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dropped valve seats?
Posted by: jjeffb ()
Date: November 22, 2019 04:30PM

what is the best preventative fix to keep those valve seats where they belong?



Edited 1 time(s). Last edit at 11/22/2019 10:53PM by MattNall.

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Re: dropped vale seats
Posted by: Pacerace ()
Date: November 22, 2019 05:25PM

Honestly? Going ahead and getting the heads deap seated. Make sure the cooling system is in order

There are 3 common circumstances that seats come out from what I've read.

1: engine braking after driving up a long Hill. Driving up the hill increases the heat load in the head, and engine braking on the other side cools the seat rapidly and it loses its press fit. Easily avoidable, just be careful and pay attention to your brakes if you're in the mountains.

2. Restarting after a heat soak. I've personally dropped a seat like this. A 10 minute drive to get breakfast, parked, came back out after maybe 10 minutes. Cranked the car, and when I tapped the throttle to back out of the space the seat came out. Not sure there's a way to avoid this other than letting it cool longer before driving, but I wouldn't let that control how I enjoy my car.

3. Overheating. I've seen them come out while it's hot, and I've dropped one shortly after an overheat. Lost a belt and didn't realize it on the way to school, noticed while I pulled into the parking lot, parked at the closest spot and went in to school. Replaced the belt when I left, and halfway home it came out. This is also easily avoidable.

I now have a set of Tom K big valve 110 heads and don't worry about seats nearly as much.

________________________________________________________

Chandler
Powder Springs, GA.



1965 Corvair Monza 110/4sp Coupe

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Re: dropped vale seats
Posted by: Frank DuVal ()
Date: November 22, 2019 08:02PM

Yes, deep seats is the only way. Staking does not work. Hoping and praying is what most people do.

Like Chandler says, get heads hot, let cool air go through the seats, they shrink, they fall out.angry smiley

Frank DuVal

Fredericksburg, VA

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Re: dropped vale seats
Posted by: Timothy Shortle ()
Date: November 22, 2019 08:19PM

I agree with these replies. I think keeping the cooling system in tip top shape is very helpful. I let my engine idle a bit before I shut it off especially after a long drive. A problem we all have is we don't really know the history of our engines. Were they overheated/driven without the fan belt in the past before we got them? Deep seats is the best "preventative maintenance". It's the only way I feel comfortable on a long trip. Steve Goodman has done my heads.

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Re: dropped valve seats?
Posted by: jjohnsonjo ()
Date: November 23, 2019 05:04AM

I have used the set screw mod on my turbo after dropping my first seat, many years and many thousands of miles and no more dropped seats. Some here flame it, but it works. A few hours of your time and your good to go. Not my idea by the way, I just read about it and gave it a try.

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: dropped valve seats?
Posted by: JimBrandberg ()
Date: November 23, 2019 06:22AM

My brother peened aluminum over to stake seats when Ice Racing in the 70s. I don't do it as it's fallen out of favor. I have a tough time explaining why since it worked for him. Same thing with extended tip Champion spark plugs.

I had a 95 HP exhaust seat come out with the engine idling at the gas pump in the winter one time. That goes against the probabilities.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: dropped valve seats?
Posted by: JerryM ()
Date: November 23, 2019 06:25AM

Has anyone tried beryllium copper valve seats?

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Re: dropped valve seats?
Posted by: v8vair ()
Date: November 23, 2019 06:38AM

If you have the seats done properly you wont have to do anything special, just drive it. Mike

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Re: dropped valve seats?
Posted by: mtmouse ()
Date: November 23, 2019 07:15AM

Ok, time for stupid question number 38. If you keep the lower shrouds on and the thermostat flaps work correctly won't this keep the heads from the sudden heat cool cycles that seem to be the issue with dropping valve seats?
Joe

Joe in South Ga
1965 Corsa 2 dr Coupe Turbo 4sp because I love the looks
18ft Chaparral 180 Sport because I live on a lake, seemed like the thing to do
Chevy Pickup to tow boat and tote things
Chevy Cavalier because they drive like a go-cart

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Re: dropped valve seats?
Posted by: MattNall ()
Date: November 23, 2019 07:37AM

To a great extent... YES

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Re: dropped valve seats?
Posted by: Mike Stillwell ()
Date: November 23, 2019 09:03AM

No! Keeping the shrouds on leads to greater temperature swings because the engines gets hotter at full temp. They all start at the same temp, say 75F degree, but if you run with the shrouds on it will end up operating from say 75F to 350F vs 75F to 300F without shrouds.

