Ignition timing question

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terribleted
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Re: Ignition timing question

Post by terribleted »

cwhunt wrote:After a good amount of searching forums etc. I finally found that clarks sells a reproduction pressure retard unit. Part no. C13269 if anyone else needs to know part number.

Is it just me that has issues finding stuff through Clark's online catalog? I seem to forget all their different catalogs chopped together.

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Buy Clark's paper catalog set. Much easier to peruse than the online version, plus , you get to see all the things you would like to know are out there that you miss bouncing search to search online. Very nice paper catalog, well indexed, and an excellent general info source as well with its many break down diagrams and tidbits of Corvair knowledge. Even better it is cheap 2 large catalogs and a price list for $6 ($3 with an order) and it includes so much reference data that you would have to buy multiple other publications to get it all.
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Re: Ignition timing question

Post by 64powerglide »

I don't see anywhere on this page that says part C7877 is not available but I would call Clark's & see.

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

Weight: 0 lbs 6 oz
Catalog Pages(s): 51,SUP,33
Price: $ 84.85
Order Quantity:
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C7877.jpg
Last edited by 64powerglide on Mon Dec 05, 2016 9:36 am, edited 1 time in total.
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Re: Ignition timing question

Post by bbodie52 »

I received a response from Clark's Corvair Parts this morning regarding my earlier question about the pressure retard devices and the difficulty in finding them in the online catalog...
Sorry, these were just reproduced for us this last year and are currently only listed in our yearly supplement flyer that we put out at the beginning of each year. Here is the link for the page that we listed them on in the newest supplement, you will find the retard for both the early and lates here as well as the advance/retard unit that we offer as well, sorry for the confusion finding these, we are working at getting some of these items updated more often, thanks.
http://www.corvair.com/user-cgi/catalog ... age=SUP-33

Clarks Corvair Parts
400 Mohawk Trail
Shelburne Falls, Ma 01370
413-625-9776
413-625-8498 Fax
http://www.corvair.com

----- Original Message -----
From: <info@corvair.com>
Sent: Saturday, December 03, 2016 8:41 AM
Subject: Technical Service Form

> comments: CATALOG FEEDBACK...
>
> C13269 - REPRO PRESSURE RETARD #224 62-64 TURBO
>
> It appears that Clark's does sell a badly needed pressure retard device for the 1962-1964 turbo Corvair, but it cannot be found using the search function with the word "retard" or "pressure". Such a search only points to page 51 and the out of stock CX3170 or out of stock CX3169.
>
> ONLY THROUGH THE COMMENTS ON THE CORVAIR FORUM (BELOW) WAS I ABLE TO FIND OUT ABOUT PART NO: C13269! No search will reveal it on your website, except for a specific search using this part number (if you already know it). If this critical part is in-fact available through Clark's Corvair Parts, why is it so well hidden on your website??? I would suggest an edit of page 51 in your online catalog to reflect part number C13269 as a viable alternative to the perpetually unavailable CX3169 and CX3170. Also, is there a pressure retard device available for 1965-1966 turbo Corvairs? Finally, clicking on the page link for C13269 takes the customer to page 33, which DOES NOT list this item!
>
> FROM THE CORVAIR FORUM...
>
> "After a good amount of searching forums etc. I finally found that clarks sells a reproduction pressure retard unit. Part no. C13269 if anyone else needs to know part number.
>
> Is it just me that has issues finding stuff through Clark's online catalog? I seem to forget all their different catalogs chopped together."
:link: http://www.corvair.com/user-cgi/catalog ... age=SUP-33
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Re: Ignition timing question

Post by cwhunt »

Ok. Thanks for the correspondence with Clark's. I guess with a paper catalog it would be difficult. Do you think I should put on the advance/retard unit or just stay with the retard unit?

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Re: Ignition timing question

Post by bbodie52 »

cwhunt wrote:...Do you think I should put on the advance/retard unit or just stay with the retard unit?
These reproduction units are relatively new, so I have yet to see any consumer comments evaluating them or their effectiveness.

A non-turbo Corvair performs better with a vacuum advance at low engine speeds, with the centrifugal advance mechanism taking over at higher engine speeds. Since there is essentially no turbo boost at low engine speeds, it would make sense to have a vacuum advance at non-turbo operating speeds, with a centrifugal advance coupled with a pressure retard when the turbo is active. How effective such a mechanical device is I don't know without reading some consumer feedback. Perhaps Clark's customer service representatives could give you some information based on their experiences with it. I doubt it would be as effective as a computer-controlled, sensor based system — but such a system would be much-more expensive. Electronic control might be tuneable, but also more complex to set up.

