Engine Runs just OK?

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Francesco
Posts: 166
Joined: Sun Nov 18, 2012 1:03 pm
Location: Thousand Oaks

Engine Runs just OK?

Post by Francesco »

Hey everyone, I recently rebuild the motor on my Corvair, and now it's running. Here's a list of what I did:
40 over TRW pistons
moly rings
STD/STD crank with new bearings
otto-tb 10 cam
I got it through break in, and while it's going it runs great, however it doesn't want to idle. I have it set around 800, and it jumps anywhere from 600 to 1000 depends on the car's mood. The only thing I haven't touched is the distributor on the car, everything else in the engine is new! It has electronic ignition as well, and the timing is set at 24 degrees BTDC(turbo motor). I adjusted the carb multiple times, and it runs completely fine while going, has power and everything. Any ideas?
Thanks,
Francesco
1966 Aztec Bronze Turbo Convertible Project (Currently not on the road)
Francesco
Posts: 166
Joined: Sun Nov 18, 2012 1:03 pm
Location: Thousand Oaks

Re: Engine Runs just OK?

Post by Francesco »

Also, just thought of this. When the motor is cold, it stalls a lot. I tried adjusting the choke, but it won't fast idle. Not sure how to adjust that, but the carb was rebuild by the carbmeister a while back, so I figured it would be fine.
1966 Aztec Bronze Turbo Convertible Project (Currently not on the road)
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91blaze
Posts: 446
Joined: Thu Jan 09, 2014 11:35 pm
Location: Indiana

Re: Engine Runs just OK?

Post by 91blaze »

Check your carburetor linkages and make sure nothing is loose or binding. Especially check that there is not much play in the throttle shaft.
'66 Monza Coupe Project: viewtopic.php?f=52&t=7188" onclick="window.open(this.href);return false;
Francesco
Posts: 166
Joined: Sun Nov 18, 2012 1:03 pm
Location: Thousand Oaks

Re: Engine Runs just OK?

Post by Francesco »

Throttle shaft is nice and tight, the carb Meister put the screw in it. The linkage is all rebuilt and new, total pain in the ass but I'm sure it doesn't bind
1966 Aztec Bronze Turbo Convertible Project (Currently not on the road)
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91blaze
Posts: 446
Joined: Thu Jan 09, 2014 11:35 pm
Location: Indiana

Re: Engine Runs just OK?

Post by 91blaze »

I would bring it to the attention of the carbmeister then. It definitely sounds like something is off in the carbs.
'66 Monza Coupe Project: viewtopic.php?f=52&t=7188" onclick="window.open(this.href);return false;
squidlong
Posts: 24
Joined: Wed Jun 10, 2015 6:36 am

Re: Engine Runs just OK?

Post by squidlong »

Sounds like it may a vacuum problem? Did you replace the two rubberr hoses that exit the carb base and connect to the vacuum tube? What about the vacuum hose from the right carb to the distributor, maybe it is brittle or too large diameter. Lastly, maybe a cracked bakelite gasket at the carb base? I have had similar problems with my 'Vairs and 60's water pumpers, rebuilding everything but neglecting the smallest detail that resulted in the same type of problem you are having. Good Luck!
Squid
Van Buren, IN
"Caddy" Mike :chevy:
Marion, IN
'66 Monza Coupe 140
'64 Corvair "700" Coupe (owner conversion)
'57 Cadillac Coupe
'64 Cadillac Coupe "500 cid"
'61 Chevy Biscayne "327"
Francesco
Posts: 166
Joined: Sun Nov 18, 2012 1:03 pm
Location: Thousand Oaks

Re: Engine Runs just OK?

Post by Francesco »

squidlong wrote:Sounds like it may a vacuum problem?
The gasket is new and not torn from the carb to turbo, and the rubber house is nice and pliable. The only vacuum leak I know I have is at the base of the turbo, I have no choke tubes because I converted to electronic ignition. When I convert to a b/f turbo I plan on filling those in with some welding rod. Could that be my problem?
1966 Aztec Bronze Turbo Convertible Project (Currently not on the road)
squidlong
Posts: 24
Joined: Wed Jun 10, 2015 6:36 am

Re: Engine Runs just OK?

Post by squidlong »

As the turbo is an integral part of the induction system, any vacuum leak would be suspect. An easy diagnosis is to take a can of gumout or carb cleaner and spray it around any suspected intake vacuum leak while the engine is running. If you notice the engine immediately speed up, you've found your problem. Turbo motors are a joy to drive when they are set up and run correctily but when they are not.....whew!! BTW I also have a lovely '66 Aztec Bronze CT with a 140/4speed. Great color and so much fun to drive. Good luck with your project!
Squid
"Caddy" Mike :chevy:
Marion, IN
'66 Monza Coupe 140
'64 Corvair "700" Coupe (owner conversion)
'57 Cadillac Coupe
'64 Cadillac Coupe "500 cid"
'61 Chevy Biscayne "327"
Francesco
Posts: 166
Joined: Sun Nov 18, 2012 1:03 pm
Location: Thousand Oaks

Re: Engine Runs just OK?

Post by Francesco »

It's not a leak at the base, there's just no choke tubes in the exhaust housing, so there's two holes in it. Should I plug them somehow?
1966 Aztec Bronze Turbo Convertible Project (Currently not on the road)
squidlong
Posts: 24
Joined: Wed Jun 10, 2015 6:36 am

Re: Engine Runs just OK?

Post by squidlong »

You may try that although the major sources of vacuum leaks would be on either head where the crossover enters, the rubber hose between the turbo and intake, the gasket between the carb and turbo, the vacuum line from the right head to the pressure retard or the actual pressure retard unit on the distributor. If you have a vacuum gauge at your disposal, it can be connected where the vacuum line enters the retard. Simply disconnect the line, put the gauge on the end of the line and start the engine. You will not have to plug the pressure retard when you do this as there is nowhere for the vacuum to go at the distributor. This will diagnose a host of problems and sort of acts as the modern day handheld OBD II unit for modern vehicles. You should see a steady 17-22 degrees of mercury at idle (800 rpm). Steady low reading of under 8 degrees indicates a vacuum leak, fluctuating needle indicates engine miss, burnt valve, or timing issues. Advance, O'Reilly, NAPA etc sells gauges for about 20 bucks. I have been using the same one for over 20 years and find it to be a priceless detection tool. I see your distibutor is untouched as well? If you feel the need, you can check the internal springs to see if one is weak, broken or missing and lasty the up/down play of the distributor shaft. These can affect the idle as well but at speed, is not as apparent. In the case of the up/down play, the distributor must be removed. Shims are very easy to install and are available in a variety of thickness to suit. I have seen minor cracks in brand new distributor caps completely frustrate me when I've done rebuilds as well. Lastly, what electonic ignition/coil combination are you running? I have had tremendous luck with some while others have ended up at the bottom of a lake someplace. Sounds like you did a great job on the motor and it will scream when you get past this dilema.
"Caddy" Mike :chevy:
Marion, IN
'66 Monza Coupe 140
'64 Corvair "700" Coupe (owner conversion)
'57 Cadillac Coupe
'64 Cadillac Coupe "500 cid"
'61 Chevy Biscayne "327"
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