Race Engine Forum UK

Hi Guy,

Blur deleted! It does seem odd that a Lucas ignition unit would be used with what is presumably a Magnetti Marelli distributor (or maybe it's just the cap that's MM).

Anyway, it seems to work fairly well, and I think the backfiring may have been down to the Facet electric pump not fuelling it at the correct rate; I have returned it to the standard Fiat mechanical pump and all seems well again...

Amend to the above:

Tonight, I took it for a quick blat along a dual carriageway and it gets to a certain point in the rev range (I have no tachometer, so I can't be more specific) then almost dies, hitting a massive flat spot, then backfires a little, clears its throat then off at full pelt again!

The other day, it wouldn't start, and I had to get the local garage mechanic to spray some brake/clutch cleaner down the carb to get it up and running - since then, it's started OK and runs pretty well.

I'm guessing this is carb related, as I've heard of others having noticeable flat spots on Fiat twin cams running the standard Weber. Something to do with the second choke kicking in, perhaps too abruptly causing momentary flooding.

Does anyone have any further ideas on this, or tips to cure it?