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MG TD TF 1500 - NGK Spark Plugs

Has anyone used NGK BP5ES plugs for a step hotter than BP6ES plugs? I've only read one archive post from a member in the UK that mentioned them, and he was very happy with them. I'm currently running Champion RN5C plugs, and I'd like to go one step hotter as a test.

TIA

Larry
L Karpman

Hi Larry,
I have used NGK plugs for some time and found them to be quite satisfactory. As far as their longevity is concerned, I cannot give you much of an opinion as my plugs are in and out at regular intervals. I am using a cooler plug as most of my driving is on the open road, with very little city driving, so the plugs do not have any chance to foul up. I find it difficult to see a lot of difference between the performance of one plug over another. The heat range can make a difference depending on your driving habits.

George Raham
TD 4224
G. L. Raham

Thanks George. I seem to have the opposite problem. My drives are short, usually slow city type, with occasional highway. Speeds are usually below 50 mph except on the hwy.

I know a lot of forum members use the BP6ES or B6ES, but I'm interested in the hotter BP5ES and anyone with experience with these plugs.

Larry
L Karpman

Larry,
With the driving conditions you describe, I think a hotter plug would be a good idea. I would suggest you try the BP5ES and see what results you get. I have had good results from the NKG plug and have not had any problems. I would suggest that you hang onto the plugs you have now, and compare them with the hotter plugs after 2 to 3 hundred miles. They should run a little cleaner than the cooler plugs under your driving conditiions.

George Raham
TD 4224
G. L. Raham

Not sure I agree with you.

Living in Texas, wouldn't you be better off with a colder plug and experience fouling, rather than risk burning a piston?

If you have a pertronix unit, the chances of fouling are considerably reduced.

Why not add a hotter coil and leave the N5 in?

Gord Clark
Rockburn, Qué.
Gordon A. Clark

Thanks George and Gordon. I am running a Lucas (modern) Sports coil and a Pertronix. Not sure I trust the modern coil, as I have no idea where it is really made. I do have a period Lucas Sports coil that I have not yet installed. Not sure how to test it.

The car has always had black soot on the plugs, with both old carbs and new. I am fairly confident the carbs are tuned correctly, and the rebuilt distributor (by Jeff Schlemmer) is set correctly. So, my choices are:

1. Try a hotter plug, or;
2. Swap to the period sports coil, or;
3. Increase the gap on the RN5Cs (I had them gapped to .035 when I first put the coil in, but had misfiring at high RPM, so I set them back to .030.)

Larry
L Karpman

Noting how this thread is developing it may be helpful(to me anyway!) to ask whether you check/use the colour of the exhaust pipe afer a long run, as an indicator of mix?

In times past, with leaded fuel, I always expected a good pink colour. as with the spark plugs. However now, with unleaded, it seems to be sooty until I get to the point of leanness which is worrying.

IanB
Ian Bowers

Larry,
IMHO, I think the black sooty condition of the plugs is directly associated with a rich carb mixture... Have you tried to lean them out a flat or two? Do you check the plugs after slow driving or idleing? Doing that will also result in black deposits on the plugs...

SPW
Steve Wincze

Larry

It is not som much the state of the plugs, which I can and regularly do. It is using the state of the exhaust as a quick and dirty indicator that a check-up is needed.

I suspect that the lead free fuel is not producing the pink colour at the exhaust pipe end which was there in the days of my youth. And that is what I was asking.

IanB
Ian Bowers

Larry,
When there was lead in the gas, I could check the setting of the carbs by reading the plugs and or the tail pipe. With the removal of the lead, I find that reading the plugs and tail pipe to be inconclusive. It seems to me that the lead left a deposit that would indicate the air/fuel mixture and I could adjust to suit the condition. I have never used the colour tune method so cannot comment on what change the lead free gas has on the results. I would expect that your required slow driving habits in the city would tend to produce a more sooty plug, and I feel a hotter plug might help under this condition. Steve's suggestion is good and you should try one flat at a time. Take the car for a run on the h'way and shut the motor down while traveling at 50 mph. Take out the 1st and 4th plug to check the balance, and see if there is any sooty deposit. This should give you some idea of the carb setting, and you can adjust from that point. I would be interested in your results.

