Post by aussieal on Aug 27, 2015 0:34:46 GMT
I thought I would share this experience as it may be of use to others.
I obtained and recommissioned my 1959 P5 Mk1 about 3 years ago.
From initial use it would "miss" at about 50mph or when under load eg when climbing hills.
The following is the sequence of activity:
1. Are the plugs fouling (all new as part of recommissioning)?, No
2. Is the vacuum advance on the distributor playing up? Stripped the distributor and thoroughly lubricated. There was no sign of parts seizing and the situation did not improve.
3. Car is fitted with an aftermarket electronic fuel pump. It was observed that fuel was dripping from the carburettor. The pump was providing 7psi pressure, and the SU carb requires 4psi. Perhaps the motor is "choking" due to too much fuel forced through carb. Installed a pressure regulator set to 4 psi. no improvement.
4. Participated in the 2013 Bay to Birwood which involved a considerable climb through the Adelaide Hills. The car stuttered all the way to the top, then ran fine on the level and downhill slopes.
5. Had the carburettor rebuilt: no improvement
6. Removed fuel tank and thoroughly cleaned: no improvement (I have installed an aftermarket in line fuel filter)
7. Took the family on a 60km run. 6 people up and it stuttered like mad.
8. Took the car out of shed a week later. Brakes had disappeared and there was a great cloud of blue smoke from the exhaust. Diagnosis: the brake booster rubbers had failed, and brake fluid was being sucked into the inlet manifold resulting in the blue smoke. I drained about half a litre of brake fluid from the vacuum reservoir. Got the booster reconditioned, and all is fine now.
Moral, if your car is stuttering under load, start at step 8 and work back!