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looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 02:23AM

Hi guys
so Ive finally got my car running almost perfectly, ive been chasing misfiring and bogging issues for months, (see other posts) still have a slight miss when under load.

My quest now is to have him running perfectly but am new to these engines.

My car
1969 110 pg
New std barrels/pistons etc from Clarks about 300 miles ago (still on running in oil)
Tom Knoblauch version 1 big valve heads
Carlifornia corvair hei distributor
Petronix Flame thrower 3.0ohm 40kv Coil mounted on back frame.
New Morroso Mag tune 8mm suppressed plug wires
Base timing at 14 degrees (not sure what full timing would be with this distributor or how to check)
Valves adjusted cold (about 5 times to get ave)
NGK B5HS gapped at 0.035"
car lives at sea level and i have 51 main jets
New chokes adjusted per manual
Carbs rebuilt as per Bob Helt (very good book)
K&N air filter in standard air box but with the 2 intakes
Dual exhaust
Edelbrock 2-3.5psi 30 gph electric fuel pump (is this a bit low psi)?
compression check
1 160 2 172
3 170 4 168
5 160 6 160
These were done cold but without all spark plugs removed.

Car starts fine and runs ok, Running on super unleaded 99ron.
Seems just a bit rich i think as plugs are dry sooty when removed after 30 minute drive. i do have a slight issue with the carbs my carbs have the number 4 above made in USA then RP but the spare carbs i have, have C1 then made in USA then BC on one carb and C2 on the other then made in USA then BC, are these a matched pair?

Quite a bit to digest but any suggestions/tweeks gratefully received.

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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 03:22AM

Sorry, forgot to add the slight issue with carbs.

Left hand carb and bank running well but right carb is difficult to set mixture. I can hold my palm over air horn and car will still run (barely) if i put my hand over the left carb the car stalls immediately.
I have replaced vac lines on left carb also changed choke pull off with 2 others and still same result, also tried 2 different base spacers with gaskets, i can adjust mixture screw all the way in, the revs rise a little but car still runs.

with these compression numbers i dont think a valve is the issue, you may disagree.
2 172
4 168
6 160

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Re: looking for tuning suggestions
Posted by: 63turbo ()
Date: November 15, 2022 04:56AM

I think I would try gapping the plugs at .028" and go one step colder on the sparkplug heat range and one step leaner on the carb!

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

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
Test Start#2 [www.youtube.com]



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Re: looking for tuning suggestions
Posted by: Lane66m ()
Date: November 15, 2022 05:00AM

Since you are running a 3.0 ohm coil, did you remove the resistance wire from the engine harness and replace it with a standard wire.

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Re: looking for tuning suggestions
Posted by: PequotMonza64 ()
Date: November 15, 2022 08:49AM

Lane66m Wrote:
-------------------------------------------------------
> Since you are running a 3.0 ohm coil, did you remove the resistance wire from the engine harness and replace it with a standard wire.


Lane's suggestion is a good one.

Regarding one carb acting differently from the other, I recently dealt with that situation. Sending my carb in to Clarks in exchange for a rebuilt one cost me a NET $160 and was the best deal I've made in a long time. I had soaked that questionable carb, put it through an ultrasonic cleaner with cleaning solution at 140 degrees twice, used various gauges of steel guitar string to clean out passages and rebuilt it twice without solving the problem. I could tell from looking at that carb that the previous owner had also struggled with it. When I finally swapped the two carbs side to side and confirmed that it was the carb and not anything else, I decided I had wasted enough time and ordered one from Clarks.

With the new carb installed, I could adjust things as described in the manuals and Bob Helt's book. I'll never know what the issue was. Either something was clogged or the carb body casting itself was defective.

Glen in Ohio
1964 Monza Sedan Powerglide 110 hp
Low mileage survivor, stock as delivered
Records back to 1967 in Pequot Lakes, Minnesota
Original dealer Mike Turk's in East Liverpool, Ohio
Located in Cleveland, Ohio area


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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 11:17AM

Lane66m Wrote:
-------------------------------------------------------
> Since you are running a 3.0 ohm coil, did you remove the resistance wire from the engine harness and replace it with a standard wire.


yes ran a new 12v feed wire.

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Re: looking for tuning suggestions
Posted by: brentc ()
Date: November 15, 2022 11:20AM

Don't read too much into plug or tailpipe colour, it's meaningless on unleaded gas nearly.

Brent

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Re: looking for tuning suggestions
Posted by: Paulsgt ()
Date: November 15, 2022 11:27AM

You said "Carbs rebuilt per Bob Helt". Did you measure all the orifices on the venturi clusters and make sure both carbs match?

Enjoy the Corvair!

Paul Sergeant
CORSA Central Division Director / CORSA Treasurer
Lee's Summit, MO
CORSA since 1975
Member – HACOA, Corvair Minnesota, CORSA, Little Indians, POCI


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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 12:41PM

Paulsgt Wrote:
-------------------------------------------------------
> You said "Carbs rebuilt per Bob Helt". Did you measure all the orifices on the venturi clusters and make sure both carbs match?
>
> Enjoy the Corvair!


didnt measure the cluster orifices and dont know if the carbs are a matched pair as i only have these markings to go on.

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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 12:57PM

carbs have the number 4 above made in USA then RP so are these a matched pair? ive no idea how to tell.

Didnt measure the venturi cluster orifices.

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Re: looking for tuning suggestions
Posted by: dryenko ()
Date: November 15, 2022 02:37PM

The fact that you can screwing the idle mixture and not completely kill the engine is a major clue.
As is the inability to kill the engine with you hand placed over the carb.
Switch the carbs and see if the problem follows the " bad " carb.
And let us know.
You " may " have a main jet fuel flow issue.

