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Spark Plug Issue

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steveg said:
Andrea,
Can you tell us why you machined off some of the threads?
Click to expand...
Hi John and Steve
I have used on my car one of the first BJ8 HEAD - this have one fall in the production-- SPARKS are recessed inside the HEAD--
I have find the solution of the LONG NOSE sparks LFR5B or LFR6 BUT my mechanic prefer machining part of threads, to avoid any difficult at the sparks change,
(the head was on side, and we haven't any possibility to control if if some treads protrude on the combustion room)probably this is my situation inside the head https://picasaweb.google.com/112770819864514987162/AHWORKSAndUPGRADEProject#6148861222216088434
https://picasaweb.google.com/112770819864514987162/AHWORKSAndUPGRADEProject#6148860632929613026

Carbs have APPARENTLY the same regulation, BUT as my oldest mechanic (have the same age of me)said --SU regulation are so unpredictable,that it will change at the first street block turn
where you work to tray to lean the FRONT CARB apparently engine are well- minimum +/- 800rpm with NO hesitation

ONE OTHER LITTLE lack that haven't any connection wit carbs-
I haven't any possibility to START the car with the clutch depressed - clutch foot must be on the floor-gearbox must be in neutral position, and car start immediately
I have read somewhere the diagnosis of this lack, but never remember the cause and remedy ??
 
I've run the car now for 3 months with 4 @ BP6 and 2 @ BP5:
plugs010216.jpg
 
Hi Steve
Th Sparks appear to be good, you probably find the better solution for your engine- what are your driving impressions?
I can follow your solution for my 3 front cylinder-but I am unsure, actually my engine go very well -(with 100 Optane fuel)
 
Looks a bit rich on the three sooty plugs. Go carefully through setting up carbs after having made sure timing is exactly right. Could be needle valves in float chambers or jet needles. Measure distance between top of jet and bridge.

35-38 thou on older cars and about 75 thou on BJ8
 
EV2239 said:
Looks a bit rich on the three sooty plugs. Go carefully through setting up carbs after having made sure timing is exactly right. Could be needle valves in float chambers or jet needles. Measure distance between top of jet and bridge.

35-38 thou on older cars and about 75 thou on BJ8
Click to expand...

My engine is a bit tired. Had oil fouling on 2 & 3 so that's why I went to the hotter 5 plug. In Calif we run 7-8 pct ethanol in the gas which seems to run leaner; my HD8 jets are .095" down. I've worked my way down from .081" but had to go that far to get rid of backfiring on downhill.

PS - my neighbor (BN7) runs his HD6s at .055" down.
 
FWIW NGK recommend B5ES for the Healey and if you used those they be paler. If a plug is a bit cold for the application, it will look black or rich. Same happens if ignition is retarded a little.

we've found the cars are actually weak on modern UK fuel which is 5% ethanol. Manufacturers set SUs at 35-38 thou down from new until they went metric, then 1mm.

HD8 2" were done on screw turns, but about 75 thou, not sure about HD6.
 
I've got a seventies NGK spark plug applications book that I've kept because it covers a lot of older cars. It recommends a 5 grade. I doubt it will matter which you use and I only mentioned it because yours looked black.

back in the seventies a Champion UN12Y would likely melt in 12 miles. Champion were a nightmare in British performance cars and bikes. They didn't have the heat range of NGKs.
 
I think a 5 would be better for a standard engine. I'm using a 6 in my high compression, 215bhp motor and the plug colour is excellent. When I got the car it had 7's installed but they are too cold and were always oiling up.
 
DerekJ said:
I think a 5 would be better for a standard engine. I'm using a 6 in my high compression, 215bhp motor and the plug colour is excellent. When I got the car it had 7's installed but they are too cold and were always oiling up.
Click to expand...

In the spirit of experimentation, I'll probably go ahead and install the 5s this winter then keep an eye on them as it warms up for the summer. I've owned the car for 15 years and never had a problem with 6s until last year.
 
I've been using BP6ES NGKs for darn near four (<4) decades, along with a variety of 2.6, 2.9 and 3.0 litre engines and states of tunes; 2 & 3 SU carb setups (1-3/4" for the dual and 1-1/2" for the triples) with stock and BJ8 cams, and triple 45 DCOEs with a BJ8 and since 1986, with an Iskenderian T3 cam. Compression ratios were always stock, or the slight bump due to a .020" to .030" bore increase.

At one point, must've been around the mid-80s, I did back to back "tests" with both BP5ES & BP7ES plugs. I was living alongside a rural 2-lane highway, so doing plug-cuts and coasting into my driveway was a breeze (and I dearly wish I had that luxury today). The 6s were definitely the right choice, and I've settled on them ever since.
 
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