I have a 73 riviera, all factory stock/original, 61,000 miles. At idle, the car runs about 190 degrees. When it has been driven between 8 and 15 miles (depending on the ambient temp) the engine temp will climb to about 210 degrees. At that point, it loses power to the point where it won't even idle in drive. As long as I can keep moving, it will drive OK but if I have to stop for any reason, it's hell to get moving again. It just dies out. I have replaced the cap, rotor, points, condenser, wires, plugs, coil, fuel pump, fuel filter, rebuilt the q-jet, verified that the timing and dwell are set correctly and gone through the vacuum lines checking for leaks, etc. This is making me NUTS! Does anyone have any experience with this type of problem or have any suggestions how to deal with it? Please help. Thanx much.
At 210 deg, it should run fine. The only thing I can think of is fuel perculation. Try putting a heat shield under the carb.
look for a severe restriction in the exhaust....test by disconnecting the exhaust from the manifolds and then drive it and see how it does....
The first thing you have to determine is what its losing when it stalls out and wont restart. Do we have a loss of fuel or spark? I would attach a temporary fuel pressure gauge to the car and run it to the windshield.
Yup. I agree. If it's all original as you say...GM used double wall pipe to reduce exhaust noise. The inner pipe has been known to deform due to heat and cause severe restriction. After it cooled it opened up. As Doc suggested...kick the pipes off at the manifolds and take it for a drive in the country.
You can also determine if it is an exhaust restriction by hooking up a vacuum gauge and seeing what happens when you rev the engine. If it drops off at steady high RPMs, that's a good clue. Then drop the head pipes and try it again. If the vacuum is OK, collapsed inner exhaust pipe is the culprit. How does it run for the first few miles? If that performance is OK, I doubt that it's an exhaust restriction.
Like I said, it runs fine until it gets hotter. I have replaced the plugs, wires, points, condenser, cap, rotor, vacuum advance, coil,rebuilt a spare q-jet (from my parts car), fuel filter and fuel pump. I have also put fresh fuel in the tank. One of the other mechanics at work suggested I change the springs on the centrifugal advance, and I'm thinking maybe there is a break in the wire leading from the coil into the distributor to the points. I think the next thing I will try is swapping the distributor from my parts car. This will take care of both those items. By the way, all vacuum hoses were changed before all this started. Thank You All for your help and concern. I will continue to try your suggestions because this is too nice a ride to get rid of.
Sell to me for a grand. :Brow: I'll fly down. Take it to a muffler shop. Replace the exhaust and drive it home to PA. :grin:
You still running the tvs? If so then did you realize that the ported and manifold lines are the same size at the switch but different sizes at the carb? When the car warms up it switches between the vaccuum sources which can cause an "only at operating temp" vaccuum leak.
Do you have an EGR valve on this engine? Try disconnecting and capping the vacuum line and see if that makes a difference.
When did the problem start exactly? Did run fine before the vacuum hoses were replaced? Or did you replace the lines in an attempt to fix the problem which already existed.
TRy plugging up all the vacuum lines you don't need. Is there one from the distributor to the carb? take it off and cap both sides. My 350 smoothed out after I did that.
That line for the distributor is your vacuum advance and it is used for increased fuel economy and better drivability. As for the high temps inspect your cooling system
I suspect the egr valve or some other vacuum operated gizmo that is connected to a thermostatic valve in the block. Or maybe a heat riser flapper valve in the passenger side exhaust pipe if it has one. There probably also is a vacuum operated flapper in the air cleaner snorkel that could be staying closed. GM started putting all kinds of weird vacuum stuff on around this time to cut down pollution and/or to assist with cold weather and faster carb warm ups. I did have a collapsed exhaust pipe back in the late 70s but you could sure hear it, it whistled like hell. Good luck.
Unless the Riv got a different setup than the Electra did in '73 I can help out with some of the gizmos. There is no heat riser The hot air door in the air cleaner isn't vaccuum controlled The only therm switch vaccuum is for the distributor advance There is a hidden vaccuum line running off the back of the carb that's used to control the vaccuum accesories such as the climate control. There's also the evap system which pulls vaccuum from the carb through a purge valve mounted on the passenger side of the intake.
SteeveeDee; The EGR valve was removed and capped off in the process of troubleshooting this problem. JZRIV; The vacuum hoses were replaced before this problem began. EEE; I have a stant 180 deg. superstat to install, but I would really like to make sure this problem is solved before I try to tackle the temperature situation. I don't like it when it runs 210. rogbo; There is no heat riser flapper valve installed in this car. I did check the operation of the snorkle hot air door as per the '73 Buick chassis manual. It checked out good. bammax; yes, the tvs is there and connected. In fact, after this problem began, I took a close look at it and discovered it was not connected as per the chassis manual, so I rearranged the lines to match the manual diagram as closely as I was able. It didn't help. Thank You all for your help. I appreciate your suggestions.
Let's start by asking the stupid question...are you sure that your choke has completely pulled off when you are having this problem? All the talk of advance components, etc should not effect your problem you describe. Advance would effect your performance at higher RPM. I guess it could possibly be the distributor, but 'hot fuel' is what keeps jumping through my mind. The thing is though, since you're all stock, I would question how 'hot fuel' could even occur and confusedly suggest distributor, especially since you have a known good one to try.