Bob C aka Dryenko
Dobson, NC 27017

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Re: looking for tuning suggestions
Posted by: Paulsgt ()
Date: November 15, 2022 02:57PM

I'd guess nearly 99%+ of Corvair carbs have been "rebulit" numerous times. Any stamping or tag on the carb is virtually meaningless. Do what Bob says but I would recommend opening up both carbs and checking the venturi clusters also the main jets (make sure they are the same size). As mentioned on here, the venturi cluster part number has little to no association with the measurements of the orifices.
These orifices are tiny and any little blockage can cause the problems you are describing.

Good luck!

Enjoy the Corvair!

Paul Sergeant
CORSA Central Division Director / CORSA Treasurer
Lee's Summit, MO
CORSA since 1975
Member – HACOA, Corvair Minnesota, CORSA, Little Indians, POCI


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Re: looking for tuning suggestions
Posted by: Murphy ()
Date: November 15, 2022 05:32PM

Had the same problem, not much Vacuum on left carb. I found the rubber hose from the balance tube got some gasoline spilled on it, softened up the hose and created a vac leak. Worth a look.

65 Monza Coupe
61 500 Coupe-W100181
Earliest '61 Alive?

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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 15, 2022 05:38PM

Murphy Wrote:
-------------------------------------------------------
> Had the same problem, not much Vacuum on left carb. I found the rubber hose from the balance tube got some gasoline spilled on it, softened up the hose and created a vac leak. Worth a look.


Thats my next job, i overlooked those connections.

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Re: looking for tuning suggestions
Posted by: DOUG WARD ()
Date: November 15, 2022 08:44PM

These are good comments. I tend to think that you should be running 52 to 54 main jets in the carbs. Also, have you checked to see if both carbs have enrichment jets in the cluster supply area ? Another thing you can check is the shape of the cluster "arms". early arms were equal spaced, like a cross would be. Late cluster arms have a more "flattened / irregular" X spacing. If they are different, side to side, the gas flow can be different between left bank & right bank. Another thing to check is the little black rubber stopper at the bottom of the carb that opens when the throttle is at idle. Check the adjustment tab that opens it that is part of the throttle arm.
When you check the timing, set it at the factory degrees & add a couple more advance degrees until the engine starts pinging, then back it off 2 degrees until it stops pinging. The highest octane we can get here in Calif. is 92. That is why I suggest that you set your timing a little higher. ( you mentioned that you have 99 octane ) 2 to 3 PSI fuel pressure sounds pretty good to me.
You seem to be pretty savvy with your research. Keep at it. You will get it sorted out soon.

Doug Ward
Orange, Calif.
65 Corsa 180, 64 Monza convertible, 61 Lakewood, 61 Monza


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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 16, 2022 01:54AM

DOUG WARD Wrote:
-------------------------------------------------------
> These are good comments. I tend to think that you should be running 52 to 54 main jets in the carbs. Also, have you checked to see if both carbs have enrichment jets in the cluster supply area ? Another thing you can check is the shape of the cluster "arms". early arms were equal spaced, like a cross would be. Late cluster arms have a more "flattened / irregular" X spacing. If they are different, side to side, the gas flow can be different between left bank & right bank. Another thing to check is the little black rubber stopper at the bottom of the carb that opens when the throttle is at idle. Check the adjustment tab that opens it that is part of the throttle arm.
> When you check the timing, set it at the factory degrees & add a couple more advance degrees until the engine starts pinging, then back it off 2 degrees until it stops pinging. The highest octane we can get here in Calif. is 92. That is why I suggest that you set your timing a little higher. ( you mentioned that you have 99 octane ) 2 to 3 PSI fuel pressure sounds pretty good to me.
> You seem to be pretty savvy with your research. Keep at it. You will get it sorted out soon.


I have just ordered new 52 main jets, power valve and accelerator pumps along with other car bits and bobs from Clarks, after researching my carbs they are 65-66 models (not air) with power enrichment and staggered venturi cluster.
I went to great lengths to adjust the little black rubber door thing so it just opens on full throttle, (tricky to get perfect)
As per timing, am i doing this correct for my engine/year? revs about 550 in drive with mechanical advance tube disconnected from carb base and plugged?

You say advance the timing till it starts to ping, would i be backing off the idle as i do this as the car would want to move. when i tried different timing settings, it was idling very nice past the end of the 16 btdc mark, i was concerned that it would do some internal damage so never actually drove the car with the timing that far advanced, it was probably around the 20-22 degrees btdc. Timings not really an area im confident with, also how do i check full advance timing? i only have a basic timing light not one of the fancy ones.

Again chaps thanks for everything, if your ever over here, the kettles always on.

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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 16, 2022 02:07AM

Just as a thought does this fuel to top of base measurement look ok, to high or low?



Edited 1 time(s). Last edit at 11/16/2022 02:07AM by sirsparkalot.

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Re: looking for tuning suggestions
Posted by: JimBrandberg ()
Date: November 16, 2022 05:30AM

I struggle with drippy venturi clusters a lot. You need to look down the carburetor throat at part throttle with the engine running which could not turn out well if it backfires.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: looking for tuning suggestions
Posted by: dryenko ()
Date: November 16, 2022 06:30AM

The rubber bowl venting disc at the base of the carb should only be open at IDLE.

Bob C aka Dryenko
Dobson, NC 27017

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Re: looking for tuning suggestions
Posted by: sirsparkalot ()
Date: November 16, 2022 10:26AM

dryenko Wrote:
-------------------------------------------------------
> The rubber bowl venting disc at the base of the carb should only be open at IDLE.

(Quote)I went to great lengths to adjust the little black rubber door thing so it just opens on full throttle, (tricky to get perfect)

sorry i meant closed.

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