Engine & gearbox.The cars come with an alloy head, or iron. Heads can be swapped but the valves are in different places so you need a matching camshaft ("Alloy" camshaft for alloy head, "iron" camshaft for iron... etc)
The engines often suffer with high backpressure (worn pistons/bores) which causes oil leaks.
An overview of an engine strip & rebuild (main & big end bearings, rebore / pistons etc) is
forum.retro-rides.org/thread/203024/rootes-engine-overhaul-regrind-reboreThere are 2 types of thermostat, "normal" and ones that isolate the interior heater when the stat opens.
In most cars of this age, you can turn on the internal heater in hot weather or if stuck in traffic to cool the engine.
Hunters can isolate the interior heater when the engine gets too hot so all the hot water goes to the radiator to get cooled.
Keep watching the temperature gauge - you might find the temp is ok even when the heater stops working.
It's something to be aware of. I normally have the interior heater on and would stop to investigate if it stopped giving out warm air, in a Hunter it's ok.
Low oil pressure is a common problem and can come from 3 directions : bearings (mains, big ends, camshaft) / oil pressure relief valve / oil pump.
Increase oil pressure / Fitting an aftermarket gauge
forum.retro-rides.org/thread/200715/retrofit-oil-pressure-gauge-hunterA few discussions about low oil pressure
teae.org/a-prime-cause-alpine-engine/oil pump refurb
teae.org/alpine-low-oil-pressure-revisited/increase oil pressure - oil pump bypass valve
teae.org/relief-valve-change-can-cure-alpine-lop/exploded (modified) relief valve (from link above)
Note. 1725 valve is unsoldered (propane?) to seperate the end cap from the body, the others are un-peened to seperate them.
Earlier engines have a cartridge oil filter, later ones have a spin-on filter. The housings can be swapped.
Warning : early spin-on castings came with a brass pressure relief valve, these are notorious for sticking open and destoying the engine due to *zero* oil pressure. Info copied from
sa.hillman.org.au/TT_OilFilterBase.htmTips :
The rocker shaft in the head is in 2 pieces. Oil is fed from below by a *fragile* copper pipe to a central casting then into each shaft. Advise you remove the rocker cover and start the engine - if there are oil leaks from the casting/shaft joints, strip and seal the joint using plumbers PTFE tape etc.
There are oilways through each rocker arm to drip-feed the valves, these are normally blocked on used (ie *ALL*) engines, advise you spend a few hours removing the rocker shafts, stripping each rocker arm (remove the adjuster + locknut, check both drillings in the arm are clear), and refit.
Backpressure.
In very worn engines, the 1" breather from the rocker cover to the air filter can't cope. Remove the 3" oil filler cap and just cover with a mesh filter or add an extra breather (from rocker cover? from timing chest cover plate?) to reduce the pressure.
An engine rebuild would fix the problem but is not a cheap option (estimate : pistons £250 a set, rebore+engineering £100, bigend + main bearings £50, oilpump £70, gaskets/seals £30 ... say £500 just for parts to do the rebuild)
It is possible to fit a modern PCV system to reduce backpressure, this does not fix the root cause but does remove some of the symptoms (smoke, oil leaks, etc). Very good guide at
sa.hillman.org.au/TT_HunterOilLeak.htmSummary in case the link above dies : drill into the manifold and rocker cover, run a pipe from rocker cover - new PCV valve - manifold.
The front crankshaft pulley has no oil seal just "scroll" grooves cut to push the oil back into the engine. Oil leaks here are caused when grooves gum up on older engines. High backpressure can then push oil out of the engine.
Fix : reduce backpressure (see above) and / or remove the front pulley and clean the grooves if you get leaks.
Engine tuning :
Read up on "Vizard head mod"
Good advice on porting / carbs / exhaust
www.sunbeamclub.com/phorum/read.php?13,3841
Carb swap options (HIF44 1 3/4" )
forum.commervanfan.co.uk/threads/su-carb-i-for-required.7168/Engine-swap options :
Pinto+box is (apparently) a bolt-in swap, but are a heavy and dated engine.
MX5 has been done and gives good results.
Commer vans use the 1725 motor, some options on their (very good!) forum
forum.commervanfan.co.uk/threads/suitable-engine-replacement.8697/Gearbox.The gearchange should be very slick with good changes, great with normal engines but can fail with big power increases / engine swaps.
Check the bolts holding the gearlever to the g/box, if loose you will get excess travel when changing gear.
Overdrive is a big bonus, highly recommended.
The overdrive has a control-box on the offside inner wing, this feeds power to a solenoid on the gearbox.
Faults/fixes :
If the overdrive won't work, remove the wire from the solenoid and check it is getting 12 volt when you engage o/drive. Most faults are electrical!
Slow changes. Check the gearbox oil level.
Harsh changes. Drain the g/box oil, refill with correct (20w/50 *not* EPxx gearbox) oil.
Gearbox swap options :
Several Commer (Rootes 1725) vans are now using Lexus 6 speed
forum.commervanfan.co.uk/threads/6-speed-gearbox-conversion.6334/page-10#post-120128Eb@y seller greenwood_auto_uk have a newly built 6-speed box listed (5+reverse, see item 283224640422 Jan 2019), may be worth looking into.
Clutches / release bearings.
Release bearings may be normal types or carbon "donut" types.
"GL" types are larger, "1500cc" types are smaller, parts are not interchangeable so make sure you know what size & type you have before ordering spares.
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