Plug gap on 308s

walawdog -- You're mixing up units and missing a "zero". People report bumping up the nominal 0.6~0.7 mm (.024"-.027") spark plug gap to .030"~.035". The 0.4 mm (.016") spark plug spec shown in the 308GT4 WSM was never really a good idea -- in the later 308 OMs they went to the 0.6~0.7 mm spec.

 

Those that go to .035" gap also have set there timing to 8-deg BTDC.

 

.040" is a little large for a conventional points-based inductive discharge set-up. What year/model/version 308 (your Profile is blank), and what spark plug construction technology are you using? (e.g., I wouldn't hassle regapping a standard set -- I'd just replace them with a NGK EVX set )

I don't know any specific resistance targets for the primary and secondary windings of the coil, but if you have two you can always make measurements of both to see if they're similar. The typical primary winding resistance would be very low, only 0.5~1~2 Ohms, and the typical secondary winding resistance something in the 10K Ohm ballpark. If you've just got the stock 308 points-based inductive discharge system, it isn't any special "exotica" so any "normal" or "hot for points" 12V coil should be OKish.

 

Steve,
What are EVX plugs and why are they good?

Birdman

 

The VX series (I shouldn't have included the "E" although that's in the PN for a 308 VX plug) are NGK's small-diameter (0.8mm) center electrode plug using Platinum for the electrodes -- very resistant to fouling compared to a "standard" 2mm center electrode plug (e.g., the NGK S series)

Usually pricey if bought thru a retail F service shop, but not too bad $-wise if sourced from www.clubplug.net (something like BPR6EVX would be a good choice for street use on a US-based carbed 308).

 

You can adjust it with the mixture screws. You can also change the jetting, but then you'll have to re-set the balance on the carbs AND adjust the mixture screws.

With out a AF meter to know what your Air-Fuel Ratio is (or a colortune) it's tough to get them exactly right.

Spitting and poping is generally a rich condition but could also occur if it's excessively lean.

Grey/White would indicate a lean condition. Try to turn each screw out about 1/2 turn and see if that helps.

 

I wouldn't want to change too much initially,...but after you get things figured out, you may wish to get larger main jets. The 78/79 cars run VERY lean with 125 mains. I had my 78 308GTS on the dyno...and after several runs, slowly upping the size, the tech settled on a 140 main. I think you could easily switch to a 135 without worrying.

 

If you're using a +12V source, you need to have some sort of reasonable load (like a small indicator lamp) in series with the points (i.e., +12V -to- one side of bulb -thru- the filament -to- other side of the bulb -to- the "+" post of points -thru- the point contacts -to- the dist body -to- ground); otherwise, the current is huge and things go "poof" (you were hooking +12V directlty to ground when the points closed).

If you're using a multi-meter in "resistance" mode, then you can just hook the "+" lead up directly to the dist "+" post and the "-" lead to the distributor body (i.e., the meter uses a low voltage and limits the current itself).

Are you dealing with an R1 point only set-up or do you still have the complete R1/R2 stock US version set-up?

 

Hi there
Does anyone use these plugs? are they any good? I am currently running BP8ES NGK plugs and they foul easily, especially if sitting in traffic for some time.

Regards
Nick

 

Unless you're doing very high speeds under heavy load regularly, I think you could go to the "6" heat range without risk (many US user have reported good results with "6", or even "5", to minimize fouling).

"8" is an ice cube

 

Does this mean running an 8 for everyday use is wrong?

Cheers
Nick

 

If "everyday" means driving in a rational way that won't land you in jail in the US, yes, 8 is probably too cold

I think some of the early US 308 documentation might have even specified an NGK "8", but in the later years even they wiggled it up to "7" (and most here run 6 or 5 in the BP type for 2-valves).

 

OK now I know what type plugs you guys recomend for carb 308.
But what do you guys recomend for an 84 308 QV?

 

i use 7's and track the car as much as possible. You could go 6 if you drive in the winter snow

 

bump so i can find thread....

 

The best spark plug today is Denso Iridium. These plugs cannot be gapped. www.sparkplugs.com