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Discussion Starter #1
Working on a 73 Mach 1 with a 351C. Just got a new chain on the car.. Start it up. check the timing and set it up just right.. Rev it up a few times and BAMM my timing jumps to -20+ degrees retarded...
Timing chain is NEW.
Petronix ignitior II installed.
MSD wires.
New cap and rotor.

Put a socket on the crank. bring it up to TDC.
check for compression stroke.
Drop in dizzy.
Aim at #1.

Start the car and everything is fine and steady..
Let the car idle for a few. Sounds good.
remove vaccum. plug dizzy.
loosen dizzy bolt.

Set timing to 10-12* and readjust idle to 800RPM.
Set timing final time to 10-12* ( its not bouncing its hard to read)
lock down dizzy. Put vaccum on dizzy.

Let car idle for a while.
go inside. rev motor a few times.
5-6 revs later WHABAMM!
car sputters. tries to die.

Restart car. Hold gas to get it to idle. jump out and crank idle stop screw on carb to keep car running.
Grab timing light. 10-20* retarded.......
Repeat from step one..

im THINKING the cam gear it slipping on the bottom of the dizzy?!?! its the only thing i can think of.
the DIZZY is NOT moving around. it is NOT loose..

help please?
 

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I'm not familiar with your engine but on some cars, I've seen where the outer ring moves on the harmonic balancer (via aged, slipping rubber) thus making it seem as if the timing was changing using a timing light.
 

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I'm not familiar with your engine but on some cars, I've seen where the outer ring moves on the harmonic balancer (via aged, slipping rubber) thus making it seem as if the timing was changing using a timing light.
+1
 

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It's your car? What is the firing order set at? Did you get the correct timing chain? Did it have the correct camshaft dowel pin? What about the crankshaft key-way, was it the correct size? Is the harmonic balancer off, like said? Did you get the correct cap/rotor? Is the distributor locked down all the way?? What does the distributor gear look like? It may be worn to when you put a load on it it turns the Dis. shaft.
 

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I'm thinking it's the distributor jumping around, or your ignition box. I would think if it is the chain, or any mechanical feature, it would do that from the start.
 

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Discussion Starter #8
I'm not familiar with your engine but on some cars, I've seen where the outer ring moves on the harmonic balancer (via aged, slipping rubber) thus making it seem as if the timing was changing using a timing light.

Wouldnt matter if it moved around once i got the timing set. and you can hear the motor come up on the timing . as the RPM increases. its rock solid as i MARKED the dampner with a white marker.

Alsoo when it comes out of time. i can see it on a light that is it off and sounds terrible. once i rotate the dizzy further to line it back up it sounds fine. so dampner isnt slipping.
 

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Discussion Starter #9
1It's your car? 2What is the firing order set at?3 Did you get the correct timing chain? 4Did it have the correct camshaft dowel pin? 5What about the crankshaft key-way, was it the correct size? 6Is the harmonic balancer off, like said? 7Did you get the correct cap/rotor? 8Is the distributor locked down all the way?? 9What does the distributor gear look like? It may be worn to when you put a load on it it turns the Dis. shaft.
1 mine/families.
2: 1 3 7 blah blah blah. dont recall it is written down out at the car.(this wouldnt move my timing around.
3 yup. Cloyes summit racing.
4 same one that has ben on this motor for 178K miles.
5same one that has been on this motor for 178K miles.
6 balancer has not spun. it is marked with a white out pin.
7 Im guessing so as it has been running for the past 3 years on that cap and rotor and i didnt change it this time.( this wouldnt move/retard my timing )
8 wasnt aware that my dizzy had a lock.. but if you mean rightie tightie lefty loosie then ya.... the dizzy it self is NOT moving the timing is.
9 looks fine. is the rotor shaft and cam gear shaft seperate. it is retarding over and over. and i keep having to clock the dizzy further around.
Im guessing the gear is spinning on the shaft.. not sure yet.
 

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Discussion Starter #10
it will set up timing and idle just fine.
But after you stab the throttle 5-6 times and rev it up one of those it will drop timing about 30* from where it was and it will be severly retarded. the dizzy doesnt move and the balance doesnt slip.

Looks like the gear is put on the shaft dith a through lock pin. and it is not slipping..
 

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Sounds like distributor to me
 

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Discussion Starter #13
looks like the gear isnt moving als on the shaft near the body is another lock pin. looks fine.. not sure how to take apart a dizzy more than the points and gear. wish there was a place in town to bench test my dizzy.
 

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Points?? Thought it had a pertronix? Check the pertronix reluctor that mounts to the shaft. try to spin it on the shaft/Breaker cam. It shouldnt move. I suspect it is loose and moving.
 

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need help!

MASTERJR33 I have a 351 c jumping time the same way as yours! new chain, gears, dist and balancer what did you end up finding wrong with yours?
 
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