I have myself a head scratcher. I installed an accel vacuum advance distributor, new coil, , new cap, new plugs, new plug wires. At first I could get the car to run but I could never get it to time. I would get to 4 BTDC and then it would just die on me. It actually liked to run advanced about 4-6 degrees, but when it got warm it would not start. I can not get the thing to time. I have dobule checked twice that I am on the compression stroke for number 1. I have triple checked that my wires are correct on the cap. Now I have gotten to the point that if I try to crank the motor it barely turns over like a dead battery, but if I disconnect the Batt wire from the distributor the motor turns over great. I think this is a timing issue but I cannot figure it out. Any help would be greatly appreciated.

 

Ok quick update, I disconnected the tach wire since my tach does not work anymore, and the engine fires up and runs pretty smooth. A little rich but smooth. Only problem is the timing is set centerline in the barrel tube that is on the timing marks. Is this acceptable? I have a vacuum gauge hooked up as well and this setting gives me the best vacuum of 19-20 is that acceptable? I have not been able to drive it and see how it feels. I am super confused...

 

Hi Nebraska Guy ,

What your describing is the classic symptom of timing that's too "Advanced" or "Early" . As the piston is on it's way up to compress the fuel/air mix , the early spark lighting the fuel charge off too soon tries to force the piston back down and thus the labored cranking .

I have seen instances where the timing marks are , for a couple of different reasons , not correct for proper engine operation . One could be if anyone during the car's life changed either the Harmonic Dampener or timing cover with not correct , but still fitting parts . Another is the "slipped dampener" where the rubber between the two pieces of the dampener has slipped , allowing the part with the timing mark to become out of orientation with it's proper position WRT the actual position of the crankshaft . As long as everything else about this engine is mechanically sound , I'd be looking into the two possibilities I've mentioned .

As a "starting point" , have a buddy turn the key while you SLOWLY turn the distributor in the "Retarded" or "late" direction ( Turn it in the same rotation as the rotor turns to delay firing) , it shouldn't take much movement at all , and once the too advanced condition is rectified in this way the engine should start .

 

Ok I will keep advancing it clockwise then as that follows the rotation of the rotor. How do I know when to stop? The car runs now. since the marks cannot be trusted howdo I make sure the timingis correct. I understand the detonation subject. Is that what I am limited too? I have a vacuum gauge hooked up and am currently at 20 inches of vacuum..is that decent?

 

What carburetor are you running?

To verify TDC, you need a "piston stop": http://www.summitracing.com/parts/pr...Fes-MgodZ1QAXw Pull the #1 spark plug, install the piston stop, rotate the engine by hand until the piston contacts the stop. Now make a mark on the damper at zero degree marking on the timing tab. Now rotate the engine back the other way by hand until the piston contacts the stop again - mark the damper at the timing tab zero degree again. Zero degrees is mid-way between the two marks you made - make a permanent mark there.

If the factory timing mark is significantly off from where you verified it, either you have the wrong damper for the timing tab (or vice versa), or the damper ring has slipped on the hub. If it's more than a few degrees, consider replacing the damper.

4 degrees BTDC is insufficent advance for a non-computer controlled distributor. More like 8-12 should make it run better (but we really need the answer to the "what carburetor" question).

 

I am runninga mechanical quadrajet do you need the actual part number? It came off of a 80 chevy pickup with a 305 in it.

 

The problem is as soon as I get close to 4 btdc the engine starts to shake bad. Right now itis running what I would consider to be 8-10 ATDC. Once I plug in the vacuum advance and rev the engine. The damper mark moves counter clockwise towards 6-8 BTDC.

 

No, just making sure you weren't trying to get a factory '84 q-jet running correctly with a vacuum/mechanical advance distributor.

 

Verify the TDC mark per my previous post.

 

I did my research before making the swap. so I will get the part and find the true tdc. I did pull the plug and use my finger over the hole and when the compression blew my finger off i checked the damper and its mark did line up with o on the markings. Also i compared where 1 is sitting with the position of the rotor on the new dizzy compared to where the original was set..I set it to tdc before I pulled it out. There are in the same place.

 

Your timing is way off from what you are reading. Do what five7kid said in post 5.

Also never set the timing for best vacuum at idle. You will almost always be way to high after full advance.

 

I ordered the tool this morning. It says it will be here between the 4th and 5th. I will keep you updated.

 

that did it I found out my damper had shifted 2 inches. I adjusted for it and everything is great. Sorry for the delay but thank you for the help.

 

You probably have a timing tab mismatch. Either mark the balancer or get a new tab. I am actually a fan of timing tape, a lot of people use dial back guns but the tape is nice because it's not error prone like the guns can be.