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Choke-less
Posted by: REM654DPG ()
Date: May 21, 2019 09:21PM

I’m starting this new thread for Rob and to keep from getting too far off topic on the bellows issue as I kind of sent it down another path. I’m neither biased towards carburetors or fuel injection and am an advocate of both. Lot’s of talk about carbs and their inherent problems that can be easily fixed by an instant FI install but we know that’s not all true so I’ll be the carburetor J3M here today. When done correctly you all know a Corvair Rochester HV can perform exceptionally well and for me that includes removing all the unnecessary (to me) factory hardware to allow them to operate with less restrictions - for lack of a better word.

Rob, unless you’re running four primaries you should only have two carbs with chokes and yes I always recommend removing all the chokes – what can I say. And of course your individual results will vairy depending on a few factors - such as climate, engine condition and how the carbs are modified to mention a few. Speaking only for my location - The climate here in Oregon is friendlier to a choke-less carb however I have run this engine in damp 30 deg weather with no real issues other than you just need to warm it up for a few extra minutes before you head out and it works just fine. Either way you do have to sit there and feather the throttle for a minute or so before it will idle by itself but that’s a small price to pay for what you gain in my opinion.

I’m running 65 carbs with the early style leather accelerator cups in polished bores because they do have to work well all the time. My original intent in removing all the choke hardware was mainly to gain airflow for what that’s worth in these little carbs and I was tired of messing with the adjustments and fast idle stuff. But once I found how well it actually worked on cold start up without them there was no going back. Granted mine is a PG and in neutral it does have a higher idle setting that helps when it’s cold and that is another factor. I also removed that stupid idle bypass valve at the base to eliminate any vacuum leaks and that’s supposed to help with hot starts but I don’t ever have any issues with that at all.

There was a great article in the last communique regarding how important it is that the carbs are identical and physically balanced and that’s worth a read. To add to it, I also like to remove and replace all of the plugs in the body to ensure the passages are fully cleaned and that they won’t leak. This is important because there is no other sure way to guarantee all the passages are clean. To improve the balance I also hand ream the venturi bores with an adjustable reamer just enough to smooth out the casting ridge and ensure that both are exactly the same size - little details but it all adds up. I wish you well with your carb issue but it sounds like your problem really isn’t all choke related and that by removing them everything will be good. You could try first by just disconnecting the thermostat arm and wire them open and see if that helps any.

Regan Metcalf
Portland, OR

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Re: Choke-less
Posted by: joelsplace ()
Date: May 25, 2019 07:36PM

Let's see that reamer. On my Lakewood with manual chokes I never use them. No need but that tells me it is too rich.

Joel
Northlake, TX
5 Ultravans, 135 Corvairs and counting...

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Re: Choke-less
Posted by: Frank DuVal ()
Date: May 25, 2019 10:00PM

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Regan
I also removed that stupid idle bypass valve at the base to eliminate any vacuum leaks

If the idle vent valve is causing a vacuum leak, you have a hole in the carburetor! That hole only connects to the top of the float bowl, through that pipe that sticks up through the bowl gasket.

It was put there to solve hot start problems of fuel percolating in the bowls, then flowing into the venturi. A problem some cars had to the point where the 1963 GM technical bulletin cure was to drill holes in the side of the venturi to vent the fuel vapor.

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I was tired of messing with the adjustments and fast idle stuff.

Hmm, my experience is set and forget.

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need to warm it up for a few extra minutes before you head out

I'm a start and drive away type. Let it warm up fast by actually having the engine do a little work.

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disconnecting the thermostat arm and wire them open

No need to wire them open, gravity does it for you. winking smiley

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I also like to remove and replace all of the plugs in the body to ensure the passages are fully cleaned and that they won’t leak. This is important because there is no other sure way to guarantee all the passages are clean.

This I agree 100% with!smileys with beer Same with removing the flashing in the venturi.

Nylocks to hold the carburetor on? I've rarely ever seen a loose one!

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small price to pay for what you gain

You do not say what you have gained over the 99% of us that run chokes. The 1962 to 1969 Corvair choke system on the two and four carburetor engines is a very simple system. Easy to set and once set, forget it.

YHs and 1960 models, different story!eye popping smiley

Frank DuVal

Fredericksburg, VA

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Re: Choke-less
Posted by: American Mel ()
Date: May 25, 2019 11:15PM

Frank DuVal Wrote:
-------------------------------------------------------

> Nylocks to hold the carburetor on? I've rarely ever seen a loose one!


