Modern petrol and starting problems

[marc500]

My 1960 on zeniths is a pig to start if left for a while, say more than a couple of days, starts ok otherwise. Always has been. I do need to go through all the earths to make it turnover as quickly as it can. I use basic unleaded. Might try the posher stuff. Sometimes I tip some fuel down the carb tops to reduce the amount of time it takes to get it going.

Also when it does fire up it runs rough as if only from one carb (nearside has the shortest run to the fuel pump) and then goes full beans after 5-10 secs which might be the offside carb taking longer to fill up as it is further from the fuel pump???

[Ashley James]

Sounds like mine. As an earlier post explained, the problem is made worse by the pump plunger diaphragms drying out, or if you leave the car for long enough with a nearly empty tank, the fuel pump takes for ever to prime. However, because it’s an idiosyncratic car, it’s also not above syphoning fuel from a full tank and filling combustion chambers if the float needles don’t seal.

[roy mawbey]

Ah the slow turnover when starting. Yes go through every earth even the battery box earth. Undo that bolt and see if you find surface rust on the washer etc. Then when you have done the transmission earth too and all the wires to the starter solinoid then take on board that after every wire, including ignition switch contacts, the bell housing bushing for the starter shaft as well as, perfect battery it should turn over fast hot or cold!

But.. I did all that more than once, even checked the starter motor brushes BUT NOT the solinoid copper contacts hidden in the small box where the wiring connects to. My late 356 A possibly like your B has a rectangular top to the box if still original factory that is soldered in place. I had no idea there were 3 contacts inside that box. The guy who checked my starter motor who knows 356 starter's well did know! he removed that 40mm square cap cleaned the terrible condition contact points and re-installed using nuts and bolts! The moment I first started the car was pure joy !! Old or cold perfect ever since!!!
Rob at Broadway Electrics in Essex was the man who did that for me!!

Be more than careful tipping fuel in the venturi's to start the car. Guys in the States have produced an in-line plunger to depress and push some fuel through to the bowls. I still prefer the correct action of the accelerator internal pumps in the Zenith carbs. They really do squirt well through the brass nozzles. Their cylinders also normally hold the fuel well and do not evaporate.

My local garage has just moved supplier to ESSO. I just have bought £30-00 worth of Synergy supreme 99 unleaded but Ethanol free petrol! £1.99 a litre a lot more but for my minimal milage worth it. Sure it would run on 95 octane fine but it will mean less cranking and maybe it will continue being available from late this year when 10% ethanol comes in?

Roy

[Ashley James]

I’ve fitted a high torque starter to mine which draws less current, so kinder to the battery and leaves more colts for the ignition system.