No half mea­sures

NZ4WD - - NIRT NATION WITH BRYAN CHANG - Pho­tos sup­plied by: Ian Withe­ford.

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.

Four-warned

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.

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