George Raham
TD 4224
G. L. Raham

I agree fully that the modern fuel makes reading the plugs like the old days useless. Remember these engines run a little rich anyway. Have you ever had a plug foul? If not, I would be leary of going hotter, since you could burn a piston at least would cause knocking. George
George Butz

Thanks all. I am going to leave the carbs alone. They react exactly as stated in the WSM for correct mixture, and if I lean any further they cause the "splashy" idle mentioned in the WSM, and will attempt to stall when the piston is lifted 1/32".

I am going to assume that it is my driving habits (lots of idling, short street runs before lights, carb and engine testing, etc.) that soot the plugs. Prior to a planned long run, I will put in fresh RN5C plugs, gapped to .030, and let her coast down after shut off and check plugs 1 and 4. If the plugs are still sooty, I will change the coil to the period Lucas sports coil I have, and gap to .035 and see what happens. I too fear burning a piston with hotter plugs.

It was 104F here yesterday with heat index at 110F, with more expected for a week or so, so I will have to get up real, real early to do this :-)

Geroge B. If you mean by "plug foul" that I have black soot on the plug - yes. If you mean did I have a sooty plug fail from the soot - no.

Cheers, and thanks again.

Larry
L Karpman

Larry, by fouling I mean either lots of black gunky carbon (not just thin soot), or ceasing to fire. A plug that looks pretty good can "foul"- ie stop firing. If it is still running fine, not missing, etc., forget about it? I never look at my plugs unless there is some running problem or misfire, etc. George
George Butz

.30 or .25?
gblawson(gordon)

Gordon, in what sense are you asking the question? Not sure I understand.

Larry
L Karpman

Larry,

Are you gapped to 0.30 or 0.25 on your spark plugs? It takes a strong coil to jump the 0.30. I personally use the 0.25 gap setting on my plugs.

warmly,
dave
Dave Braun

Dave: I thought I was at 0.30, but that was with the plugs I pulled a few weeks ago. I'm gapped at 0.25 with the plugs I put in after the new carbs were installed. I was previously at 0.30 and was considering going back to that, but not sure I have confidence anymore with this modern sports coil.

I understand that John Twist recommends 0.35 with the Pertronix and sports coil. All I really want is a hotter spark, and have always thought that the greater the gap the hotter the spark. How I get there is the dilema. I do have an uninstalled period sports coil I could try.

All that said, I am very pleased with the way the car idles and runs at speed, but it's the constant soot on the plugs that really bothers me.

Cheers

Larry
L Karpman

Sorry... yes, spark plug gap... takes a lot of power to jump great distances...
I installed an electronic ignition kit in a Mini I owned in the early 70's and they opened them up to about 45...but stock coils/systems I have used 25
gblawson(gordon)

0.35 per John Twist is what I have been running w/ Pertronix. I have been running Bosch Platinum plugs for years and been very happy with them. I have been slowly bringing my TF back to life after an extended "nap". (over 2 years).
The car started and ran great but recently took carbs off to clean float bowels and have had some problems after. Ran just as before for a week ...then yesterday developed a miss. Bummer, yesterday was first time I got her out on the road. Checked all spark...good to go there. But has developed a miss and seems way rich now ...even though I changed no settings on the carbs. Put in a set of NGk's and ran fine...went for short ride and when I got back was missing again. Did not notice it whilst driving ...but I had windscreen down and very had to hear anything with ears flapping in the wind!
Stupid question: I shortened my #3 plug wire (had a bad "cap" on it and was a bit long) This shouldn't effect the timing..should it? Wire test fine...but since I did this I have the miss.
Oh well ...it felt good to get some bugs on the teeth again!
Must mow grass today so will try and find my problem tomorrow.
Any ideas ..I'll try them!
Cheers, David 55 TF1500 #7427
David Sheward

David asked: "Stupid question: I shortened my #3 plug wire (had a bad "cap" on it and was a bit long) This shouldn't effect the timing..should it? Wire test fine...but since I did this I have the miss."

