1976 2.0L D-jet, distributor vacuum Options

[Ron914]

@emerygt350
I was asked my a member helping me with my high idle /vacuum leak problem how I currently have it hooked up .This is the diagram I am using .

[emerygt350]

Let me see if I understand what you posted. When you plugged the MPS vacuum at the plenum and gave the MPS 22inhg with a warm engine the idle dropped to where it is supposed to be, and the MPS is leaking down as well?

I would double check your valves because it is relatively easy, but check your vacuum at the plenum first, it would be nice to know where it is at currently. Use the MPS port on the plenum. Just hook your mityvac to it and read the vacuum off of that. Be sure the engine is warmish when you do check or at least that the aar is closed or blocked and the leaking MPS is unplugged. If the vacuum is up around 18-20 inhg I might not bother with the valves just yet.

I would also time your engine for the moment using the vacuum method. This is the way people used to time their engines in the old days. Disconnect the retard. Get the engine warm and idling at that 900 again (disconnect the mps or whatever was necessary). Check the vacuum, turn the distributor either way and watch the vacuum. You want to find the highest vacuum with the engine still running well. Then back it down 1-2inhg. If the vacuum is quite high (over 21inhg) I would just bring it down to 19inhg. If 19 or 20 is as high as it goes, I would maybe bring it back 1 inhg so it's between 18 and 19 just to be safe.

If you don't have much faith in your timing marks or the light this should work fine. You could now check the timing with the light and see where you are at idle and all in at 3.5k rpm.

Since you have a 2056 I don't know what to think about the 'euro spec' MPS. Sounds like the daiphragm is busted anyway so you will probably need one of Chris Foley's rebuild kits and at that point you will be tuning your own MPS anyway. I am not sure if the 2056 sucks enough gas over the stock to require that inline resistor though. Your ECU is already richer than the 73 that required that resistor. Better rich than lean and if you have a hunting idle, I would keep it for the time being. You might try richening the ECU pot to see if that hunting idle goes away.

While you are working on this you may just want to keep that retard disconnected until everything is where it should be, then deal with the retard afterward. The nice thing about the retard is that you can put some extra timing into your engine and still have it start up nice and easy but we are not there yet.

[Ron914]

Let me see if I understand what you posted. When you plugged the MPS vacuum at the plenum and gave the MPS 22inhg with a warm engine the idle dropped to where it is supposed to be, and the MPS is leaking down as well?

I would double check your valves because it is relatively easy, but check your vacuum at the plenum first, it would be nice to know where it is at currently. Use the MPS port on the plenum. Just hook your mityvac to it and read the vacuum off of that. Be sure the engine is warmish when you do check or at least that the aar is closed or blocked and the leaking MPS is unplugged. If the vacuum is up around 18-20 inhg I might not bother with the valves just yet.

I would also time your engine for the moment using the vacuum method. This is the way people used to time their engines in the old days. Disconnect the retard. Get the engine warm and idling at that 900 again (disconnect the mps or whatever was necessary). Check the vacuum, turn the distributor either way and watch the vacuum. You want to find the highest vacuum with the engine still running well. Then back it down 1-2inhg. If the vacuum is quite high (over 21inhg) I would just bring it down to 19inhg. If 19 or 20 is as high as it goes, I would maybe bring it back 1 inhg so it's between 18 and 19 just to be safe.

If you don't have much faith in your timing marks or the light this should work fine. You could now check the timing with the light and see where you are at idle and all in at 3.5k rpm.

Since you have a 2056 I don't know what to think about the 'euro spec' MPS. Sounds like the daiphragm is busted anyway so you will probably need one of Chris Foley's rebuild kits and at that point you will be tuning your own MPS anyway. I am not sure if the 2056 sucks enough gas over the stock to require that inline resistor though. Your ECU is already richer than the 73 that required that resistor. Better rich than lean and if you have a hunting idle, I would keep it for the time being. You might try richening the ECU pot to see if that hunting idle goes away.

While you are working on this you may just want to keep that retard disconnected until everything is where it should be, then deal with the retard afterward. The nice thing about the retard is that you can put some extra timing into your engine and still have it start up nice and easy but we are not there yet.

Thanks Emery,
all good suggestions . My day is growing short as we have a dinner party to go to @5:00 so I might not be able to do all this today .Lots of great suggestions . That would great if I didn't have to worry about adjusting the valves today . I am going to have to look up and do some studying it's been almost 50 years since I last did this on my VW's and I read somewhere that I will need to remove my HE's for access this might take a while and I still need to have a TDC mark I can trust . I do have this to help There is a mark on my flywheel and I can see it . Maybe tomorrow when girlfriend is here I can get her to look for the mark when it is aligned where the cases meet and hold my accelerator to 3500 for me . I believe Blue Lighting used this mark in one of his posts . I will jack the car up and put in 5th and turn the rear wheel while she looks for it . Not sure how once aligned I could use that to add a paint pen mark to my cooling fan as I cannot see any marks in the V cutout on my fan.

