Hi All
Been here and there on the forum, though haven't updated my progress. Well to be honest not a lot has been done, lots of other things have kept me off the van for some time.
Some time back I finally retired my trusty rusty Datsun Sunny Wagon, at 590,000 km. Rust was becoming an issue, mostly cosmetic, but I was needing more space for moving things, which was the original reason I bought the Commer. I needed a van and ended up getting a 1993 Mitsubishi L300 van. I still intend to push on with the Commer, I just need something to bridge the gap.
Now before I get branded a traitor, Let me explain that it isn't as bad a decision as you might think. Firstly and most important, it isn't a VW. Secondly It was cheap, running and registered at the time. Thirdly, it is a distant nephew to the Commer. Let me explain, as we all know, Chrysler/Dodge took over from Rootes many years ago, then here in Australia Mitsubishi took over the operations of Chrysler/Dodge. So I consider my L300 the Great Nephew of the Commer. Let’s be honest, all families have a relative that they don't talk about, marrying a "commoner" and producing offspring that were often disowned. Well that's me at the moment.
The L300 works well, though the torsion bar front suspension give a ride on bumpy road's not to different to what a Joey in a Mother Kangaroos pouch must feel like.
All was going fine until the temp gauge started running high and after checking things it looked like the sender or gauge were playing up. I continued on and though it did seem to be running a little hotter it seemed OK until when I lent it to a friend and it cooked itself on the expressway heading south about 100kn south of Sydney. The outcome was not good, totally cooked, scored bores and pistons and a knackered head.
As there are heaps of these vans in wreckers I thought a quick engine swap and off we go again, but trying to find one was another matter. those that were available had a zillion Km so I elected to have the motor rebuilt. Not the cheapest option and got in contact with the specialist that built my rally car motor and the motor for my old Sunny Wagon.
The new motor was needed to be a good street motor for a van, and built along a similar spec to the Sunny. I had been very disappointed with the fuel economy of the Std 2 litre 8 valve Mitsubishi motor, getting at best 20 mpg more often 16-18 mpg. I'm a reasonably economical driver and used to get 16- 18 mpg out of my Range Rover, so you can understand my disappointment with the van. You felt like you were flogging it most of the time for not a lot of action.
So I decided to use the rebuild as a test for the type of spec I want for the 2.4L Nissan motor I am planning for the Commer. Gaining power through improvements in the motor's efficiency, by letting it breath better.
The short motor was rebuilt, new pistons, bearings etc and is basically a stock short motor built by a specialist. The original head was beyond repair and replaced with a new one that is bog standard. I contacted a company call Camtech here in Sydney as they had an upgraded cam profile that gave good improvements in low down power and fuel economy, while retaining a smooth idle, sounded perfect to me. I had also bought a set of extractors with 2.25” outlet plus a 32/36 DGV Weber and adaptor to suit the standard manifold to get started. I cleaned up the manifold with my die grinder, as the production casting was very poor and rough, plus cut more of a tapper into the adaptor plate and manifold to reduce interference to flow for when the second barrel opened up.
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Once the cam was back in I put it all together and installed it back in the van. I bought a bunch of 2.25” mandrel bent exhaust fittings, some straight pipe, a Lukey free flow muffler plus resonator and set to work making the exhaust system. With everything now done, I added my running in oil and coolant and fired it up and have been knocking up the miles since.
To say I am pleased with the outcome would be an understatement. Everyday driving mostly requires just the first barrel of the Weber and only occasional the second, even when loaded. It revs to the red line if needed and is more than happy sitting on 3000-3500 rpm on the expressway. The exhaust gives it a pleasant note and not too intrusive in the cabin, though it would be worse if the rear load area didn’t have the layer of underfelt and carpet to soften the noise. The best thing of all is the fuel economy has improved to 25 mpg, and only drops to 22-24 around town when loaded and it is now quite fun to drive.
This confirms the spec the Nissan motor will be for the Commer and the importance of looking at your motor as a complete package. I know many of you have change to SU’s and fitted free flow exhausts, but the camshaft will still dictate the breathing of the motor. Standard cam grinds are such a compromise and the factory always goes for the most conservative option available. I know that a cam change in an overhead valve engine a major effort, but if you have the motor out or are rebuilding spend the extra money and get it reground, as it is the key that makes all other modification work.
On closing I will relate a brief story I was told when I was attending a course on Quality Assurance many years ago. The trainer was very well qualified and experience went back way before the term QA became what we know of today. He was a Pom and had done his early training at Ford in the UK and they were looking at improving production efficiency and seeing what other results they could get. He said they decided to build a 1600 cc motor using all standard parts from the factory and built by the guys that built the motors normally. The difference was they halved the design tolerances of the standard parts. The QA team did this by picking and measuring all the standard components and only used those that fell into the closer tolerances they had specified. Once the motor was built they took it plus another “normal” motor picked at random to the dyno for testing. The outcome was the Special motor produced about 5 hp more than the standard unit. Apparently the outcome was plans to attempt to reduce the previous tolerances in production. With the UK motor industry in chaos at the time, the trainer deciding to emigrated to Australia and was unsure what happened as a result of their work.
Cheers
Stephen