Hi, Looking to replace plugs and have seen these two in past threads, etc. NGK BPR7EIX...Per John Corbini NGK BPR8EIX...per NGK website for 308 ( Dino not listed) Any current wisdom appreciated. Car has stock ignition. Thanks, Skipp
Image Unavailable, Please Login Image Unavailable, Please Login # 5 cylinder is down and here’s the fouled plug and current type
I also use NGK BPR7EIX Iridium Plugs with stock points and Winterburn CD box. I’ve been really happy with them. Freeman
Thanks Freeman. Hope you’re doing well. I’ll try those too. Should be getting Winterburn box this Fall.
I ran NGK BP6ET first 4000 km after engine overhaul with no issues what so ever. It is a cheap conventional plug and it ran fine on both stock ignition and the new MSD upgrade I installed last year. Just changed to the more expensive NGK Iridium plug BPR7EIX and have driven 500 km with no issues. Hard to feel any difference between cheap and expensive and no significant difference in cold/warm starting either. My preliminary conclusion is "save the money on the plugs and use them on ignition and carburetor maintenance"....- Best Peter
Thanks Peter. I ordered the iridium plugs already. What’s really outrageous is the $70 gap feeler gauges I also ordered based on amazon reviews of the cheap Chinese versions not being accurate. Can’t believe the accurate ones cost that much ! Anyway, hope to have the car running tip top again soon. What would the likely cause of one fouled spark plug be ? Skipp
If you have a fouled plug that is so fouled it causes a misfire there must be something wrong somewhere. A CD ignition should not have any problems with that (dinoplex/winterburn/MSD). Especially strange with such a hot BP6ES heatrange plug. If your CD ignition system is functioning properly a standard BP6/7/8 plug should do fine and i doubt it will benefit from the iridium ones.
Have always used NGK BP 7ES, the EIX plugs are a waste of money and very much doubt you would ever notice the difference. Fouled plug could me a lot of things or simply just an incorrect carb setting. Tony
Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Thanks again guys. This car got little use for the past 15 years and the plugs were 15 years old. I’m going to put the new plugs in and see how it goes. Inspecting the distributor and carbs, etc. is on my list. As you know it’s a process....the rest of the plugs looked like this:
Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login I successfully changed the plugs today. Unfortunately it didn’t make a difference. When pulling the leads off #5 and maybe #6 there isn’t any affect. 1,2,3,4 clearly drop out when the leads are pulled. There’s plenty of spark based on all the shocks I received! When revving the engine up to around 4K rpm, things seem smooth. Not rough at all. My mechanic thinks it’s time for a compression test. Car has 30k well documented miles and no record of any head work. 1,500 miles driven in the past 15 years. 500 of them by me in the past year.
Have you checked and cleaned out the caburators including the idle jets...The idle jets covers the first 3000 to 4000 rpm and any obstruction here will typically make the car run bad at rpm's less than 3000 to 4000. Best Peter
The first 4 plugs look fine, the last two (which I guess are no 5&6) look fouled or running rich. If oil (slimy soot) fouling then you may need to look a little deeper, if wet (petrol based) then as Peter has said you may just need to clean the idle jets and reset the air mixture screws to get it to fire properly. The 246 is temperamental in this area. The BP6 is a little to hot for the 246 imo Revving the car to 4K brings in the main jets and or accelerator pump circuit and that tends to mask idle circuit issues especially revving the car. Make sure the accelerator circuit is not dripping fuel down the diffuser at idle as this can cause flooding and a over rich situation. Check you get a good spark from 5 & 6 leads via a spare spark plug ground to earth. Dirty contacts on the distributor / rotor arm? Make sure the carbs are in synch (airflow) and the idle is set to around 900 rpm, any higher readings in airflow means the butterfly throttle plates are open too far and this will bring in the first stage of the progression port which will give you a rich condition.
Thanks very much Peter & Tony. I’m in the middle of a 355 engine out, so it will be a little while before I tackle the Dino. Ive been reading old threads where you guys helped an Australian Dino owner with similar issues. I’ll corrrspond what I find in the near future. I have not done any carb or ignition tuning on the car since I purchased her last year so that could be where the problem lies. We will see. Thanks Skipp
Do you guys have a link to diagrams showing the different parts to the carburetors and what to look for in trouble shooting my situation? I know very little in this area. Skipp
Can I add to this - first stage of the progression port which will give you a rich condition & render the mixture screw inoperative. ie it doesn't respond to turning in or out. Make sure the throttle linkages are good as well, ie no slack in the heim joints This shows a good exploded view. https://www.carbparts.eu/exploded_view/WEBER_40_DCNF
Also check for a "leak" in the spark wires. What I do is put the timing light on every spark wire. Aim the light at the timing marks. You won't always see the timing marks, but you'll be able to tell if the cylinder is firing erratically. If it is, replace the spark wire. If it isn't, go on to other things.
Would it hurt anything to pull the #5 plug wire off with revs above 3,000 to see if the cylinder is firing at higher rpms ? Would that point to a idle jet issue ?
No, I wouldn't do that as it will not prove much and you will get a nasty shock if you do. If you have a healthy spark at tickover and no signs of tracking to earth (faulty leads) then I don't foresee any reason why it will not work at higher RPM. Don't discount new parts being good, some of the items sold today are basically rubbish. The only advice I can give is to work in a methodical way. Test the ignition, timing, distributor cap (tracking to earth) etc etc and then move onto the carbs. Some of these issues are carb related but we tend to blame the carbs when in fact its a poorly set up ignition system. If you are running points system then the dizzy really does need to be set up perfectly. From what I can see 1-4 are fine as the plugs show a good brown colour indicating good combustion. I would say your carb set up is a tad out of sync and you need to blow out the idle jets with compressed air, reset the airflow so they are equal over all 6 chokes and then adjust the idle mixture screws. Did 5 & 6 fire ok when you put in the new plugs? Does it pop or spit back through the exhaust or carb chokes?
Thanks again Peter & Tony. 5 & 6 did not fire properly at least at idle after putting in new plugs. That’s the whole issue. I hink it’s the idle jets which I believe controls things below 3,000 rpm. The car has always required me pumping the throttle up to 3,000 prior to letting out the clutch from a stationary position. That stands to reason that I’ve possibly never had the idle jets working. Above 3,000 rpm the car appears to rev smoothly, which is when the main jets take over. I’m going to remove the leads from plugs #5 & 6 and see what happens above 3,000 rpm. If it’s not smooth once I remove 5 & 6, I think that would say 5 & 6 are working once the MAIN JETS take over when the leads ARE attached properly.
