So with going over everything with the car I've found a few things to investigate. According to my research I have a ignition issue...... I get a very rapid 1hg vibration of vac at idle that smooths on acceleration...... Vac gauge tuning guide says that's an ignition issue.... Plug wires appear good with good ohm readings.... Got around 1.8-2.4 depending on length. Plugs look good with a 45 gap. I'm running a petronic with a Mallory hyfire vi box and blaster 2 coil. Any checks that I can do to try and figure out what it is??? Other symptoms I'm getting are a real light exhaust popping at idle. Thanks
Any idea guys? Gonna let the car run and spray each header pipe. I'm guessing I will find that I have a mis on one cylinder.... Checked my plugs and wires cap and rotor and they are all in good shape.
I'm having the same exact issue. about one hg of vacuum, slight pop at idle, the whole deal. i think its a mis as well. i was gonna get a new dist, maybe hei, and a set of good wires to see if it'll help. but yeah same problem as you. if you figure it out let me know so i know what to look for!
Check your wires first with a multimeter. Mine were really good. Only thing I can think if it is a mid is that my box is messed up......hope not. Will have an update tonight
No resolution tonight. Only had time to let it run til it got hot and all headers burned off the water at the same rate...... Gonna squire a temp gun and try that tomorrow but I don't appear to have a dead miss like I suspected....... Its never easy.
A sticking valve can give the same vacuum reading. What's your ignition timing? Also check the inside of the distributor cap for carbon tracking.
I was under the impression a sticking valve would cause a larger vibration like 2-4hg. Initial is 18 and 36 total. Normally I run 18 and 38 with my vac pot cranked in but I just started playing with bringing it back in.
any cam that is bigger than stock will cause a vacuum gauge needle to bounce at idle. the more aggressive the cam, the more it will bounce. the intake valve is opening right before the exhaust valve is closing. on more aggressive cams this overlap is bigger. its this over lap the create the lope at idle. i suspect your chasing a ghost.
I will post a video of it later this evening. I just thought it was weird that it would vibrate so much at idle and completely smooth out higher in the rpms. Its vibrating so fast at idle it blurs the needle lol.
Stick finger in tailpipe to see how much soot is present. Black = too much fuel. Do you have access to an O2 tail pipe sniffer? What Carb are you running?
Seems like a lot of initial timing. What happens when you bring it back to 12deg? Maybe close the spark plug gap to .040...
No soot in exhaust at all. I can crank the pot back in to bring it to 16 then back all my timing off 4 that would give me 12 initial and 32 total. Carb is a holley 600 secondary vac 4160 with the quick fuel metering plate and secondary vac diaphragm. Current is : 66 primary and 72 secondary Green pump cam 1st position 40 squirter
I love asking guys at car shows who tunes their car... The look on their faces is priceless. When you get done you can say I did it myself!!!!
Difference between me and them is they have money Lmao. I don't have a choice but to do it myself haha
