DIRTY STUFF

I CHECKED EVERYTHING, KNEW THE CAM TIMING WAS SPOT-ON, AND FINALLY PLUGGED IN AN ENGINE VACUUM TEST GAUGE. SPUN OVER THE ENGINE BY THE STARTER MOTOR, AND THE NEEDLE OF THE VAC GAUGE DIDNíT EVEN TWITCH

WILLIAM PORKER

HAD an odd one the other month. A while back I had rebuilt a Fordbased 105E race car engine with mostly all-steel internals, of screaming up to 10,500rpm and belting out 125hp. These 1.1-litre engines cost upwards of $30,000 to build, and only last 1200km before they have be overhauled. Anyways, this one had chewed up the crankshaft thrust bearings and damaged the expensive steel crank, so I got into the fixing of that and fitting less-crazy camshaft, aimed at reducing peakiness of this engine, where useable power only came in above 6000rpm and idled erratically at 5000.

So sent the crank to Crankshaft Rebuilders, bought a milder-profile billet cam from local specialist shop, and put in 40 hours assemble the engine. Ran the engine on floor for 20 minutes at 4000rpm on inner valve springs only to work-harden the new cam, rang the owner to say his engine was ready.

The owner picked it up and bolted it back into the race car, but it had only run at events before the team detected metal in dry-sump oil. They dropped the sump, looked into the innards, and the new cam was a old mess Ė it looked like a mob of starving rats had been at the lobes. After they lifted the engine out and stripped it, they saw that the steel cam followers were untouched; it seemed as if there was something wrong with the metal of this cast-iron camshaft.

After much detective work, it appeared that the cam had been one of a number of raw billets bought in from a foundry that had cast these with the wrong mix of iron. It was then machined by the cam-grinding shop, which didnít have a clue that this cam was never going to survive.

I remember a neat HG Kingswood powered by a blown 350 that needed an overhaul; the cam and lifters were stuffed and so were the pistons and crank journals. Got those basic bits fixed by a rebore and crank grind, and asked a local cam grinder to supply a billet cam to the same specification as the bumpstick that had come out of this small-block.

Got all these bits back, refitted the engine, and the damn thing wouldnít start. Checked everything, knew the cam timing was spot-on, and finally plugged in an engine vacuum test gauge. Spun over the engine by the starter motor, and the needle of the vac gauge didnít even twitch.

It had to be the cam lobe profiles, so we whipped it out and ran it over a Cam Doctor to look at what was wrong with this hydraulic stick. The cam lobe profiles were ridiculous! Way past full race specs, so both the inlet and exhaust valves were off their seats almost to TDC compression, which meant the incoming gas mostly went out the exhaust valve. No wonder the mouse motor wouldnít go! So had a serious disagreement with the owner of the cam reprofiling shop, bought another readyto-run billet pack from a known good supplier, and the Kingswood roared again.

I know a bloke with a well-kept six-pot HK Holden Monaro that also had a cam problem. First off, it stripped the cotton phenolic drive gear, so he decided to rip the cam out so a new alloy gear could be fitted. Discovered that several lobes were stuffed, so he bought a new improved-profile cam and lifters from Repco, stuffed all of that in, set the timing right and went driving.

After a few short trips, the 186 died on the road. The bloke investigated, discovered that the dizzy rotor wasnít turning, and extracted the unit to find out why. Something had chewed up the plastic drive gear, so he bought and fitted a new one and went driving. The Munro died again, this time so far out from home that he had to ring a mate with a truck. Same stuffed distributor gear, so he reckoned there was something wrong with the new cam.

He ripped the stick out and went to see Repco. The counter guy said yes, we now know all about this problem; our outside supplier didnít cut the distributor drive gear right. But we have fixed that, so here is another brand new cam. From a different supplier!

I CHECKED EVERYTHING, KNEW THE CAM TIMING WAS SPOT-ON, AND FINALLY PLUGGED IN AN ENGINE VACUUM TEST GAUGE. SPUN OVER THE ENGINE BY THE STARTER MOTOR, AND THE NEEDLE OF THE VAC GAUGE DIDNíT EVEN TWITCH

I used to work for a guy who owned a go-faster shop and had an agency for Waggott reprofiled cams, so he stocked a fair few, ready to fit and power up customersí cars. We had a MkII Zephyr drop in. Dave had a MkI mechanical stick ready and while he was fitting that, I went on porting heads. He reached the stage where he hit the starter motor to fire up the engine, and it went clunk. Tried again, same result Ė engine seized. Cam timing was right, so the decision was made to drop the sump, discovering that a conrod was hard up against the eccentric that drove the AC mechanical fuel pump. Ford had gone to a longer-stroke crank with the MkII/MkI-block engine, found that the conrod fouled, so the Ford engineers lump simply on shifted the half-speed the position camshaft! of the s eccentric