bosch platinum plug ?

chromedog · Jul 19, 2007

has anyone here ran the bosch platinums in a sbf? the reason i ask, i just did a cam change, and switched in a set... the car is now hard to start, sounds like it is idling on six cylinders, gets rotten milage, and is basically a pig. my ignition is: duraspark II, msd blaster tfi coil, moroso blue max wires. i feel the only weak link is the plugs. ive heard some bad things about the bosch, mostly in chevys, and not until i had installed a set!

ratio411 · Jul 20, 2007

They are touchy in my experience.
I haven't figured it out though.
When they run, they run good.
However, I have used them in an engine and couldn't get them right,
until I took them out...

So, yes I have used them with great sucess on SBFs, and with terrible sucess on others.
I have heard in the past that some ignition components don't like them.
Maybe it was coils are sensitive to them, I don't recall exactly.
What are they gapped at?

67coupestang · Jul 20, 2007

i ran them in my explorer 5.0 for about 10,000 miles, then they crapped out, so i put in autolite platinums, 30k and strong

HistoricMustang · Jul 20, 2007

Been using them for years with no issues.

HistoricMustang

65fastbackresto · Jul 20, 2007

Just a thought....

I have a very limited understanding of this issue, but this came to mind.

Platinum is a better electric conductor then a normal plug, correct?

If thats true, then the spark is not only stronger, but hotter, changing the heat range of the plug maybe......

chromedog · Jul 20, 2007

they seemed to run good, until i let them gas foul, now they seem tempermental. ive also ran them in a 4.0 explorer, 30,000 plus miles with no problems.

ratio411 · Jul 20, 2007

67coupestang said:
i ran them in my explorer 5.0 for about 10,000 miles, then they crapped out, so i put in autolite platinums, 30k and strong

Just a tid-bit of knowledge I picked up from tinkering with a late model GM...

Bosch is the only platinum plug that uses a pure platinum electrode.

The issue is that the others, (AC Delco problems is where I picked this up)
use only a platinum tip that is installed on the end of a standard electrode.
Usually, depending on manufacturer, they are a disc of platinum brazed to the electrode, ground strap, or one disc on each.

To the point:
The discs are KNOWN to fall off the tip of the plugs under "spirited" driving conditions. Leaving the plugs in a state of being non-platinum anymore, AND gapped slightly wider.
I am sure most know that when GM went to platinum tips, they listed spark plug change intervals at 100k miles.
Folks with "spirited" driving styles were burning plugs out in just a few k miles.
Anyway, they found the discs fall off after about 5k rpm... if not the first trip that high, soon after.

Point being that for folks that rev their engines, platinum tips are NOT the way to go. Bosch is the only one that won't come apart.
Either them or stick with standard plugs.

FWIW
Dave

ratio411 · Jul 20, 2007

65fastbackresto said:
I have a very limited understanding of this issue, but this came to mind.

Platinum is a better electric conductor then a normal plug, correct?

If thats true, then the spark is not only stronger, but hotter, changing the heat range of the plug maybe......

Not a better conductor so much as they don't wear when conducting.
Regular plugs wear out every so often and need to be changed.
The sharp edges get round and the gap gets wider.
With platinum, the process of wearing out is much slower.
That is why new cars have spark plug change intervals of 100k miles instead of 8-10k miles. They have platinum wear surfaces and stay sharp/gapped for much longer than without platinum. At least until, as I just posted, a driver gets frisky with the throttle.
Dave

RFMustangGT · Jul 20, 2007

I had them in my 95 5.0 and it ran like crap. pulled them out after 1500 miles and put in a set of autolite and it runs great.

rbohm · Jul 20, 2007

i have used a variety of plugs in my engines, and i have found that the good old autolites are the best in my opinion. bosch makes a good plug, but they are not any better than any of the others.

bnickel · Jul 21, 2007

i had a set of bosch platinum plus 4 plugs in my jeep that worked awesome, i've also run the regular platinum plug in the mustang when it was all stock and didn't have a single problem with them but they aren't so great in the non stock engine that is in the car now but the engine isn't even broken in yet either so the rings are still trying to seat

69gmachine · Jul 21, 2007

I've been told by a friend who is an ASE mechanic that the platinum plugs are very sensitive to running rich, and will gas foul pretty easy. They usually work great in EFI applications, but carburetors generally aren't nearly as precise over the whole RPM range and usually run rich somewhere either idling or transitioning at part throttle. I switched to Autolites and never looked back. No problems. At the time I was running a Duraspark ignition, which is rock solid reliable.

pazur · Jul 22, 2007

avoid these. why?

Man, just yesterday I put them on my gf's vw jetta 3 because trying to improve rough starting. Brand new platinums make starting much more rough compared to regular old bosch non-platinum plugs. And these were very old, because these cars have stupid engines that whole intake has to be removed to get to spark plugs. I bet noone ever replaced these plugs because of this. The old plugs had tips cracked, redish, but still worked much better than new platinums. After installing them, engine started right away but only for the first time. Then check engine light went on, after some 5 minutes engine start running rough (what never happened before, just starting it was rough) and stalled eventually. Since then it takes to rev it like 10 times, although check light disappeared. Never again.

StangDreamin' · Jul 22, 2007

Almost the same story as most of the posters here. Put them in my '91 Silverado with 20,000 on the odometer. Switched to Autolite platinums with 30,000 on the clock. Bought another set of Autolite platinums at 141,000; traded in the 15-yr-old truck (168,000 miles) before I could shange them again.

Seems like they should be one of the best plugs, with that solid platinum tip. Appearances sure are deceiving.

headgrinder · Jul 24, 2007

oe plugs best

I had a parts store for 18 years and I found that the oe plugs worked best for each application. Gm use ac ford use motorcraft toyota nippon denso german cars bosch
and so on.

You see gm makes 75- 100 Plug style/heat ranges for gm cars and bosch fits all gm cars with 20-30 styles /heat ranges(they make many more) the oe makes the specific plug that the car maker wants and they tend to work better in most situations. This is especialy true in late model computer controled cars.
I am not saying that they won't work but you have a better chance with oe brand.

bosch platinum plug ?

chromedog

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