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Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: June 01, 2011 08:22PM

allright, so I did something stupid with my timing the other day and advanced it way too far. I drove around a little and the engine was pinging like crazy. i stopped driving and backed it off to 14 degrees. just before i got home, the car lost power in kind of a big way.

there were no strange noises, but it wouldn't idle anymore. it would still hold at 650 rpm, but now i had to push on the throttle a little to get it. if i just let go of the throttle while it's warm, it dies. it will start up from cold as if nothing was ever wrong, but as soon as it warms up a little it dies.

i proceeded with a dry compression test:


good side problem side

6: 145 5: 160
4: 140 3: 161
2: 135 1: 150


the spark plugs on the right side seemed a little oily which i could have something to do with the higher numbers on that side.

i presumed that everything was fine and began a carburetor synchronization as outlined in the shop manual.

after i used the paper drag test to set the idle screws and used a vacuum gauge connected to the spark ports with a barbed "T". vacuum was already very even between the carbs with the problem side not quite an inch lower.

i was going to adjust the choke control rod when i realized the rod on the passenger side hadn't extended to open the choke at all. the left side carb had fully opened the choke as it had been running for awhile. i checked the thermostat doors and the left one was starting to open, but the right side was totally closed. i touched the thermostat shroud and it was noticeably cooler than the side with the open door.

i next idled the engine at 1100 rpm with the turnbuckle set up and started grounding spark plugs. grounding the plugs on the right hand side had no effect on engine speed. grounding plugs on the left hand side definitely slowed the engine down. i replaced the spark plugs on the trouble side with some brand new ngk's to no effect. i really pressed down on the wires to make sure they were seated too.

i confirmed the electric fuel pump was feeding the weak bank by observing the accelerator pump squirting fuel into the carb throat.

SO... what do you guys think? overly rich mixture? clogged jet? i'm pretty much going to assume it's something up with the carb unless someone has another idea.


post script

prior to all this timing nonsense, i was trying to fix a really strange vacuum issue where i got about 12 inches at 700 rpm with a gauge connected to the balance tube. the more throttle i gave it the vacuum i got. at 3000 rpm i got 25 inches of vacuum and full throttle it gave me 0 inches. this is all measured with a gauge in the engine compartment. i've never measured it from the cabin while driving. i don't know if you'd see different vacuum numbers that way.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: bubba ()
Date: June 01, 2011 08:36PM

check and see if its gettin enough gas on the "bad" side. my 80 hp had the same prob. come to find out, one side of THE FLOAT was really bent.

bubba, chester ca.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: June 01, 2011 08:43PM

dang, how's something like that happen inside the carb after it's been installed?

=================================================

'65 Black Monza Coupe w/black interior
110HP w/4-spd

Greetings from Oakland, CA!

no trim badges anywhere (and there never will be!)

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: Marco_a_p ()
Date: June 01, 2011 08:45PM

Sounds like you either have the idle mixture screw closed.
Turn the screw all the way down - GENTLY! and then back out 2 1/2 turns.
if it idles poorly (weak) adjust the idle mixture screw slowly out more. If no difference, go the other way, you want the strongest smoothest idle you can get.
If you listen closely, you will hear the difference,

If that fails, turn the curb idle screw in a 1/4 turn at a time to see if it comes to life.

It sounds like you are not getting fuel the weak bank, so either its shut off at the idle mixture screw, the throttle plate is shut, or you have dirt in the jet or the air bleed tubes. if all the carb adjustments to dont help, pull the carb top off and look in side. if its full of trash, you need to remove the carb and clean it out good. Pull the venturi cluster and hold it up to the light. If you dont see light through all the brass vent tubes...you found your problem.

If the carb is full of trash, you need to repalce the filter stones at the inlet and add a good disposable filter at the rubber line behind the LH rear wheel.

Marco
A 2nd Gen Monza Wagon, a 2nd Gen GB 8door, a 2nd Gen (61's were 1st Gen) R/s and a 62nd Gen Turbo coupe..

Hanging out with the scorpions, king snakes, road runners, coyotes and quails In the southern desert of the silver state
Mesquite NV 89024

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: June 01, 2011 09:07PM

what about that vacuum issue, anyone able to tell me what i'm seeing there?

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: MattNall ()
Date: June 01, 2011 09:09PM

mechanicalman Wrote:
-------------------------------------------------------

> prior to all this timing nonsense, i was trying to
> fix a really strange vacuum issue where i got
> about 12 inches at 700 rpm with a gauge connected
> to the balance tube. the more throttle i gave it
> the vacuum i got. at 3000 rpm i got 25 inches of
> vacuum and full throttle it gave me 0 inches. this
> is all measured with a gauge in the engine
> compartment. i've never measured it from the cabin
> while driving. i don't know if you'd see different
> vacuum numbers that way.

