I have a 400 SBC in my '57 3200 with the type of distributor with the mech. advance just under the round screwed on rotor. What is the secret for presetting the points gap? I can't even see when the cam bump is set on the points and sure as heck can't get a feeler gauge in there to measure. Before the points where changed, the dist hold down loosed up so the timing is off too. So it's not something I can fudge the gap, get it running and then use a dwell meter. Or at least I think that's the case. Thanks in advance for any help.