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CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: Timothy Shortle ()
Date: November 16, 2020 10:23AM

I know the general consensus is if we want to be able to drive our Corvairs the valve seats need to be replaced with deep seats. (This I know first hand).

How about if we have NOS cylinder heads? Sure, they are approximately 50 years old but have zero miles or heat cycles. Thoughts?

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: RobertC ()
Date: November 16, 2020 10:28AM

I would think they would last a long time.

100,000 miles or more.

IF "they" did not suffer from multiple fan belt failures (and driven too far without a fan belt) or driven "too lean".

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: isucorvair ()
Date: November 16, 2020 10:30AM

My opinion would be that they should be good for some time - but how long?

I know my Dad's relatively low mileage 67 dropped a seat (at about 40k miles). I've dropped 2 recently, but they were in 'unknown mileage' engines (and one was thoroughly abused)


Eric P.
DeWitt, IA

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: RobertC ()
Date: November 16, 2020 10:43AM

isucorvair Wrote:
-------------------------------------------------------
> My opinion would be that they should be good for some time - but how long?
>
> I know my Dad's relatively low mileage 67 dropped a seat (at about 40k miles). I've dropped 2 recently, but they were in 'unknown mileage' engines (and one was thoroughly abused)
>
>
> Eric P.
> DeWitt, IA

Interesting.

My 110 did not start losing seats until the heads had over 300,000 miles on them. The seats were staked at one point by my mechanic.

First lost valve seat in my 140 was at 188,000 miles.

Different people have different experiences.

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: MattNall ()
Date: November 16, 2020 10:56AM

Since I buy "project / need work" cars....and do my own work. If I have one I pull the head anf get that ONE fixed. re-install and drive..

I have never had a second seat fall on the same head. Other side? many times.

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

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: isucorvair ()
Date: November 16, 2020 11:15AM

MattNall Wrote:
-------------------------------------------------------
> Since I buy "project / need work" cars....and do my own work. If I have one I pull the head anf get that ONE fixed. re-install and drive..
>
> I have never had a second seat fall on the same head. Other side? many times.



I had a 140 PG engine that had evidence of #4 seat having come out, and been repaired - then while I owned the car, #6 dropped! The engine did come from your part of the country smiling smiley


Eric P.
DeWitt, IA

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: Paulsgt ()
Date: November 16, 2020 11:42AM

I wonder if it has anything to do with how soon in it's life that it was deflashed?

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: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: azdave ()
Date: November 16, 2020 11:54AM

Timothy Shortle Wrote:
-------------------------------------------------------
> I know the general consensus is if we want to be able to drive our Corvairs the valve seats need to be replaced with deep seats.

That is the consensus but not my experience. Still tempting fate with statements like this one but I haven't dropped one ever and I run mostly 140's in Phoenix and have two Vairs with 140's and working A/C. Guess I need to drive'em harder. smiling smiley

On a NOS head I would not bother with deep seats but I don't bother with them on well-used heads either.

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



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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: isucorvair ()
Date: November 16, 2020 12:05PM

azdave Wrote:
-------------------------------------------------------
Still tempting fate with statements like this one but I haven't dropped one ever and I run mostly 140's in Phoenix and have two Vairs with 140's and working A/C. Guess I need to drive'em harder. smiling smiley


I made roughly that same statement at the Independence MO convention a few years back....then I dropped the seat in the 140 the day I got home!


Eric P.
DeWitt, IA

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: RobertC ()
Date: November 16, 2020 12:06PM

> I have never had a second seat fall on the same head. Other side? many times.
>
> Matt

Have not shared your luck - where only the one bad seat is replaced.

> I wonder if it has anything to do with how soon in it's life that it was
> deflashed?
>
> Paul

To add a different experience.

None of my heads, original and replacement, have been de-flashed. At least no record of paying for it.

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: Timothy Shortle ()
Date: November 17, 2020 09:10AM

The 2 times I dropped valve seats in my Rampside was on the way or coming back from Palm Springs. Once in Colorado and once in Arizona. Yuck! I picked up a 65 Corsa Turbo convert. a few years back that came with 6 140 heads. ALL 6 had dropped valve seats.

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: isucorvair ()
Date: November 17, 2020 10:26AM

Has anyone ever dropped a DEEP seat, or do we just not talk about it smiling smiley



Eric P.
DeWitt, IA

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: dryenko ()
Date: November 17, 2020 02:37PM

Yes they do drop, if abused.
In this case of a client of mine driving 10 miles on the highway at 70 MPH ignoring the fan belt departure light.
Until the noises became rally BAD.
Tried to blame me, the worthless prick.
Luckily there was honest witness.
Personal responsibility seems to be a lost virtue, and getting mush worse.
I won't get into mask wearing...

Bob C aka Dryenko
Dobson, NC 27017

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: Layton Curtis ()
Date: November 17, 2020 04:39PM

I have only dropped one seat in a unknown 110 in about 500K miles the last 40 years. In my experience knowing the history of the head is key.