================================================================

Typical for an UNLOADED" "engine.... when driving the vacuum acts totally different..

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: vairchet ()
Date: June 02, 2011 09:00AM

From what has been described, it would appear to be a classic case of crap stuck in idle circuit of right carburetor. Corvairs can deceptively idle on one carburetor with ease.

To repair: Remove idle mixture screw and use compressed air to blow out threaded passage. Reinstall idle mixture screw. Turn idle mixture screw until gently bottomed out. Back out screw approximately 1 1/4 to 1 1/2 turns. Start car. Then tune engine for best idling performance.

As for a possible vacuum leak: Check carburetor base gaskets; hoses that connect to crossover tube; if early, worn out PCV; if late, enlarged port in CCV tube (suppose to be about .060); failed choke pull-offs; ill fitting or split hoses to choke pull-offs; if automatic, damaged connector hose to modulator.

Carburetors that are not balanced properly, will also give low vacuum readings. So will low idle and retarded timing. Timing shouldn't be set beyond twelve degrees initial advance unless there's a super duper cam installed (or turbocharged).

Speaking of camshafts: Cams that have large amount of valve duration will also have low idle vacuum. Even restrictive exhaust can lower vacuum readings.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: bubba ()
Date: June 02, 2011 02:43PM

mechanicalman Wrote:
-------------------------------------------------------
> dang, how's something like that happen inside the
> carb after it's been installed?


dude, i have no clue. it was on there for about a year and when i took a right hand turn at speed, it died on that one side only. i took off the top of the carb and holy chit!! the one side of the float was about a half in. higher than the other side. float gremlins, i guess.

bubba, chester ca.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: June 02, 2011 08:48PM

whelp... took the carbs off and apart. the idle jet tube on the venturi cluster for the problem side was almost totally clogged with some trash and i imagine other various orifices had some junk in them too. the whole thing is apart and soaking in cleaner now while i await a teflon shaft bushing kit from clarks.

i also noticed that one of the carbs was sucking air around the choke shaft when i put my hand over the intake. should i be worried about that and how would i go about fixing it? haven't really seen an accepted solution for sealing the choke shafts.

you guys think i should swap the carbs, left-to-right, when i reinstall them to make sure they were the problem in the first place?

=================================================

'65 Black Monza Coupe w/black interior
110HP w/4-spd

Greetings from Oakland, CA!

no trim badges anywhere (and there never will be!)

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: LeeS ()
Date: June 02, 2011 09:39PM

Leakage around the choke shafts is why I balance my carburetors with a vacuum gauge instead of a UniSyn.

Other than the fact that the air is unfiltered, I cannot imagine any problems with such leakage and so I haven't worried about it.

Just my two cents worth...

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: corventure Dave ()
Date: June 03, 2011 02:07PM

Not sure if this is your problem... buttt it gives me a chance to tell a story!
Many years ago I did a carb job on one of my Corvairs. Had some major distractions throughout the job, so I was pulled away again and again. When I finally go to starting the engine it would idol but had no power. The left bank did not fire. After running for 10 - 15 minutes, I could hold onto the exhaust manifold with a bare hand!!! What tha???? OK... to get to the chase....it turns out that it was a bad defective thick Felpro carburetor base gasket. Major vacuum leak! Changed the gasket and all was well again in the world.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: June 30, 2011 10:36PM

Okay, so this turned into a big case of "while I'm at it.

Aside from rebuilding both carbs with teflon bushings on the throttle shafts, new choke shafts, caged ball valve for the fuel inlet, along with the normal rebuild components (accel pump seal, pump needle valve, new main jet <51>, new PEV valve, filter stones, float settings, all new gaskets) and finally deflashed the throat of both carbs with a rotary tool. I also took the top engine cover off and cleaned all the cooling fins with degreaser and a pressure rinse, opened the crankcase cover, and cleaned the mating surfaces while installing new gaskets with new bolts and lock washers to stop any future leaks.

I also went and painted the cooling fan and carb bowl covers with VHT metallic engine paint (burnt copper) which I don't recommend for anyone ever. The paint is way too soft and prone to chipping when contacted with metal tools of any kind (this is after oven curing and plenty of dry time). The paint on the cooling fan is fine, but anytime I bump the carb body with the blade of my screwdriver, the paint chips angry smiley .

Another thing that gave me problems; I tried to install the Swivel Linkage kit that Clarks sells, but the end of the bar on the passenger side bumps into the engine shroud before I can back the idle screw out far enough to get a 650 rpm idle (stops at around 900 rpm idle). I ended up leaving the stock wire in on that side. I suppose if I bent the end of the throttle shaft linkage up it'd give it enough room, but I'd hate to upset another part of the linkage that way.

