No half measures
The big news this month is that another four- cylinder ProLite race truck is joining the class 8 ranks this season.
Long- time Challenger ace Campbell Witheford has scored a truck out of Maine in the USA. He originally intended to buy i t as a donor truck to fill out a new frame, but when he laid eyes on the Ranger- bodied racer he changed his mind.
“I was originally importing i t to strip it down and use the parts to build a ProLite as the details of the truck were very vague and the owner was very unhelpful, but the price was right so we put i t on the boat and a month later i t was here. Once I saw i t for myself and found out more information about it, i t would have been and waste to use i t as donor car.”
This truck will be the first in New Zealand to feature a half-V8 based on a Chev block. The resulting four cylinder engine is a naturally aspirated 2.7 litre four cylinder with beefy 350 Chev connecting rods, pistons and head.
All the goodies
“This engine has all the goodies, being completely forged internally and running a huge valve train,” he says.
The cam on i ts own is impressive enough with 17.7mm of lif t and 253 degrees of duration topped off with 1.7 ratio rockers. It is running dual Weber side draft carburettors – but could potentially switch to fuel injection.
Campbell says the engine is still in the middle of a freshen- up which has been hindered due to part hold- ups, but he plans to have i t together this month for dyno runs. Until then he’s keeping his thoughts about power and torque numbers to himself.
The gearbox is a G- Force 4- speed dog box with a push pull H pattern shifter, which, says Campbell, i t may take some time getting used to i t . The diff assembly is a full chromoly tig welded Tube Worx housing with a Ford diff head and spool. The truck runs Pro Am full floating hubs driven by 35 spline axles.
The right stuff
On all four corners the truck is running Fox coilovers and Fox triple bypass shocks. Up front has the regular ProLite ‘A’ arm suspension with 12 inches of travel, and the rear is a four- link set- up with 14 inches of travel. The steering rack is a Howe power steering rack with remote mounted Howe pump and control valve.
The chassis is a full chromoly tig welded tube chassis built by Jimco in the USA.
Watch for this one – once tuned and sorted, the Witheford will definitely be out the front. There’s a strong rumour i t will be wearing Chev panels in recognition of the original parentage of that tough four cylinder engine.
Speaking of four- cylinder Pro Lites we took our GT Radials four- banger out for a run recently too, at a night run at West Melton. I hadn’t planned on doing the event but the novelty of racing in the dark got the better of me.
The whole experience is different at night, the bumps look different and the novelty of setting up the light bar to give forward and side vision was interesting. There’s nothing to stop clubs with purpose- built tracks from running round of the regional or national series at night, in fact he have run in the past under lights at Woodford Glen.
If we all had to race a rocky surface though the toll in smashed lights could be pretty hard to handle!
The West Melton evening was a good chance to shake the truck down for the opening southern round of the national championship next month, the Ruff’n’Tuff 250 at Nelson. The Nelsonians do know how to turn on a good forest enduro, and they are very fortunate to have a great relationship with some of the forest managers in their area.
That said, I do recall being one of a number of teams who ended the last enduro we contested up that way in an unhappy state – in our case upside down on an earth mound, well clear of the track!
Campbell Witheford’s new Chev-powered ProLite race truck.
The unique ‘half-a-V8’ Chev four-cylinder engine.