chyene

Hello , have a 72 olds cutlass with a bad/broken DVCS and car wont shift out of first gear can i bypass? also did a intake, carb, distributor swap edelbrock..so any suggestions would like to keep oem part if any one has one for sale that would be great

Octania

I don't think it works that way
Your trans should get manifold vacuum from the manifold directly, not thru any sort of switch.

If you are talking about that thermal sensitive three nipple [possibly with electrical connections 70-72] device at the front of the intake.... please describe what you think that item's function is and how it is [should be] connected.

I believe, from past experience, that if the vacuum hose to the trans modulator valve [RH side, where the vacuum hose is] gets disconnected, you will experience no shift until a very high RPM. With all the work you did, I would say this is a good possibility, and certainly easy enough to check at the trans. If the hose is still on, pull it off and verify that it has manifold vacuum when the engine is running.

MDchanic

+1. DVCS has nothing to do with shifting (or with anything important at all, really).

Check your modulator hose to be sure it's connected properly, both top and bottom.
If it is, then check inside for the presence of ATF - if it's there, your modulator's shot.
If there's no obvious ATF, suck on the engine end of the line. You should be able to pull and hold a vacuum (no leaks).
If that works, then try it again with the lower end of the line disconnected from the modulator - if you can still pull a vacuum, then the line is blocked.

Welcome to ClassicOlds.

- Eric

Octania

oh damn that was a really well summarized troubleshooting procedure for the vacuum feed to the modulator.

While it is possible for the modulator to fail w/o leaking ito the vacuum line it is extremely unlikely and an incorrectly connected modulator vacuum line is far more likely.

Macadoo

Did you mess with/upgrade anything else? It could be your kickdown cable that runs from the accelerator pedal to the trans. Make sure it's adjusted properly and not sticking.

I deleted my DVCS with no ill affects.

oldcutlass

Wow Mac, good suggestion, you beat me to it.

Macadoo

I learned from the best

chyene

the electric connection on top of the Dvcs what should i do with this if i by pass i was reading in the service manual cd that i just got today that it hooks up to the transmission switch? do i leave it alone maybe tape it up ? and thanks for all the input guy im still learning ....

chyene

thanks for the suggestion weather suck right now maybe check on it when the snow blows threw

MDchanic

Ignore it.

It activated the DVCS, which you are not using.

And advance your timing to at least 5 to 10° BTDC at idle with the vacuum advance disconnected.

- Eric

chyene

got it running at about 11 pretty smooth thats with the hei dist with the vac pulled and cap hope tommorow weather is better so i can get some car time

MDchanic

If you're running an unmodified HEI, you may need to advance it to about 20° at idle.

- Eric

Macadoo

IIRC, I have mine at about 18 at idle with a stock HEI. But I also added a limiter to the vac advance; mine was allowing way too much.

Fun71

Stock HEI (at least the GM made ones) have ~14-16º mechanical advance, so the initial needs to be ~20º.

oldcutlass

I would set your total mechanical timing without vacuum to 34-36 at around 3600 rpm, and then see what your initial is at idle. Make sure it doesn't advance any further up to 4500.

Fun71

Yep, that is the best method. Initial is just whatever it happens to be after the total is set to the desired number.