I also started installing a megajolt setup, but stopped short of installing the coilpack. Right now it's just monitoring the engine while the dizzy continues to control the ignition. Once I nail down an ignition table, I'll start a new post on that installation.

Also put a VDO Viewline Onyx Tach in the clock spot.

=================================================

'65 Black Monza Coupe w/black interior
110HP w/4-spd

Greetings from Oakland, CA!

no trim badges anywhere (and there never will be!)

Attachments:


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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: cnicol ()
Date: June 30, 2011 11:03PM

I like the look! The black/met orange is something I've never seen and I like it.thumbs upthumbs upthumbs up Ya thinking about another color for the wires???

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: July 01, 2011 12:02AM

cnicol Wrote:
-------------------------------------------------------
> I like the look! The black/met orange is something
> I've never seen and I like it.thumbs upthumbs upthumbs up Ya
> thinking about another color for the wires???

yup! flat black! because that's the color edis wires come when you get 'em from the FLAPS. winking smiley

I'm definitely happy with the color scheme, but I absolutely don't recommend the VHT metallic engine paints. I don't expect the coat to last but a year before the paint chips to the point where I'm totally irritated and end up removing them to be cad plated somewhere.

Who knows? Maybe the paint will harden up over a month of use.

I'd like to eventually do a few more small parts in that copper scheme, maybe cunifer fuel lines, copper tubing for the crank breather, cad plating for the balancer tube, and linkages.

This is the first old car I've ever worked on like this and I wasn't really around cars growing up, so I'm not too familiar with what's out there.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: davemotohead ()
Date: July 01, 2011 07:15AM

Did you bake the VHT engine paint in the oven like it says to do? I have had great results with the VHT paint! I bought some high Dollar black krinckle paint at a auto paint store and it sucked and used the VHT krinckle and it turned out realy good!

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: July 01, 2011 08:18AM

davemotohead Wrote:
-------------------------------------------------------
> Did you bake the VHT engine paint in the oven like
> it says to do? I have had great results with the
> VHT paint! I bought some high Dollar black
> krinckle paint at a auto paint store and it sucked
> and used the VHT krinckle and it turned out realy
> good!

oh yeah, i did everything the label asked and used everything the label told me to. used a high heat duplicolor engine primer on the bare metal after bead blasting and everything.

the only thing i can think of that i might've done wrong is coated the parts too thickly.

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: ubuck ()
Date: July 01, 2011 11:53AM

Sweet work! I do like the looks! But, the question remains un-answered...

Did the cleaning and rebuild solve your problem??? grinning smiley

Brian<br><span style="color: white">63 M</span><span style="color: blue">o</span><span style="color: white">nza Con<span style="color: black">vert</span><span style="color: white">ibi</span><span style="color: blue">l</span><span style="color: white">e </span>Sprint Clone</span>
<span style="color: blue">64 M</span><span style="color: white">o</span><span style="color: blue">nza Cou</span><span style="color: white">p</span><span style="color: blue">e Sprint Clone</span>
<span style="color: red">65 Monza Con</span><span style="color: white">vert</span><span style="color: red">ible</span>
<span style="color: red">66 Corsa Con</span><span style="color: white">vert</span><span style="color: red">ible</span>
<span style="color: brown">69 Grand Prix Model J</span>
<span style="color: red">2004 SS<i>R</i></span>
<br>
South Holland, IL

Corsa/CCE



<i>"Let's agree to respect each others views, no matter how wrong yours may be." Ashleigh Brilliant </i>

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: mechanicalman ()
Date: July 01, 2011 01:41PM

ubuck Wrote:
-------------------------------------------------------
> Sweet work! I do like the looks! But, the question
> remains un-answered...
>
> Did the cleaning and rebuild solve your problem???
> grinning smiley


i was so worried after all the changes i made that the car wouldn't start, but after turning on the pump and filling the carbs, i cranked the starter and it leapt to life before it even turned over twice! I was so damn proud i didn't mess the whole thing up. This was my first experience dissasembling a carberator, so it was all new ground.

After warming her up thoroughly, i took it for a spin down the frontage roads and brought it up to 5500 in all gears. ALL the power is back and then some! I'm real curious to see what switching over to the megajolt does, but for now i'm just enjoying having her back in my arms!

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: MattNall ()
Date: July 01, 2011 03:02PM

Life is good!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
...............110-PG.................................................Webered-Turbo

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Re: Weak Power. Right Cylinder Bank Dead?
Posted by: MrChips ()
Date: July 01, 2011 03:06PM

From what I understand, you'll enjoy the megajolt...

Did you get the unit w/ Bluetooth so you can fiddle with the curves 'live' with your cell phone?


Where Santiago and Live Oak Canyon intersect in Orange County, Ca

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