Slant Six Forum :: How do I check my vaccum advance

The easiest is to use your timing light.
Check the timing with the advance line disconnected and plugged. Then check it again with the advance hooked up.
Is there a difference in timing?
or idle speed?
Read page four of the distributor recurve instructions and adjust the pod so there is no difference in timing on the light or idle speed when reconnected.

Your other option is to suck on the line going to the advance of hook up a vacuum pump and gauge and see if it holds air.

I prefer 10 or 12 degrees of initial timing and another 20 mechanical and another 20 or so from the vacuum advance.

Author:	/6 Matt [ Wed May 05, 2010 4:24 pm ]
Post subject:	How do I check my vaccum advance
About a week ago, I reset the valve lash hoping it would fix my idle. Unfortunatley, it didn't... So the next thing I checked was timing (about 2 days ago) and it was at 12 degrees advance . So I set it to 5 degrees advance, and reconnected the vaccum advance hose and took it out for a spin. Well now the huge dead spot is back (the one dad "fixed" most likely by advancing the timing). So this is making me think that the vaccum advance isn't working properly. The dead spot in question is at 15-25% throttle and will stall the car in gear, in neutral the engine stumbles when revved. The problem seems to be worst when the engine isn't at normal operating temp. The accelarator pump shot looks normal, and the rest of the carb. looked normal when me and dad rebuilt it about 2 years ago. So, how exactly do I check to ensure the vaccum advance is working properly? BTW: I figured out why the engine was running abnormally "cold" with a brand new 190 degree thermostat. I disconnected the wire coming from the sending unit when I was trying to negotiate the rocker arm cover out. When I plugged it back up and started the engine the temp. gauge was reading normally. Apparentley, the connection must have been bad and increased the resistance in the circuit, cause my readings to be low.

Author:	Aggressive Ted [ Wed May 05, 2010 4:53 pm ]
Post subject:
Quote: So, how exactly do I check to ensure the vacuum advance is working properly? It's easiest is to use your timing light. Set rpm to 750 rpm and run the test. Check the timing with the advance line disconnected and plugged. Then check it again with the advance hooked up. Is there a difference in timing? or idle speed? Read page four of the distributor recurve instructions and adjust the pod so there is no difference in timing on the light or idle speed when reconnected. Your other option is to suck on the line going to the advance of hook up a vacuum pump and gauge and see if it holds air. I prefer 10 or 12 degrees of initial timing and another 20 mechanical and another 20 or so from the vacuum advance.

Author:	/6 Matt [ Wed May 05, 2010 5:02 pm ]
Post subject:
Quote: The easiest is to use your timing light. Check the timing with the advance line disconnected and plugged. Then check it again with the advance hooked up. Is there a difference in timing? or idle speed? Read page four of the distributor recurve instructions and adjust the pod so there is no difference in timing on the light or idle speed when reconnected. Your other option is to suck on the line going to the advance of hook up a vacuum pump and gauge and see if it holds air. I prefer 10 or 12 degrees of initial timing and another 20 mechanical and another 20 or so from the vacuum advance. When I reconnect the vaccum advance, it goes to 12 degrees advance and the idle goes up a little (no tach, no definite number) maybe 200 rpm at most. Can I adjust the stock vaccum pod? I thought an adjustable vaccum pod was part of what came with the mopar performance recurve kit. I think I'll try the "sucking" method, that sounds easiest and most promising.

Author:	Aggressive Ted [ Wed May 05, 2010 5:06 pm ]
Post subject:
No need to suck on it, it's working. Yes, a 73 is adjustable, read the instructions on page 4. Use a 3/32 allen wrench. Timing Curve/Recurve information link under Engine FAQ Your pod is working if the idle is going up when you plug it back in...... Set it so it doesn't change when plugged back in. Your just throwing away off idle punch the way it is..... Mine is set at about 3 turns out from full on. It comes on right at 850 rpm and then comes on hard. Enough to break both rear tires loose. Why don't you read the PM from a week ago.....

Author:	/6 Matt [ Wed May 05, 2010 6:05 pm ]
Post subject:
I do need to look back over that article when I get the chance... Thanks for the reccomendation on the coil BTW.

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Author:	DusterIdiot [ Wed May 05, 2010 7:25 pm ]
Post subject:	Maybe...
Quote: Yes, a 73 is adjustable, read the instructions on page 4. Use a 3/32 allen wrench If it's OEM, it will...you may have to pull the dizzy to see if the can is "stamped" with a part number or not, or if the back of the can has a black letter and number set... some of the aftermarket replacement cans will not adjust with the allen key...and the ones on the cardone remanfs are a real hit and miss affair... -D.Idiot

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