Spark plug shimming help

So iv been having this issue with my flathead 6, it rad good first time i fired it, and has ran like shit ever since. I was thinkin mabey the carbs were flooding out. Well, i yanked the plugs to see if they're wet, and i found that they all had a gap similar to a piece of paper, and you can see where the valves had been tapping on the ground strap. Not enough to close them completely, but any mechanical interference is bad. I put some copper washers on the bottoms of the plugs to raise it bout a 32nd of an inch, but i may have to go more. Motor is a 230 plymouth, plugs are champion H10s.

Any advice?

 

Wrong plugs (too much reach into the chamber)?

If the valve hits up solid it could kill your timing gear. Happened last year to one of the guys here.

 

See if you can get the same heat range plugs that are shorter inside the engine. Do the present plugs have a extended tip?? A jobber that's got something on the ball should be able to help you out on this.

 

You should use Autolite 4S-140 plugs maybe ???????????
http://www.secondchancegarage.com/public/436.cfm

 

Ok, so i searched Champion, and they say use a Rj12c, 14mm, 3/8 Reach, while the RH10c is a 14mm 7/16ths reach.

off to the autoparts store tomorrow.

 

No, the plugs go in over the valves. Its a rebuilt motor.

 

The autolite 4S-140 is also 14 mm 3/8 reach. Use what you can find.
http://www.oldengine.org/members/diesel/Plugs/equiv.htm

 

I also most instantly thought we used to run UJ12y and UJ14y champions in flat head 6's. Do not use a J12y as it Has an extended tip and will still cause problems.
Use this one http://www.gsparkplug.com/products/spark_plug/champion/uj12
Do not use this one http://www.gsparkplug.com/products/spark_plug/champion/j12y

 

Sorry I had to do some editing there because the first time I posted it the links would not work. Paul

 

Your are right my brain and fingers are not connected and I should have left the Y off.
UJ12 is the right one

 

So just a UJ12, and ill be good? Thanks for the help fellas

 

In case it is really a clearance issue and not a wrong plug issue:

http://www.jegs.com/i/Moroso/710/71900/10002/-1?CT=999

Typically for getting the ground side away from the flame, but they work just as well for spacers.