Joined: Jan 2021 Posts: 162 Threads: 71
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Location: California USA
Car type: 1929 austin 7 chummy AD
i just need you people to set some thing straight. Does the advance/retard lever do anything whilst running. i know that it is supposed to do something but my father seems to think that when fully on the accelerator he can move the lever and it should go faster but is only makes the motor run funny. is this all it is supposed to do. i know how it works and what it is supposed to do from my family having a 21 model T. but the seven is a completly different breed. please help.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
20-09-2021, 07:36 AM
(This post was last modified: 20-09-2021, 07:58 AM by Bob Culver.)
Some cars have acquired an auto distributor which also with manual can get confusing. Presume not the case.
I presume you have a stock non sport or racer.
Assuming the linkage is assembled so that it is fully effective, the range in crank degrees is very considerable (twice the angular movement of the distributor). Once started very little of range is used. The max advance should be set just as far advanced as necessary for max power at top revs used (maybe 4000 rpm for stock non sports). The optimum is easliy found with a manual advance by arranging for intial over advance (say 2 inches, 22 deg on flywheel) and resetting after experiment. Noise and exhaust note increases markedly with advance and must not be used to judge apparent power. When full throttle revs drop to 2000 or so 1/4 range retard on lever eases load on engine. A light spring may take lost motion out of linkage. Do not be in a hurry to go auto. Manual eliminates many vagaries. And on a Seven acceleratrion allows plenty of time to play with it!
To give some idea of how little range need be used the early Ruby auto distributor only had a range of 6 crank degrees.
When climbing short walls can retard further and avoid a change to 1st. Full manual retard is not necessary even for starting.
The Model T system is very quircky, non linear, and the spark delays and responses quite unlike any other. it is possible to select positons where the ignition effectively fails!
(More advance can assist economy at light throttle. Sevens are rarely driven that way and power is nowadays the overriding consideration. But avid enthusiats may set for max over advance and avoid except when on light throttle)
