayne Samuels describe what was done most recently and why:

Head gasket pattern in place over the head.  
Roger Lorton.

Glyptol coating the block interior
Roger Lorton

"After disassembly, the block was stripped and baked to remove all oils and residues It was then shot abraded to clean and remove casting flashing, etc. After all the machine work the block was jet vatted then cleaned with Prepsol and virgin lacquer thinner to prepare all surfaces for coatings. The oil contact surfaces were coated with "Glyptol" (as was the original finish) - this seals the cast iron, preventing minute iron particles from breaking free and entering the oil system and creating a "slick" surface to promote oil return to the sump.


The photo above (right) is of the trial assembly to check deck height of assembled crank, piston and rod for determination of head gasket thickness to maintain desired compression ratio and verify all clearances."

The new custom head gasket.  Roger Lorton.

"Here is the sheet metal head gasket pattern I made to have a composite gasket made up. Then it was used to finish the torque plate dimensions as shown. Next the torque plate was installed on the block to imitate the cylinder head load on the deck and cylinders. The block was then bored, honed, and plateau honed to facilitate ring mating and reduce "crowns" in the hone cut that can tear into the ring face microscopically."

Machining the torque plate.  Roger Lorton.

Boring the cylinders with the torque plate in place.
Roger Lorton.

New valve guide (right) compared to the old
one.  Roger Lorton.

"This is a pic of the redesigned valve guide that Roger and I came up with. It incorporates a valve seal (the originals had no seals). The install height limit seat (on the guide) is at a new position that corresponds with the change in the valve spring seat necessary to utilize the valve springs we sourced in lieu of any custom made units and the "available but not desired" units that also cost a lot more. 

Additionally, each guide is independently machined for the desired fit into the cylinder head as each bore was found to vary in diameter. The guides are honed to size internally after installation to insure proper oil guide wall to valve clearances as the interference fit distorts the dimension causing a slightly smaller i.d. than prior to installation."

If this level of engine work seems excessive, remember that the engine appears to have been "rode hard and put away wet" during the first 14 years of its life before it ended up in my garage.  DeWayne and Roger found abundant evidence of "deferred maintenance" and even improperly performed repairs. 

Replacing the engine oil with STP, hosing it off and repainting it was not an option.  It had badly worn cams, burnt valves, a broken valve spring, and worn main bearings that needed replacing, so as long as it was apart we decided to address ALL of its issues at the same time. After all, it is the whole, original, numbers-matching engine. Engine-building has come a long way over the last 60 years. Why not incorporate some of that experience in the rebuild?