Removing Spark Plug washers

[Dave Damouth]

I run them with the washer. I checked the depth on the threads before assembly, and these housings could run them without. I wouldn't run them without the washer unless you had the engine open and verified the depth of the thread.

Side fire. The plugs are the exact same length as the stock plugs, when modified. Prior to modification, they're a bunch longer. They won't fit unmodified. Unless you want a new motor, don't try. Really. Imagine a 50 thou gap and another 70 thou of ground strap trying to fill that 30 thou opening. Plus, even if it looks like it might fit, remember that metal tends to grow and move around at high temps...

Non Resistor NGK racing plugs, if I remember correct. Might want to check the NGK catalog if resistor is a big deal to you, I'm kinda fuzzy on why the part # starts with "R".

[BrianB]

Dave,
I got an old housing to measure . It's a 2gen 13B. The plug washers are typically .080 thick. A stock plug,less washer, doesn't bottom on the thread,but has about .050+/- to spare. The stock plug threaded in tight without the washer, leaves about .050 clearance to the trochoidal surface at the closest point. I believe that the stock plug or the modified side fire can be run safely without the washer, without bottoming on the threads(provide the side fire is threaded like the stock plug). Losing the washer moves the plug approx. .080 closer to the mix.
Seeing is believing ,so check out a housing with an old plug.
The trochoidal surface moves away from the plug end. It's closest at the leading edge, and about .020 further away at the trailing side of the plug hole. Indexing the plug in the housing with the ground to the trailing side of the plug hole offers an additional margin of clearance.
So take that washer off,and let me know how you make out

[BrianB]

Non Resistor plugs can throw off some "electronic noise" that can mess with the on board computer.With a stock BUR9EQ plug the R signifies a resistor plug.
Brian

[Dave Damouth]

No problem running them modified, just don't go for unmodified. And don't assume that all housings ever built were threaded to the exact same depth. Even Toyota couldn't pull that off....

Computer? Us 1st gen guys don't need no stinking computer. We're just one generation removed from the hand crank....

Allen, you mentioned compresion=hp, I think it was paul yaw that said it dosnt apply to rotarys, is that right Dave?