Spark plugs and ignition

Spark plugs and ignition

Postby RobHomewood » Sat Mar 11, 2017 10:59 am

Last December having reviewed what others have suggested about spark plugs for my P2 ('47 16 engine) I changed my Lodge CB14 plugs for NGK B6ES plugs which many seemed to favour. However after very little mileage I found that 3 of the 6 were not operating. Following a carburettor replacement the engine was stumbling and not picking up on the throttle etc and I found that I could remove spark plugs 2, 4 or 6 without the engine noticing! I then swapped No 2 plug to No 3 cylinder and that transferred the problem as well. So 3 duff plugs I reckon. I put 3 Lodge plugs back in and that allowed the engine to run properly. Has anyone else had similar problems with these NGK plugs? I am not sure what gap they should be set at but in the absence of any other information I used 15 -18 thou as in the original handbook.
Secondly there are suggestions that with modern fuels and plugs the ignition should be advanced. I have mine set at the manual listed position of 11 deg BTDC and the octane selector doesn't seem to make much difference - at least at idle- so what additional advance should I be looking at?
Grateful for any suggestions Rob
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Re: Spark plugs and ignition

Postby luli » Sat Mar 11, 2017 12:52 pm

I am using Champion's N5c successfully. For initial fire advance setting (idle) I am using a vacuum gauge. For high revs you need to verify that your distributor is in a good condition. You can read on it and watch a little movie here: http://wp.me/pXLKy-2cK that shows how to get the actual advance curve and compare it to what it should be. A 'look alike' electronic distributor can be a successful substitute. see here : http://wp.me/pXLKy-2ht
Rover 10 1946 RHD
Rover 10 1947 LHD
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Re: Spark plugs and ignition

Postby RobHomewood » Tue Jun 06, 2017 3:38 pm

More on the spark plugs for my 1947 Rover 16 engine. After the failure of several of the new plugs the supplier Green Spark Plugs sent a new set of NGK B6ES plugs but also told me that there is a problem becasue modern spark plugs are not glazed on the end of the centre electrocde insulation and if this gets 'contaminated' say by flooding the carb it shorts out and remains duff.
Well I fitted the new set of plugs following the installation advice carefully ie warm the engine up first before installing the new plugs and dont flood it. They were OK at first but after about 150 miles over the following 6 weeks, in the middle of a trip out the engine started misfiring and runnning lumpy. Foolishly I did not at first consider it possible that the new plugs could be the cause and checked everything else out (new dist cap, condenser, clean fuel filters etc). When I did clean the plugs and refit them the problem was still there. I then put in the old Lodge CB14 plugs and problem had gone away. Now, I know that my engine seems to run rich -even with the replacement carburaettor) so it seems I cannot ever use modern plugs.
Unless anyone can tell me of any suitable modern plugs which are fully glazed?
Secondly the advice on the multi electrode plugs like the Lodge CB14 is not to try to adjust the gap but accept them straight out of the box. However mine vary quite a lot - even on the same plug. Can anyone tell me what the correct gap would be? My average seems to be about 26 thou but I have seen advice for a Lanchester using this plug at 30 thou.
Any answers gratefully received as always
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Re: Spark plugs and ignition

Postby 47p2 » Tue Jun 06, 2017 10:54 pm

My 16SS was fitted with NGK-B6ES and tended to run a little lumpy, I was advised to fit NGK-B5ES (25thou gap) as they are a hotter plug and I never had any problems after they were fitted. I have 3 Lodge CB14 plugs for sale, they are still in the original boxes, one box still sealed, second box opened by me to have a look fitted to the engine but never started and third box opened, plug fitted to car but never started. For some reason I seem to have misplaced the seal and top nut from the third plug... :roll:

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Here is an old advert from Lodge regarding plug gaps, I'm not sure of the date but 18thou is recommended

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EDIT According to the RSR manual the plug gaps as below

All models if using old coil:- 0.015" - 0.018"... If using modern or oil coil 0.025"
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Re: Spark plugs and ignition

Postby RobHomewood » Wed Jun 07, 2017 11:35 am

Thanks for that information and I would certainly like to buy your Lodge CB14 plugs. Please email your price to EDITED email address removed to prevent spam
I do have a modern coil so tha gap should be about right at 26 thou. As I said I found it difficult to alter the gaps - is there or was there a special tool available for these multi electrode plugs?
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Re: Spark plugs and ignition

Postby 47p2 » Wed Jun 07, 2017 4:14 pm

Sent you an email Rob
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