DIRTY STUFF

THE DRIVING RAIN WAS REDUCING THE T-BUCKET BLOKE TO A MISERABLE DROWNED RAT, WHILE THE ONE STEERING THE LITTLE CHEVY WASN’T GETTING OFF MUCH BETTER

WILLIAM PORKER

SOMETIMES, you have to suffer for your sport. Tooling down the highway a couple of weeks back, I spotted two clean and neat hot rods driving towards me. One was a T-bucket, the other was probably based on an early Chevy. The Chevy had a hood but no side curtains, while the T-bucket was completely open with only a minimal windscreen, and it was bucketing down rain. They were obviously going north for a show ’n’ shine or a hot rod event, and had chosen to drive with the wind in their hair, and bugs in their eyes.

The T-bucket bloke was leading, the driving rain reducing him to a miserable drowned rat in a soaked coat, while the one steering the little Chevy wasn’t getting off much better, as the rain was horizontal and he needed windscreen wipers on his glasses.

But there they both were, determined to sit on 100 clicks and suffer, soaked through and freezing – as long as the other bloke was in front or behind, there was no giving up and looking for shelter from that ice-cold driving rain. Both hairychested blokes, I reckon!

Saw a sad example recently. A race engine had developed a major bottom-end rumble, which sounded like a typical broken crank. They had no spare engine at that event, so the team pulled the plug and became spectators until the noise and fury was all over.

Towed the race car home, ripped the engine out the next day, bolted it into an engine stand and dropped the sump, and looked at the internals with a mix of disbelief and astonishment. Then they got on the dog-and-bone to bring me into this scene, as they thought my old age and experience might be able to diagnose why one of the main bearing caps had been ripped clean off the block. They were only two-bolt cast-iron main caps without support bars across the tops, and this engine had been built by a performance screw-it-together man. The team had no clues as to why their block had let go.

It wasn’t a difficult problem to diagnose, after looking at the still-intact cap with the two high-tensile bolts still attached to broken-off bits of cast-iron block. The engine builder had replaced the original factory bolts with nonstandard- length, over-the-counter HT pieces, in case the originals were too tired and stretched.

Fair enough, as I would have done exactly that during the rebuild. But where this nong had stuffed up was to buy bolts without the underhead shoulders that are essential to locating the caps, and then tighten these as usual after fitting the crank, not realising or caring that these replacement bolts were half an inch too short.

Sure, they obviously torqued up okay without stripping the threads, but with the big ask on to resist the massive forces of high revs and doublestock- horsepower loads, there wasn’t enough deep thread-grab in that block, so the fragile iron casting simply gave up, and two big chunks with bolts still attached ripped out. Luckily, they had shut the mill down in time to save the steel billet crank.

It was a case of the original engine designers specifying what was essential to keep their mills together, and if you want to change stuff like that, have a really good look and a think, before acting!

There was another block problem I ran across a while back, where another race car engine had been seeping coolant down into the oil, and the owner-engineer kept on changing head gaskets and bearings, because the contaminated oil wasn’t slippery enough to keep the conrod shells alive, and he was looking hard at the cylinder head for cracks in the inlet ports and rust holes through the cylinder-bore walls.

Finally, after a telephone consultation where we discussed block and head porosity problems and various ways of diagnosing these, I said to pull the engine, strip it to a bare block, plug up the holes and fill the coolant passages to the top deck with kerosene. Then stand the six-pot casting upright on a pair of carpenter’s saw horses, so we could look at the undersides of the cylinder bores.

After that was done and this lump of cast iron had sat and contemplated its navel overnight, we had a look in the morning, and between two cylinder bores in the floor of that block, the clear kerosene was slowly dripping from what was obviously a crack between the two holes.

What this owner-engineer hadn’t seen when he bought this engine second-hand as a bargain performance mill was that two adjacent cylinders were sleeved. And the reconditioning shop had bored right through to fit the interference-fit sleeves by pushing them through, instead of bottoming them on a land at the base, and this stress had caused the hard-to-see crack, and the poor bloke all that grief.

All we could do was dump that bargain block, and begin a major, expensive rebuild. s

THE DRIVING RAIN WAS REDUCING THE T-BUCKET BLOKE TO A MISERABLE DROWNED RAT, WHILE THE ONE STEERING THE LITTLE CHEVY WASN’T GETTING OFF MUCH BETTER