Are You Using Bosch Spark Plugs?
 

And if so, what engine do you have and what plug are you using?

RE: Are You Using Bosch Spark Plugs?
 

I've been using Bosch Platinum plugs in my 87 Vette conv't now for over 14 years without any problems whatsoever. My engine is a partial Lingenfelter 350 with over 195,000 kms, and I have many mods on the engine and it runs like new. I inspect the plugs before I put it away for the Winter, and I change these plugs every 25,000 kms whether they need replacements, or not. A lot of people don't like the Bosch platinums, but they've been excellent for my Vette. :)

mypetu39

RE: Are You Using Bosch Spark Plugs?
 

I use the Delco Iridium plugs on my 86.

RE: Are You Using Bosch Spark Plugs?
 

I have the Bosch 4208 Platinums in my Cast Iron L98 - so far, so good.

RE: Are You Using Bosch Spark Plugs?
 

I am using 4205's (Aluminum heads) and they seem to be great. Left them gapped as-is out of the package, although I cannot remember what that is/was now.

RE: Are You Using Bosch Spark Plugs?
 

Ooh...not good. The gap 'out of the package' is about .045 - .050 - which is way out of spec. You should have gapped them to .035 mate.

RE: Are You Using Bosch Spark Plugs?
 

According to my GM service manual(s) ($120 via the Internet - thank you) the gap for a VIN P (LT1 motor) should be .050. The AC/Delco's that came out were gapped at .045 ~ .047. The only reason I replaced them with all new ones was because I broke an insulator trying to check the suckers.

The VIN J is specified as .035.

CG

RE: Are You Using Bosch Spark Plugs?
 

Silly me - I was assuming you had the L98.