Dwell angle and timing are way off

Icefan71

Icefan71

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I had lots of trouble getting my 72 Lemans 350 2bbl running. I finally got it running and set the dwell angle to 30 deg and timing at about 10 deg btc. I had the vacuum advance hose off and the port plugged. It ran but it was rough. And it would stall out if I gave it some gas. Didn't matter if I did it slow or fast. So I played around with the points and the timing and now it runs much better and I can rev it up and it runs great. But my concern is that the dwell angle is now down to 23, and the timing is just past the end of the scale so its probably around 16-18 btc. Those numbers are no where near what they should be but the motor runs so much better. Idle is still a little rough. Am I doing something wrong? Are my tools not working right? I have an old Craftsman dwell meter that was given to me and a borrowed timing light thats pretty old. Also I have 87 octane gas in it.
 
I have no way of knowing if you equipment is defective. 30 degrees of dwell is correct and the timing number sounds about right. The advanced timing is covering up the underlying problem assuming your equipment is correct. Look for a vacuum leak, rotted hose, carburetor base gasket, etc. Also do a compression test to check for burnt valves or worn rings. Another thought would be the timing chain is worn out.
 
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The previous owner said the timing chain was bad and he couldn't keep it running. Since I got it I replaced all the fluids and new plugs, points, wires, cap, rotor, and coil. It runs rough, but it runs so I thought the chain was ok. Maybe thats the problem after all. I also forgot to mention that I noticed the part of the distributor where the points are mounted rotates back and forth slightly when the motor is running. Is that normal? The distributor hold down bolt is tight and the distributor does not move.
 
When you set the timing does the mark on the harmonic balancer hold steady or move back and forth a couple of degrees? The amount of movement of the breaker plate should be minimal. The factory timing gears were metal with a nylon coating for quiet running. Over the years the nylon coating fractures and falls off the gears causing lots of slop in the chain. Replacement gears are all metal.
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that could be just the breaker plate. I saw a picture of the engine from another post so I would chase for a vacuum leak from a rotted hose or the carburetor base and do the compression test.
 
I did a compression test. 120-125 on all 8 cylinders. I checked the carb, vacuum hoses for leaks and found none. I read where you can turn the crank and watch the distributor to check for excessive play in the chain. I should try that next.
 
going back to your dwell meter, do you have a way of calibrating it for 4, 6, or 8 cylinder engines?
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and does it use an internal battery and if so is the battery new?
 
No battery. Its an old one though. Probably 30+ years old. It was given to me complete with the owner's manual. I just followed the directions and made sure the needle was zero'd
 
OK, another thought, the harmonic balancer has a rubber layer which over time will deteriorate causing the outer ring of the balancer to shift giving you incorrect timing. Check if the outer ring looks like it has shifted.
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Melsg5, I feel pretty ignorant right now. I just put a new condenser in and the motor runs absolutely fine. Dwell is back to 30 deg, timing is set at 10 deg btdc. The timing mark is rock steady now. It idles smoothly and revs right up. An $8 part was causing all these headaches. Well, I'm learning, lol. Thanks for putting up with me.
 
great that you found the problem and didnt cost much. I got rid of points and condensor about 20 years ago, put in a Mallory Unilite.
 
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