Hi,

A No. 8? I could not get the engine to run on a 6, a 7 seemed even worse?

In my case TopGun suggested I go down to a 5 or even a 4?

I thought the higher the number the colder the plug. You tend to run 7 & 8 in .21's

I've always run 6 in my .12's because they tend to need a hotter plug.

I thought the lower numbered plugs have a thinner wire which get hotter which tends to be needed in a .12 because of the small compression & most run 16% fuel.

With the .21 you have higher compression & most run 25% fuel so you don't need as hot a plug.

Have I got this right or am I completely wrong??

All the above relates to Novarossi glow plugs.

Thanks in advance

Edward,

Maybe I am wrong, but the temperature rating of a glow plug doesn't control the operating temperature of the engine, but it actually controlls the combustion event of the fuel mixture due to the temperature that the filament glows. Similar to ignition timing of a gas engine. Well actually, I kinda answered my own question, ignition timing can indirectly affect overall engine temp.

So if this is the case would a cold rated plug be like retarding the combustion event, and a hot rated plug be like advancing the combustion event?

Please clarify this for me.

BK

Hi Kevin,

You are right in your theory. Most .12's do require a hotter plug and on my RB I was using a No. 3 OS Plug.

However, when you remove a shim you increase the compression level and induce pre-detonation. To counter this you need to put in a colder plug.

As I was mentioned earlier adjusting the needles didnt cure this problem for us.

Chris figured out what the problem was with this at St. Annes on Sunday. You could possibly have air getting in via the carb neck. He noticed that the Nova based carbs have a longer neck compared to the carb mount on the engine and they dont seat properly.

To cure this you can either grind the neck of the carb to allow it to seat better or add a second o-ring. After adding the o-ring Chris' engine ran perfectly and the high idle was gone.

PE: now that explain my air leak problem i was having when i get my PS12. After I put in 2 o rings on the neck problem was gone.

Hi Brian.
Actualy you did answer question and yes, hot plug will advance ignition and cold opposite. Also we can advance ignition by making combustion chamber smaller ( it won't be direct , but increasing compression ratio will bring ignition earlier and in the mean time will bring more HP). This is why if I want to make combustion chamber smaller- I am using coldest plugs ( colder plug compencate ignition advancing due to combustion chamber volume decreasing).

Hi Top Gun 777,

Now that's interesting.

I removed one shim (now have two on the button)

I'm running a No.5 plug (This is a hot plug, I think!)

I could not get the temp above 160 on a nice warm sunny day.

And I'm being told my piston looks like I'm still running rich.

If I go back to a 6, 7 or 8 will the temp not drop?


Many Thanks

Kevin

Long time:
If you are going to be at the Nats. in Ohio look me up.
Sorry I hav`nt talked lately but I have been quite busy with house upgrades.
Paul Rush.............................................. .......

Hi Kevin.
It is strange that you can't get temperature going up. Take one more shim and lean top further. What is atmospheric pressure there? 760 mm mercury column?
Temp shouldn't drop if you use #7 or 8, but idle can be more difficult.
Paul, I might be at Nats in last 2 days, I am not sure if I will get vacation. I realy want to go and watch, but we have 3 events comming in our area and my son wants to participiet all of them, on top of it so many projects are rolling up, so I am not sure if I can go in Ohio.
Best regards
Edward

Cogratulation
fill us in when you have time.

Hi Guys,

I was reading on another thread that changing from a long to a short reach plug but keeping in the same heat range can also effect the running of the engine.


How can you tell if you have a long or a short plug?


What difference will it make to the engine?


Many Thanks

Hi Guys,

Had the engine at the track today.

Got the temp up to about 240-250. (2 shims, No. 5 plug, 16%)

During the heats I had a fellow club racer with a 5 port turbo Max engine behine me, I could hold him off with the PS12.

I sill think the engine is running a bit rich + I'll need to change my gearing to allow the engine to rev a bit more on the top end.

So far I'm very happy.

Thanks for all you help

Bought a PS12 and want to fit into a V one RR using a Kfactory engine mount. The engine is about 3~4mm wider than standard novarossi engine, so it simply will not fit into the standard engine mount or the kfactory optional engine mount. Anyone had this problem, how do you solve it.

The engine is slightly wider than conventional engines. This is unfortunate but necessary for the design concept. The only way around this with some cars is to use standard engine mounts and machine out the chassis slots if necessary.
I am currently working on the design of a new PS12 mount which will allow it to install directly into any car without any modifications.

Hi Eric.
I sent you email about fitting, but I guess it never reach you. Engine is 2 mm wider then Novas-27 mm vs 25 mm. We never try in one piece engine mounts, but on regular maunting it is fit pefectly on all car so far we use. -710, MTX3, VoneR, NTC3.
Edward