180 Turbo Distributor Questions

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Pdxr4000
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180 Turbo Distributor Questions

Post by Pdxr4000 »

Hello everyone, this is my first post! Thank you all in advance for any ideas you might have...

So, I'm rehabbing my 66 Corsa coupe 180 turbo, and I feel like it's almost there but something is not right. It starts and idles just fine, and revs out pretty much fine, but under load it's popping and sputtering and doesn't sound good at all. I've been going through most systems chasing this with all new intake-side seals, new exhaust packings, and a rebuilt carb in place of the original which was set up with a water injection system. It has the correct turbo, correct engine, correct 329 distributor. I just installed a Petronix II which seems to make the car feel stronger but did not solve the problem - the intensity might be worse now. I tested compression and got around 150 psi on all cylinders. It sounds good but can't make power, or boost.

Timing is set at 24, but I've noticed that if I leave the timing light on and rev the engine, at higher revs the timing goes way beyond 24, off the chart to the right of the 24 mark. What should be happening here as I rev the engine? I was expecting it to dial in around 18 on the scale and not fly off the other direction.

Inside the distributor, the shaft is stamped 201, and the base is 738. Are these correct? Seems like the weights and springs only go together in one possible way.

Any ideas? Thanks!!

joelsplace
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Re: 180 Turbo Distributor Questions

Post by joelsplace »

The advance weights will give it more timing than your static timing starting around 3500rpm. I can't remember how much. The stock cannister on the distributor is a pressure retard only so it will only change the timing on boost. If the arm moves when you plug in the vacuum line it is either the wrong one or it's on of the aftermarket advance & retard units. Mine is stamped AR. The stock one has a three digit number but I don't remember what it is.
113 Corvairs, 5 Ultravans and counting
Northlake, TX

Pdxr4000
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Re: 180 Turbo Distributor Questions

Post by Pdxr4000 »

Yes it has the correct retard not advance unit, with the barb end. When I unhook the vacuum line the engine wants to stop running. Not sure if it's a factor. With my timing light it's around 24 until prob around 3500 and then it goes way beyond 24. But maybe this is correct, just not intuitive. 24 + 18 would be 42 which would be way to the 'right' of the scale which ends at 24. And that's what I see with my strobe as I move up the rev range. Ummm...

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thewolfe
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Re: 180 Turbo Distributor Questions

Post by thewolfe »

Your distributor appears to be working correctly. The advance comes on late(above 3500 rpms) and will go off the scale as it advances. If you're not making boost and the ignition is good then you either have a leak in the exhaust, issue with the turbo or carb. What condition are your spark plugs in and what's the gap? You should not need water injection with a stock turbo motor. I would disable that for the time being. Have you checked to see that the turbo wheels spin freely?
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bbodie52
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Re: 180 Turbo Distributor Questions

Post by bbodie52 »

The chart below compares the specifications for the various turbocharged Corvair model years. It shows that a change was made in 1963 that limited the total centrifugal advance to only 12 degrees instead of 17 degrees that was programmed into the 1962 distributor. The new 1963 specification remained in 1964, but the pressure retard specification changed in that year. The distributor timing specs changed again in 1965, but so did the 1965-66 turbocharger capacity that took advantage of the engine displacement increase that was dialed-in in 1964.

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The Clark's Catalog page below provides some information on the pressure retard device (224 or 231 for 1962-1964, and 250 for 1965-1966 turbocharged engines. Past comments I have read about the pressure retard unit seems to reflect negatively on its accuracy or reliability, but it was the only variable tuning factor that was intended to prevent detonation. Even if it did work it certainly was not as sophisticated as modern computer-based systems that respond to engine sensors and electronically control electronic fuel injection and ignition systems to manage turbocharged engine operating parameters.

I don''t believe the Corvair turbo system was ever designed to manage sustained boost conditions over long periods. Brief periods of boosted acceleration could be accomplished on Premium fuel with a properly tuned engine, but I discovered the hard way that continuous turbocharged boost of an engine while climbing a long highway grade on a warm day is asking for trouble, as I found out when I melted a "hole-in-one" (piston) on a warm spring day near the top of the Conejo grade on the Ventura freeway in 1971!
...and a rebuilt carb in place of the original which was set up with a water injection system...
Are you indicating that you (or a previous owner) installed a water injection system, but it is no longer in operation? If that system has been removed, you only have the pressure retard unit left to prevent detonation. Are you certain it is actually working? As you can see in the distributor chart, the engineers designed the centrifugal advance system to dial-in additional advance as engine speed increases, but it also relies on the pressure retard device to reverse some of that timing advance when the turbo boost is present. Without it detonation (explosions) in the combustion chamber are certain to occur (a death rattle sound) that can quickly destroy a turbocharged engine. A properly functioning water injection system can allow somewhat longer periods of boost without engine damage, and could even compensate somewhat in the event of a failed pressure retard device (which provides the driver with no warning upon failure, except the sound of engine detonation if you are paying attention)!
...but under load it's popping and sputtering and doesn't sound good at all...
If you have eliminated the water injection system, and if you are not certain that the pressure retard unit is functioning (you are hearing detonation when the turbocharger is providing boost) I would suggest that you might want to invest in a replacement aftermarket unit from Clark's, as shown below. Try installing the proper unit in your Corvair, and see if that eliminates the "popping and sputtering" you have described.

