Tom and Martin,
Thanks for the replies. Actually I have a TR3A, 4cyl. I believe that the
NAPA guy looked it up in the book before I went to the NGK plug, but its
possible he just did a cross reference from whatever plug the PO had in
there, I don't remember. In either event it could well be the wrong plug,
so please let me know how this changes for the TR3 if you know.
Martin, I am not getting any pinging under load, do I don't think the
timing is retarded. I will try to get it on a machine this weekend.
I really appreciate the help,
Bob
>Tomislav Marincic wrote:
>
>> Bob,
>>
>> RE:"Thanks very much, particularly for the tip on the plugs. It
>> says to
>> increase the gap, but doesn't say how much. I have been running NGK BP4HS
>> at .32 and they keep fowling with black carbon. I figure the mixture is
>> too rich, but the carbs seem to be set up right according to the Haynes
>> manual. Are the NGK BP6ES plugs hotter? Will they last longer?"
>>
>> You are using the wrong plug for a 6-cylinder TR (is that what you
>> have?)
>>
>> NGK plugs are numbered just the opposite of Champions. With NGK, a
>> lower number signifies a higher heat range. TR250's and early TR6's were
>> equipped new with Champion N12Y plugs. Later TR6's had N9Y, which crosses
>> to an NGK BP7ES I believe. My car idles rich from ovalled jets, and uses
>> some oil from worn valve guides, so I use a BP6ES, which is approximately
>> correct for my car anyway. (TR250) It's a safe choice, since most of my
>> driving is part-throttle on country roads at 40-50 mph.
>>
>> Here's a breakdown of NGK's numbering in this case: BP6ES and BP4HS
>> B=14 mm thread
>> P=projected type tip (tip protrudes into combustion chamber a bit
>> more)
>> 6,4=Heat range, numbered from 2 (hot) to 10 (cold). You are running
>> a very hot plug.
>> E, H= Plug reach. 6 cylinder TR's need an E, 19mm. Your car has H,
>> 12.7mm, which is probably why the plugs are not getting hot enough
>> to self-clean. Someone has tried to compensate by using a much hotter plug.
>> I'm surprised the car runs at all.
>> S=standard 2.6mm center electrode.
>>
>> You didn't mention what year car you had, but try starting with a
>> BP7ES. If it runs well and the plugs don't foul, you're all set. If your
>> plugs foul, try BP6ES, particularly if most of your driving is around town.
>> If they don't foul with BP7ES, but you do a lot of aggressive high-speed
>> driving, consider BP8ES as a precaution. BP4ES is way too hot, and BP4HS is
>> both hot and incorrect.
>>
>> Good Luck,
>>
>> Tom Marincic
>> CD3574L
>
>You've talked about every plug except the one I've had the most luck with in my
>TR6. For over a year now, I have been using NGK BPR5ES with very good
>results. For the first 6 months, I had a conventional points ignition. Now I
>am running a Crane XR700 and a new Lucas Sport Coil. Plugs seem to work even
>better. I now gap at .034", while I used to gap at .025" with the points.
>
>Remember, too, that cold fouling (black, sooty plugs - not oily) can be the
>result of too much ignition retard as opposed to improperly set carbs.
>
>Just my two cents worth...
>
>Martin Libhart
>1972 TR6
>1970 Spitfire
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