TR4/4A NGK Spark plugs BPR5HS for TR3A/TR4A

[karls59tr]

I found a new set of these plugs in my parts bin. I think they might be what is referred to as a " hot" plug. If I was to use these plugs in a 4A engine rather than the stock plug would there be serious side affects or would it make that much difference?

 

[Tim Tucker]

This web pages says it's a possible equivalent:
https://www.sparkplug-crossreference.com/convert/NGK_PN/BPR5HS

I was on the NGK website looking at new plugs for my TR4. The NGK website calls for BPR6. As you said: BPR5 is hotter.
https://ngksparkplugs.com/tech_support/spark_plugs/p2.asp?mode=nml
I'll be buying the BPR6HIX plugs. If you have cylinder a bit down on compression the hotter plug is handy... If not, I'd stay stock. IMO.
Tim

 

[BillyB62]

I put NGK's into my 3A this summer and the car ran very poorly. I had also replaced the points, cap and wires at the same time and took turns swapping them out to try to find the culprit. As it turned out (after reading posts on this forum), I went back to Champion plugs and the car runs like a top again.....just saying....

 

[Tim Tucker]

So much for buying those NGKs! I guess I'll save the money and just replace the Champions. Thanks for the sharing the experience.