Distributor thoughts needed on an issue

[SirRobyn0]

Ok, I've got a couple igntion issues going on, but for this thread I want to concentrate on this one thing. When checking the timing, with the vacuum advance disconnected set the base timing at idle. Now a while back I wanted to check the mechanical advance so I started revving the engine, right off of idle, the timing looses about 4 degrees, and then when the mechanical advance kicks in of course the timing goes up. For the record this is an ESC truck but it is currently bypasse as it's not functioning. I mention that so you know it's not the ESC backing timing out. If you wanna talk ESC I have another thread for that. I just wanted to mention that. So in November when I had the transmission out rebuild I replaced the timing chain thinking I much be seeing slack in that. No change after replacing the timing chain.

Now today I gave the distributor a close inspection. There seems to be quite a bit of sloop, well watching the videos would be best. The movement is definitely not the mechanical advance, and frankly to me it felt like the gear to cam gear movement. I've got a distributor on order and should see it tomorrow at work.

What do you think?

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[AyWoSch Motors]

That looks pretty normal. Every distributor I've ever messed with about that much play.

 

[fast 99]

Normal, has to be some movement like you show and vertically.

 

[SirRobyn0]

Ok thanks for that @AyWoSch Motors & @fast 99 . I've never really run into the issue I've got before I've seen timing needles that bounce around but not this. I would not think twice about the play if it weren't for the timing anomaly I've got.

So you guys got any thoughts on that? With the vacuum advance disconnected right off of idle, the timing looses about 4 degrees, and then when the mechanical advance kicks in of course the timing goes up. That's not normal and apparently not in the chain.

 

[fast 99]

Only thing I can think of is advance weights sticking, unless there is chain play.

Did you check that by watching the dist rotor and turning the crank back and forth?

 

[AuroraGirl]

Only thing I can think of is advance weights sticking, unless there is chain play.

Did you check that by watching the dist rotor and turning the crank back and forth?

the return weight toward him appears to have a worn spring. i would get a recurve set and pop the same size ish things back on

 

[RanchWelder]

From what I've read, almost all the recurve kits are really made for race applications...

I can see if I have a spare large cap distibutor laying around with good springs... If I can find it, it probably needs a new coil under the magnet and new ignition module.

It was originally from a crossfire...

Let me know & I'll hunt it down...

**** Oh... your Rooster say's he hungry...

 

[AyWoSch Motors]

Ok thanks for that @AyWoSch Motors & @fast 99 . I've never really run into the issue I've got before I've seen timing needles that bounce around but not this. I would not think twice about the play if it weren't for the timing anomaly I've got.

So you guys got any thoughts on that? With the vacuum advance disconnected right off of idle, the timing looses about 4 degrees, and then when the mechanical advance kicks in of course the timing goes up. That's not normal and apparently not in the chain.

Does the 4 degree drop in reliation to slightly higher RPM, or movement of the throttle? Becase if your opening the throttle, could be a momentary drop in vacuum, a slight drop in rpm, and therefore time. Maybe a little stumble or an unperceivable drop in rpm, enought to drop time a little.

If not, that sticky weights, or maybe sloppy valve lash/valve train..

 

[SirRobyn0]

Only thing I can think of is advance weights sticking, unless there is chain play.

Did you check that by watching the dist rotor and turning the crank back and forth?

And @AuroraGirl No I have not done the slack test for the timing chain, but the chain was installed in November, this issue was there before the chain replacement and after. Old chain had some slack, but really was not as bad as I expected. New chain was fine with no excess slack.

Taylor, so both weights have a bit of movement at the pivot points, and yes I agree the springs are not the best. And the rear weight the one furthest from me is just starting to mark up the plate under it. If all I had was the weight issue I'd just monitor it, but with all this other stuff going on I'm leaning towards replacement.

 

[Ricko1966]

As many pinging issues,distributor problems as you've had I would not put anything,spring,weights or distributor cam that wasn't original for an esc distributors,. Remember I learned this the hard way also.

 

[SirRobyn0]

From what I've read, almost all the recurve kits are really made for race applications...

I can see if I have a spare large cap distibutor laying around with good springs... If I can find it, it probably needs a new coil under the magnet and new ignition module.

It was originally from a crossfire...

Let me know & I'll hunt it down...

I would love to take you up on that but the ESC distributors use different weights and springs than the standard GM HEI units. Well I guess I don't know the springs could be the same the weighs are different for sure. Plus I'm under the gun, likely I'm towing my trailer over the pass next Saturday so I need to do what I can before then. New distributor should be at the shop Monday anyway.

Does the 4 degree drop in reliation to slightly higher RPM, or movement of the throttle? Becase if your opening the throttle, could be a momentary drop in vacuum, a slight drop in rpm, and therefore time. Maybe a little stumble or an unperceivable drop in rpm, enought to drop time a little.

If not, that sticky weights, or maybe sloppy valve lash/valve train..

RPM increase. vacuum advance is disconnected when I see this so it's not a vacuum change. Pretty much it's got to be in the distributor if it's not in the chain is my thinking.

 

[SirRobyn0]

As many pinging issues,distributor problems as you've had I would not put anything,spring,weights or distributor cam that wasn't original for an esc distributors,. Remember I learned this the hard way also.

I agree.

I tried that once too. I stabbed a regular HEI distributor in it and had a ping fest, I had to modes, no power or severe pinging, I had it in for one day and went back to the original unit. Original style new production distributor on order. Once I get it I will crack the cap to see if it's got the same weights in it.