Optimal Ignition Timing??

[Huicho417]

If the timing is moving by itself then check to see if the distributor is loose (with the engine off)

I checked that and the distributor was held down tight and I could not move it myself.

 

[toolmanmike]

I checked that and the distributor was held down tight and I could not move it myself.

THe timing itself couldn't move. If it appears to move you may have a old worn out harmonic balancer and the outer ring is moving slipping in the rubber ring.

 

[Huicho417]

Thanks for all the feedback everyone, really appreciate each and everyone of you.

I went home during lunch and checked the engine vacuum and also tried to show the timing mark jumping around (not very successful). It looks like it jumps about 5 degrees to the before side then jumps back to the zero mark. The second video is of what i perceive as play in the rotor/gear slot, but maybe this is normal. The images included is after I removed the distributor to see if the slot in the intermediate shaft was worn.

The jumping of the timing mark does not concern me that much as the engine is running great and maybe it is the harmonic balancer skipping. I can replace that later. What does bother me is the timing reverting back to 10-12 after I increased it to 18.

Video showing play in rotor.




Video showing vacuum and erratic timing mark.

 

[Huicho417]

Attached are two videos of the findings after removing the intermediate shaft and bushing. Both the bronze bushing and slot in intermediate shaft gear had some wear on them. I have not checked to see if this solved the timing mark jumping around. However when driving today on the highway it seemed like a much smother drive and at 65 mph I was only at about 2000 rpm. Where as before I had to push it to get to this speed.

 

[diesel_lv]

Attached are two videos of the findings after removing the intermediate shaft and bushing. Both the bronze bushing and slot in intermediate shaft gear had some wear on them. I have not checked to see if this solved the timing mark jumping around. However when driving today on the highway it seemed like a much smother drive and at 65 mph I was only at about 2000 rpm. Where as before I had to push it to get to this speed.

If your RPM's were higher before to get to 65, then one of 2 things was happening. Manual transmission, clutch slipping. Automatic trans, torque converter slipping. Timing will have absolutely nothing to do w rpm at a speed. Trans final drive ratio, rear gears and tire diameter will determine rpm/mph.

 

[Randy Wilson]

Front driven dists are not 'loaded' like rear mounted dists where the valve springs acting on the cam acts as somewhat of a damper.

Depending on how much slop you have in the dist drive, you can get a few degrees variation.

Dist drive wear areas:
- dist shaft tongue
- timing chain
- cam/oil pump drive gear wear/mesh

This issue can be a bastard. It can cause the idle speed to fluctuate at idle. I have a new cam, double row chain and drive gear and get timing variations of a degrees at idle. Does it w a few different distributors , 2 of them brand new out of the box

 

[Some Car Guy]

Timing moving around at idle can be the chain. Test by baring the motor over and watching the rotor for movement.

 

[RJRENTON]

Car is a 1967 Coronet 440 with 318, automatic 727 Torqueflite. I have been having a lot of fun with it after chasing a rear main seal leak and bad distributor gasket/clamp. I have upgraded the engine with hooker headers, flow master dual exhaust, Edelbrock intake and four barrel carb. The distributor has also been converted to electronic and switched to a double roller timing change. When I get on the highway I get the feeling that it just lacks power when pushing past 60. It will do it, just felt forced. After reading several articles on timing I decided on tuning this to see if it makes any changes. When I checked it this weekend with my timing light showed 11 btdc, I cannot recall why I tuned it to this. Possibly because the service manual suggest 10, but for the stock engine. Which it no longer is. I changed it to 15 btdc and noticed a very positive change when I drove it this morning. It accelerated much quicker from light to light and it seemed to get up to 75 with little effort.

Question is: How much more timing should I add and what can I look for before it starts having a bad effect on the engine? One article I read mentioned you can add until you start hearing pinging from the engine. Which in their case was to about 18 btdc. TIA.

Perhaps consider.......just enough but not too much......the engine will tell you what it likes best....
BOB RENTON

 

[diesel_lv]

I've seen engines that run 34-36° but make same power at 22°. Don't go to most timing without detonation, go to lowest timing with same power.

 

[Randy Wilson]

Timing moving around at idle can be the chain. Test by baring the motor over and watching the rotor for movement.

Just tried this. Rotor movement is instantanious with movement of crank pulley. Forgot to mention that my bushing in the block was replaced. Timing only fluctuates at idle. Stays steady after about 1200 RPM. Some one suggested that the high volume oil pump may be causing this. Any thoughts?

 

[Dave6T4]

You might have a broken advance weight spring, or too soft a set of springs in the distributor. Chrysler designed these engines with ported vacuum to the distributor advance, so that is what I use. I don't worry too much about initial advance setting. I plug the vacuum advance, so it is not in the equation. Then I rev the the engine to a point where all the mechanical advance is in; say 3000-3500 rpm, and set total timing at 34 degrees. I have one of those timing lights that have the adjustable timing dial. I set the light to 34 degrees, and then the timing mark at the damper lines up at Zero. Then, initial timing is just what it is. My engine is a fairly stock 440 Magnum in a 1967 R/T. It always starts well, hot or cold, and does not ping with premium fuel.