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Re: Weber 45 DCOE Turbo Tuning
Posted by: tboltkc ()
Date: September 24, 2017 01:06PM

Yep. When I did this last time, I used what I had to get it as good as I could but this time I bought a selection of jets to try to get it as right as I could so I used Kevin's parameters in a previous post in this thread to begin with.

And it seems to work pretty well except this WOT at idle stumble and super lean condition.

One thing I don't quite get is that you state how important it is to start with the butterflies in the right spot in relation to the progression hole. Once you do that though, and use the idle stop screws to get a decent idle RPM, that all goes out the window. Are you not supposed to touch those once you get the butterflies in the right spot?

Kevin, thanks for the help - it's good to have the voice of experience.

-Travis


'65 Corsa; '63 Convertible; '62 Wagon; '65 4 Door
Heart of America Corvair Owners Assocation (Kansas City, MO)
[www.hacoa.org]



Edited 1 time(s). Last edit at 09/24/2017 01:07PM by tboltkc.

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Re: Weber 45 DCOE Turbo Tuning
Posted by: 63turbo ()
Date: September 25, 2017 09:37PM

Thanks Travis! one thing you may want to try is see how the A/F's are doing
when you are driving, as the engine wont be able to change its rpm nearly as fast when the car is moderately loaded. As long as you aren't getting a lean pop out of the air cleaner you probably aren't far off. Remember the way the carb is being used on the turbo, is totally different than they were designed for so you have to "cheat" the rules somewhat. When cruising along on level ground, the primary is running on the main jet and is partially pulling open
the secondary, so the primary main jet is sort of running the show, not the idle jets. Be happy with 12.5 to 11.5 under light loads, and go for around 11.5 under boost, and don't be surprised to see it lean out under a hard load before boost... this is a good thing, but is different and weird to see the A/F move around so much... it is just the way it is with those carbs used that way. Perfection is simply not attainable!! Any pinging under boost must be taken care of by richer jetting, and or slowing down the rate of opening of the secondary by going tighter on the spring.
What ends up happening when the "throttle stop screws are tweaked a little"
is that the blades of the throttle are now actually covering that first progression hole instead of being at the front edge... this is also fine. It is
when the blades are well past that first hole that the problems begin! By starting the idle mixture and speed adjustment with the back edge at the front of that first hole, you guarantee that you aren't trying to adjust the idle while the engine is running on the progression circuit, the mixture screws don't do anything when the blades are open that far!!

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Weber 45 DCOE Turbo Tuning
Posted by: tboltkc ()
Date: September 26, 2017 05:15PM

Thanks Kevin - makes sense. Hopefully soon I'll have it at least satisfactory.

-Travis


'65 Corsa; '63 Convertible; '62 Wagon; '65 4 Door
Heart of America Corvair Owners Assocation (Kansas City, MO)
[www.hacoa.org]

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Re: Weber 45 DCOE Turbo Tuning
Posted by: JimBrandberg ()
Date: October 05, 2017 04:27AM

The owner of the one I was working on experienced some detonation under boost and went froma 36mm Primary venturi to 32mm along with some other changes including switching back to F2 Emulsion Tubes from F16.
Since he does most of the work on the Corvair himself, I delivered it back running okay with some final tuning needed. I was a bit uncomfortable with the process of "drive it like you stole it" testing in case something else should go wrong, sure enough the clutch slips under full acceleration in 4th gear.
Some of the jetting was done with parts on hand like changing the Air Correction rather than Main Jet to richen a tad. He reports:

" Final setup looks like this:
PRIMARY SECONDARY
CHOKE 32 36
MAIN 160 180
A/C 190 190
E-TUBE F-2 F-2
IDLE 55F9 60F9 "

I hope this can help someone doing a search in the future. It runs good, idles at 1000 RPM and makes boost in 2nd, 3rd and 4th gears with the Early turbine/Late impeller turbo. It was running good with the Carter YH we removed but the conversion was definitely an improvement.
He has a Safeguard with O2 sensor. I don't think the stock pressure retard would be good enough.
My thinking with detonation under boost would have been to reduce the Secondary venturi but it sounds like I was wrong. I would like to read more about it if someone would help reason through it.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Weber 45 DCOE Turbo Tuning
Posted by: dryenko ()
Date: October 05, 2017 05:03AM

Hi Jim,
Was this with a 40 or 45 DCOE carb??
Just confirming...

