Thread: 2.25 petrol - an annoying miss

Buy good quality plugs such as NGK - Champion is rubbish.

Having used the Iridium plugs on my Disco, I now fit them to everything, despite the extra cost, because they will last for a very long time and out-perform the copper-cored ones,

Cheers Charlie

The plugs have been replaced with some (gapped) NGK iridium ones.. Yet the miss is still there. It may have been smooth for the first little while, but I am not sure. I have played with the dizzy timing to lessen the miss as much as possible, but will rip out the timing light tonight to see if I am in the right ball park.

Here are the plugs that came out, the two middle are quite blackened and pretty bad considering they were not very old at all. Is this a sign of running rich?



When it does miss, putting your hand over the exhaust gives you little droplets of fuel.

Can it be something to do with the extractors? Or carby?

Regarding compression, I always assumed my 2.25 was a 8:1, due to being right at the pointy end of the 2a production. (241 548 80A). CalVIN says this was used for both early 2a motors and early 3.

But what JDNSW says is making that a little murkier...

Here is the front-most part of the head,


The back,


and the middle.


The motor has been refurbed during my tenure, so even if it is a 7:1 head, it could be 8:1 anyway. Incorrect plugs wouldn't give it a miss like this though, would it?

Cheers everyone

Sam

Originally Posted by series3

My coil is either a GT40 or GT40r, i cannot remember which at the moment, about 3-4 years old. I'll check later tonight.

GT40. no R.

Sam

The boss with the CR on it is the extension of the seat for the headbolt in the picture showing the middle of the head.

The sparkplugs suggest to me two cylinders (which ones?) are fouling due to stuck rings or plugs are too cold. Alternatively, two cylinders too rich, the other two about right - suggesting a manifold leak affecting those cylinders, with the mixture set to compensate for this, resulting in being two rich for the other two, and resulting miss.

John