BP5E or BP5ES and gaps

[Andrew S]

Hi All,

Been a while since I fitted new plugs but instead have just cleaned them. The time I feel has come as when under good acceleration, get to about 3000 revs and there is a slight hesitance or misfire so could be plugs or leads.

A few months back I fitted a Flamethrower coil, the 40kv oil filed type to match my pertronix electronic ignition so running now on 12v direct feed. This leads me onto my next question, when fitting new plugs, would I be better off opening the plug gaps to say 35thou to get a better spark?

Finally, heard that there could be the same symptoms as I am having with the BP5ES's compared to the BP5E plugs

Any experience and advice appreciated

Thanks

[DJT]

FWIW, I am running with BP5ES set at 35 thou as recommended by Martin at DD. Pertronix ignition with 1.5 ohm oil-filled Flamethrower with 12v direct feed.

[Andrew S]

Interesting, thanks Dave. 35thou it is then and interested to know if that gives a better performance

[jbuckl]

Here’s a previous mention of this

https://socforum.com/forum/forum/stag-owners-club/soc-forum/14708-ngk-v-champion

[flying farmer]

I have to go the opposite direction with my high performance engines and close the plug gaps to 25 thou or the spark blows out at high rpm. Any weakness in the coil or leads will be highlighted by big plug gaps.

A weak mixture needs a good strong spark to ignite it, a richer mixture will ignite more easily.

[Andrew S]

Here’s a previous mention of this

https://socforum.com/forum/forum/sta...ngk-v-champion

Thanks

[Andrew S]

I have to go the opposite direction with my high performance engines and close the plug gaps to 25 thou or the spark blows out at high rpm. Any weakness in the coil or leads will be highlighted by big plug gaps.

A weak mixture needs a good strong spark to ignite it, a richer mixture will ignite more easily.

Thanks

[DJT]

Aware that it was 5 years and over 16,000 miles since I fitted the BP5ES plugs, and reading the views that BP5E plugs are better, I did some price comparisons online and picked up 8 BP5E plugs at my local GSF Car Parts for GBP26.11. Set to 35 thou, the big test will be the 250-mile drive to Liverpool on Monday.

[wilf]

I have used BP5ES plugs for ages - just recently completed a 850 mile round trip to France and back on a fresh set with no issues at all.

[jbuckl]

Worked on a stag tonight that had poor cold starting issues.

1. checked cold compression values as the engine was original never rebuilt. All acceptable for cold 115-145.
2. Checked fuel delivery as issue became apparent after the fuel pump was replaced. 0.66 litre per 30 seconds….ok.
3. Checked inertia switch contacts (slightly oxidised) electronic ignition supply was from inertia switch (dislike that)
4. Car reluctant to start still when cold.
5. Noticed ballast bypass wire from starter was de activated. (Folded over and taped up at coil)
6. Measured ballast bypass wire voltage from starter was zero anyway! (No time to investigate)
7. About to fit a new substitute (viper) low ohm coil.
8. Then noticed existing coil fitted had pink ballast wire on -ve coil terminal!
9. Removed coil, turned around 180 degrees in bracket, swapped spades over, refitted. Noticed coil was marked 6v underneath anyway. (No-name coil…. Measured 1.4 ohms)
10. Cold start checked….. much better, even sans ballast bypass power from starter supply.

Relevance finally:- car was fitted with new NGK bp5es plugs.

seemed fine.

caution:- coil was incorrectly fitted / bodged by a renowned and prolific specialist …. Some time ago

[DJT]

I have used BP5ES plugs for ages - just recently completed a 850 mile round trip to France and back on a fresh set with no issues at all.

I've not had any issues with the BP5ES plugs. Just time to replace and thought I would try the 'better' ones. The old ones will be in the boot - just in case

[MikeParker]

If you get misfires at full throttle, but then it fires correctly as you ease off the throttle, then that is a sign of gaps too wide. That's because more mixture in the cylinder needs more volts to form the spark. So big gaps will show up any insulation breakdown problems in the leads, coil or distributor. It can improve mpg and allow a slightly weaker mixture because the bigger spark will zap more mixture, so start the fire a bit quicker.

[AndyM2]

Worked on a stag tonight that had poor cold starting issues.

1. checked cold compression values as the engine was original never rebuilt. All acceptable for cold 115-145.
2. Checked fuel delivery as issue became apparent after the fuel pump was replaced. 0.66 litre per 30 seconds….ok.
3. Checked inertia switch contacts (slightly oxidised) electronic ignition supply was from inertia switch (dislike that)
4. Car reluctant to start still when cold.
5. Noticed ballast bypass wire from starter was de activated. (Folded over and taped up at coil)
6. Measured ballast bypass wire voltage from starter was zero anyway! (No time to investigate)
7. About to fit a new substitute (viper) low ohm coil.
8. Then noticed existing coil fitted had pink ballast wire on -ve coil terminal!
9. Removed coil, turned around 180 degrees in bracket, swapped spades over, refitted. Noticed coil was marked 6v underneath anyway. (No-name coil…. Measured 1.4 ohms)
10. Cold start checked….. much better, even sans ballast bypass power from starter supply.

Relevance finally:- car was fitted with new NGK bp5es plugs.

seemed fine.

caution:- coil was incorrectly fitted / bodged by a renowned and prolific specialist …. Some time ago

I thought a variation in compression of up to 10% was OK.
Perhaps repeat with hot engine.
The bypass wire is often bypassed if it fails and or if a 12v coil is fitted or a electronic ignition system requiring a 12v coil.