No, wouldn't affect the timing, David, but you may want to check to ensure it's bottomed out and tight in the distributor cap.
Gene Gillam

Gene,
Thanks, knew this would not make a difference running points...but was wondering if it was some strange "quirk" with the Pertronix as that changed my timing considerably when installed.(years ago)
Checked all plug wires through dizzy cap with meter and are good. Also checked "spark" on each cyc with one of those little fancy "gap checkers" ..all show good. Pulled each plug and grounded on block ..all good. And changed the plugs also. (Bosch to NGK)
The thing I can't figure out is it started and ran perfect one day ...then next time I started was missing badly. Made no changes between. My neighbor thought I had started the TR7! LOL
Going to pull the NGK's out today and see what they look like.
Maybe put my points back in and see if perhaps the pertronix is faulting?
Cheers,
David 55 TF1500 #7427
David Sheward

PS : Have never messed with the carbs since John Twist set them up. Other than cleanning float bowls recently. (Checked with 3/8" dowel) When I put them back on check with a synchrometer and did "tube listen" for hiss ...all was good.
Got to be something stupid I did!
Hoping I can find it today.
David
David Sheward

Did you try a different rotor? Lots of bad rotors out there. Also, make sure all 4 plug wires and the coil wire are not loose or burned off at the dist. cap ends, including the coil end if the original screw type. Easy for them to work loose and burn partially off, or pull one out when working on another. George
George Butz

Larry,

There is a way to check your plugs using today's fuel if you want to try it...vintage racers do it all the time.

Find a straight stretch of road with a safe turn off at the end that you can coast into. Get the engine hot and haul a$$ down the road, then shut the engine off (while still under power) and coast into the turn off. You can then pull your plugs and check them for the proper color range.
Gene Gillam

Thanks Gene. I'd have to get to that stretch of road via warm up at idle and slow city driving, so I assume I'd change the plugs when I got there before starting the run? Just checking.

Larry
L Karpman

Larry,
Not necessarily...a good fast run under load should burn your plugs clean...they start to foul when you slow down or idle...that's why shutting the engine down while it's still under a hard load is important. It doesn't matter how far you have to coast after you shut it down to get to a safe place to check the plugs.
Gene Gillam

Thanks Gene. Will do.

Larry
L Karpman

Thanks Gene,
I will give this a try also.
"Izzy" is happy again ...followed "the book" for setting carbs today Don't havea clue what I did wrong last time...but started over and all is well. Was running way rich (4 full flats). checked with my Grunsen Color tune ...something I purchased long time ago but never used because she always ran great after Mr. Twist re-built my carbs!
Put the Bosch plugs back in and purrs like a kitten.

I am curious...what plugs do you run Gene?

Anyway ...I won;t feel silly going back to polishing neglected chrome now that the old girl runs good again. (Hard to get motivated cleaning something that didn't run right.)
Cheers,
David 55 TF1500 #7427
David Sheward

David,

I use the NGK's...seem to work well.

Gene

Gene Gillam

Larry,
I have experimented with the heat ranges of spark plugs and do not think that one range higher would present a problem such as burning a piston. I think it might be worthwhile to try a short test with the warmer plug. If you see no difference, then the problem lies elsewhere.

George Raham
TD 4224
G. L. Raham

I agree George. It's finding the hotter plug that was the basis of my original question. What plug is 1 step hotter than the Champion RNC5 (14mm 3/4" reach)? I got no responses or confirmation to the one I identified (NGK BP5ES).

