Spark plugs (again)

[jeff jackson]

Hi Chaps,
Sorry to bring this up again, but the previous thread moved away from plugs to ignition and coils.
I wonder if I could bring this back to plugs please?
I have had my Plus 2 for nearly 15 years. In that time I have rebuilt everything bar the 5 speed gearbox (too scary, not broken so don't fix it). But for the life of me I can not get the bugger to run right.
Heres the story so far. After an engine rebuild, with new everything, I fitted an aldon ignitor ignition, The car would not start. Turns out that if you fit an Aldon ignitor with copper core cables the back emf blows up the electronics, so 75 quid down the drain. Switched to points, condenser and all was well. But the car was running rich, sooty plugs.
I have tried all sorts of plugs, Champions, Bosch and now NGK. I went for BPR7ES.
The car was running, but rich, and started ok. But since the winter layup, the car will not start without me removing the plugs, cleaning the soot off them, heating them up on the gas stove, and putting them back in. Strangely putting them in cold, doesnt work, they have to be warm.
I checked the compression (hot) and have 180 on all four cylinders.
I have D'ellorto's and they have been rebuilt, new needle valves, float height has been done, checked, and re-done till the cows come home. The carbs have been balanced using a manometer, and I have replaced the some of the jets to try and make the car run a bit leaner - according to the book on tuning your Webbers and D'ellortos. I do have a colourtune, used it, but makes cack all difference.
The thing is now that the car will not start from cold, (hot, is no problem), and still runs rich - plugs are always sooty.
So any ideas on this? Cos I am at a complete loss. Is it plugs? Fuel? My stainless exhaust system? I never had this problem with the first elan I had in the early 80's, also on D'ellortos.
Any advise gratefully received!!
Kind regards
Jeff 72+2

[kstrutt11]

Jeff,

Firstly how old is the petrol, the change from last year is probably because the fuel has gone off a bit, For starting and low speed, the mixture screws should adjust the mixture, if you can't get this correct it would indicate there is a problem with the jetting. Mind you mine are a bit black after idling and low speed running as well despite running and starting very well and delivering 40 odd to the gallon.

I use Escort Coswoth double platinum plugs in mine, since using these I have never had any problems with fouling.

Kevin

[jeff jackson]

Hi Kevin,
I did think that petrol was the problem, but I have had the car running, and a fresh tank of petrol is in it right now.
It's just that it refuses to start from cold, and when it does the plugs are always sooty, even after a long run.
What are the numbers of the Cosworth plugs you are using?
Kind regards
Jeff

[kstrutt11]

Jeff,

The plugs I have are motorcraft AGPR 12PP but I think there are other equivalents.

I have Dellorto's with the standard jets and a Lumentation ignition system with 12V Lucas sport coil.

other thoughts,

- Have you checked the igntion timing?
- Have you tried it with the two vacuum connections blanked off?
- Is the air cleaner blocked?
- Do you have a ballasted ignition system, if so is the 12V feed on cranking working?

Kevin

[terryp]

Jeff
I would fully commend the use of NGK BP6ES instead of BP7ES. I had exactly the same problem. Unless you are flooring the accelerator between every junction the plugs sort up with BP7ES

Bon Courage
Terry

[jeff jackson]

Hi Terry,
Do the NGK BP6ES plugs burn hotter? what are the differences between these numbers?

Kind regards
Jeff

[richardcox_lotus]

I too use NGK6's rather than 7's for every day use. They still soot occasionally (eg traffic holdups etc) but seem to be more tolerant of everyday conditions. For the price - ?15-?20 - I would see it as a no-brainer to try it.

Richard
'72 Sprint

[terryp]

Hi Terry,
Do the NGK BP6ES plugs burn hotter? what are the differences between these numbers?

Kind regards
Jeff

They do burn hotter. I suppose the answer is that ideally a twin cam would want BP"6.5"ES , if you search the forum there are posts by Rohan which basically say that for normal every day use BP6ES. For sustained motorway driving (probably not relevant in the UK anymore!!!!) BP7ES and for track use BP8ES

I have never used anything else, if you are nervous, try them and keep on removing the plugs to check whether there is any erosion (As the Haynes manual!!)

