Distributor??

[Gary_gtx67]

Guys I need your help maybe I'm in the section then guide me.

Come to find out it seems I have multiple issues on my 383 and 727 tranny. On the 383 I'm finding out that my distributor is advancing to 47 degrees when I hit the throttle don't know if I can fix it or I need to buy another new one. It's just a factory replacement upgrade electronic from points. Temp runs at about 205 and I want it around 180. Running with the factory clutch fan and a 4 core rad. Any suggestions would greatly help. I will ask about tranny later.

 

[383man]

Do you have the vacum advance hooked up ?? Ron

 

[Coronet 500]

Hey Gary, I would look at the basics with a timing light and tach. I'm assuming you have a marked balancer as your seeing 47. Remove and plug vacum advance hose, then check initial timing at idle, maybe lowering idle RPM to be sure it's at it's lowest. Then raise engine RPM slowly taking note of when secondary advance starts, continue raising until total advance is seen and at what RPM. If for example you have 10 degrees of initial advance and it continues up to 47 then something is missing or broken at the mechanical advance stop. If you pull the rotor then the plate below you will see the mechanism and it might be quite obvious. Easy to do and look inside before throwing parts at it. Good luck.

 

[fugly]

quite common on the replacement distributors- it will likely need recurved-you may want to read this on my site:http://www.diamondbackengines.com/technical-white-papers/ignition-101/

 

[Gary_gtx67]

My initial is 10degrees at idle then with the vacuum
Off as I raise throttle by 1k rpms it slowly advances itself to only 34 degrees. But with it hooked up she jumps to 47. I call my buddy at my machine shop and he did mention that it's a very common issue with these distributors to do this and he will charge me $40 to fix so I think I'm going to let him do it.

 

[Coronet 500]

That sounds about perfect , when you rev it the vacum should drop reducing advance and having only mechanical. If it stays up at 47 your vacum canister is the problem, some can be adjusted but if it is stuck it should be changed. That much advance is good for gas mileage at low throttle opening, that is part of the design for a street engine.

 

[Gary_gtx67]

But she pings like no other! I'm running super and even a little 110 in her.

 

[daredevil]

Is your distributor hooked up to constant vacuum or ported vacuum? You want it connected to ported vacuum

 

[Gary_gtx67]

Ported.

 

[67 B-body]

That sounds about perfect , when you rev it the vacum should drop reducing advance and having only mechanical. If it stays up at 47 your vacum canister is the problem, some can be adjusted but if it is stuck it should be changed. That much advance is good for gas mileage at low throttle opening, that is part of the design for a street engine.

Ported vacuum increases with engine rpm. Thus providing more vacuum advance not less.

 

[Coronet 500]

Some carbs have the ported vacum opening just below the throttle blade seeing full vacum at idle, as the blade opens it exposes the port to atmosphere and reducing the vacum. This is the way I understand it works.

 

[fugly]

disconnect and plug the vac line- if the ping goes away, it's just a matter of adjusting the vacuum advance- if not you may be running too lean on the carb

 

[Gary_gtx67]

How do I adjust the vacuum advance? Is it like chevrolet with an Allen wrench in the vacuum port on the distributor?

 

[Budnicks]

Some of the new versions of the electronic ignitions have an allen wrench adjustment inside the vacuum port you go thru the nipple were the hose is hooked up & turn 1 direction or another, to advance or retard total added vacuum advance. Try after adjusting it , checking it at at least 2500-2800rpm you should have all the advance in by that point mechanical & vacuum, you could have the mechanical advance too light of springs , you can mess with them also. Moroso sells a good kit with 3 sets of 2 springs marked by different colors for light to stiff.

 

[fugly]

if the vacuum can on the distributor is hex shaped by the port, it is adjustable- clockwise to lower- by the way vacuum does not advance or get higher with rpm necesarily- it goes up with decreasing load on the engine, down with higher load- in most cases when the car is floored, you will have very little vacuum showing- if you have high vacuum with the engine floored, there is a restriction on the intake(typically too small a carb or restricted aircleaner)

 

[Gary_gtx67]

Well it's a 750cfm Holley double pumper and I can garauntee the air filter is not to small in fact not just the sides breathe on my filter but so does the top and my hood scoop kinda acts like a forced Induction when driving.

 

[67 B-body]

Some carbs have the ported vacum opening just below the throttle blade seeing full vacum at idle, as the blade opens it exposes the port to atmosphere and reducing the vacum. This is the way I understand it works.

As a rule of thumb you can concider any vacuum generated below the throttle plates to be Manifold vacuum. Anything that gets vacuum from above the throttle plates is concidered ported vacuum. Manifold vacuum always drops as the throttle plates are opened and the manifold is exposed to atmosphere or greater than atmosphere through forced induction. Ported vacuum is something that is generated as velocity increases through the ventury of the throttle body "open throttle". This increase of vacuum advances the ign timing with engine speed.

 

[Gary_gtx67]

Have I ever said how much I love this forum! You guys are great!! Now to fix the tranny. :-(