Good Afternoon,
I’m hoping you’ll be able to offer me some guidance with the poor running of my car.
The car is a 1974 Mini saloon; it was originally fitted with a 998 engine that has been swapped for a stock 1275cc from a 1989 Metro. 65d electronic ignition. The standard HiF44 carb is on a Mini Spares inlet manifold, with a K&N style air filter, the needle has been replaced with a BBW needle from Mini Spares, and I have an RC40 single box centre exit exhaust on an LCB manifold.
So essentially has a stage 1 kit.
The compression was checked prior to my “clutch issue” and shows good and consistent compression across all cylinders, I’m sorry, but I can’t remember what the figure was, but it didn’t cause concern.
Having taken the car out for a further shakedown run after sorting the clutch out, I noted that the car did not want to idle without choke, even when the car was warm.
But when the car was in motion, it would pick up and go relatively well, although not brilliantly, and I suspected that it was down on power, as I was expecting a little more pep from the 1275.
I checked the around the inlet manifold for vacuum leaks, by spraying some brake cleaner, but didn’t note any increase in the engine speed, so I didn’t think a vacuum leak was the cause.
A check with the timing gun showed that the timing was badly off, it looked to be in excess of 20 degrees BTDC at idle, I admittedly did not check the timing at full advance. The timing was reset to 11 degrees (Vacuum advance off @ 1000rpm) and the car seemed to happily start and idle without choke, and behaves very well at slow speeds (up to 30mph) but now has no power.
A further check of the plugs revealed that the mixture is very rich, the plugs are very sooty, which was also an issue I noted prior to resetting the timing, but put it down to having to use the choke at slow speed/idle while out and about. I’m trying to get my hands on an Colour Tune to try and lean the mixture out to a more acceptable level.
Also occasionally, following the retiming, the motor will backfire through the carb, although, I had trouble trying to get it to happen consistently, but it seemed to happen in 2nd or 3rd gear at about 20-30mph. I didn’t enjoy replicating the issue as it sounded like a shotgun going off.
What else could you suggest?
Could the rich mixture produce a lack of power above 20/30mph?
After checking/adjusting the mixture should I check/re-timing the ignition?
Any guidance you could share with me would be really appreciated!
Thanks,
Matt