Cheers

Larry
L Karpman

David Sheward,

What probably happened is when you cleaned your float bowl and adjusted with the 3/8 rod, you probably raised the float in the float bowl, which raises the level of fuel in the bridge. I have found the adjustment range for fuel in the bridge is about .120 to .200 below the bridge (the SU book says 1/8 to 1/4 inch which would be .125 to .250 below the bridge) I use 1/6 of an inch or about .160 below the bridge.

If Mr. Twist used a 7/16 rod and was on the wide side, and you used a 3/8 rod and were on the tight side, you could have raised your float level by almost .125 inches and made that carburettor richer at idle. Also, cleaning the float bowls may have dislodged something in the fuel lines or sent something into the transverse arm from the float bowl to the carburetor disrupting fuel supply, which would make the car backfire because of a lack of fuel on that side. Finally, not all floats float alike, and if you accidently swapped them from side to side, you may not have had fuel to the proper height in the bridge.

I'm glad the color tune worked well with Izzy, the new unleaded fuels all burn a bit yellow and it is difficult to detect the 'bunsen blue' that the color tune is offering up.

Dave Rome has asked me to write a comprehensive article on carb setting, something I will do this winter when I'm not having so much fun driving Tommy!

warmest regards,
dave
Dave Braun

Thanks Dave,
That makes a lot of sense ...far less disturbing having some idea what the problem was. I'll look forward to adding your paper to my collection. Always enjoy your writings. She was definitely way too rich. I went through the drive-thru for a bag of ice and nearly killed them with the smell! The other stupid thing I did was failing to "lube" all my linkage after I cleaned the surface rust off it. (Maybe one too many "cold-ones" during the process! I mean, how sober do you have to be to clean rust off!) I seem to recall getting a bit tipsy whilst doing that. Getting old ...got drunk on 2 beers...yep #15 & #16 ...that's the two that did it!
Cheers & thanks to all,
David 55 TF1500 #7427
David Sheward

Larry,

I have not used a champion plug for 35 to 40 years, so cannot answer that question for you. I have not experienced your particular trouble with plugs in quite awhile. The NGK plugs have given me good service and would suggest that if you are interested in trying them, you should go to an automotive store and ask for the NGK plug that is one step hotter than the Champion RNC5. They should have a chart that will have that information on it.

George Raham
TD 4224
G. L. Raham

Larry,

Not sure if this info is of use to you but it's good reference:

http://www.kaila.net/tl125/tl125ngkcode.html

http://www.angelfire.com/extreme4/skidoolympique/SPARK_PLUG_CROSS_REFERENCE.htm
Gene Gillam

Gene: I'm pretty sure the NGK BP5ES is one step hotter than the BP6ES many on this board use in lieu of the Champion RN5C, but I can find no chart or other info to confirm it. Guess I'll try at the auto parts store (NAPA) for a heat cross-reference as George suggested.

Cheers

Larry
L Karpman

Larry,

According to the first link above (http://www.kaila.net/tl125/tl125ngkcode.html) the smaller the number, the hotter the plug, so you're correct.
Gene Gillam

OOps! I missed that in the chart you posted Gene. (Gotta read slower :-) Thanks!

Larry
L Karpman

Larry, the NGK catalog cross-reference chart shows:
Champion NGK
N5C.....B6ES
N9YC....BP6ES
N11YC...BP5ES

RN5C....BR6ES
RN9YC...BPR6ES
RN11YC..BPR5ES

I normally run with the BP6ES plugs. I have been known to install a set of BP5ES when participating in long parades.

I see no reason to use resistor plugs in a T-car. Bud
Bud Krueger

Getting old ...got drunk on 2 beers...yep #15 & #16 ...that's the two that did it!


Gotta remember that line Dave, Thats a keeper.
LED DOWNEY

Sad but true ...
when I was younger it was #26 & #27 that did it!
David
David Sheward

This thread was discussed between 27/06/2009 and 02/07/2009

MG TD TF 1500 index

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