My 68 with a slightly built 350 has developed a stumbling problem when I jump on it off the line.

It does not do it if the RPM's are up.

It has MSD 6al and MSD distributor and MSD coil. Holley 750 double pumper with Mech secondaries with no choke.

I also have begun to notice some black soot on the ground when warming her up in the garage (mostly from passenger side exhaust).


What do y'all think it is.


Thank you in advance for and advise.

Black Soot is from running rich ... Running rich will eventually foul your plugs. Check your plugs first and then re-check your timing ...you may even try bumping timing some... Use a vacuum gauge to adjust idle mixture ... I see you are not running a choke ... YOu may need to look closer at linkage oper to make sure accelerator pumps are not over-adjusted

Black soot is not good. To much fuel and to little
spark. Check the float level and be sure to replace the spark plugs with a higher heat range. Drive it 20-30 miles after the change and check the plugs. graemlins/beers.gif

Excellent advice gentlemen.

Thank you.

took her out for a drive yesturday and now it's much worse. It stumbles pretty much all the time.

Is this because the plugs are probably fouled?

You are going to get black soot on the ground,especially if your choke is hooked up. It almost sounds like you may have gotten some dirt in the carb,holding the needle valve open or the choke is sticking closed. Have you changed carburetors recently? Its always better to be slightly rich than to be lean.

Robert...thanks for the reply.

I purchased the car pretty much as is. The choke is not even hooked up (I believe it would be manual if it was).

This issue has developed very quickly. The only thing I have done recently is I had the trans rebuilt and a 2500 stall put in.

Do you have your idle turned up so much that you have defeated your idle circut? Look in your carb, when the motor is not running, and look at your butterflys. They should be closed or darn near closed. If they are cracked open you need to back off your idle adjustment and adjust your air screws until it idles again.

The choke is pinned wide open and does not move. This was done by the previous owner. In other words no choke. It starts right up but obviously I have to keep it reved to about 1500 until she warms up a little.

I have it in the shop right now and have relayed the information I have gotten here. I will let you know how it turns out.

here is the information from my machanic. Needs hotter plugs (we already determined that). The coil is not putting out a hot enough spark to take advantage of my MSD box and dist. And the weights in the dist are sticking (cuasing timing problems). Cap and rotor are toast as well.

I'm going to have them take out the 1" spacer between my carb and minifold as well.

Carb needs to be adj. slightly.

Thanks for the help and guidance.

Car is running great!!
May try bumping the timing for a little more power.

Thanks again for the help.