son bought a 72 chevy Nova, 350 with automaic trans.?

Question

Starts up ok but everytime you put in gear it dies, isn't that a vacmun leak going to trans?

Answer 1

It could be several things, put a vacuum guage on it & that will tell you if the vacuum is low. Unhook & plug the lines one at a time to find where it is leaking & check the carb base gasket. Set the timing & give it a tune up, it may also need a carb rebuild.

If it's a 2 door super sport or rally, it can't be fixed. Call me & I'll come over immediately and get it out of the driveway for you! :)

Answer 2

Many answers, many possibilities, one or two unlikely, one or two from left field... I'll try to sift through them for you.

Scenario 1:
Could be a vacuum leak, even a small one, in park, the engine with a vacuum leak might idle around 600-650, putting it in drive, rpm's drop to around 550, but vacuum leak will cause it to die. Could ba a vacuum leak anywhere, not just on the modulator, take a can of carb cleaner and spray around your vacuum hoses with the engine running, if the RPM's drop, you found your leak

Scenario 2:
Could be a timing issue, best way to check is with a timing light, disconnect the vacuum line from the distributor and plug it, and check your timing. Many timing problems show themselves at higher idle, usually by backfiring or sputtering, if you haven't noticed these symptoms, I would rule that out.

Scenario 3:
Torque converter is a possibility, but not likely. If a torque convertor gives it up it does one of two things, it free spins, which makes all gears seem like neutral, or it locks up, which usually means if you put it in gear, it doesn't slip, causing the transmission to stall the engine, which is usually a very violent stall, I'm sure it is something you would have noticed.

Scenario 4:
Lean mixture to the carb is a good possibility, but maybe something as simple as a fuel filter being plugged up. Check that before replacing fuel lines.

Scenario 5:
Takes us back to the transmission. Assuming it is the original engine and transmission, the transmission would be a TH350 Chevy would not have put a TH400 in a Nova. Realistically, the engine and/or the tranny have been swapped out sometime in the past 35 years. Chevy used the Powerglide transmission until 1973 in Chevy Novas originally equipped with a six cylinder engine. Easiest way to determine your transmission is by the transmission pan, TH350 pan looks like a square with one corner cut off, a powerglide pan has three square sides and one long angled side, the TH400 pan looks vaguely like the state of Texas, about 7 or 8 distinct sides.

Personally, I would look towards a plugged fuel filter or air filter, vacuum leak, timing issue, then transmission problem in THAT order. No sense assuming the transmission or torque converter is bad without looking at the more likely problems.


Can't even begin to explain where a clogged governor comes in...there is a governor in the transmission but it doesn't clog and you don't "just take it off and get a new one"... there is no governor on the engine

Answer 3

It could be.
It could also mean some other things.
As far as the vacuum leak, there is a vacuum modulator, that the line to it, runs from the intake to the trans. Its purpose is mainly for telling when the trans should shift. There is a hose connected to a metal line going to this. Check this for leaks. You should have a tool such as MITY-VAC with a guage, so when applied should not lose any pressure. If it loses pressure, there is a leak. If not move on to other diagnosis.
It should be a turbo hydromatic 350 or 400. Both trans are pretty much the same, except for the heavy duty-ness.
It could also be idle/carb/timing/tuning issues. Check all these also.
I luv these old Chevys. Good luck.

Answer 4

I doubt it's a vaccum leak, more likely a problem with the torque converter in the trans. Or the idle RPM is too high. When you put the car in gear the engine is put under load so it could be many different things in the engine. When an automatic transmission is in gear the job of the torque converter is to allow slipping (similar to a cluch) when you reach the stall rpm of the converter (by reving up the engine) it stops slipping and starts turning the input shaft of the transmission which turns the drive train. Typical stall speeds for factory equip is around 1500-2000 rpm, if there's a performance conveter in it the rpm could be much higher. If the converter is not slipping properly it would be like popping the clutch on a manual trans which can easily stall the engine.

Answer 5

Part of that depends on if you are truly wanting to add 'horsepower' or if you are actually seeking to add more 'torque'. A lot of people mistake torque for horsepower. Torque is the tire smoking power you get when you stomp the gas while you're sitting at a stoplight or something. Horsepower is on the top end, higher RPMs. If you are truly wanting horsepower, the high rise open plenum intake with dual carbs is a great way to go. If you are wanting bottom end torque, go with a dual plenum intake instead of open, you don't get as much top end but more off the line. A great way to get bang for the buck is to go with a pre-designed package like the edelbrock performer or performer RPM manifolds with the edelbrock carb and cam. Headers, dual exhaust and high performance coil or MSD iginition box (if money allows) are fairly simple upgrades that really add some power. Just remember, as you add power you will also start to strain some factory components (ie. rods, crank, pistons, rear end, transmission, etc...) just be careful not to do too much without changing some of these other components also.

Answer 6

Sounds like another case of the mislocated vaccuum advance hose. If this is a holley carb, the vaccuum advance hose should go to the port that is on the side of the carb, up on the metering block. Not the port close to the manifold. When it is connected to the port close to the intake manifold, it idles fine until pulled into gear. The load on the engine makes the engine drag down, causing it to loose vaccuum, and also causeing the vaccuum advance to loose timing. Kinda like a domino effect. If the vaccuum advance is connected to the upper vaccuum port, the idle screw may have to be tweaked up slightly but, the timing won't drop off when pulled into gear and the engine should stay running when pulled into gear.

Answer 7

No, normally a vacuum leak, unless very large will not make a carburated car die. I would look at timing and idle speed. Also put your hand over the carb when running, I mean litterally on top of it, if it idles better than you have a vacuum leak, if it starts to die then your ok.

Answer 8

vacum leak or lean mix due to carb hand chokeing the carb will tell you. then check for weak spark at plugs . set alltune adjustments timing hot and cold idle. also has car been in storage might try fresh fuel. agas can with a rubber hose to fuel pump inlet also check fuel pump

Answer 9

Sure I would check all vacuum hoses maybe replace them all I remember a 68 ford truck I had ran ruff skip cutoff Fixed all that and more I replaced all vacuum hoses and I wish I still had that truck Hope this helps

Answer 10

The governor on the car is clogged. Take it off and put a new one on. Hope that helps