Thread: Ideas for improved economy from Holden 186 in SIII

I do not know about your specific case but I can give you some guidelines.

1 gearing- the higher the gearing within reason, the better economy so maybe if you have 4.7 diffs go to 3.54.

2 advance - try the maximum advance that he engine will stand without pinging, by advancing 1 degree static at a time until you get pinging then back off a couple of degrees.
3 Fuel mixture- Get an adjustable main jet and tune it as lean as possible on cruise consistent with smooth running. This may be a problem with an old iron head 186 as the leaner the hotter and the more chance of burnt valves, seat recession on unleaded. I would suggest a dyno and exhaust sniffer for this but you probably don't want to spend the money.

4 - weight/air resistance. Take off the roof racks, and ditch all the unecessary gear inside, maybe even the spare for local trips.

5 tyres - a modern tyre with mild tread will use far less juice than bar treads.
6- ensure the engine is in good condition, plugs, wires, dizzy, coil, carby not leaking or worn out needle and seat, good compression.
Regards Philip A

A Hiclone will give up to 15% better fuel consumption and more power. The Tv said so. Put one in each inlet port and you will get a 90% increase!


My experience with the 186 is that apart from extractors, good timing and obviously good plugs and filters there is little to be done without starting to spend big and the results wont justify the outlay (i.e carby, inlet manifold mods, head replacement / work)
You could fit a later model commodore head with EFI. I think it was the VK had EFI 12 port heads. Again the expense wouldnt justify the gains overall. But would be good talking point.
An overdrive might be the best mod you could do.

cheers

Originally Posted by strangy

A Hiclone will give up to 15% better fuel consumption and more power. The Tv said so. Put one in each inlet port and you will get a 90% increase!


My experience with the 186 is that apart from extractors, good timing and obviously good plugs and filters there is little to be done without starting to spend big and the results wont justify the outlay (i.e carby, inlet manifold mods, head replacement / work)
You could fit a later model commodore head with EFI. I think it was the VK had EFI 12 port heads. Again the expense wouldnt justify the gains overall. But would be good talking point.
An overdrive might be the best mod you could do.

cheers

From what I've been told a 186 with an overdrive will shred the overdrive or the gearbox pretty quickly because it has too much power for it. I figure that I have to outlay about $1100 for gas after the rebate, I ruin the originality of the car and lose some cargo space. I will consider rebuilding or kitting the carby, tuning a bit and see where it goes from there. I'm not sure if changin the archaic oil bath filter for the standard holden type air filter for city driving.

Not much evidence to say that hiclones really work!!!

I had a 186 with yella terra heads,twin barrel stromy with a power cam and 3'' sports system and I drove it like I stole it and never broke anything.The series gearbox's are allot stronger than people give them credit for.I'd get higher diffs. Pat

Decent spark will allow you to run lean mixtures. I would fit an electronic dissy from a blue motor, adjustable main jet sounds like a good idea, viscous or electric fan, then an O2 sensor and a little mixture read-out kit from Jaycar so you can see what the mixture is doing.
Later model head and extractors if you can fit them in.
Oh and take the roof off and drive with the windscreen down. Felt hat with cord needed.

Diffs as said, XE/XF falcon webber carby (included elec choke) jetted correctly makes it go much better, won't be worried off road by angles and is much nicer to drive and there is an adaptor plate off the shelf. Extractors, better exhaust, if you want to go all the way yella terra head and cam done right will even out fuel vs performance.

Originally Posted by PAT303

I had a 186 with yella terra heads,twin barrel stromy with a power cam and 3'' sports system and I drove it like I stole it and never broke anything.The series gearbox's are allot stronger than people give them credit for.I'd get higher diffs. Pat

Is it possible people who convert a 4 cyl Landy to a holden 6 might be the ones having problems, ie is it a different gearbox? Mine was originally a 6. Considering they came out with 3.5 litre V8s as well, I can't see the boxes not being able to handle a 3.3 red 6.

So to change the diff is that just the diff centre or do you have to drop the whole diff and replace the whole thing including the painful bleeding of the brakes?

If mine is the standard series 3 diff for a 6 cylinder petrol, what diff will give me better economy? And does the ratio of the front diff need to change as well? What sort of land rover or other diff centre will go straight in without a fight?