So it came as a surprise that my car has 12mm plugs. I thought all 914's had 14mm?
The PO was using NGK DP8EA-9. Looks like they have a pretty high heat rating at 8. The 14mm plugs most people seem to recommend, and that I used on my old 1.7 are the NGK BP6ES, which have a heat rating of 6.
Should I be looking for a similar rated plug for my current car? It's a 2270 with Mallory Unilite dizzy, MSD 6AL, and MSD Blaster 2 coil. Is there a better plug for my setup than the DP8EA-9?

Unless you've justified a different heat range, the DP8EA-9s will work fine. 12mm spark plugs are a common modification to try and keep the heads from cracking as easily. The plug itself is just one of the few 12mm plugs that fits/works.

I run them without issue, what issue are you having?

Ok thanks, good to know!

No issue, just curious if they were optimal for my setup.

Is this on your 2270cc?

Look at your plugs electrode, is it a nice tan/brown colour?
Then you are golden, stop overthinking things.

If the electrode is bright white then you have a big problem.
All dirty black, problem but not as bad.
...and both of the above could be timing and/or jetting and still not be plug related.

Yeah its for my 2270. Ironically I had planned to do a full tune up before whatever it is that happened to my engine happened. Just wanted to have new plugs on hand to install with my new cap, rotor, and wires for after I fix the issue. The brand new set of BP6ES that I had bought will go for sale in the classifieds.

I'll post about the old plug condition in the other thread I have going just to keep all the info together in one place.

I have a 2056 with 12mm plugs, Mallory Dizzy with an Igniter II conversion & low impedance .6 ohm Igniter coil.... Dellorto Carbs. The plugs I am running are NGK DR7EIX Irridium. The car seams to start easier cold and the idle stabilizes faster than with the copper plugs. Other people will tell you not to run anything but copper but in my opinion with a hotter ignition you might as well run a plug that doesn't constantly wear out.

Have you run the DP8EA-9's?
If so, how long did they typically last for you?

No...I was running NGK D7EA. I assume a 7 is colder than an 8 with a shorter insulator and electrode. They run a nice tan color at my altitude of around 2500'.

I read you other post regarding your Dellortos. I had a hard time getting mine set up initially. The guy in Italy on ebay sold me some rebuild kits and different jets & vents. Once I got them set up correctly they are extremely reliable.

Newer cars all run something besides copper and I just wanted something I could install and not have to mess with again. They work well for me.

I was under the impression that the higher the number, the colder the spark plug.

http://www.ngk.com.au/spark-plugs/technica...nge-explanation

Yeah, my dells were super reliable until last week. I hadn't tuned them since mid last summer and my head temps and AFR were still spot on. Although still not sure they were cause of the issue I'm having. They definitely seem to be 'set and forget' carbs.

NGK and Champion plugs are hotter with lower numbers - Bosch is hotter with higher numbers. For NGK a 5 is considered hot(ter), a 6 is medium and 7 is colder. Same for Champion.

I have a new set of B6ES out in the garage from before the heads were converted to 12mm. I am not sure why I ended up going with a colder plug. Before I put classic car insurance on it I used to have to pass emissions and the HC was always too high. It always runs between 275 and 300 degrees and the plugs are the right color so I think the plugs are close to the right heat range.

I have rounded up all of the parts to convert it back to injection. Never did it because it runs so good I am afraid of loosing performance and reliability.