Spark plug clearance

[Columbiacaterham]

Newbie question.  I have an early nineties 1700 crossflow. Plugs could stand replacement. B8EC S stock plugs aren’t readily available but I found a set of BPR7ES that some suggest are a good replacement option.  However when I lay them next to each other I noticed that the 7ECS plug tip extends farther than the 8ECS. (See photo). If I install these will I have a clearance problem?  Thanks.

[MV8]

Probably, but why risk it? B8ES  (2411) are available and a closer fit to what you have.

[Columbiacaterham]

Thanks. I will take a look at that plug. Part of the reason to consider the BPR7ES was to go a heat range hotter.  

[fastg]

BPR7ES is a resistor plug, that is what the R signifies. MV8 is right B7ES is a better choice.

 

Graham 

[IamScotticus]

The last plug my Sprint ran on was NGK BPR6ES.

 

The thing with engines, you never know what you have until you do some checks.

It's not too difficult.

 

Take the plugs out,

Put a long wood rod in one cylinder,

Hand turn the engine to establish top dead center,

Mark the rod at the hole shoulder,

Compare that with your spark plug length.

 

Then install one questionable length plug and hand turn.  If there is contact you will feel it or see it on the tip when removed.

 

I will admit, the Caterham spec spark plug for 1600 Sprint is not the same for 1700.  Interesting but makes sense as the pistons will have been changed out.

 

I think MV8 is on to something.