I only ordered that hot set up resistor because the box of stuff that came with the car had a homemade thingy that looked like an inline resistor ( it feel apart on me ) I had no idea what it was for so I searched and found this on AA site.However the motor was the stock 2.0L although Im not sure why it was in box with the other parts of the motor or if was even connected inline with the CHT. I have the ECU adjustment knob set at 9:00 position as I read somewhere
I am pretty sure I warmed up the car with everything connected then I removed the 10mm & 5mm hoses that went to the decel and plugged them, I removed the 10mm that went to my MPS and clamped it close and added another hose to my MPS and added 20inHG to it and then started the car again.
Now to testing the vacuum on the plenum .
Im a bit confused about how to use the mityvac to test the amount of vacuum in the Plenum so let me think about that one for a bit and Ill get back to you .I like that method
let write a list outlining the steps for you to confirm my understanding in a bit

[emerygt350]

Definitely check the vacuum before you go breaking into the valves. If the vacuum is good, that really points to no real problem with the valves. No need to go crawling around if you don't have to. All you need to do is attach the mityvac to the hose that would normally go to the MPS or even the vacuum retard port on the TB if you want to leave the MPS attached. The engine vacuum will register on the mityvac gauge (don't pump it or anything).

When you do get around to adjusting the valves, I seriously suggest you do the crusty method, that allows you to set the gap without having to worry yourself about which cylinder is on a compression stroke. You just turn the wheel till a valve is completely compressed (very easy to see as you roll the wheel back and forth) and then adjust the opposite valve on the engine. There are only four lobes on the cam each lobe operates 2 valves on opposite banks, so when cylinder 1 exhaust is completely compressed, cylinder 3 exhaust is as loose as it can get.

[Ron914]

Definitely check the vacuum before you go breaking into the valves. If the vacuum is good, that really points to no real problem with the valves. No need to go crawling around if you don't have to. All you need to do is attach the mityvac to the hose that would normally go to the MPS or even the vacuum retard port on the TB if you want to leave the MPS attached. The engine vacuum will register on the mityvac gauge (don't pump it or anything).

When you do get around to adjusting the valves, I seriously suggest you do the crusty method, that allows you to set the gap without having to worry yourself about which cylinder is on a compression stroke. You just turn the wheel till a valve is completely compressed (very easy to see as you roll the wheel back and forth) and then adjust the opposite valve on the engine. There are only four lobes on the cam each lobe operates 2 valves on opposite banks, so when cylinder 1 exhaust is completely compressed, cylinder 3 exhaust is as loose as it can get.

Very sound advice Emery ,
I will use the Crusty method , Im all about efficiency and things that don't waste my time
I was trying to figure out about checking the vacuum first but I had to pump the mighty max to add 20inHG on my MPS I wasn't sure how I was going to connect to my plenum and read the draw, makes since the way you just explained . I love working on this car, learning things as I go .As the quote goes "You can give a man a fish to eat today but teach him how to fish and can eat for life " Thanks again for working with me and I've been collecting more cool tools

[Ron914]

Definitely check the vacuum before you go breaking into the valves. If the vacuum is good, that really points to no real problem with the valves. No need to go crawling around if you don't have to. All you need to do is attach the mityvac to the hose that would normally go to the MPS or even the vacuum retard port on the TB if you want to leave the MPS attached. The engine vacuum will register on the mityvac gauge (don't pump it or anything).

When you do get around to adjusting the valves, I seriously suggest you do the crusty method, that allows you to set the gap without having to worry yourself about which cylinder is on a compression stroke. You just turn the wheel till a valve is completely compressed (very easy to see as you roll the wheel back and forth) and then adjust the opposite valve on the engine. There are only four lobes on the cam each lobe operates 2 valves on opposite banks, so when cylinder 1 exhaust is completely compressed, cylinder 3 exhaust is as loose as it can get.

Very sound advice Emery ,
I will use the Crusty method , Im all about efficiency and things that don't waste my time
I was trying to figure out about checking the vacuum first but I had to pump the mighty max to add 20inHG on my MPS I wasn't sure how I was going to connect to my plenum and read the draw, makes since the way you just explained . I love working on this car, learning things as I go .As the quote goes "You can give a man a fish to eat today but teach him how to fish and can eat for life " Thanks again for working with me and I've been collecting more cool tools

I'll be asking for help when I get to adjust the valves down the road , How often ?miles should I be adjusting them . I probably have just a few hundred miles on my new motor now while testing driving around in my neighborhood.

[Ron914]

Definitely check the vacuum before you go breaking into the valves. If the vacuum is good, that really points to no real problem with the valves. No need to go crawling around if you don't have to. All you need to do is attach the mityvac to the hose that would normally go to the MPS or even the vacuum retard port on the TB if you want to leave the MPS attached. The engine vacuum will register on the mityvac gauge (don't pump it or anything).

When you do get around to adjusting the valves, I seriously suggest you do the crusty method, that allows you to set the gap without having to worry yourself about which cylinder is on a compression stroke. You just turn the wheel till a valve is completely compressed (very easy to see as you roll the wheel back and forth) and then adjust the opposite valve on the engine. There are only four lobes on the cam each lobe operates 2 valves on opposite banks, so when cylinder 1 exhaust is completely compressed, cylinder 3 exhaust is as loose as it can get.

Very sound advice Emery ,
I will use the Crusty method , Im all about efficiency and things that don't waste my time
I was trying to figure out about checking the vacuum first but I had to pump the mighty max to add 20inHG on my MPS I wasn't sure how I was going to connect to my plenum and read the draw, makes since the way you just explained . I love working on this car, learning things as I go .As the quote goes "You can give a man a fish to eat today but teach him how to fish and can eat for life " Thanks again for working with me and I've been collecting more cool tools

I'll be asking for help when I get to adjust the valves down the road , How often ?miles should I be adjusting them . I probably have just a few hundred miles on my new motor now while testing driving around in my neighborhood.

With your help I think I will be able to drive it to WCR this year in June .