22-05-2023, 11:55 AM
(This post was last modified: 22-05-2023, 11:56 AM by David Stepney.)
I am sure that my Seven, whilst lying idle in the garage, which, as some of you may know, is not ofter, thinks up new and improved ways of making mischief.
For a week or so, although the car seemed to be running well, I noticed a slight decrease in performance coupled with the occasional backfire on deceleration. The engine was running sweetly - almost too sweetly, so, yesterday evening, I thought that I would give it a bit of a tune up.
The pints gap was correct, the timing was right and the carb seemed not to need much attention, with good pickup and a nice even tickover. As part of the operation, I checked the tappet clearances to find that they had closed up almost to nothing.
Now I am a bit fussy about tappet clearances, preferring them to be a touch on the generous side rather than the other way about. So I reset them to my accustomed setting of 4 thou inlet and 6 thou exhaust and a short test drive showed an immediate improvement. The car almost felt lively (if one cans use such an expression about an RP saloon in standard trim).
All the locking nuts were tight when I came to them but the adjusters themselves all required turning back several flats to get the required gaps. I should perhaps record that my car, for some reason now lost in the mists of time,is fitted with the later 'pin type' valve spring retainers rather than collets.
I must also admit that I haven't looked at the tappets since I last had the engine apart to fit new pistons, which is now some while ago, as the job with the engine in the car and the manifold in place is not the easiest of jobs.
The question is this: Has anyone else had experience of this phenomenon? If so, is there a solution, or should I be checking the tappet clearances more often?
For a week or so, although the car seemed to be running well, I noticed a slight decrease in performance coupled with the occasional backfire on deceleration. The engine was running sweetly - almost too sweetly, so, yesterday evening, I thought that I would give it a bit of a tune up.
The pints gap was correct, the timing was right and the carb seemed not to need much attention, with good pickup and a nice even tickover. As part of the operation, I checked the tappet clearances to find that they had closed up almost to nothing.
Now I am a bit fussy about tappet clearances, preferring them to be a touch on the generous side rather than the other way about. So I reset them to my accustomed setting of 4 thou inlet and 6 thou exhaust and a short test drive showed an immediate improvement. The car almost felt lively (if one cans use such an expression about an RP saloon in standard trim).
All the locking nuts were tight when I came to them but the adjusters themselves all required turning back several flats to get the required gaps. I should perhaps record that my car, for some reason now lost in the mists of time,is fitted with the later 'pin type' valve spring retainers rather than collets.
I must also admit that I haven't looked at the tappets since I last had the engine apart to fit new pistons, which is now some while ago, as the job with the engine in the car and the manifold in place is not the easiest of jobs.
The question is this: Has anyone else had experience of this phenomenon? If so, is there a solution, or should I be checking the tappet clearances more often?