Major tuning problems -too much vac. advance???

[goinbroke2]

Sedanman, checkout my reply on your other thread.
You don't need to pull anything apart just yet.

 

[Lazy JW]

Total advance at about 32 deg, is indeed what I have with the vacuum unplugged. When I hook up the vacuum advance (with the new carter YF carb) is when it goes up to 50 deg. Again, this carb only has one vacuum port so I know I'm using the correct one. I really can't go the route of adjusting the distributor before the carb as I have a worn out 1100 on there right now that does not give any advance at all.

See my other thread "Vacuum advance tuning" where Mustang Six made an interesting comment "You may well have 50 degrees of total advance at no-load, high rpm operation (initial+mechanical+vacuum) such as coasting, but the vacuum advance will retard under load" this confuses me a bit as a recent article I saw on checking total advance said that it should be no more than about 35 deg total, but with all advance including vacuum (or I thought so). I have to go back and check that again....

Thor

There is much confusion abounding about the definition of "Total" advance. Many folks refer to initial+ mechanical as "total". I am confident that this is what the article you refer to meant as this is a very common defintition. I, however, happen to disagree, because I believe that "total" should mean TOTAL! At any rate, your 32 degrees without vacuum indicates that your distributor is working fine on the centrifugal advance.

As MustangSix noted, it is indeed possible to pull a lot of advance under certain conditions, but I am also certain that you weren't testing it under those conditions. You would still only need another 18 deg of vacuum advance to reach 50, and you noted that you were getting 26. Was this at idle?
Joe

 

[Anonymous]

There is much confusion abounding about the definition of "Total" advance. Many folks refer to initial+ mechanical as "total". I am confident that this is what the article you refer to meant as this is a very common defintition.

You would still only need another 18 deg of vacuum advance to reach 50, and you noted that you were getting 26. Was this at idle?
Joe

Joe,

This thread is turing into quote city The article does tell you to check total timing with the vacuum disconnected. However, then it tell's you to hook up the advance, rev the engine to about 3500 rpm, and rotate distributor until it starts misfiring, then back off until it smooths out, and that total timing (init+mech+vac) should be no more than 36-42 deg. So my interpretation from that is that total advance with everything hooked up should be no more than the prescribed numbers above, and 50 is just plain too much. This is why Mustang Six's comment confuses me......

At approx. 1000 rpm the intitial was set at 12 deg- same as at idle(idle is set at about 800 rpm) By the time I hit 1500 rpm it rises to 50 degrees. This is when the engine starts to misfire. by comparison, I had a total of 18 deg. advance at 1500 rpm with the vac. not connected.

However, since it also misfires at 1500rpm without the vac. connected and the plugs are white, the misfire at this point has unanimously been attributed to the YF being too lean. I currently have the 1100 on, and there is no misfiring. I'm awaiting the arrival of another reman. YF from the parts store to try and resolve the lean condition I had with the other one.

Common sense might be to just keep the 1100 on and put up with the lousy idle and flooding since it drive's fine, but it's for a 170 and has the SCV - definately a performance limitation with my rebuilt 200 with a big log head. This thead is for "Ford Six Performance", not "lousy inline performance with good driveability"