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: vairmech ()
Date: November 17, 2020 04:53PM

dryenko Wrote:
-------------------------------------------------------
> Yes they do drop, if abused.
> In this case of a client of mine driving 10 miles on the highway at 70 MPH ignoring the fan belt departure light.
> Until the noises became rally BAD.
> Tried to blame me, the worthless prick.
> Luckily there was honest witness.
> Personal responsibility seems to be a lost virtue, and getting mush worse.
> I won't get into mask wearing...
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

LOL. Bob, remember Moby Dick Racing? I'm sure you do! LOL again. Then with the guarantee of the valve seats "guaranteed not to fall out even under racing conditions"? Did I get that right?

Fast forward, what 40 years?, and guess what? How about a dropped seat on a set of Moby Dick Racing heads! I didn't bother to ask for the warranty repair, LOL. I do not mean this to degrade anyone or anything, just pointing out that age takes it's toll on anything.

That is why I stop short of guaranteeing any valve seat coming out. Yes, normal warranty service if it would happen, no one is perfect!

To get back to the NOS heads, I would very thoroughly deflash the heads and drive them! It is generally overheating or hot spots that will drop seats.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: jjohnsonjo ()
Date: November 17, 2020 05:57PM

There are probably more than a few Vairs that went from cradle to grave without loosing a seat.

A long time ago I posted some pics of the original factory heads on my turbo car. They looked more like something Honda made as opposed to GM. When I first heard about deflashing I couldn't wait to get at it. To my surprise I could not find one flashing issue or offset fins. Shined all kinds of light through them. Later through out the years I found some that were nearly totally blocked and offset fins that almost were of by 50%. I had one with a big pile of aluminum that I removed. I weighed it and it was significantly more than my original heads. Probably written down somewhere, but I'm not about to go digging for it.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: REM654DPG ()
Date: November 18, 2020 09:30AM

NOS or used the odds are still 50/50 that a seat will come loose. Truth is we really don’t know when a seat will come loose so it’s always a gamble or risk either way. I’ve run both factory and deep seat heads and have honestly never lost a factory seat – yet – even on a turbo which I knew was risky. However, for me the reason I deep seat my road car is because I like to travel long distances from home and way outside of my tow range and know that I won’t get stranded in the middle of Kansas or Canada because of a dropped seat. My around town car, I’m not so concerned about and am content to run original seats in those heads.

And yes, I have had two of my deep seats come loose but both were subjected to abnormal and severe heat conditions for what that’s worth. One was a turbo coming home from Palm Springs that got so hot it turned the chrome turbo shield blue and melted the top of the tar top battery. The other was a 140 in an FC that detonated the chamber so bad that the quench area in the chamber was about half gone. The good part, if that’s possible with a dropped seat, is that the 3/8 deep seats I use are extremely strong and will not break apart. Plus, being 3/8 deep they are far less susceptible to getting lodged sideways in the hole. They basically just move up and down and enlarge the hole quite a bit but they won’t leave you stranded and put shrapnel through the other cylinders.

The turbo was still able to drive all the way home to Portland with just a noticeable miss on the left side (#3 intake). The head was unfortunately severely warped beyond fixing and we tossed it in the scrap. The FC head was the same deal, it was in a Rampside and the driver could not hear the detonation and drove it to its ultimate death. It also made it home with an obvious miss (#5 ex) as the seat pounded a hole about halfway through the head. Both situations only had a noticeable miss but no horrible noises once the seat came loose which is why they kept driving them. So, deep (3/8) seats do make a difference but can still come loose if conditions are extreme.

Regan Metcalf
Portland, OR

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: nirvairna ()
Date: November 18, 2020 05:58PM

Hello Regan

I've noticed many seats in newer cars are powdered metal - what do you think of them?

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: flat_six ()
Date: November 18, 2020 09:34PM

Interesting question Tim and one I’ve pondered lately. Just finished building a 180 motor with NOS heads. What I did notice about these is that, due probably to the late production timing of the heads, the quality was terrible.

The casting was hideous - presumed to be due to tooling that was on its last legs and maybe even foundry workers who were not experienced with setting up parts for that discontinued Corvair. Core offset, tons of excess flashing, a gaping hole in the intake manifold that I had to pay to be welded shut. Evidence of weld repair on both heads.

I also had to chase every thread in both heads so the bolts would go in. Could the cylinder head shop in Tonawanda have worn out taps by then?

So I wonder if the seats in these heads were installed well, at least as good as seats that were done during the height of production.

Time will tell Tim! ????

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Re: CORVAIR CYLINDER HEAD VALVE SEAT QUESTION
Posted by: joelsplace ()
Date: November 18, 2020 10:01PM

Most Corvair heads I've seen had weld repairs from the factory. I figured it was poor casting that had to be fixed.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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