[Alex_M]

Hey all, back with another distributor question. I was working on the truck tonight. Hooked up the new timing light, dialed it in at 10* at idle. I went to Rev the motor to see what the advance looked like and.... Nothing. Steady 10* all the way to ~3k.

This is a distributor without vacuum advance, and I've retrofitted a GM HEI module, just so you know what's in the truck. I have a vacuum advance distributor on its way, but it hasn't arrived yet.

Now, that advance didn't seem right, considering it wasn't. I pulled the distributor out, pulled it apart, and  what I found dumbfounded me. I see no mechanical advance mechanism at all. It appears to be a solid shaft all the way to the gear that messes with the cam. What the heck? Does this truck have zero mechanical advance built in?

I'd love some insight. I'm about to throw it back together so I can drive it to work in the morning. Thanks guys.

 

[DODGEBOYS]

the timing advance is controlled by the computer = solid shaft Dist

 

[Alex_M]

Ok, interesting. I guess I'll just drive it as is till the vacuum unit comes in. Thanks.

 

[gremlinmt]

That's cool, I hadn't ever considered using a stock distributor for aftermarket ECU timing control.  I always thought all stock distributors had mechanical advance.

 

[Alex_M]

As had I. Unfortunatwly I can't seem to find much info on how this system works online. I'm going to have to do more research on this and see what I can turn up. I wonder if this system could be used to retrofit knock sensors?

 

[gremlinmt]

Well, it looks like a 3 wire plug, that can really only be crank and cam signals and a ground. 

 

[DODGEBOYS]

Well, it looks like a 3 wire plug, that can really only be crank and cam signals and a ground.

yup

 

[Alex_M]

On the distributor or the ECU? My distributor only has the two wore plug. I'm very curious how this system works if anyone has more info.

 

[SuperBurban]

In the stock system, before you swapped in the HEI, the dizzy provided the signal to the computer, and it decided when to trigger the coil. So the computer controls the advance, based on the several inputs. Not near as advanced as the later fuel injection computers did, but similar.

 

[DODGEBOYS]

the timing advance is controlled by the computer = solid shaft Dist

same thing l said