Bob

Bob C aka Dryenko
Dobson, NC 27017

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Re: Weber 45 DCOE Turbo Tuning
Posted by: wv-geo ()
Date: October 05, 2017 06:13AM

dryenko Wrote:
-------------------------------------------------------
> Hi Jim,
> Was this with a 40 or 45 DCOE carb??
> Just confirming...
>
> Bob

I'd say it's a 45DCOE, 36 chokes are rare for a 40DCOE.

Jim Brandberg, what cam was he using?

Dan Stark
Hurricane, WV

1961 Lakewood 500, 80HP, PG
1964 Corvair 500 Coupe, 140HP, 4spd (Christine)
1965 Mustang Coupe, 6cyl, 3spd

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Re: Weber 45 DCOE Turbo Tuning plus 40 DCOE
Posted by: dryenko ()
Date: October 05, 2017 07:34AM

I asked because I am considering installing a progressive 40 DCOE on a 145 CI 150 HP turbo, and am thinking the 45 DCOE may just be too big for that application.
For street driving, that is.
So, with that in mind, does anyone have some suggested specs for the above mentioned application ??
I assume some of the same idle jet, venturi and main jet / AC sizing / size multiplier rules apply, but Kevin's notes about the pulses and tip in of the main and idle jet circuits might apply here as well ?
For the record, I do , along with others, run 36mm venturi's in my 40 IDA webers on my GT# and other engines, and they seem to work quite well.
Have much less expreience with Weber carbs on Corvair turbos.

Bob C aka Dryenko
Dobson, NC 27017

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Re: Weber 45 DCOE Turbo Tuning
Posted by: 63turbo ()
Date: October 05, 2017 06:50PM

Bob- The only difference that I know of between the 40 and 45 DCOE is the inside diameter without installing the 'chokes"... the 45 DCOE is 44mm without
chokes, and the 40 would be smaller. If Weber was consistent with their numbering rules, the 40 DCOE would be 39mm. The net effect is that the 45 will
allow larger chokes to be used than the 40 will. I had a 45 DCOE on my 145 for
a long time, and used a F/B turbo. To get 18psi in third, I used a 29mm primary
and a 35mm secondary (29 primary and 38secondary was over 20!!)- These are not, as far as I know normal weber choke sizes-
I created a 35mm choke by sleeving down a 38mm choke, and the 29 was accomplished be sleeving down a 32mm. For a long time I used f16 emulsion tubes
but I later found that either an f9 or f7 (cant quite remember) on the primary
seemed to work quite a bit better and either a f11 or f12 on the secondary...
again my memory is vague on this. Again the weber rules for main jet sizing and
air corrector's are a great place to start, you may have to go 10-15#'s higher
when finished. Some weber minutia that you may or may not find helpful:
Be DARNED careful when installing the jets!!! pay attention to how tight or loose those jets fit in their holders! you want those jets to have a nice snug push fit into their holders!!! When installing the jets, leave them a bit proud
in the holder, do not push them all the way down in their holder as the jets all need to seat on the face of the big chamfer on the nose of the jet down in
the well- it is a relatively common problem for the jets to not actually seat correctly in the well- if this happens, the jetting will not be driven by the
hole size on the jet, but by how much clearance there is between the nose of the jet and the well, and jetting changes will not work.... Leave the jets sticking out of their holder and let the internal chamfer in the bowel of the carb seat the jet correctly as it is tightened. If you notice any grooves worn
into the face of the chamfer on the jets, you are better off discarding those and starting over with new ones as those grooves will cause inconsistent seating, and you will be pulling your hair out trying to figure out why some jetting changes don't seem to do anything, and others only slightly different cause a disproportionate change!

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Weber 45 DCOE Turbo Tuning
Posted by: JimBrandberg ()
Date: October 06, 2017 06:13AM

In answer to questions above. The one I was working on was a 45 DCOE. He mentioned forged pistons but I don't know about the cam so assuming stock.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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