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Posted by: OU8AVW Sep 9 2015, 09:04 AM

I have a built 2056 with stock D-Jet set up based on a 1974 motor. I have it pretty dialed in and my air-fuel ratios are pretty sweet. I'm happy with how it runs, pulls and how fast it is. (It's pretty quick )

My next challenge is to sort out the deceleration issues. I have a decel valve installed but I am not sure that it's working or even plumed properly. I have a vacuum gauge on the way so I can test it accurately.

I understand that I should test the valve by revving to 3k and dropping back to idle while looking for vacuum to happen for a short period when the air intake closes.

I also see a vacuum fitting on the retard side of the distributor. I think that the die-on-decel issue comes from the AF mixture changing too quickly when the air intake is closed while the dizzy is still advanced from being revved at 3k. Is the retard side vacuum fitting used to counter act this tendency? Right now it's left open....

Thanks in advance, or retard, whichever is applicable

Posted by: LowBridge Sep 9 2015, 09:40 AM

I don't have an answer, but EPIC close on the post

Posted by: era vulgaris Sep 9 2015, 10:05 AM

Are you using the 2.0 DJet setup? The vacuum fittings on the dizzy canister should connect to the ports on the throttle body.

On my old 1.7 I simply adjusted my decel valve by trial and error. Turn the adjuster nut until it behaves the way you want it to.

Posted by: boxsterfan Sep 9 2015, 01:05 PM

http://bowlsby.net/914/Classic/zTN_FI_Hose_Vac_2.0L_1973-Early1974.jpg

Posted by: r_towle Sep 9 2015, 05:39 PM

So, the advance and deceleration in the distributor are for emissions.

Try plugging both ports on the throttle body and leaving both ports on the distributor open to the air.
See how you like it.

Advance gives you a slightly better slow acceleration off the line without you needing to rev it up to 3k to pull away from a light...which most of us do anyways.
The main advance is mechanical and happens at about 3k Rpms.
The advance pulls the plates slightly advances as you pull away from a light, it has some positive affect, but not loads.

The decal valve is to prevent over run as you slow down, it helps keep yr mixture lean.
It pulls the plates back from full advance as y slow down, burning less fuel.

The car runs perfectly fine with no Deceleration valve hooked up
It runs slightly worse with no advance hose hooked up, but it's negligible if you are an aggressive driver...

Rich

Posted by: OU8AVW Sep 9 2015, 06:37 PM

Rich,
Thanks for always replying to my questions. I have honestly tried every bit of advice you have given me. Mostly they work out pretty bad.

What I'm trying to do is hook all this stuff up as it came from the factory and then back up from there. Seems like it gets better with every original bit I hook up and get tuned.

Posted by: r_towle Sep 9 2015, 07:12 PM

Well carry on then.

You will learn by doing.

Posted by: Highland Sep 10 2015, 08:58 AM

My car only has the distributer retard port ('74), so is it okay to leave it not connected?

Am I doing any damage by not retarding the timing at idle cause the engine seems to idle much better without the retard line hooked up?

Posted by: OU8AVW Sep 11 2015, 07:28 AM

If we learn more from our failures than our successes I ought to be a frigging genius by now

Posted by: OU8AVW Sep 11 2015, 07:37 AM

A few points of question on the image....

Posted by: rhodyguy Sep 11 2015, 07:46 AM

Did you check the stacked elbow for cracks? Where the green and red lines in ? connect.

Posted by: OU8AVW Sep 11 2015, 01:27 PM

No stacked elbow installed yet because the oil breather is not on. I have a good one to install.

Posted by: r_towle Sep 11 2015, 03:40 PM

Don't follow my advise.
If you are trying to sort out the vacuum leak, and performance, you may want to actually hook everything up as it's supposed to be hooked up, all elbows etc.

Posted by: OU8AVW Sep 12 2015, 06:26 AM

That's the idea. Maybe then i can work backwards and pull unnecessary stuff off.