help reading plugs....

[61ragtop]

I have a 383ci sbc and have gone from 9.7:1 to 10.2:1 compression by changing from the old style AFR heads to the new eliminators milled down from 75 to 72cc. I have NGK BKR6E plugs now but the instruction manual recommends BCPR5EY.

Will the small bump from 9.7-10.2 need a change in heat range?

thoughts on A/F ratio or any other info you can read off these would be great.......

Here are some pics that i hope are good enough for you to read. Some are not that good but I think some turned out better.

They are all in fours each pic is either the even cyl's or odds. the odds are the ones with the two corroded ones. They are #3 and 5. Ignore those obviously as they were caused by my porous head weeping coolant.

They go from the right to left as 2,4,6,8 on the better ones and 1,3,5,7 on the pics with the corrosion......

[Vegas69]

I've always read that heat range is determined by the ground strap. A change in color around half strap indicates the right heat range. Your plugs make it tough to determine but I'm guessing they are to hot. Here is an article I found.
http://www.angelfire.com/fl4/pontiac...Readplugs.html

You could screw in a plug a couple heat ranges colder in a cylinder and see what happens.

I need to check mine! I did on my old engine and don't recall checking this one thoroughly.

[Shaker455]

Besides the water in one cylinder the plug look good to a tad lean.

I would jet up the primary 2 sizes from where you are now.

[61ragtop]

Originally Posted by Shaker455

Besides the water in one cylinder the plug look good to a tad lean.

I would jet up the primary 2 sizes from where you are now.

Thanks Shaker