Engine suddenly pooped out.

[RBohl]

I have a 1965 Corsa with a rebuilt 140 engine, which has a slightly hot Clark's cam and a Pertronics 1 ignition. I very recently refit the primary carbs on the engine as the engine rebuilder had installed mismatched carbs, one was an earlier model w/o the engine enrichment circuit and a too-small main jet; I exchanged that with a 1965 primary with a 0.052" jet. The second carb, was the correct vintage but a main jet that appeared to have been drilled out to a questionable size, so I changed that as well to a 0.052". After checking the float rise and fall, resetting the carb's links, reinstalling the carbs, adjusting the cross-over linkage, and syncing the carbs to about 750rpm, I took the car for a spin. It ran great, the engine settled to a nice idle and performed better than ever under throttle. So I patted myself on the back, a big mistake.

Today I decided to drive around the neighborhood to warm up the engine so I could flip the Summer/Winter plate. For about a mile, the engine ran very well. Then I pulled up to a stop sign and the engine settled back to idle. However, when I pulled away from the intersection the car stumbled (with very little power) and this continued while I limped home. When home I removed the air cleaner and visually checked the linkage (looked OK), the two chokes (fully open), and the timing (dead on). When blipping the throttle equal amounts of gas entered the carbs. All the plug wires appeared to be seated, The harmonic balancer also checked out OK and there was no apparent flooding. The only thing I noticed was that the engine temp barely reached 200 degrees after approx. 2-1/2 miles, and that the right side thermostat door hadn't opened. Considering that the engine didn't get that warm I thought that this wasn't a concern (the thermostats can be a bit cranky). I'm sure many of you had situations where your Corvair ran well until it suddenly didn't,so you can understand my frustration. I'm not sure what to check next so any advice will be appreciated. Thanks.

[RexJohnson]

I would be checking the carb on the right side. If you put your hand over it does it make the engine run any different?. Since the right thermostatic door didn't open it sounds like it's not making any heat on the right side.

[jfreez]

I would take a look at the plugs and see if it looks to be running too rich on the cold side.

Its just an easy place to start

[Spectre]

Double check the linkage thoroughly. If one of the primaries became disconnected, it will run like you described.

[American Mel]

You might also want to check the vacuum balance tube.
I had one fall off once and the engine acted the same way.
Running perfect, then stumbling horribly.

[bbodie52]

If one carburetor is "dead", your dual exhaust should help to provide a clue. The exhaust sound and the temperature of the exhaust gases should be noticeably different from the other side.

If you are effectively running on three cylinders, an ignition problem is unlikely. That leaves fuel... since you had been playing with the float settings, could the needle and seat or float assembly be stuck somehow in the faulty Primary?? If the float bowl is empty, I would guess that there is no output from the accelerator pump as well.

If you disconnect the throttle linkage connection to each carburetor and manually open one carburetor throttle at a time, you may get a noticeably different response from the "dead" carburetor. Opening up the carburetor and inspecting the float mechanism may reveal the cause of your problem.

[RBohl]

Thanks for all your suggestions. BTW, I think I mentioned the right primary as being the carb with the thermostat door symptom. My goof it's the left carb . I have been going through each of your suggestions and could not find anything out of place, etc. until I fired up the engine (still the same problem) and found that gas was not being pumped out of my left carb's discharge/squirt hole; this was not the case during an earlier inspection but...
It looks as if I'll have to remove the left primary carb AGAIN to find the problem, which may be connected to the accelerator pump. its spring, its needle valve, the float valve, or a clogged port. Have any of you had this experience? I have all the parts mentioned except the pump itself. Meanwhile, it appears that I have a three-cylinder engine. Thanks for your help.

[Scott H]

Thanks for all your suggestions. BTW, I think I mentioned the right primary as being the carb with the thermostat door symptom. My goof it's the left carb . I have been going through each of your suggestions and could not find anything out of place, etc. until I fired up the engine (still the same problem) and found that gas was not being pumped out of my left carb's discharge/squirt hole; this was not the case during an earlier inspection but...
It looks as if I'll have to remove the left primary carb AGAIN to find the problem, which may be connected to the accelerator pump. its spring, its needle valve, the float valve, or a clogged port. Have any of you had this experience? I have all the parts mentioned except the pump itself. Meanwhile, it appears that I have a three-cylinder engine. Thanks for your help.

I had a similar problem recently on my dad's car. The carb float got stuck. Turned it into a 3 cylinder.