Hi Fastlaners,

I have a factory stock 186 engine (unaltered head and block) with bolt on factory 186s goodies (carbs, exhaust and inlet manifold and headers) and have now fitted a reconditioned+regraphed (by Performance Ignitions Ringwood) VC Commodore Bosch HEI and NOS Bosch Coil. My queston is what plugs and gap setting would people recommend? I am currently running NGK BP5ES plugs with a 1.0mm gap. Runs ok like this, but I am unsure if I am getting the most out of the setup.

Any advice would be appreciated.

Cheers

htprem

Factory spec on those HEI systems is 1.5mm. I know it sounds wide, but it's a very capable system.

If you're still running the original compression ratio (or a little more) and it's not on LPG, then go right ahead and open them up.

If you are running more compression or LPG, it can be a little wide. In my VL stroker with higher comp, and straight LPG, it doesn't like more than about 1.25mm, so I run them on 1.1mm for a clean spark with no misses under load.

Thanks for your replies - the engine and head are absolutely untouched factory original, cam etc - head has never been pulled off, mileage is around 70,000 miles (had the car for 25 years). I have only switched to HEI as I finally got sick of the poor quality aftermarket (in Bosch boxes, but clearly not Bosch) points. I had 3 x sets fail over a 4 month period, after which I put some original old pitted Bosch points back in and the car ran fine for 12 months before these were beyond it, which suggests the problem was the aftermarket points and not some other gremlin in the old ignition system. The engine runs 1000 times better with the upgraded Bosch HEI ignition.

I have not tried opening the gap to 1.5mm - wouldn't that mean that the electrodes on the plug would no longer be parallel or does this not really matter?

Cheers

htprem

The transmission is the factory Powerglide that came in the car - it was tecently reconditioned by Raceglides.

What is the difference between the 186 and 186S cams? Is there a way if relling which cam us in the car?

For what its worth the car is an April 1970 build HT.

Cheers

htprem

Will check. From memory HT 186 manual and Powerglide had the 186S cam, it was the trimatic engine that used the HK 186 cam. Will check when I get a chance.

Edit: just found the relevant page in HG Features Manual. 185 uses the 186S cam except for Trimatic which uses the 161 cam.

Edited by user Wednesday, 20 February 2019 7:58:30 AM(UTC)  | Reason: Not specified

I just happened to be (by major coincidence) looking in the HG features manual at the time. HT is the same, but there is no Trimatic update in it.

Others here will be better for advice on the plugs. The dizzy curve will be more influenced by the cam. I’ll have a look at the curves for you.

Edit: same dizzy for 186 and 186S regardless of cam. So all good.

Edited by user Wednesday, 20 February 2019 8:00:07 AM(UTC)  | Reason: Not specified

I’ll get you the specs of both, but the 186S cam in the 186HC engine gave the HT an extra 5hp advertised over HK.

Could well be Terry. I read the lower figure of the HR/HK 186 advertised power curve which I just copied yesterday. I don’t have the HK figures at hand.

I believe that the primary reason for there being fewer sales of 186S in HT/G would be the availability & price of the 253 V8 & to a lesser extent the 308 V8.

When the 307 was first released (in HK) it was a fairly expensive option being imported with the Powerglide as a mandatory option, but the 253 V8 (in HT/G) was far more affordable.

Dr Terry

Edited by user Thursday, 21 February 2019 11:01:57 AM(UTC)  | Reason: Not specified

The electric aerial didn't become an option until HT & like radios, heaters & other options of that type they were more expensive than 186 engines & disc brakes etc.

One of the main reasons for this was the stupid old sales tax system we had in those days (pre-GST). Of course, radios & aerials etc. are also a lot cheaper these due to them being sourced in countries that have much lower labour rates than Australia nowadays.

Can you believe that these options were deemed to be 'luxury' items & were taxed accordingly. Cigarette lighters were included.

The same applied to the cars themselves.

I remember in 1970 sedans & wagons had 27.5% sales tax applied, while utes & vans (because they were for commercial usage) only had 15%.

The same applied to any options. For example an auto trans was around $250 extra for a sedan but only around $230 for a ute.

Dr Terry