timing

[reworked]

Ok...
I have a 71 440 rebuilt with everything new......but for the life of me cannot get rid of that dreaded pinging rattling sound of timing....
what are some of the causes of not being able to get the car timed right....
I used 91 octane and added octane boost.....still rattle rattle rattle
the car is put away all this year so far as it is a slug and cannot get it timed right....
makes me wanna sell it!
any ideas

[alfaitalia]

Compression ratio?, current ignition advance?, cam duration/timing?....need a bit more info.

[firefighter3931]

Too much total timing will cause detonation. As mentioned above we need to know where your total timing is at right now as well as where it's at with the engine at idle. 


Ron

[reworked]

the timing jumps all over the place when im trying to set it....I have tried timing in every position adjusting it a bit either way and cannot get it to stop rattle rattle rattle......
I am really hating this car

[reworked]

in idle it sounds  ok and doesn't rattle only under acceleration
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[XH29N0G]

See what others say about jumping around  (I am much more of a novice than the others who have replied)

I would think it would have to do with how the advance is working 9either vacuum (which should be disconnected to set initial and measure total) or something with the mechanical advance (springs?).  What I did wat to remove the cap and see how the mechanical advance worked.  On my distributor there are little weights that move out and are pulled back by the springs. I don't see exactly how it would not move smoothly, but suppose if something were broken it would show up.  The other possibility I can think of is play in the rotor, but I don't know how to determine how much would be acceptable or what would produce it.

I'll be interested to see what you find out from it jumping around.  Is it jumping erratically, or just changing every time you do something?

[firefighter3931]

It sounds like the distributor shaft has lots of slop/play on the shaft support. That is what causes the timing bounce. You should consider swapping in a new modern style electronic distributor. 


Ron

[reworked]

It sounds like the distributor shaft has lots of slop/play on the shaft support. That is what causes the timing bounce. You should consider swapping in a new modern style electronic distributor.  


Ron

I have a brand New Firecore setup in it lol......I bought from you hahaha....it was almost two years ago though, no miles on it yet....I replaced a brand new Mopar performance one with the firecore and coil
I left the springs in the dist that came with it....I still have the second set that came with Dist

I am in Waterloo Ontario...any experts near by

[firefighter3931]

It sounds like the distributor shaft has lots of slop/play on the shaft support. That is what causes the timing bounce. You should consider swapping in a new modern style electronic distributor.  


Ron

I have a brand New Firecore setup in it lol......I bought from you hahaha....it was almost two years ago though, no miles on it yet....I replaced a brand new Mopar performance one with the firecore and coil
I left the springs in the dist that came with it....I still have the second set that came with Dist

I am in Waterloo Ontario...any experts near by

The FC distributor comes with 20-22* of mechanical advance pre-set from the factory. I would try to set the base timing at 14-15* at idle then rev it up to 3000 and check the total timing. It should be in the 36* range or thereabouts. The bouncing timing seems odd. Did you replace the oil pump drive when the engine was rebuilt ? If the slot in the oil pump drive is worn/enlarged and there is slop when the distributor shaft is installed it will cause spark bounce.


Ron

[BSB67]

I think you are correct, if ignition ignition timing is that challenging and upsetting to you,  this hobby is not for you.

[LaOtto70Charger]

Is the timing bouncing around with distributor bolted down tight and engine runnning rough at idle?

[Paul G]

From the beginning;

Is your vacuum advance disconnected and plugged? If not, then do that first and leave it plugged for a while. Does it change the ping with it disconnected? 

What ignition box are you using? Multiple discharge ignition type boxes, MSD, etc., will screw with a dial back timing light. Are you using that type of ignition?

A sloppy timing chain will cause erratic timing too.

[XH29N0G]

My guess is that you can get a lot of information by popping the cap and seeing if there is play in the rotor.  Ron can correct if I am mistaken, but I think if there is play in that slot where the distributor slots in.  My guess is that it will be little (5 degrees of slop is probably yery little, but maybe it can sensed and checked or evaluated with a little video.