• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR2/3/3A "Cool running"...Hottter plug? TR3 carbon fouling.

Share this page

K

karls59tr

Obi Wan
Bronze
Country flag
Offline
"Cool running"...Hottter plug? TR3 carbon fouling.

I came across the term "cool running" in the TR4 Bentley manual accompanied by a picture of a dry black carbon fouled spark plug looks (as opposed to a a pic of a too rich mixture plug that was wet and oily). The plug looks like mine. I'm trying to track down carbon fouling of my plugs after an hours driving that is causing missing and sputtering. Does "cool running" mean I need a hotter plug?....and how do I determine what plug to go to? I'm running a street cam and header and TR4 long intake manifold.
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

Karl,

I had a rich fouled plug problem (black sooty flakey, not wet)on 1&2 that, no matter what I did with the ignition and carb tune-up, would not go away. I was running NGK plugs that many have great success with. I changed to Bosch platinum and the trouble went away. Champion was OK but not as good as the Bosch. ymmv but I'm done with NGKs on the 3A.

-Pete
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

Well that might be worth a try. What type or # Bosch Platinums did you use?
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

Hey Poolboy Good site. My plugs are definetly #3 carbon fouled. Rest of the Ignition system is good. I've been trying too lean out the carbs to no avail so it has to be that I need a hotter plug. Someone on another forum had success with NGK6ES but after reading Peter's post I 'm in a quandry. I've heard stories of Bosch Platinums not being suitable for a lot of cars but I guess its a trial and error thing.
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

I'm using Bosch Platinum Plus #4032 in my TR4 and have been quite happy with them.

Randy
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

karls59tr said:
I've heard stories of Bosch Platinums not being suitable for a lot of cars but I guess its a trial and error thing.
Click to expand...

I run Bosch Platinum +4's in my Honda's and regular Bosch Platinums in my Spit... No problems here. I'd run them in my John Deere too if the thing ever seemed to need replacements... but nothing runs like a Deere is an understatment...
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

karls59tr said:
Well that might be worth a try. What type or # Bosch Platinums did you use?
Click to expand...

#4032 same as Randy.
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

I never had very good luck with Bosch platinums in various Triumphs. Champions, AC, even OEM Lodge and K.L.G. plugs are fine, though....

I did have some Volvos and a Saab 99; they all liked Bosch just fine.

Go figure.
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

Rich mixture leaves black, fluffy, 'dry' deposits. If they look oily, it's oil burning, IMO.

Having a plug too cool for conditions does allow deposits to build up, which are dark (though usually not carbon-black). But an hour's operation seems too short for that to be your problem. I would guess that your combination of components is allowing the mixture to go rich under the conditions you are operating.

Try leaning out the mixture adjustment and see what happens. Yes, that will screw up the idle, it's just for a test. If it fixes the problem at speed then you need to choose different needles and/or spring to accomodate your intake and exhaust changes.

BTW, I run Bosch WR7BP (which I recall is the same as 4232) and they work well for me. Been running them ever since Ken G. said they found another 5 hp on the dyno with them.

Note that valve lash, and valve timing can also have marked effects on plug readings. Friend of mine once put a Honda 4-stroke motorcycle engine together with the valve timing off; and it would foul the plugs within about 20 minutes.
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

I'm going to try the Bosch Platinun 4032's to see what happens. I've tried leaning out the Su's with no success so I've orered the Lean needles (SL) from Moss. I'll track it down yet. :smile:
 
Re: "Cool running"...Hottter plug? TR3 carbon fouling.

Andrew...That's what I've heard that the the Bosch Platinum seem to work better in Swedish and German makes and not so much in others. Seems odd that everyone has a different experience with them.
 
Back
Top