19-09-2020, 01:40 PM
Your post suggests that whilst the car goes like the clappers when all four plugs are firing, there are times when one or more plugs aren't firing?
As discussed on here previously, the 36 head is prone to plug fouling partly due to the position of the plug. If there is any oil getting up the bores past the pistons it will cause problems.
I would try the car with the mixture a flat leaner to see if it improves matters. Look at the plugs again and if necessary go a further flat leaner.
If that doesn't work, try a grade hotter plug (B5HS?).
If that doesn't work consider fitting a Ricardo aluminium head.
As discussed on here previously, the 36 head is prone to plug fouling partly due to the position of the plug. If there is any oil getting up the bores past the pistons it will cause problems.
I would try the car with the mixture a flat leaner to see if it improves matters. Look at the plugs again and if necessary go a further flat leaner.
If that doesn't work, try a grade hotter plug (B5HS?).
If that doesn't work consider fitting a Ricardo aluminium head.