I have rarely never seen a loose one either.
BUT, . . . I have seen several that people have OVER tightened because they had been loose enough to vacuum leak, or were afraid that they would loosen!
I can see Nylocks being a FANTASTIC security measure in this application.
Great Idea Regan! thumbs up
I wish I could take credit for that one.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border, I am not at the end of the world, but you can see it from here.

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Re: Choke-less
Posted by: steve c goodman ()
Date: May 26, 2019 08:16AM

I agree that chokes are not necessary for cold
starting IF accel pumps are working and IF a
little patience is shown by the driver to feather
the throttle on cold temp mornings to keep the
carbs working until some heat is developed.

BUT for most drivers the chokes are nice to have
and are 'necessary' for ease of operation. I also
would not be keen on eliminating the bowl vent
system. There is nothing in the bowl vent that
either adds or detracts from carb operation.
Removing/replacing every soft plug is not something
I would suggest for a beginner either. Ensuring
every soft plug replaced is a tight fit might be
daunting to a new owner OR someone with few skills
and/or experience.

All Rob needs to do is unhook the choke rod. The
choke plate will fall open, no need to secure it
with wire. After the carbs are tuned/synched the
choke rods can be adjusted and simply hooked back
to the arms.

As always the above is my opinion only.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: Choke-less
Posted by: Richard ()
Date: May 26, 2019 09:28AM

I would agree that those carb mods are ill advised.

Being able to operate a cold manual choke engine without actually engaging the choke doesn't mean the carb is rich. As Steve pointed out, subtle feathering
the throttle will provide enough accelerator pump shot that the auto-choke would take care of effortlessly and predictably.

In most applications the nuts don't turn to become loose. The gaskets become compressed from heat cycle compression. Oil pan bolts should never be over tightened, but you usually want to lightly snug after one or two heat cycles.
A common topic is loose fuel pump screws on new pumps. They have three diaphragm thicknesses that dry out and shrink from sitting on a shelf for years, decades. Over tightening those screws is as ill advised as over tightening pan bolts. Many guys mention warped pumps.
No Nylock is going to compensate for normal gasket issues.

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Re: Choke-less
Posted by: REM654DPG ()
Date: May 27, 2019 06:57PM

Thanks for all the great feedback, this forum is great and I don’t disagree with any of your comments as you all have valid arguments. I’m guessing my operating and driving habits are different than most and maybe that’s why these mods work so well for me. My disclaimer here is that none of these mods are for the faint of heart or the purist and as mentioned above everyone will have different results and of course preference whether to modify or not modify.

If you know me you would know that I can never leave anything alone as far as stock condition goes - it’s just my nature and I can’t help it. It used to be my job and I was paid to modify everything that came through the front door and now I just can’t stop – sorry. I promise that everything I mention, suggest or describe here on the forum is not made up from some theory or crazy idea but from actual experience and time-tested results – it really works. I won’t post anything that I think is a maybe, or might work, or someone said, it has to be something I know is absolutely true and functional – unless I’m joking.

The “gain” that I claim is mostly in the air flow as with the choke valve, shaft, and whatever that horn thingy is in the top of the bowl cover completely removed it has to make some kind of difference. The engine seems to respond well to it and is very drivable. How much is gained exactly I don’t really know but I’m sure it’s comparable to those modified carbs they run in the Nascar circuit. (That’s one of those jokes)

The bowl/base vent is an interesting thing because I know what its purpose is but with it plugged off the engine runs really good and has absolutely no hot start issues. I just never cared for the way the cheesy little rubber valve would semi seal the hole and then get rock hard in short time. But that’s just me again.

The plug issue is a big one. I agree it’s not for a beginner, but to do a complete and full rebuild you have to take them out. Many times you’ll find that some of them (the small ones in the bowl) just about fall out when you grab on to them and those are the ones that seep and leak gas. The other two soft plugs are sometimes loose too and can cause a vacuum leak on the idle circuit if not replaced and sealed well. IMO - If you pay a claimed professional vendor to rebuild your carbs and they do not replace these plugs then I would consider that a “partial” rebuild and would question the quality of the rest of the work. Just food for thought.

