spark plug gap
 

Maybe a stupid question, but I'm kinda stuck in the middle of changing my spark plugs

I've a '73T and the old spark plugs are Bosch W3DPO. They've a gap of 5-6 mm (as in the specifications for a '73 911).
I want to change to Bosch Super plus WR5DC+. They're preset to 8mm.
Should I change the gap on the new spark plugs to 5-6mm or does it depend upon the design/brand of the spark plug wich gap they should be set too (and can I leave them at 8mm)?
Thanks in advance
Johan

bump, sux being in the middle of somthing with no answers

This quote below is from another discussion on this board about gaps, different plugs etc. This is how I've always viewed plugs too. Also, if you look in your manual, it won't say anything about brands, just gap for your car.

"AFAIK, the gap is determined more by the type of ignition you have and not the brand. The electricity doesn't now what brands are. The manufacturer of the plug is assuming you have stock ignition when they recommend a gap for a particular application. So, if you have the right heat range, etc., I'd open the gap. Apparently, there is not enough spark intensity with the smaller gap to do the job. That's the best I can offer."


If you search on the Technical forum using these words:
spark plug gap

you will find a lot of threads on the topic.

Hope that helps.

-Chris

There was a recent thread on gapping plugs and someone suggested that different brand plugs (even different ranges within the brand) might take a different gap. I don't buy it, but I'm far from an expert. My personal opinon is to gap the plugs according to the ignition source that you have. So, I'd go with 6mm.

LOL!

That discussion that I referenced and that quote I pasted are from Milt (zeke)

:)

-Chris

Was that pre-10k or post 10k??

Johan,

As you are probably aware ... W3DP0 weren't the correct plugs for your engine! The gap was not adjustable, either!

Conventional copper spark plugs with adjustable ground electrodes usually get 0.7 mm - 0.8 mm gaps, and some people use even wider gaps. The 0.8 mm gap sounds just fine to me.

Thanks for the answers.

Khamul, thanks for the 'bump'