Iridium spark plugs.

#1
Will i gain any advantage by fitting this type of plug in my 1949 Rover P3/75 sedan, would they burn a bit hotter and eliminate this soot deposit that i am encountering at the moment. i have NGK BP5ES in the vehicle now and the car runs ok but they soot up rather quickly . so i regularly remove and clean, put them back in and away we go for a while. i have checked the mixture and the timing and all seems to be ok. any advise would be greatly appreciated. best degards Derrick.Smith.
 

PeterZRH

Well-Known Member
#2
I'd say without a higher powered electronic ignition you'll gain nothing at all. Not even a longer service life which these plugs usually give if they soot up all the time.
 

quattro

Administrator
Staff member
#3
I use them in my Kwakker and they do seem to make it run smoother, but then it revs to 10,000rpm. I'm not convinced they would help with sooting up, have you checker your air filter?
 
#4
Iridium will help but i think your issue is the plugs you are using are too cold; I'd try a hotter plug first, maybe go up two numbers. Those plugs you have are quite cheap, so you work your way up without too much expense or fit increments of one in each cylinder and see which one runs best...Iridium's are expensive but they last forever and the gap voltage will be lower to fire them so you will get a better spark but you would want to have the heat range right before you buy them. I'd also check your leads and make sure they are not burned out. They have a limited life.
M
 
#6
I use them in my Kwakker and they do seem to make it run smoother, but then it revs to 10,000rpm. I'm not convinced they would help with sooting up, have you checker your air filter?
Thanks for your reply, i have not checked the air filter or silencer as they call it. the filter is still the original big brute of a thing. Derrick
 
#7
Iridium will help but i think your issue is the plugs you are using are too cold; I'd try a hotter plug first, maybe go up two numbers. Those plugs you have are quite cheap, so you work your way up without too much expense or fit increments of one in each cylinder and see which one runs best...Iridium's are expensive but they last forever and the gap voltage will be lower to fire them so you will get a better spark but you would want to have the heat range right before you buy them. I'd also check your leads and make sure they are not burned out. They have a limited life.
M
Thanks for the information, would a hotter range plug make the engine run any hotter. no i have not checked the leads as they are still the ordinary wire ones, are they prone to breaking down the same as the newer carbon type. Derrick.
 

colnerov

Well-Known Member
#8
Hi, The heat range of plugs is about dissipating the heat of the centre electrode into the body of the plug not about the heat the engine runs at, other factors affect that. A hotter plug will burn off deposits on the electrodes better.

Copper wire plug leads usually have resistor plug caps, Carbon leads have a resistance factor to them and so don't need resistor caps. You shouldn't mix the two up as it can affect the spark and the running of the engine.

Colin
 
#10
Hi, The heat range of plugs is about dissipating the heat of the centre electrode into the body of the plug not about the heat the engine runs at, other factors affect that. A hotter plug will burn off deposits on the electrodes better.

Copper wire plug leads usually have resistor plug caps, Carbon leads have a resistance factor to them and so don't need resistor caps. You shouldn't mix the two up as it can affect the spark and the running of the engine.

Colin
Thanks again for all your help, i think i might have found the problem. i checked every component in the ignition system and bingo a little condenser 200 miles old and made in Italy . i fitted the old spare condenser that i carried, this one was made in England. i have now been for a test run of about 100 miles and no miss, pulled the plugs out and checked and no soot. i hope this is the long term cure. regards Derrick.Smith.
 
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