Popping sound from exhaust at low speed....

[CudamanTom]

8" of vacuum seems a bit low unless you have a very lopey cam and your car has a rough idle.

Check for vacuum leaks (any lines coming or going from the carb, then you might have to check your intake gasket next). Your advance seems well at bit advanced to be running 40 at idle? You should be down somewhere near 16 at idle then allow your mechanical advance to take you up to 36.

Since I'm not sure what cam I have, I can only assume it may have a lopey cam and it does have a rowdy idle, smooths out a little when warmed up. I will check for vacuum leaks with carb and intake.
Still not sure on the timing of 40 at idle part. Should be 16 at idle? And how do I "allow" my mechanical advance to take me to 36? I'm not very knowledgeable in that area.

[HP_Cuda]

See in the attachment where it says factory equipped cars. So with 2 heavy springs and a blue stop bushing you get 20 degrees total advance and it shows you how much over what range. Basically at around 4k rpm it has flatlined.

You want a faster advance. So with the light blue and light silver and blue stop bushing you still get 20 degrees total advance but you hit it faster at 3k rpm. So if you set your car up at 16 degrees or thereabouts depending on how you like it and then add another 20 degrees mechanical advance. You then hit the magical number of 36 degrees total advance. Make sure you have the blue stop bushing as well, most don't change this out but its possible.

My cam is a bit on the wild side and I expect 10-12" vacuum. If your car smooths out when warmed up, I have to ask do you have an electric choke?

B

[CudamanTom]

B,

I don't have a choke. I keep the foot on the gas a little to keep it running till it warms up.
If I try to go 16 at idle, it won't run. unless maybe I crank up the idle screw. Is that what I need to do?
I think I'm still missing the point.
You say idle at 16 and then add another 20 mech advance. So how does that happen? 
The chart isn't helping me on the physical part of what to do.
I know I'm lookin like a real idiot right now.  Just haven't grasped the understanding yet.
I've looked at videos but all they show is turning the distrib to time it.
I will check and verify the blue stop bushing.

God I feel like an idiot here.   

[HP_Cuda]

Tom

No worries, by the way did you take the blaster2 coil and turn it facing upward yet? I still need to do this on one of my cars as well.

Let's start over. What kind of harmonic balancer do you have on the car? Is it stock or an aftermarket one like this.

http://www.motorsportsofkc.com/images/mkchbf440.jpg

B

[CudamanTom]

Tom

No worries, by the way did you take the blaster2 coil and turn it facing upward yet? I still need to do this on one of my cars as well.

Let's start over. What kind of harmonic balancer do you have on the car? Is it stock or an aftermarket one like this.

http://www.motorsportsofkc.com/images/mkchbf440.jpg

B

Thanks B,
I haven't moved the coil yet but will.
I have that same balancer like in the link you provided.
Attached is a pic of mine.


Tom

[HP_Cuda]

I don't understand setting initial timing at 40 degrees and I wish I was closer so I could just come over. Maybe you can get a pic at idle? I know it's a pain but I'm a bit lost with running that advanced at idle.

Here is a trick you can try to find vacuum leaks. Take a can of carb cleaner, take off the red straw because you need a fine mist. Start the car and let it warm up, then you take the carb cleaner and lightly spray around the base of the carb, intake, lines to see if there is any leak - if there is one then you will hear the motor go up in rpm.

[CudamanTom]

I don't understand setting initial timing at 40 degrees and I wish I was closer so I could just come over. Maybe you can get a pic at idle? I know it's a pain but I'm a bit lost with running that advanced at idle.

Here is a trick you can try to find vacuum leaks. Take a can of carb cleaner, take off the red straw because you need a fine mist. Start the car and let it warm up, then you take the carb cleaner and lightly spray around the base of the carb, intake, lines to see if there is any leak - if there is one then you will hear the motor go up in rpm.

I wished we lived closer too. We could work on each other's rides. 

The 40 at idle has me goin too. I will try to take a pic.
I will also do what you suggested on the carb cleaner. Good idea. 

[Chryco Psycho]

you can use a piston stop to find TDC @1 or 6 & see if the damper is correctly indexed

[CudamanTom]

Okay guys,

I did a couple things here.
I took out the old stop bushing  in the distrib (which was rusted up but looked the size of the black one) and put in the blue stop bushing.
I turned my coil vertical. 
And lastly........
I reset my timing light. It's the top the of line Innova timing light. Being a new and high tech light, I am still learning how to use it.
I'm not sure what I did made a change but now I get a reading I can adjust to specs. I'm betting it was my settings on the timing light. 
I adjusted idle timing to about 16 and it shows about 38 at 2500 rpm and up.
Is this good?
The vacuum still shows around 8in at idle and does go up with higher rpm. I'm thinking with a mild or more cam this might be close to where it should be? 
I sprayed carb cleaner around the carb plate and intake and didn't get any rise in RPM.

I ran out of time to take it out to see if it pops anymore so hopefully I will do that in the morning before it gets too hot.
We will see....

[HP_Cuda]

I was thinking this as well, there is no way it's 40 at idle.

you can use a piston stop to find TDC @1 or 6 & see if the damper is correctly indexed

[HP_Cuda]

Great news Tom!

Looks like you have the timing figured out. 38 degrees at 2500 and above is close and comes down to personal preference and hopefully no detonation. Man you must have a beefy cam if you only get 8" vacuum and there is no leak.

If you get a chance, whats the lowest rpm you can set the car to at idle without killing the motor and then take a vid? I'd love to hear it.

[CudamanTom]

Great news Tom!

Looks like you have the timing figured out. 38 degrees at 2500 and above is close and comes down to personal preference and hopefully no detonation. Man you must have a beefy cam if you only get 8" vacuum and there is no leak.

If you get a chance, whats the lowest rpm you can set the car to at idle without killing the motor and then take a vid? I'd love to hear it.

Thanks B,
I'll see if I can break her out tomorrow morning before it gets too hot outside and take a short vid. That and in between honey-do stuff.

But I have a question. I'm not sure what my preference is except for optimum performance. How or what do I do to see if I'm at that level?

[HP_Cuda]

Another old school trick.

Find the steepest hill in your town, hopefully > 35 degrees. Advance the timing, drive up the hill and find the point where you get detonation, then back her off a bit and you are at the top of your curve.

To your point Tom 36-38 degrees is pretty much at the sweet spot. We havent determined what kind of grind you are running so it may vary a little but you must be close.

B

[CudamanTom]

Well with the stuff I did in the last post, I finally got it out today.
It still pops. Moved the distributor both ways a little and still get it. 

[HP_Cuda]

Ok now I want to hear this pop.
Can you take a vid of the car idling and then juicing it to say 2500rpm and still getting that pop?

I'm going to go out on a limb here and say:

The two things that really come to mind is
1) some sort of vacuum issue
2) bad electrical issue (connectors, plugs, wires, bad MSD box, etc)