The angle of the fuel pump lever has to match the camshaft lobe.
Camshafts had different lobes over the years.
You may have a different cam in your engine than was stock.
I have a 1962 235 which was rebuild at some point before I got it.
If I use the correct 58-62 fuel pump it gives me just enough fuel for all driving conditions, but doesn't always keep the glass filter bowl filled, mounted just before the carbs.
If I use a 55 fuel pump, the fuel gushes out if the glass bowl is not tight enough, it pumps so much.
But be careful, you can break a fuel pump with too much lever angle against the lobe.
Also only buy new fuel pumps - never remanufactured or NOS !!
And watch out - Vendors don't always sell the right one for the correct year.
It's 2006 now and people don't know (or care) about the subtle difference in fuel pumps over the years.
They always think everything goes and works with the old inlines anyway.
