Ignitioncarparts.co.uk seemed to have a compatible module for the Marelli S178 distributor fitted to my 1500...unfortunately, it wasn’t, it didn’t fit and after a number of emails to their support people I returned it for a refund and stuck with the original points.
Conventional points work well enough up to a, err.....point! But they require regular adjustment to keep the car in tune which is not easy on some designs and they don’t provide consistent timing operation especially higher up the rev range. They require a condenser (a high voltage capacitor) to stop them arcing in operation, arcing erodes and transfers material from one side of the points contact to the other; they end up with a hole on one contact and a lump on the other making adjustment with a feeler gauge impossible so the contacts need filing down or replacing....it gets to be a bit of a faff.
The heel of the points wears down over time closing the point gap taking the engine out of tune and the transition of the points from closed to open varies slightly each time.
Electronic points replacement units are a solid state switch, a sensor is placed where the old points would be in the distributor and a trigger piece is slid over the central distributor shaft. There’s no physical switch or moving parts. The Dwell angle (a measure of the points gap) is inbuilt to the sensor/trigger and remains consistent at all speeds giving a much more accurate spark and greater reliability. The car remains in tune much longer.
BART runs a Marelli S135 distributor so I decided to give ignitioncarparts.co.uk another go and ordered a unit. This time the unit fitted, although, not without some tweaks.
The distributor is buried at the back of the engine close to the bulkhead on the drivers side. Fiat had obviously thought about this and provided an access panel in the engine bulkhead. The spare wheel needs to be removed from behind the drivers seat and 4x 10mm securing nuts holding the panel in place.
The instructions call for the condenser to be removed and as access was still tight I elected to remove the distributor to make the job easier, noting the position of the distributor and the central cam...this was just as well as fitting required a bit of thought. The first issue was the wires where too short to reach the coil, the coil didn’t have any spade terminals and the hole to be used for the exit wires in the distributor was too small!
I removed the condenser and the low tension (LT) wire and connection assembly to the points, then I made up some extension wires to reach the coil and enlarged the hole in the distributor where the LT assembly was as the spade connectors would not pass through. Bullet connectors would be better here.
With the points removed I trial fitted the sensor and found the mounting screws where too short, so I sourced a longer M4x10mm screw and lock washer. The sensor should have shipped with some heat sink compound but it didn’t, luckily I have a tube and smeared some on the bottom of the sensor mounting plate. With the sensor mounted and the wires routed through the enlarged hole I pushed on the trigger ring over the central cam. It was a tight fit and required some force to go on, I checked for a 1mm clearance between the trigger ring and sensor and remounted the distributor on the engine.
I connected up the extension wires I’d made earlier and fitted some spade connectors to the coil. It was then just a case of connecting the red wire to the positive coil terminal and the black to the negative. To my absolute astonishment BART started first time!
I warmed BART up a bit and attached my strobe light to check the timing, it was retarded way too much, I’m surprised it ran, rotating the distributor soon had it purring set to 5 deg BTDC at an idle of 900RPM.
Test drive to BlackBoots scheduled for tomorrow!
No comments:
Post a Comment