401 or 403 cam ?

[RALPH M]

New member here so hope I am doing this correctly. I now have a 1951 401, chassis 903 and an engine with a 403 head. It is a running car and I would like to get it running more smoothly but before I take it to my local garage with the rolling road I want to try and find out whether the motor was rebuilt with a 401 or 403 cam. I know for sure it is a 403 head. I understand the valve lift is the same on both so the only way I can think of is to try and measure the dwell angles. BUT.......with the engine in place! One idea is possibly to fix a temporary protractor to the pulley?.. then turn the motor and with a dial gauge on one of the rockers watch the point of lift. Perhaps I am crazy.

My reason is to be able to put the right jets in the carbs and rebuild the Lucas distributor with the correct springs before taking her for the tune up.


Any suggestions welcome.