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Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: American Mel ()
Date: October 14, 2020 08:08PM

Vairy interesting!
I have always balanced my carbs, and then adjusted the linkage to begin opening both butterflys at the same time.
That was how I was taught, and I have never considered that it might be wrong.
Who'da thunk it? eye rolling smiley

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: RobertC ()
Date: October 15, 2020 01:53AM

American Mel Wrote:
-------------------------------------------------------
> Vairy interesting!
> I have always balanced my carbs, and then adjusted the linkage to begin opening both butterflys at the same time.
> That was how I was taught, and I have never considered that it might be wrong.
> Who'da thunk it? eye rolling smiley

Do not think you were / are doing anything wrong.

As long as your engine idle is smooth and is smooth through the rpm range; you were / are fine.

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: azdave ()
Date: October 15, 2020 04:22AM

RobertC Wrote:
-------------------------------------------------------
> As long as your engine idle is smooth and is smooth through the rpm range; you were / are fine.


True. You could have one carb way out of sync with the other and not notice any roughness because our engines are inherently balanced, even if one whole bank of cylinders are not pulling their weight.

If you choose not to balance the carbs off-idle that is your choice but it does matter to some of us and is the proper procedure. If it's not important, why did the engineers make the linkage adjustable and detail the tune-up steps showing their mechanics how to set it?

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: Harry Moore ()
Date: October 18, 2020 02:50PM

It took a while but things are moving along with the carbs. I put new Seth wires on, timed it to 14 degrees, and adjusted the RPM to 650 after I recorded the video using an old CORSA tach.

I was hoping for better immediate results with the Dwyer gauge hooked up to the choke pulloff ports (I was testing other ports in the video - does the same on the vertical ports), but the needle is bouncing all over. Do you think this is due to a valve issue?

Check out this video of the needle bounce in the gauge. Here is the video

BTW, the car starts easily, sounds strong, and idles nicely. But when I put the air cleaner on the RPM's drop fast and the car stalls.


Harry Moore
66 Monza Sedan 140/PG
Southern California



Edited 2 time(s). Last edit at 10/18/2020 02:54PM by Harry Moore.

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: RobertC ()
Date: October 18, 2020 09:08PM

Well, to get your thread back to the top, I will make some probably dumb and wrong statements.

Never used a vacuum gauge on a Corvair engine except the one in my Corsa.

Always thought that the reading at the vacuum advance port was zero at idle.

The needle should not fluctuate like yours.

Have you adjusted the valves recently?

Stalling at idle after putting the air cleaner (stock?) on makes no sense to me since the stock air cleaner flows enough air for 5000 rpm.



Edited 1 time(s). Last edit at 10/18/2020 09:12PM by RobertC.

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: American Mel ()
Date: October 18, 2020 09:19PM

I thought that I had read somewhere that due to the dynamics of our intake's shape, and the odd number of cylinders, the vacuum will vary extremely WILDLY.
Thus it was necessary to use a balance of the two sides to monitor vacuum.
But I have wondered about that statement, because I know that there are guys who balance their carbs with a vacuum gauge.
It kind of seems like someone had stated using some kind of restriction in the line to reduce the huge bounces in pressure/vacuum differences.
Hopefully some will chime in with a definitive answer.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

Re: Keeping carbs in balance throughout the whole range of operation
Posted by: MattNall ()
Date: October 18, 2020 09:48PM

Sadly, on our Rochesters...factory 2x1, ONE carb is pulled UP to open, the Drivers side PUSHED Down! [ bad design? ]

Even with Heim style joints there is a TEENY bit of movement, not enough to matter "IMO".

I learned while "fine tuning" mechanical / hydraulic actuators on Gas Turbine powered Electrical AC Generators that were certified not to vary more than 1/2 of ONE percent with changing load...no matter how large the transient.

My '67 110 is the only 2 carb engine I have at this time

It has Steve in Marietta's Ebay Adjustable ball links, good enough for street use, "IMO".

Idle speed is set with the passenger's Idle speed screw" [ I'm left handed ] only!! after initial Balance is achieved.

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

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: RobertC ()
Date: October 18, 2020 09:49PM

The instructions for balancing carbs with a vacuum gauge in the 65 shop manual state that the “idle” rpm should be 1200 rpm. Maybe that is an issue.

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: MattNall ()
Date: October 18, 2020 09:53PM

American Mel Wrote:
-------------------------------------------------------
> I thought that I had read somewhere that due to the dynamics of our intake's shape, and the odd number of cylinders, the vacuum will vary extremely WILDLY.
> Thus it was necessary to use a balance of the two sides to monitor vacuum.
> But I have wondered about that statement, because I know that there are guys who balance their carbs with a vacuum gauge.
> It kind of seems like someone had stated using some kind of restriction in the line to reduce the huge bounces in pressure/vacuum differences.
> Hopefully some will chime in with a definitive answer.

You are correct! Dwyer's have an orifice to dampen.

My experienc with fluctuatiom is rpm sensitve, some engines do...others don't!

If it idles SMOOTH "Forget about it" GG

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

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: MattNall ()
Date: October 18, 2020 09:59PM

RobertC Wrote:
-------------------------------------------------------

>
> Always thought that the reading at the vacuum advance port was zero at idle.

IT is if throttle plate is 99% closed. Harry said he used Choke pulloff ports!



>
> Stalling at idle after putting the air cleaner (stock?) on makes no sense to me since the stock air cleaner flows enough air for 5000 rpm.
--------------------------------------------------------------------------
That is strange to me as well and I would need to be there in person to diagnose

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

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: RobertC ()
Date: October 18, 2020 10:20PM

MattNall Wrote:
-------------------------------------------------------
>
> IT is if throttle plate is 99% closed. Harry said he used Choke pulloff ports!
>

Well his video shows the hoses attached to the vacuum advance ports.

Confusing?

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: MattNall ()
Date: October 18, 2020 10:35PM

RobertC Wrote:
-------------------------------------------------------

>
> Well his video shows the hoses attached to the vacuum advance ports.
>
> Confusing?




------------------------------------
He says he was testing other ports in video.

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

Re: 1.125 inch Bore Carburetors with 56 Jets
Posted by: RobertC ()
Date: October 18, 2020 11:44PM

MattNall Wrote:
-------------------------------------------------------
> RobertC Wrote:
> -------------------------------------------------------
> >
> > Well his video shows the hoses attached to the vacuum advance ports.
> >
> > Confusing?
>
> ------------------------------------
> He says he was testing other ports in video.

Yeah, that is part of the problem (causing confusion to me).

I finally ignored the comments in his post and the comments in the video and just concentrated on the LOOKING in the video - which shows the tubes / gauge at that time connected to the vacuum advance ports.

Which is why I posted that the balancing carbs procedure with a vacuum gauge had the "idle" speed set at 1200 rpm.

"Even with Heim style joints there is a TEENY bit of movement, not enough to matter "IMO"."

True Heim joints, unless worn out, "do not move".



Edited 2 time(s). Last edit at 10/18/2020 11:47PM by RobertC.

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