To end I’ll just say – be nice to my Nylocks guys. I know they aren’t really necessary but if you have a large stash why not use them – they’re friendly yet sensitive little nuts and I like them.

And Joel, here’s the reamers I mentioned.

And I hope you all had a great Memorial Day! God Bless America!

Regan Metcalf
Portland, OR

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Re: Choke-less
Posted by: joelsplace ()
Date: May 28, 2019 11:34AM

Thanks for the pictures and information. Where do you get your plugs?

Joel
Northlake, TX
5 Ultravans, 135 Corvairs and counting...

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Re: Choke-less
Posted by: MattNall ()
Date: May 28, 2019 11:37AM

I'll bet this person has lots of experience!!

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Re: Choke-less
Posted by: joelsplace ()
Date: May 28, 2019 11:44AM

I doubt I'll live long enough to build that many carburetors.
I posted before Matt's and it didn't show up so here goes again:
Thanks for the info on the reamer.
Where do you get the plugs?
Tricks to install them?

Joel
Northlake, TX
5 Ultravans, 135 Corvairs and counting...

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Re: Choke-less
Posted by: toms73novass ()
Date: May 28, 2019 12:58PM

They appear to be solid Aluminum Brazier Head Rivets....

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
62' Wagon rebuild MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block (Sold)
86' BMW 325es
67' UltraVan 211 "Violet"
NFCC, UMCC
Grand Island, NY

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Re: Choke-less
Posted by: Richard ()
Date: May 28, 2019 02:41PM

Aluminum rivets would be too hard.

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Re: Choke-less
Posted by: JimBrandberg ()
Date: May 28, 2019 06:51PM

One thing I found interesting above that I never thought about was polishing the accelerator pump bores.
The only leather cups I've seen have been horribly dried out and deformed but it's a nifty idea.
I got a few aluminum plugs from Grant Young but I would like to find a regular source. Can you get sizes you need instead of a whole assortment where you only use a small portion?

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Choke-less
Posted by: REM654DPG ()
Date: May 28, 2019 09:55PM

Joel, Tom is correct they are aluminum aircraft rivets that I cut down as shown. And as mentioned above if I wasn’t 100% sure that these work, I wouldn’t have posted it with pictures. The plug kit that Richard shows is a great idea too but even if they are made from a softer grade of aluminum the kit does not have the sizes you need for the HV.

And Jim, the leather cups are a set of NOS ones I had and they’ve been in those carbs for about 10 years now. I think the key is not letting them dry out – so far so good…

To remove the plugs, first drip some WD-40 down the passages so that they will be lubed and rotate and pull out without galling. Then you need a set of (good condition sharp teeth) miniature vice grips that have a sharp face ground on the jaws to grab the head and rotate back and forth as you pull them out.

I use the 5/32 reamer by hand just to clean and chamfer the first ¼ or so of the hole and that’s all. Once the carbs are cleaned, de-greased and ready to assemble the plugs are then tapped in and sealed with 609 Loctite and as you can see in the picture they don’t leak. The other two larger holes are just 5/16 and 3/8 soft plugs but I made solid ones with a little taper as they just look better. I buy the rivets by the pound and like my nylocks I have plenty of them. If you PM me your address I’ll gladly send you what you need. Although, after looking at your car lot are you sure those parts cans from Matt didn’t come from there? One pound may not be enough – LOL.

Regan Metcalf
Portland, OR

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Re: Choke-less
Posted by: triumphcorvair ()
Date: May 29, 2019 08:04AM

How are you polishing the accelerator cup bores?

Darrell McCracken
Huntsville, Texas

65 140 Monza
71 Triumph Bonneville Bobber

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Re: Choke-less
Posted by: 66vairman ()
Date: May 29, 2019 09:07AM

All I can add is that once I get the chokes sorted they are trouble free.

Considering the venturi size vs. larger upper opening that the choke resides in, I doubt an open choke mechanism restricts the air flow. A flow bench would tell the story.

Carburetors get hot - not a good place to use nylock nuts. I use a lock washer and washer - never had one come loose.

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Re: Choke-less
Posted by: REM654DPG ()
Date: May 30, 2019 09:33PM

Darrell, for polishing I just use some gun cleaning pieces and open up the slot in the one tip to make it wider. With a cordless drill, I start with some scotchbrite then use an old towel with some polishing compound and work it to the shine I'm happy with. If anything it looks flashy!

Regan Metcalf
Portland, OR

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