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Old 01-29-2007, 01:43 PM
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Corvair engine running troubles

I have a 62 engine in a dune buggy. It is having terrible running problems and I am not sure exactly what is going on. Here's what I have tested:

1) Rebuilt carbs, then replaced carbs with used carbs
2) Adjusted carb floats
3) Connected loose piping to tranny (vaccuum lines)
4) Replaced alternator
5) Replaced fuel lines and installed new tank, added new electric fuel pump
6) Adjusted the air/idle mixture with syncrometer.
7) Replaced plugs
8) Changed oil and found no metal chillings

The engine idles reasonably okay. In neutral, whenever I step on the gas the engine wants to die. If I slowly increase the gas it runs faster, but then might might backfire either out the exhaust or the carbuerator. I think the problem might be the gas delivery. The outlet on the new tank is a little small. I am running 1/4 inch lines. when I got this dune buggy it was running off gravity feed and had the throttle fixed about half open. So you put it in gear and go... When I was adjusting the air/idle mixture I let it warm up then I removed the thermostats hooks (so they are wide open) and then tune it. I was told the belt has something to do with timing. I have no idea how to set timing on the engine. My best idea at this point is that the fuel delivery is inadequate or restricted in some way. Any thoughts? I just bought a corvair troubleshooting booklet for mechanics to see what's up. Thanks everyone. -Mike

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Last edited by lugog; 01-29-2007 at 01:50 PM.
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Old 01-29-2007, 01:55 PM
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Sounds like fuel pump.........You said gravity feed....Is there not a fuel pump on these?

OK..you said electric fuel pump.......Maybe those small fuel lines are hampering flow.
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Old 01-29-2007, 02:00 PM
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Quote:
Originally Posted by poncho62
Sounds like fuel pump.........You said gravity feed....Is there not a fuel pump on these?

OK..you said electric fuel pump.......Maybe those small fuel lines are hampering flow.
Sounds like the acellerator pumps in the carbs need replacing or it could be a timing issue.
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Old 01-29-2007, 02:02 PM
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Check the pressure on the fuel pump. To much pressure will cause the carbs to flood. Make sure you have the crossover pipe connected and that it doesn''t have any leaks at the hoses. I have rebuilt my carbs several times and still could not get it running right. I finally sent them off to an expert and he sent me back a list of all things I did wrong even when I carefully followed the instructions on the kit. My carbs were flooding so bad I ruined a $45 zero balance guage. Tune up is the same as any chevy. Set the timing to 8 btdc. The trick with these is to balance the carbs. Sounds like you have done that but a syncrometer is not the most accurate way to do it. Use a zero center guage or make one by putting your vacuum guage in a sealed bottle and attaching a fitting to the lid. connect the vacuum guage to one carb and a hose to the fitting to the other carb. You should be showing no pressure on the guage if it is balanced. You may have to reverse hoses to check since the guage stops at zero.

Double check your plugs. Don't use platinum plugs. They fail almost immediately. I use Bosch Supers.

Make sure there are absolutely no vacuum leaks.
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Old 01-29-2007, 02:03 PM
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Definitely not accelerator pumps. I rebuilt the carbs then replaced them with a used pair that was working on another engine when removed. Timing? I don't know how you check/set that on a corvair. A vw you do it by moving the pulley to 4 or 7 degrees and using a checklight at the coil.
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Old 01-29-2007, 02:08 PM
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Quote:
Originally Posted by Mertz
Check the pressure on the fuel pump. To much pressure will cause the carbs to flood. Make sure you have the crossover pipe connected and that it doesn''t have any leaks at the hoses. I have rebuilt my carbs several times and still could not get it running right. I finally sent them off to an expert and he sent me back a list of all things I did wrong even when I carefully followed the instructions on the kit. My carbs were flooding so bad I ruined a $45 zero balance guage. Tune up is the same as any chevy. Set the timing to 8 btdc. The trick with these is to balance the carbs. Sounds like you have done that but a syncrometer is not the most accurate way to do it. Use a zero center guage or make one by putting your vacuum guage in a sealed bottle and attaching a fitting to the lid. connect the vacuum guage to one carb and a hose to the fitting to the other carb. You should be showing no pressure on the guage if it is balanced. You may have to reverse hoses to check since the guage stops at zero.

Double check your plugs. Don't use platinum plugs. They fail almost immediately. I use Bosch Supers.

Make sure there are absolutely no vacuum leaks.
Ah okay, I'll check for leaks... I forgot to mention. I replaced the coil, spark plugs. I added a fuel regulator guage to let me dial in the pressure because I assumed my problem was flooding to start off. I am using platnum spark plugs. Why do these get ruined? I am also running platnum plugs in my air cooled vw. Maybe I should change them all.
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Old 01-29-2007, 02:12 PM
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Thanks for all your fast responses so far. I am new to this forum and this is really helpful. Sooner or later, I'll get my projects posted on this site. (two avengers, fiberfab banshee, dune buggy)
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Old 02-02-2007, 02:03 PM
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This may be late but you can set 0 tdc by setting your timing mark on the damper to 0 making sure you are on #1 cylinder. Remove the #1 plug and reattach the wire. Lay it on the engine were you can see it and it is grounded. With the ignition on turn the distributor until you see spark at the plug. This will set the timing at 0 tdc. You can set it at 8 BTDC by setting the timing at 8 btdc and turn until you get spark. You need to turn the distributor in the direction opposite that the rotor turns so it will be on the front side of the contact like it would if the rotor was turning and not the distributor.

Hope this helps.

I don't remember why the platinum plugs fail but they do and in a hurry. Try the Bosch and you won't have any more problems.

Let us know if you get it running right.
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