All the best

Terry

[jeff jackson]

Thanks Terry, I will order some 7's then.
Another question, what leads do you use? I am still using the old copper cored cables, that have been around since Elans were first made. Can you use the newer lead types, but still use the old 23D distributor? I ask because the cap is a screw in type.
Kind regards
Jeff

[terryp]

Thanks Terry, I will order some 7's then.
Another question, what leads do you use? I am still using the old copper cored cables, that have been around since Elans were first made. Can you use the newer lead types, but still use the old 23D distributor? I ask because the cap is a screw in type.
Kind regards
Jeff

666666666666's !!!!!!!

I have the later distributor the one where you can fit pull on leads rather that the one with the screw into the copper cored cable.
I have a feeling you can't but a phone call to Susan Miller will get you the answer

Terry

I would buy the plugs on eBay , you can get them really cheap!

[VDB 50K]

HI jeff,
I,m no expert on theses matters,but it would appear that it makes no difference to what type of plug is fitted for starting from cold.Are u sure the basics are correct for firing up ie.
petrol mix,spark,ignition timing.From what u say I would plum for ignition timing,remembering that u had Aldon's ignitor fitted,did u send the Dizzy to Aldon,or did u mod the Dizzy yourself.I say this becos' I also had fun and games with one of their recon's which in the end was found to be faulty,so check static ignition and that it advances the full 14 degrees ie from 12 to 26(at 2,500 revs).I use a snapon timing light with which u can set the 14 deg. advance on the gun at the correct revs(rev counter built in).
Also on your Dell's,have u checked the idling by-pass jets.Depending on the age of your carbs the later come with an idle bypass jet,usually found under a metallic seal.I don't know how far u went with the carb rebuild but these are a small adjustable screw jet which let in small ammounts of air for fine tuning at idle,not in any manuals I've come across.I found them by accident.U probably know about these as i see u used a manometer(essential) for balancing,but u never know.
When u are starting from cold have u checked,with a plug out ,that u at least have a good blue spark...most ignition related probs are in the Dizzy ie. loose cons,pitted points,cracked cap,condenser gone...although i would imagine these have all been checked.
Have'nt had a lot of experience with ballast type ignition systems but were'nt these designed to make starting easier by fitting a smaller voltage coil,as under starting conditions most of the current goes to the starter thus taking current away from the ignition system.Your ignition system thererfore must be in tip-top condition for it to work efficiently.it goes without saying that your Battery is also in good order.
Happy hunting...would'nt life be boring with Lotus...

[types26/36]

I doubt spark plugs are the route of your problems,I realize you have checked the carbs and replaced various things but as it is running rich I think the more likely cause of the non cold starting is that it is flooding when standing over time.
Try this, remove the spark plugs and leave overnight,the next morning spin the engine over a few times on the starter.....you could even hold some cardboard over the plug hole to catch petrol (or even water but that's something else) see if anything is blown onto the cardboard.
Fit the clean plugs without warming them....pump the accelerator twice then try to start.
This assuming the electrics and ign system is all OK.

[jeff jackson]

Hi All, Going out to the car now, have ordered some NGK BP6ES plugs anyway.
I will re-check ignition, floats all over again.
WRT to the air idle bypass, these are present on the later type D'ellortos, I think,stand to be corrected here, on the Elite/Eclat but not on Plus2.
Mine is a late 72, so I have the earlier type.

Thanks for all replies.

Kind regards
Jeff

[69S4]

I have tried all sorts of plugs, Champions, Bosch and now NGK. I went for BPR7ES.
The car was running, but rich, and started ok. But since the winter layup, the car will not start without me removing the plugs, cleaning the soot off them, heating them up on the gas stove, and putting them back in. Strangely putting them in cold, doesnt work, they have to be warm.

The thing is now that the car will not start from cold, (hot, is no problem), and still runs rich - plugs are always sooty.
So any ideas on this? Cos I am at a complete loss. Is it plugs? Fuel? My stainless exhaust system?

Jeff 72+2

I had a similar problem with my 70's Honda 400/4 (a motorcycle!) over the last couple of months. Just wouldn't start without preheating the plugs, was misfiring and the plugs were always black and wet. The answer was an Italian tune-up . 20 miles of thrashing it round the local roads a couple of weeks ago and it now starts on the button.

Back with the Elan, I've had the odd bit of in-the-garage misfiring with BPR7s. Changed to 6's and it's been fine, even with extended motorway running (although we're talking 70-75mph max).

[Craig Elliott]

As on other post on this subject BP6ES plugs seem to make a big difference - they certainly did when I had the same problems. I've also noticed that fuel additives make a difference - with some (in my case Castrol Valvemaster+) BP7ES plugs would soot up very quickly.

C