spark plug reading

[SRT_DSTRHOLC]

I read some where that when reading the spark plugs the top of the porclen is for idle/ low range and the middle is for mid range and the very bottom is for top end...if its blackish on the mid to high parts. What jets do I mess with.. the front 2 or the rear 2?

 

[scamp173124]

got pics of the plugs? (if possible) do you know what you have for jets now? Motor specs?

 

[SRT_DSTRHOLC]

specs are in another post...72in back 70 or 72 in front

 

[scamp173124]

go to 68s in the front ,also make sure you do not have any small vacum leaks

 

[Snake]

I agree with scamp, 68 is a good starting point up front and 72 rear.it takes a long time to read a fresh set of plugs.i like to see most of the isulator a tan colour an even burn.One day fro the hell of it i will post plug colour and jet changes in my SB.What size holley are you using now.anouther trick is to index your plugs so all tips are facing the same way in the head by means of washers.When you got a hot motor geting every inch of free power is were its at.now i am just going on lol.good luck.

 

[idrift]

try this.

 

[idrift]

Mike,

Unless your driving around with your secondaries open (vac carb right)
adjust your primaries. I'd say based on the tuning I did with a wideband on
my car, you need 68's in all 4 corners. Try a heavy spring (black) in the
secondaries and drive around not over 55 and then look at the plugs.
I doubt that powervalve is opening while cruising but you are welcome to
the 3.5 I have if you want it.