Cold Plugs

[Tham]

Since converting to full electronic ignition after the
installation of an electronic distributor, I note that
the engine runs somewhat hotter than before.

I am using standard "hot" plugs, such as Bosch W8DC,
Nippondenso W16EX-U or NGK BP5ES.

I wonder if switching to "cold" plugs, such as Bosch W7DC,
Nippondenso W20EX-U or NGK BP6ES, might lower
operating temperature ?

[oldcorollas]

nope. the heat range of the plugs s how fast the plug conducts heat from the tip to the cylinder head.

if the plugs are getting overheated tips, then you would swap to a colder plug.

plug heat range is ONLY designed to keep the tip at its servicable temperature range.

it's more likely to be due to incorrect spark timing that has changed the runnign temperature.

[Vios-GT_07]

hmm... one electronic ignition conversion i did was stuffed because the vacuum line that advances the timing pushed it a bit too high, causing leaning out of fuel at higher revs and generally made the car run really hot especially after a high-speed long distance cruise.. it made me wonder if there's such a thing as too much vacuum .. or that the dizzy itself was an issue (because we picked it from a later model and weren't aware of any changes internally or so).. then again i could be wrong as we never solved that problem.

i did think about enriching the fuel mix a bit, or checking to see if the dizzy was stuffed i.e. not supposed to advance so much like a spring inside was loose or something coz it was second hand.. or maybe the engine was older and need a rebuild.. or maybe the newer model had something the older model engine didn't... ?

[LeeRoy]

Lean = Hotter burn. Caused by less fuel.
Rich = Cooler burn. Caused by More fuel
Advanced Timing also causes hotter burn.
Retarded Timing also cause cooler burn

Simple

[oldcorollas]

you mean "advanced" instead of "lean"? timing shouldn't affect the AFR as such...


Tham, perhas you could try runnign with less than 20deg advance.. try 15 and see if it makes a difference.

[Vios-GT_07]

i did this while as an apprentice to learn how to change a dizzy.. and the dody asian mechanic i was working with decided to get an electronic dizzy coz he picked it up cheaper than the direct replacement.. (is it even considered electonic because it's just advanced by vacuum??)

but yea it seemed to "lean out" when we revved it.. i heard from my colleague that the timing at idle was 12 deg, but when revved it spiked to 25 deg or something... and because it ran off a vacuum line we couldn't just tell it to not advance more than 20 deg or so... i think it was stuffed..

oldcorolla : is it possible for an older engine to be pinging as a result of excess advance?

[kingmick]

i did this while as an apprentice to learn how to change a dizzy.. and the dody asian mechanic i was working with decided to get an electronic dizzy coz he picked it up cheaper than the direct replacement.. (is it even considered electonic because it's just advanced by vacuum??)

but yea it seemed to "lean out" when we revved it.. i heard from my colleague that the timing at idle was 12 deg, but when revved it spiked to 25 deg or something... and because it ran off a vacuum line we couldn't just tell it to not advance more than 20 deg or so... i think it was stuffed..

oldcorolla : is it possible for an older engine to be pinging as a result of excess advance?

? so it was a points dizzy and had vacum advance? um thats not an electronic dizzy.

[Tham]

is it even considered electronic
because it's just advanced by vacuum??

Electronic distributors fitted as stock items to most
engines in the 80's to early 90's came with vacuum
advance, I believe. This would be the case if one
went to a salvage yard in Malaysia and purchased
one as a replacement for the 4K's points distributor.
It was only the ignitor that is electronic.

It was only in the late 90's or so that most of these
units came with full electronic advance, either built
into the distributor itself or controlled by the engine
management computer, depending on the car model.
For example, the later model Proton Sagas in Malaysia
had the ignitor, electronic advance and coil all built
into the distributor.

One solution to your problem (which I would like to
convert too), would be to build and install Silicon Chip's
programmable ignition unit, with which you can program
the amount of advance you need. It was sold as a kit by
Dick Smith and Jaycar at one time, but I think it is no
longer available. I believe it can be used with both
points and electronic ignition.

[joecoolmk2]

all electronic ignition dizzy caps are screwed down, not clipped down that's the easiest way to tell. the advance required depends on the engine. a lot of dizzys have octane selector screws on the vacuum advance unit. this can be screwed in to reduce the amount of vacuum advance, and corrected by turning the dizzy. that's if whats needed, and if it has the octane selector.

[Tham]

(Sorry, this was posted twice and there was no provision to delete it.)

Thanks, will try that again.

I did try that setting when using points (with or without
the High Energy Igniton unit), and it was very sluggish
and had trouble climbing slopes.

I pulled the No.1 plug out as advised by ToyCrash in
the other thread, looked at the the top of the piston,
noted the timing marks on the cam cover and the
position of the distributor rotor, and it appeared to
be at the proper TDC.[/LEFT]

[kingmick]

the vacuum advance isnt much of a problem! you dont really need it as its for low down and for towing! its good to put this back the way they where but its not really needed! cant imagine much towing going on ?

[Tham]

Tham, perhas you could try runnign with less than 20deg advance.. try 15 and see if it makes a difference.

Thanks, will try that again.

I did try that setting when using points (with or without
the High Energy Igniton unit), and it was very sluggish
and had trouble climbing slopes.

I pulled the No.1 plug out as advised by ToyCrash in
the other thread, looked at the the top of the piston,
noted the timing marks on the cam cover and the
position of the distributor rotor, and it appeared to
be at the proper TDC.

[Vios-GT_07]

dang... i just realised after reading this thread and doing some ressearch i've missed out on a few things about the distributor.. guess that's why they call it forums! means me old problem could be adjusted.. good thing i stopped going to dodgy asian shops

erm.. one suggestion i could make is to check how much timing u're getting under load i.e. run it on a dyno.. or if you're using electronic ignition and distributor is there any way u could check the timing whild driving? a diagnostic port maybe?

erm.. being electronic it wouldn't have a rotor... soooooo.. contact-points? or anything of concern internally of the dizzy?

the other thing i can think of is the spark plug and its gapping should follow the one used with the electronic dizzy and ignition...

[Tham]

I think the engine runs hotter possibly because the
electronic ignitor tends to fire a hotter spark ?

[LeeRoy]

Hot hot the spark is will have little impact on burn temps.

Hotter burn is a result of:
- Leaner tune

Cooler burn is a result of:
- Richer tune

ie. the more fuel being pumped in lowers the air fuel ratio and creates a richer tune and the less fuel or more air results in a leaner tune.

A richer tune can also be a result of retarded timing and will result in a colder burn. The opposite will be advanced timing igniting fuel earlier, however, excessively advanced timing will be noticable in pinging and eventually an engine that goes bang!

Do a search on google for stoich or stoichemetry and all your questions should be answered with some reading. Also try www.wikipedia.com

- LeeRoy