Timing on a 400
Cargo Master
Joined: Oct 2020
Posts: 2,703
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It would be interesting to take it to a track or a chassis dyno to get the wot spark advance figured out. It is possible to have way too much timing for best performance yet the engine not have any detonation. My best 2 barrel carburetor circle track engine makes the best torque and horsepower with 28 degrees of timing(locked out). Giving it more just reduces performance as does less. At under 12:1 compression with restricted induction with good gas it can't really go into detonation very easily especially at high RPM.
At part throttle (high manifold vacuum) I would experiment with more and more timing until you start to get a misfire and then back off a few degrees. What an engine can take will really vary a lot. Earlier this year I had a 408 Mopar small block on my dyno(very mild engine for a street rod pickup) and with mid 30's as best maximum timing for wide open throttle it would only tolerate about an additional 5 degrees from the vacuum advance before it would start to misfire. It had an adjustable can on the distributor so at first I took it all out and then just kept giving it a little bit more at a time under light load. This should help economy at part throttle.
Experimenting with this stuff takes time but having that distributor is a cool and it should make it pretty easy to get it dialed in.
At part throttle (high manifold vacuum) I would experiment with more and more timing until you start to get a misfire and then back off a few degrees. What an engine can take will really vary a lot. Earlier this year I had a 408 Mopar small block on my dyno(very mild engine for a street rod pickup) and with mid 30's as best maximum timing for wide open throttle it would only tolerate about an additional 5 degrees from the vacuum advance before it would start to misfire. It had an adjustable can on the distributor so at first I took it all out and then just kept giving it a little bit more at a time under light load. This should help economy at part throttle.
Experimenting with this stuff takes time but having that distributor is a cool and it should make it pretty easy to get it dialed in.
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