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Question - Why Not Platinum Plugs ???

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PAUL161

PAUL161

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Reading an article by John Twist in the North American Journal, MGB Driver, a very knowledgeable person on MGs, John gave the proper spark plug make and number for a 74B, (Champion RN9YC, SET AT 0.035)for the MG engine. But in the same article he said, Do Not use Platinum plugs!! Does anyone know why he would say this? I've used platinum plugs for years in my trucks and never had a problem. I could write him, but I thought someone on the forum might know. Nothing Major, just curious. /ubbthreads/images/graemlins/confused.gif PJ
 
I've no idea why he would recommend against Platinums. I've been using them in my '76 B for the past 2 years without any problems that I can attribute directly to the plugs themself.

So, I too would like to hear the reasoning behind not using Platinums on a B...
 
For some reason I'm unsure of, the Plat's seem to foul in my B and Champ's go on forever... The Alfa is JUST the OPPOSITE!!! Go figger.

Plenty of pro's seem to have a problem with the Plats. "introduced miss" is one way a guy described 'em to me. I've had generally good performance from 'em, other than as noted above with MY MGB. I've wound 'em into about everything I've worked on.
 
Among the Mini owners I correspond with there are similar comments about the Pt plugs. From what I remember they had comments about them not firing well at high speed... but I'm too old to trust my memory. If I find their old correspondence I'll summarize it and post it here in a subsequent reply.

At the recommendation of an Austin America friend of mine, I'm currently running Bosch W7DTC plugs. These were commonly installed in water cooled VWs where high life between changes was the goal. So far, so good. One caveat about these plugs though... they are easily oil fouled in high-mileage LBCs.

EDIT:
From another board...
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As I understand it, the +4 are an improvement over the standard platinums, but I have no experience with them.

You are correct that the folks that seem to run platinums most successfully have very hot ignitions. A SuperCoil is a VERY hot ignition.

The other thing we found, though, is that even in cases like yours (where platinums were being successfully run) swapping to a set of cheap 99 cent Bosch Supers never degraded performance and often improved it over the pricely platinum plugs.

I concur that you want a good strong ignition, but once you get past a really good quality set of silicone wires and good solid plugs (agree with Todd that the DTC are hard to beat), claims of "exotic" ignition parts begin to sound like snake oil to me...
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To summarize what I found on the thread above and other similar posts, there are expensive racing grade platinums that offer good performance but those for street engine only offer benefits when used with hot ignitions... at least according to my acquaintance.
 
hmmm... I've seen 'em in "oil burners" and when pulled they look like they should have stopped working LONG before, but no miss was exhibited. Very odd. I've always considered 'em to be a plug what would fire "in the bottom of a bucket of excretia" frankly.
 
DR, the W7DTCs I'm talking about aren't Pt plugs but they aren't too traditional either. They have a traditional center electrode but use three ground terminals surrounding the center electrode. This isn't a snake oil approach to a hotter spark, its just to provide more area for wear/erosion. The problem with them is, the W7DTCs have lots of area to collect and trap carbon. I love the plugs... they gave me a great incentive to rebuild my oil burner.
 
so, basically it boils down to the typical iginition setups on some (or most?) of our LBCs just doesn't have the power to consistantly push a good spark through them at all engine RPMS?

I'm running a Crane XR700 electronic iggy with IR trip in the dizzy, and an Accel coil on my '76 B. Maybe I'll play around with some of these less expensive plugs sometime to see if there's any difference in how the car runs over longer than normal drives....
 
I've always had single platinums in my car. They burn at the perfect color with my CDI ignition, Lucas Super coil, and being gapped at .040 thousandths.
 
[ QUOTE ]
DR, the W7DTCs I'm talking about aren't Pt plugs but they aren't too traditional either.

[/ QUOTE ]

I know the W7DTC's ain't plats, the multi 'trode arrangement is another animal. I've only thought about trying 'em in the Alfa, mebbe I'll wind a set inna B on the evidence of your post... I've had equally good luck with Bosch "standard" W7D plugs in the Alfas. They seem to go for a bit longer in the B (than the plats) as well.

My conclusion is: It's ALL VOODOO!!! /ubbthreads/images/graemlins/jester.gif
 
.040 thousandths?!?!

...interesting. /ubbthreads/images/graemlins/grin.gif
 
I was running .040" on my Plats for a good long while. Only recently reduced the gap to .032"

ermmmm... of course, I see the "interesting" part in .040 thousandths now... /ubbthreads/images/graemlins/smirk.gif
 
I wanna see how to SET that gap. "Worker bees" mebbe?
 
electron microscope?
 
I run standard Bosch Platinums in all my cars... Gotta get some for the 'yota before I put her back together. They've worked well in the B for the past 2-3 years, and the Talon seems to run fine with 'em. I was told NOT to use them in the Alfa, but if'n yours works fine with them Doc, I'll probably run them in that too.
 
I run Bosch platinum in a GM V6 turbo on instruction from the kit provider and have never had any problems. They said they'd had regular plugs have the tips blown off them, so I didn't bother trying to confirm that......
 
Well, with all the input on this subject, it seems to me that it might have something to do with the amount of juice going to the plug. Point ignition verses electronic. Stock coil verses super coil. As you say Doc, your B works better with the Champs and the rest works better with the Plats. Does your B have point ignition? This whole thing is very interesting! /ubbthreads/images/graemlins/driving.gif PJ
 
Simply put it takes considerably more voltage to fire a platinum plug. A stock point and condenser system just will not do it.

Alan T
 
My B runs fine with Platinums and points.
 
Well I just don't get it...A customer had me install a set in a 1972 MGB and the car did not get out of the gate.
Alan T
 
[ QUOTE ]
Simply put it takes considerably more voltage to fire a platinum plug. A stock point and condenser system just will not do it.

Alan T

[/ QUOTE ]

Could this be from the standard gap-- right out of the box?

Most recommendations for Platinum plugs come from manufacturers that use high energy ignition systems. Gaps should be .045 to .060 for them. Regular ignition system gaps are in the .025 to .035 range. It shouldn't take any more voltage to fire a Pt plug than a regular plug if they have the same gap. In fact, it may be even a bit less because the tip is much smaller.
 
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