[Stikman33]

Ok guys, i have a sometimes intermitent problem. Here is my situation. On my 327 i have and edelbrock 600 cfm carb and a 4 hole spacer, factory fuel pump, HEI ignition, Taylor wires, New autolite 75 plugs, and am MSD 6A box. Here is my perdicament. The car seems to sometimes stubmle at idle, it will idle, but it is weak and i have to turn it up with the idle screw to keep it from dying at lights. When it is demonstrating the idle problem i experience this. In park in my driveway i can sit there and accelerate the motor, and it is very sensitive on the lower rpms, i take it to about 1200 watching the tach the whole time where it jumps all of a sudden about 4-500 rpm. I was going into it very slowly and when it got to that point it decided to jump, hold it there and the rpms stay higher and they bounce around a hundred rpm or so in either direction, you can hear the engine change. As i accelerate more the surging/stumbling effect minimalized until it is no longer noticeable above 3000. When it is at the higher rpms it almost feels like a miss, because it is a very quick blip in the engine sound, not even noticeable on the tach. The car will behave like this in park or driving around town, hot or cold outside. I say it is intermitent because a day ago it decided to start working normally for a couple of hours out running errands, i brought the idle back down to where it normall was and drove around happily figuring it was a blockage or something that had worked itself loose.

I checked the plugs and they look alright, no problems. I read the plugs and the mixture looks alright with no problems. I richened it a bit just to see if it were a lean stumble but it is not that. I adjusted the floats on the carb to make sure that they were in spec. I am going to hook a vacuum gauge up to it this weekend as i will be out of town for the holiday.

Are my weights sticking and then bouncing around. I checked them and put a little lithium grease under the weights to help that if any. Is my MSD box deciding to not work some of the time? So i sound like i have a fuel problem? Filter is clean with no obvious problems. This is really frustrating me and i want to try to figure it out. Any suggestions would be helpful. My BBC won't be done for several months so i want to get this figured out. Thanks

Daniel

 

[BillK]

Stick,
It could be the advance weights. I would get a degree tape for the damper, watch the timing with your timing light while you slowly accelerate the motor. You should see a smooth increase in the advance. If it sticks and then bounces up, you might have found your problem. Only other way to tell for sure is to get someone to put the distributor on a machine and check it out.

------------------
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

 

[John D]

Bill!! Are we the last people on the planet to know how to use a SUN StroboScope??

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'64 El Camino
383 - TH-350 - 12bolt - 4wh pwr discs
Bedded down for the Winter.

 

[airrj]

<BLOCKQUOTE>quote:</font><HR>Originally posted by John D:
Bill!! Are we the last people on the planet to know how to use a SUN StroboScope??
<HR></BLOCKQUOTE>

Nope! My buddy scored one of these at a vocational school auction 2 years ago. We use it all the time. Great Tool.

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R.J.
1972 Chevelle
TC Member #1525
RJ's website
2003 Northern Chevelle Gathering

 

[Jim Elliott]

Hi Stickman
DIRT in the carb !!!
All of my Edelbrock/Carter carbs GOT nutso with just a small dab of crud in the idle circuit. Get some berryman B-12 and clean the heck out of every hole in that carb (wear eye cover)and you will be suprised how good it will run. Also a good "not glass" fuel filter helps to keep it clean and running a long time.

Jim

 

[CHELKAMINO]

Disconnect your vacuum advance, see if the problem goes away. Sometimes the vacuum canister on the dist. can actually pull more advance then your motor needs...thus causing some timing problems. Also, an MSD will not act like that...when they go bad...THEY GO BAD...meaning you'll be walkin!!!!!

 

[Mike Feudo]

HEI's are very prone to sticking the advance tower. Take the cap off and see if the tower moves. If it is stuck sometime you can use carb cleaner on the shaft but most of the time you must pull the dist apart.

 

[Stikman33]

Guys, thanks for the ideas. Dirt in the carb sounds like a possibility because i always seem to have a little in there somehow, so i will check it out. I will also take a look at the distributor and see what is going on there.

Also the advice on the MSD. I am more or less new to the MSD world and didn't know the extent of what to expect out of this thing. Hopefully i can check out all this stuff tomarrow. Other ideas are of course welcome.

Daniel