tr4 CONFUSING IGNITION

[Willie]

Hi Folks,

Another question which I can't get my head around. My car as a late TR4 [July 1964] is displaying strange combustion. Twin CD175 Strombergs are fitted. Numbers 1 & 4 spark plugs look as if the mixture is leanish, whereas numbers 2 & 3 look as if the mixture is too rich! How can the front carb create lead cylinder lean and trailing [#2] cylinder rich, and the rear carb create lead [#3 cylinder] rich and trailing [#4] cylinder lean? To my amateurish eye, it just doesn't make sense!

 

Best wishes Willie

[Willie]

Sorry folks, I thought the first posting hadn't worked so I rewrote the question more concisely! Yours red-faced, Willie

[TorontoTim]

No problem - I'll hide the first one.

[RogerH]

Hi Willie,

if your inlet manifold is not tightened down fully or the gasket it leaking air then you could get your symptoms.

For instance if #1 has a leak and the carburettor adjusted to try to get a correct mixture then #2 (no leak) will go rich.

 

Roger

[Willie]

Thank you Roger. I am very relieved to hear it is not an expensive solution!

 

Best wishes Willie

[Willie]

Hi Roger,

Here is the layout on my car from the Moss catalogue. That emission valve was obviously a TR4A feature. Mine takes rocker breath straight through the air filters to the induction manifold. I'll check tightness of the manifold bolts.

 

Best wishes John