Looking for spark plug recommendations

356 Porsche-related discussions and questions.
Message
Author
User avatar
Eric Wills
356 Fan
Posts: 120
Joined: Thu Mar 27, 2008 10:54 am
Location: Fairfax, VA
Contact:

Re: Looking for spark plug recommendations

#16 Post by Eric Wills » Tue Sep 04, 2018 7:04 pm

NGK. BP6HS in any engine that has the clearance. B6HS on the others that do not. Sometimes a 7 heat range depending on the engine build.
Attachments
NGK356plugs.jpg
Eric Wills

User avatar
Jim Liberty
356 Registry Member
Posts: 2502
Joined: Tue May 06, 2008 3:47 pm
Location: Orange Co., CA

Re: Looking for spark plug recommendations

#17 Post by Jim Liberty » Tue Sep 04, 2018 8:11 pm

I'm using 4111 NGKs in all my 356s. Good results in many cars, over many years. ………………..Jim.
Jim Liberty

User avatar
C J Murray
356 Fan
Posts: 7263
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA

Re: Looking for spark plug recommendations

#18 Post by C J Murray » Tue Sep 04, 2018 8:57 pm

NGK has 2 numbering systems for each part. 4111 is a BP5HS which is on the hot side. I would use a 6 on most street cars, 7 on modified engines or for very aggressive driving. The 5 is for gentlemen with very reserved and socially responsible driving characteristics, like Jim.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car - Finally Finished!
'63 GS 2133 coupe
'64 Elva Courier mk4T
'67 911 S Original Owner

Martin Benade
356 Fan
Posts: 3585
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: Looking for spark plug recommendations

#19 Post by Martin Benade » Tue Sep 04, 2018 10:02 pm

But we like Jim anyway.

User avatar
David Jones
356 Fan
Posts: 3413
Joined: Tue Mar 25, 2008 6:32 pm
Tag: I wish I knew as much as I think I know.
Location: Harrodsburg, Kentucky

Re: Looking for spark plug recommendations

#20 Post by David Jones » Tue Sep 04, 2018 10:25 pm

I need a BP4HS for my sedate driving style.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

User avatar
Ron LaDow
356 Fan
Posts: 6205
Joined: Wed Mar 26, 2008 11:45 am
Location: San Francisco

Re: Looking for spark plug recommendations

#21 Post by Ron LaDow » Wed Sep 05, 2018 1:12 am

Eric Wills wrote:NGK. BP6HS in any engine that has the clearance. B6HS on the others that do not. Sometimes a 7 heat range depending on the engine build.
Years ago, the "P" plugs seemed to avoid fouling better than the non-"P" plugs under the claim that the projected tip got 'dusted off' by the turbulence in the chamber. But that was long enough ago when we still got lead in the gas and I didn't bother overmuch with the quench clearance, so they worked.
While it could also be better QC on the plugs, a fouled plug has been pretty rare over the last, say 20 years in my experience. Tightening up the quench and using the non-"P" plugs hasn't delivered a fouled plug in a LONG time.
Ron LaDow
www.precisionmatters.biz

User avatar
Dave Wildrick
356 Fan
Posts: 1759
Joined: Wed Mar 26, 2008 2:10 pm
Location: Houston, TX

Re: Looking for spark plug recommendations

#22 Post by Dave Wildrick » Wed Sep 05, 2018 11:10 am

Eric Wills wrote:NGK. BP6HS in any engine that has the clearance. B6HS on the others that do not. Sometimes a 7 heat range depending on the engine build.
Ditto. Have used NGK BP6HS in both of my C coupes for over 15 years.
Dave Wildrick
Houston, TX
#10230
64C coupe
65C coupe

User avatar
Jim Liberty
356 Registry Member
Posts: 2502
Joined: Tue May 06, 2008 3:47 pm
Location: Orange Co., CA

Re: Looking for spark plug recommendations

#23 Post by Jim Liberty » Wed Sep 05, 2018 2:09 pm

Chuck Young, my partner in crime builds all the motors here. About 30 per year. I use Carrillo rods, and Shasta Pistons and cyls. We balance and measure everything. He always says, why do you bother Jim, your cars only see 3500 RPM.