In addition to the pressure retard device, Premium fuel, and proper tuning, a knowledgeable owner who is well-aware of the turbocharged Corvair engine design limitations is the best bet for preventing your engine from self-destruction!

:link: http://www.corvair.com/user-cgi/catalog ... IN&page=51
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Clark's Corvair Parts has had a number of vacuum advance and pressure retard units reproduced. The numbers stamped on the originals have been carried over to these reproductions and are shown below.
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:link: http://www.corvair.com/user-cgi/catalog ... age=SUP-39

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:banghead: :angry: :whoa:
Detonation – What Causes It And How To Control It...
:link: https://www.enginelabs.com/news/detonat ... using-efi/

WHAT IS DETONATION?
:link: http://www.misterfixit.com/deton.htm

What is Detonation, and How Can It Kill Your Engine?
Brad Bodie
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acarlson
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Re: 180 Turbo Distributor Questions

Post by acarlson »

The Clarks Pressure/Vacuum canister has part #2500 stamped on the timing control arm.

Alec
Alec Carlson
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Restoration "In Progress"...

Pdxr4000
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Re: 180 Turbo Distributor Questions

Post by Pdxr4000 »

I wrote a lengthy response earlier this am, but it didn't seem to show up.

- I have the correct vacuum retard unit #250

- I'm going to try new plugs - NGK B6HS plugs - and a new rotor cap.

- I'll keep you posted!

Pdxr4000
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Re: 180 Turbo Distributor Questions

Post by Pdxr4000 »

One question that I haven't been able to clarify- at idle when I remove the vacuum retard hose, the engine wants to die. I quickly put the hose back on the barb end, and engine running returns to normal.

Is this correct for this engine?

Thanks!!

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bbodie52
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Re: 180 Turbo Distributor Questions

Post by bbodie52 »

It sounds like you are creating a vacuum leak at idle by disconnecting the vacuum hose from the pressure retard unit and not plugging the open hose. The factory pressure retard unit only has the capability of moving the breaker plate in the direction needed to retard timing, which is the opposite of the vacuum advance unit fitted to non-turbocharged distributors. At idle the vacuum from the intake manifold would not move the pressure retard arm at all, but disconnecting it would create a vacuum leak at the intake manifold at the other end of the hose. This would cause the right cylinders to run very lean and likely cause the engine to die at idle.

I'm not sure how you can test the pressure retard device to see if it actually works to retard the timing at boost pressure. But if it is not actually functioning to retard the timing, engine detonation at boost would likely occur, which can damage the engine if it is allowed to continue.

Clark's actually makes a combination vacuum advance/pressure retard unit which does both. They recommend starting with 18 degrees static advance at idle, instead of 24 degrees. The vacuum advance provides some low speed advance when manifold vacuum is high, and then switches to pressure retard when the turbocharger pressurizes the manifold at high engine speeds. I have not actually read any feedback on how well this works. Not cheap, though.

Part number C7877: TURBO ADVANCE/RETARD *SET TIMING TO 18 BTDC (TO START)

Weight: 0 lbs 6 oz
Catalog Pages(s): 51,SUP-39
Price: $ 82.80


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Brad Bodie
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miniman82
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Re: 180 Turbo Distributor Questions

Post by miniman82 »

Bad running with the hose removed is the result of the vacuum leak you just created, it’s running lean and will do so unless you plug the hose.

Sound to me like you have the wrong main jet in your YH, or the lifting arm isn’t raising the needle properly to enrich the mixture, or your turbo is seized. No way to confirm without a wideband O2 sensor, but let’s assume the issue isn’t in your ignition system since that all seems to be fine with the right parts and whatnot.

If it’s running lean when you attempt full throttle, it will tend to surge or pop back through the manifold and have a noticeable loss of power. If there’s no loss of power but it’s still stumbling, your probably spraying too much water and it’s blowing out your spark.

I think you need to disable the water injection in order to diagnose this properly, there’s too many turds in the punch bowl to make sense of it right now.
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