84 Chevy K10 Distributor

[jnt412]

After having my K10/305 shut down during very hot temps and start back up after its cooled.. (and some volt testing).. the pickup coil needs to be replaced.  Deciding to install a new distrib.  My current distributor has no vacuum advanced but its connected to the ESC.   The vacuum line that would connect to my vacuum advanced is plugged.   This was done by the shop who installed the distributor a few years ago.  According to the service manual, a distrib with a ESC connection AND vacuum advance should be used.  I noticed Rock Auto has one for my truck here - http://www.rockauto.com/catalog/moreinfo.php?pk=1123438&cc=1299696

I read the Service Manual and it doesn't explain (at least to me) how this distrib. will use both the ESC and vacuum advance to run the truck.   Usually its one or the other.    Does anyone know or heard of both being used or this kind of distrib being used?

[Captkaos]

I would get rid of the ESC.  There are several posts on getting rid of it.

[jnt412]

I read the popula ESC Bypass here - http://www.73-87.com/7387garage/drivetrain/escrepl.htm

Since the distributor I posted included a vacuum advance and a connection to the ESC.. I thought the two worked together  for timing and knock.  From readhing the ESC Bypass, I see two options...
 
Option 1. Under Old Parts removal... it seems the ESC is completely removed. I could disconeect the ESC (leave the ESC mounted for the time being), do other wiring and drop in a HEI distrib. with a vacuum advance and adjust timing.. (Important note - no green/black wires to connect together)
 
Option 2. It seems the way 86Scottsdale described.. a distrib like the one I posted (ESC/HEI) has to already be installed. The A,B,C,D wires come from the distrib. leading to the ESC connection plug (as seen in the pic I posted). The ESC/HEI distrib. I posted has these wires.. BUT.. a HEI distrib (non-ESC) wont have it..
 

Summary:
 
Option 1 - buy a HEI distrib with vaccum advance - Around $50 on up..
Option 2 - buy the ESC/HEI distrib like the one I posted - will cost twice as much...
 


jnt412

[zieg85]

Option 1 is the way to go.  Your truck will thank you!!

[VileZambonie]

You are correct however as you can tell everyone is in favor of bypassing the ESC module. Just run a standard vacuum advance HEI or if you want to invest go with an entire ignition system upgrade. Either way you won't regret it, you'll get better power and economy.

HEI's are super cheap these days

http://www.ebay.com/itm/SB-SBC-GM-CHEVY-HEI-Distributor-Clear-Cap-65K-Coil-350-/330588689439?pt=Motors_Car_Truck_Parts_Accessories&hash=item4cf89f141f&vxp=mtr

[jnt412]

Unplugged the ESC connection to the distributor and the electric plug to the vaccum switch to make sure the K10 started.  Once it started I took a reading from the plugged port that the vacuum advance would connect to at idle.   I was getting around 17 psi at idle.  Is this reading correct for vacuum advance at idle?.. It my understanding that little vacuum should be present during idle and alot of vacuum when hitting the throttle.

Vacuum Switch:

The vacuum hose that runs from the vacuum switch is split and ran to a few places.

1.  To the vacuum port that screwed in the block (open/closes by coolant temp)
2.  To the air cover
3.  To the back of the engine (behind the carb.)

Do I need to cap these ports since the vacuum switch will not function.. or just leave these hoses there..



Thanks.

jnt412

[jnt412]

I'm back with pics.. 

 The pics below shows where the vacuum hose from the vacuum switch connect to and the vacuum reading from the vacuum port where the vacuum advance would connect to (according to the vacuum diagram).   The reading was taken during idle..

[VileZambonie]

I was getting around 17 psi at idle.  Is this reading correct for vacuum advance at idle?.. It my understanding that little vacuum should be present during idle and alot of vacuum when hitting the throttle.

You are not going to read positive pressure you are going to read vacuum (negative pressure) on your gauge as you can see in inches of Mercury (in HG).  You should have high vacuum with the throttle closed and vacuum should drop as you open the throttle at least initially.

What do you mean since the vacuum switch will not function? Are you saying it does not function or that you are disabling it?

[jnt412]

I installed the new distrib.  over the weekend.   The vacuum adv. is plugged into the port I placed the gauge on (which is the port identified on the emissions label under the hood).   This port is full vacuum, thus advances my timing and giving me decent throttle response.    There is a port on my carb. that advances only when the throttle is pressed.   When using this port, I didn't have a good throttle response compared to the other port.   Actually, it was like having the old distrib. back in.   So, I switched it back.

VileZ,

The vacuum switch electrical is tied into the ESC, so unplugging it or not didn't matter.  I guess my initial question is.. should I plugged all the ports that tied to the vacuum switch?..



jnt412..

[VileZambonie]

Are you bypassing it? What is your goal? If nothing is connected to it just leave it alone.