Cliff is right. ..Jim.
Jim Liberty

User avatar
Jim Liberty
356 Registry Member
Posts: 2502
Joined: Tue May 06, 2008 3:47 pm
Location: Orange Co., CA

Re: Looking for spark plug recommendations

#24 Post by Jim Liberty » Wed Sep 05, 2018 2:12 pm

Cliff, is the vent in question facing the right direction. On my sons AC, I had it 180 degrees wrong, and it spit oil until I turned it around. ……………….Jim.
Jim Liberty

User avatar
C J Murray
356 Fan
Posts: 7263
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA

Re: Looking for spark plug recommendations

#25 Post by C J Murray » Wed Sep 05, 2018 4:39 pm

Hi Jim, I think you are right about the vent.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car - Finally Finished!
'63 GS 2133 coupe
'64 Elva Courier mk4T
'67 911 S Original Owner

User avatar
DonCichocki
356 Fan
Posts: 360
Joined: Thu Aug 22, 2013 4:29 pm
Location: Lafayette, NJ

Re: Looking for spark plug recommendations

#26 Post by DonCichocki » Thu Sep 06, 2018 9:09 am

Like Eric said, be careful with projected nose plugs. Those marks on the piston crown are from the ground tang of projected nose plugs.
Attachments
DSCF0197.JPG

User avatar
Leo Dreisilker
356 Fan
Posts: 80
Joined: Fri Jan 07, 2011 11:02 am
Location: Wheaton, Illinois
Contact:

Re: Looking for spark plug recommendations

#27 Post by Leo Dreisilker » Sat Sep 08, 2018 10:19 pm

My engine had Denso W20PP's in it for 21,000 miles(oops, forgot to replace them earlier) and had no issues even after three long trips. Just installed NGK's. Will replace on regular basis in future.
 

User avatar
Ron LaDow
356 Fan
Posts: 6205
Joined: Wed Mar 26, 2008 11:45 am
Location: San Francisco

Re: Looking for spark plug recommendations

#28 Post by Ron LaDow » Mon Sep 10, 2018 12:35 am

Leo Dreisilker wrote:My engine had Denso W20PP's in it for 21,000 miles(oops, forgot to replace them earlier) and had no issues even after three long trips. Just installed NGK's. Will replace on regular basis in future.
My comment earlier suggests there is no reason for "P" (projected tip) plugs since lead was removed from gasoline; I'd say most any plug is pretty 'durable' now. I don't know if this is the direct result of the lead or some combustion by-products, but fouled plugs have become pretty rare.
Not sure what a "regular basis" is but you might wait until you find some issue. And if you are getting 21K miles from you current choice, well, I might change to those.
Aside:
Several years back (maybe more), I got the minutes from a Benz tech session where some questioned the recommendation of changing the plugs at 75,000 miles (that's from memory, but it was a really big number. I really think, from memory, it was 100K miles)
The only gripe concerned the build-up of deposits on the exposed threads, making removal difficult. No one suggested the plugs wouldn't do the job. And I'd also bet if you stuck with the recommended plugs, there would be no 'exposed threads' in your Benz.
Ron LaDow
www.precisionmatters.biz

Martin Benade
356 Fan
Posts: 3585
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: Looking for spark plug recommendations

#29 Post by Martin Benade » Mon Sep 10, 2018 12:54 am

It's not the same, but it seems like modern cars are typically still running perfectly on original plugs at 140 K miles. If it ran well, I wouldn't feel bad at still having my 356 plugs in at 21 K miles.

User avatar
C J Murray
356 Fan
Posts: 7263
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA

Re: Looking for spark plug recommendations

#30 Post by C J Murray » Mon Sep 10, 2018 7:13 am

Around 15 years ago I bought a new Ford F250 with a V8. That engine had a very odd spark plug whose end looked like the St. Louis Arch. It was projected to put the spark kernel well into the chamber and I guess the arch allowed the spark to jump to the easiest to attain point. The plugs were not meant to be changed much but when you did you often had an expensive problem because they froze in place and long breaker bars and WD-40 had to be used. Unfortunately that doesn't always end well and the plug snaps in two. Then you had to make an attempt with a fancy Easy-Out and that didn't always work. Final step, remove the cylinder heads. Owners of these engines don't change plugs and pray for no plug failures.

Ron, although extended tip plugs do run cleaner they also have the benefit of placing the spark kernel deeper into the chamber and that results in a better flame front and more complete combustion in cases where there is room for them. On the other hand, if you remove "normal" tip plugs from an engine DO NOT install extended tip plugs unless you are 100% certain that there is room for them. A strong hit to a plug can break off ceramic chunks that are extremely hard and will score the hell out of your cylinders.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car - Finally Finished!
'63 GS 2133 coupe
'64 Elva Courier mk4T
'67 911 S Original Owner

Post Reply