A
Anonymous
Guest
Does anyone know what the stock total advance is for the stock 76-83 250 is? Example 32 degrees at 3400rpm?
Thanks,
Ken
Thanks,
Ken
66200i6
Famous Member
That is a complex subject. Get on the web and Google "Timing Curve" or "Vacuum Advance".
There are several things to consider here and all of the different parts of what make up the "Total" advance vary from engine to engine.
Conceder "Initial" or "Static" advance (same thing different names), "Mechanical" advance, "Vacuum" advance (the source of which is debatable between ported and manifold) and last but not least at what RPM does the mechanical advance kick in and finish.
There may be some here that have gone through this that can share what engine type they have and the final settings they found works best for them.
Time to “Nerd Up†and start reading.
Have fun, Ric.
There are several things to consider here and all of the different parts of what make up the "Total" advance vary from engine to engine.
Conceder "Initial" or "Static" advance (same thing different names), "Mechanical" advance, "Vacuum" advance (the source of which is debatable between ported and manifold) and last but not least at what RPM does the mechanical advance kick in and finish.
There may be some here that have gone through this that can share what engine type they have and the final settings they found works best for them.
Time to “Nerd Up†and start reading.
Have fun, Ric.
Generally speaking, when talking about total advance at X rpm you're ignoring vacuum advance and referring to initial plus mechanical "all in".
I forget, but I think our sixes like 30-34 all in by 2800rpm, with 10-12 degrees initial advance. But that's off the top of my head, so I'd get a second opinion.
I forget, but I think our sixes like 30-34 all in by 2800rpm, with 10-12 degrees initial advance. But that's off the top of my head, so I'd get a second opinion.
It sometimes helps if you think of the vacuum as a retard rather than an advance since thats more what it does. It retards the timing under load.
A
Anonymous
Guest
What happens if the advance get's in at ~2400 on a basically stock 250? I mean, I have this friend, see????
Ok, I am having mine recurved to 24 degrees total at 2400 rpm. I have 8 degrees initial. The car starts easily with 8 degrees initial but runs like crap on the highway. I don't think it was advancing enough at cruise ~2400 rpm. I have 3.25 gears and 14" rims.
Do you think it should be ok without pinging?
Thanks, Ken
Ok, I am having mine recurved to 24 degrees total at 2400 rpm. I have 8 degrees initial. The car starts easily with 8 degrees initial but runs like crap on the highway. I don't think it was advancing enough at cruise ~2400 rpm. I have 3.25 gears and 14" rims.
Do you think it should be ok without pinging?
Thanks, Ken
By total, I'm assuming (hoping) you mean only the distributor's centrifugal advance, which with the 8 degrees initial, would give you a real total advance of 32, which I'd think would be ok. If you're meaning 24 degrees total including 8 degrees initial (which would mean the dizzy is only adding 16 degrees) then I don't think that's enough.
But really, engines vary, so the best thing to do is unhook your vacuum advance to eliminate it, then advance the distributor (initial timing) and go driving, then advance it and drive again until it pings. Then put a timing light on it, rev it up and see what the max advance is. Back off a couple of degrees from there, and you'll have the TOTAL advance you can run and be on the safe side of pinging.
TOTAL Advance = Initial + Centrifugal (ignoring vacuum advance)
Then you can tell whoever is recurving the dizzy that you want X total with Y initial, or just X minus Y = centrifugal (distributor) advance.
Clear as mud?
But really, engines vary, so the best thing to do is unhook your vacuum advance to eliminate it, then advance the distributor (initial timing) and go driving, then advance it and drive again until it pings. Then put a timing light on it, rev it up and see what the max advance is. Back off a couple of degrees from there, and you'll have the TOTAL advance you can run and be on the safe side of pinging.
TOTAL Advance = Initial + Centrifugal (ignoring vacuum advance)
Then you can tell whoever is recurving the dizzy that you want X total with Y initial, or just X minus Y = centrifugal (distributor) advance.
Clear as mud?
