The forum has had a few mentions of the Commer knocker truck engines, we had a 1957 Commer 5 speed box and 2 speed no 4 eaton diff with 15ft (4.5 metre) long log bolsters.
We used it to cart logs out of the bush in Gippsland and deliver sawn timber in the in the late '60's and '70's.
The are was very steep, we dozed in the tracks up to the ridges,followed them and down into the gullies, we had a 400 litre water tank under the tray filled with water to get to some of the logging areas to give us traction, then would empty the water once in there. We would load up with about 7 tonne of logs, and head off back up the hill out of the gullies, low low flat chat, what a racket the old 2 stroke made echoing around the hills, put a GM to shame.
We did the motor up a couple of times, they had a habit of breaking the dykes type L shaped top "fire rings" and would be hard to start without aerostart.
We re-ringed, honed, de-coked the ports (had to take the inlet and exhaust manifolds and scrape the coke out of the ports when the super charger pressure became higher than normal) all in a day without draining the radiator, emptying the oil from the sump. All we did was take 2 big side plates off each side, undo the piston conrod and the crankshaft conrod from each of the 3 big rockers down each side, pull the pistons out, 3 from each side, hone from each side, careful not to hit the injector protruding in the middle of the bore, fit the rings, poke the pistons back in reconnect the conrods, put the covers on start her up. No timing, no bleeding.
Part of the knocking could be from the fact the clearance specs say 2 thou mains, 1.5 thou bigends, 1.5 thou 1st conrod, 2.5 thou rocker bush, 1.5 thou 2nd conrod, 1.5. thou gudgeon, comes to 10.5 thou to take up EACH side TOTAL 21 thou each time the pistons came together.
Another fault was the timing chain to drive the fuel pump it would stretch and if you flipped the throttle too quickly when changing gears, it would jump a tooth, loose power, blow black or white smoke, or stop, to fix had to take gearbox off.
As only the pump had to be re-timed, it had a drive above the gearbox end, take the cover off, and there was a splined drive for the pump, problem, it has one blank spline, so cut out the blank spline, turn the motor over and fit timing dowel into the flywheel, line up the timing mark on the inline CAV fuel pump, slide modified splined drive back on and back, on the road again.
I think the later engines had timing gears.
I think the Knocker motor started out about 90 hp, then went to about 120 hp 260 ft lbs, to 135 hp 300 ft lbs odd, and last 150 hp 385 ft lbs.
The first I think was 198 C.I. and the latter was 214 C.I.
They were reliable if driven to about 2400 RPM, but would poke out more horsepower at 3000 rpm.
They had 3 big bolts through the block holding the 2 big rocker shafts down each side.
The later engines sometimes split the blocks if these bolts lost tension.
The later engines had rotary pumps, the pumps had the horsepower as part of the pump serial no.
We ran our sawmill for awhile with a later 135 hp engine, with a pulley on the end of a Commer heavy duty 4 speed box in 3rd gear.
The pulley was 6 D section vee belts and the engine used to make them slip on a big log.
It has been said Commer had a 8 piston engine on the drawing board,but this was shelved when Chrysler took over the Rootes group and then used the 318 V8 petrol.
The Knocker had a Roots type supercharger, no connection to the Rootes Group name.
With careful driving at 2000 rpm 85 klm our olg Commer would do about 12 to 15 miles to the gallon.[img][/img]
