STOP me if you’ve heard this one. Bloke wanders through a swap meet and comes across two good-looking alloy V8 cylinder heads. Shifty-looking lights up and says they’re off a Holden 308. Bloke owns an HG, checks out the rusty valve springs and pokes a finger up the ports, but they look okay. Custodian says he’s selling the heads cheap for a mate, who is banged up in hospital and needs money to pay for his medical bills.
“Six-hundred clams for you, old mate; and that’s breaking my heart.”
“Too dear. I’ll give you 400 for the two.”
“Aw geez. I’ll come down to 500.”
“That’s a lot of money. I’ll split you. Four-fifty, cash.”
Custodian thinks for a bit, and scratches his noggin: “Okay. He’ll kill me for this, but it’s a deal!” Bloke is happy, pays the money. Then comes the sad part.
To be on the safe side, the bloke takes his bargain heads to a reco shop for surfacing, new springs and a valve job. He gets them back with a guarantee, bolts them onto his 308 block, and smiles as the mill rumbles to life. After the lifters settle down, it revs real well, and the bloke runs it until it’s hot, figuring he’ll re-torque the bolts in the morning after the heads have cooled. Does that before breakfast, hits the key again, and the motor starts shaking like a terrified dog in a thunderstorm, obviously missing a couple of cylinders. Stuck lifters? No, nothing is rattling. He pulls the sparkplug leads off one by one, discovering two and seven are not firing. Rips those plugs out and both have insulators wet with new coolant. Bugger! Must be stuffed head gaskets, except these are fresh out of the packet. He lifts the bargain heads off after the bolts are out to discover there’s coolant mist in the crook cylinders but the head gaskets are like new. What in hell is going on? Better take them back to the reco shop.
The shop performs a pressure test on the castings, which shows there was porosity in the inlet ports, which had allowed coolant to seep into the cylinders overnight.
“Bad luck, mate, but there might be a fix. There is a mob down south who seals up crook castings in a Loctite bath, and we’ve heard that it works real well.”
Long time ago, the Henkel Corporation, manufacturers of Loctite products, developed its unique porosity sealing systems. Aimed at retaining fluid under pressure and commonly used on hydraulic components, fridges, gas meters and automotive stuff, the systems use liquid methacrylate or polyester resins applied with either immersion or spray-on techniques.
The most common system is the Loctite Resinol RTC, or room-temperature curing, where crook castings are immersed in a Loctite-filled tank. The air is then evacuated, leaving only a vacuum. Castings are left until porosity sealing is achieved, spun in a centrifuge, and lowered into a wash tank. Exposed to a plain water rinse, the Loctite cures quickly and plugs the porosity and the remaining sealant under that cures slowly until it solidifies.
The Loctite liquid inside the immersion tanks is stopped from going off by light aeration and temperature control. Brilliant for fixing porosity problems in aluminium castings caused by gas inclusions or shrinkage during the initial casting process, Resinol RTC has saved many machined castings from certain death.
I know a local bloke who is involved with a unique sports racing car from the early 60s called the Centaur, that was powered by one of Merv Waggott’s twin-overhead-camshaft conversion heads that he developed for the FJ Holden engine. Breathing through six AMAL motorcycle carburettors, this 2.4-litre 1950s mill punched out 212hp on the Waggott Engineering dyno. The engine was then fitted with triple sidedraught Webers and replanted in the racing car, and it won every race in its class bar one.
This GT car went on to be re-powered with the later EH 179 red six, while the Waggott twin-cam was sold off for speedway use. The car was modernised by monocoque panel additions, but eventually it was decided to restore it back to original, tube spaceframe spec.
After a major search effort, the original engine was found and a deal was done to reunite it with the GT chassis. But the restoration team knew the OHC head had a long-standing porosity problem in at least one inlet port, so it was sent to the RE Davison Group in NSW for a porosity sealing fix. It worked a treat, and that unique old racing coupe can now be seen and heard circulating on tracks around Australia, the Waggott wailing at 7000rpm, dual exhausts decimating echoing thunder the opposition.