The repro pressure retard unit is about $65, and the vacuum advance/pressure retard combo unit is about $20 more.

Many turbo Corvair performance modifications are something of an experimental, trial and error process. If you decide to go ahead with a pressure retard reproduction, or the vacuum advance/pressure retard combo, any feedback you can provide that tells of your experience with that system would be helpful to others and appreciated here on the Corvair Forum.
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Re: Ignition timing question

Post by toytron »

Brad,

I must say that I thoroughly enjoy your thoroughness when it comes to providing information to this forum. :not worthy: :ty: :clap: :clap: :clap:

You are a tremendous asset to this board. Please keep up the good work. This also goes out to many others that are so informed and helpful. I am privileged to be associated with this group.
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Re: Ignition timing question

Post by cwhunt »

I will go for the advance and retard unit and will post my experience with it and see if it does a decent job. I do want to go electronic, but that is farther down the road due to money that needs to go elsewhere in the car.

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Re: Ignition timing question

Post by miniman82 »

Just for reference:

Vacuum advance works in tandem with lean mixtures at cruise to give better economy; the slower flame speeds experienced with lean mixtures means the spark has to happen earlier, hence the timing advance. What this means is if you can't lean out during cruising situations, much of the benefit of a vacuum advance is lost.

This also means you need a way to know how rich or lean you really are, and that entails a wide band oxygen sensor and not one of those cheap red/yellow/green LED gauges. If you want it to work right, you can't just slap on a vac unit and expect results- never works that way.

Here's the other problem with turbo corvairs: I can't speak for all cars, but mine was pig rich when I started tuning it. The YH carb doesn't have a whole lot of range to it, which meant that by the time I got it lean enough at cruise there was no longer enough fuel flow for boosted driving. Well known fact I've never been a YH fan, this is one of the reasons why. It really only has two settings, idle and wide open. Between that you sort of get what you get, which is usually too much fuel.

Anyhow if you're serious about getting the most out of this engine, it takes a lot of tinkering. In my case it meant dispensing with the stock ignition entirely, because it's too much of a compromise to give me what I was after. That was followed by getting rid of the stock carb, in favor of something with a whole lot more tuning ability. I now have a DCOE, and there's a big ole Zenith in the garage if that doesn't work out.

I wish you luck, if you need help you know where to ask.
Last edited by miniman82 on Mon Dec 12, 2016 6:00 am, edited 1 time in total.
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Re: Ignition timing question

Post by cwhunt »

I totally agree with you. My engine is running pretty rich right now and it has been difficult to adjust. I would love to do more with the ignition system but the money just isn't there. I am just replacing the retard unit as it is stuck and doesn't operate. I am also trying to correct timing being way off as well. Further down the road, I will end up replacing the whole ignition system.
Thanks for all the help.

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Re: Ignition timing question

Post by miniman82 »

No problem. Whatever you do, don't allow the engine to detonate for very long. Sounds like someone's shaking a rattle can of paint inside your engine, but it's actually preignition trying to melt your pistons. Can be a result of too lean a mixture under heavy load, too much timing advance, or the heads overheating for some reason. If you have a loud exhaust you may never hear it till it's too late, which is why I run the best flowing and also quietest muffler I could find!
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Re: Ignition timing question

Post by cwhunt »

That's great advice. Mine does have a loud exhaust and timing has been set way too far advanced. I had a boat engine that ate a hole through a piston before, would I get any warning signs before complete blow out? i.e. white flakes of metal on spark plugs like my boat did?

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Re: Ignition timing question

Post by miniman82 »

Probably not. Because these engines run so rich, carbon immediately covers up any aluminum flecks that would have migrated to the plug electrodes. Just listen for signs and be careful.
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Re: Ignition timing question

Post by cwhunt »

Installed the new repo advance and retard unit and timing is now back on spot. Engine running smoother and more quite. World of difference!Image

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Re: Ignition timing question

Post by acarlson »

What timing are you using - 18 or 24 or something else. Clarks says use 18-20 with this vacuum/ retard unit. 24 would be with the stock retard only unit. Just curious.
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Re: Ignition timing question

Post by cwhunt »

After installing this unit it placed the timing back to 24. The old unit was stuck and putting it off the scale by about a half inch. I then adjusted to 18 like Clark's recommended.

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