Can we have a quick poll for the regular city drivers of carb'd cars. I'm running BP6ES's and have to clean/change them every 6 months or so. I do a lot of city driving and I reckon I've got my carbs set up now. Car always runs like a dream with a new set of plugs. Thinking of trying the 5's to reduce fouling What do you run ? Lee
I run 5s.......here, I think the alcohol additives are really softening varnish. And I make a point of a high speed blast once in awhile (when no one's looking!) Make sure to adjust the gap..........022 seems a sweet spot (015 -.025 spec'd.)
They are a little more pricey, but the NGK Iridium BPR5EIX or BPR6EIX will be much more resistant to fouling IME. BigTex -- What is your reference for the .015" - .025" spark plug gap specification? In the 308GT4 WSM, I think they made a typo error and listed it as 0.4 mm (.016"), but every carbed 308 OM that I've come across gives the stock spark plug gap spec as 0.6 - 0.7 mm (which gets translated into .024" - .028" or .024" - .027").
From my 1977 North American Owner's Manual.....admittedly, for old Champion plugs! Rifledriver told me to stay in the upper range, but that's banged down considerably, from how they come "in the box"..(.035)
When I was on the stock ignition I used BP5ES and never had fouling issues. .024" gap. With the electromotive I use the 7's. Birdman
I had to go to the hotter plugs with carbs as well, even with MSD. But once set up, no fouling problems at all.
Interesting -- I found the same .015" - .025" spec given in the 1977 NA version 308GT4 OM, but the 308GT4 euro version OM 91/74 gives .020" - .025": Image Unavailable, Please Login Although, per the same specs, Lee SHOULD be cleaning them every 6 months
I'm using 5's in my 77 and had just changed them after 5 years. They still look good. I have Pertronix ign.
Glad you concur Steve, I only have the 1976, 1977 Owners Manuals, although I do have the earlier GT4 WSM, also.......
Good question -- What are you guys using with the Electromotive?? I think I've got BP6ES's in the car right now. Just wondering if that's the right plug with the Electromotive coils. And what gap?
I'll be interested too. Nick suggested a plug that is no longer available so I kept the BP6ES plugs. I used the gap that was suggested in the Electromotive instructions. (Can't remember what it is now...) JIM
This thread is going way off topic, but I had Crane ignition boxes on my carb 78 308GTS and ran BPR6ES at .034 gap. Ran great! It was gapped by a tech at .025 in error during a plug change and immediately had a high end miss. Changing the gap had it purring again. I would not worry with running NGK 5's if you are experiencing some fouling. Many I hear are using them sucessfully.
I had Crane ignition boxes on my GT4 as well with the BPR6ES..I don't recall the gap, but I did widen it.
BPR6ES's were sputtering in mine a bit, went to BP6ES and it ran awesome. Points cars can have trouble with resistor plugs. I too dropped to 5's, I think Tex hit the problem, our fuel sucks.
George good to see progress with your engine.Just a quick question,what fuel are you using, regular unleaded or premium?
Just a note on our spec miata w pro motor, Engine builder they told us not to run the nippendenso irridium due to porcelin flaking off & scoring cylinders, I ran the NGKs instead. FWIW
BP6ES. No fouling issues. I still use stock ignition except for Bosch 'red' coils which were a noticable upgrade and keeps a very stock look. They keep the plugs firing very well.