Mike
YS-117



Edited 1 time(s). Last edit at 11/23/2019 09:04AM by Mike Stillwell.

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Re: dropped valve seats?
Posted by: mtmouse ()
Date: November 23, 2019 10:03AM

But wouldn't keeping the shrouds on keep the heads from cooling or heating in quicker cycles. Seems that slower heat/cool cycles would help with keeping them in place.
Just asking. Seems to be seperate trains of thought here.
Joe
Mike Stillwell Wrote:
-------------------------------------------------------
> No! Keeping the shrouds on leads to greater temperature swings because the engines gets hotter at full temp. They all start at the same temp, say 75F degree, but if you run with the shrouds on it will end up operating from say 75F to 350F vs 75F to 300F without shrouds.
>
> Mike
> YS-117

Joe in South Ga
1965 Corsa 2 dr Coupe Turbo 4sp because I love the looks
18ft Chaparral 180 Sport because I live on a lake, seemed like the thing to do
Chevy Pickup to tow boat and tote things
Chevy Cavalier because they drive like a go-cart

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Re: dropped valve seats?
Posted by: nirvairna ()
Date: November 23, 2019 10:52AM

JerryM Wrote:
-------------------------------------------------------
> Has anyone tried beryllium copper valve seats?


IIRC I saw a set about 10 years ago at the 'toss, Jeff Ballard had them on display, beautiful work. I think they were BeCu, but they could have been bronze seats. Maybe Jeff will comment.

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Re: dropped valve seats?
Posted by: 66vairman ()
Date: November 23, 2019 12:03PM

mtmouse Wrote:
-------------------------------------------------------
> But wouldn't keeping the shrouds on keep the heads from cooling or heating in quicker cycles. Seems that slower heat/cool cycles would help with keeping them in place.
> Just asking. Seems to be seperate trains of thought here.
> Joe

Both have valid points - HOWEVER based on small aviation engine head failures there are two things ruin heads.

1. Rapid changes in head temperature does in fact cause damage. Considering that GM tested fully shrouded Corvair engines in Arizona during the summer and found NO over heating issues there is no reason to remove the thermostats and shrouds except for going racing were the engine is a maximum power most of the time.
2. Over heating a head will damage it. It's important to make sure the cooling system works properly and there is no blockage due to critter nests, rags, and flashing material on the heads.

Finally - you can't make a seat fit tighter by peenning. As soon as you go through a few thermal cycles the peening will be squeezed back. Deep seats simply increase seat to head contact area and retaining tension and it's been proven to work.

Set screws may work, but it one comes loose it won't be pretty. Up to the owner too decide.

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Re: dropped valve seats?
Posted by: Frank DuVal ()
Date: November 23, 2019 09:54PM

Quote
Joe
If you keep the lower shrouds on and the thermostat flaps work correctly won't this keep the heads from the sudden heat cool cycles

Nope, it is the relative difference in temperature from the aluminum to the steel that is the issue. When the aluminum head heats up, it expands. The steel seat also expands maybe not as much as the aluminum, so the grip on the steel seat gets less than designed. Now, crest the hill after hard climb, which gets the aluminum head and the steel seat up in temperature, now go down the hill in gear, cool mountain air rushes into the combustion chamber, chilling the steel intake seat, which shrinks the seat, head still very hot, grip now really less than designed, seat falls out. Easy Peasy!grinning smiley


Driving with the lower shrouds off and splashing water on the head cools the outside of the head, by the time the seat gets cool, the head is already cool, so the seat stays in place.

Same thing when you overheat the head, both get hot, then cool air, relative to the head temperature, blows past the intake valve, shrinking the seat, and pop pop pop the seat falls out. Exhaust seats do not fall out as often, but they do too!

And of course, many seats get loose, then fall out later when idling.winking smiley I've had many snap back into place, run for a while, fall out, snap back in place.....eye popping smiley

Frank DuVal

Fredericksburg, VA

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Re: dropped valve seats?
Posted by: Ron62 ()
Date: November 24, 2019 05:42AM

How is it that some folks have run corvairs for well over 100K miles as daily drivers and never had an issue with a valve seat falling out. Based on the discussion in this thread it would appear it would be a consistent problem with all engines at most likely much lower mileage.

If the problem is really this bad then all of us who have restored these cars and enjoy driving them as daily drivers are driving a time bomb and therefor not worth putting any more money into the restorations as cars to be driven.

Where the cars are not worth a lot on the market as compared to other classic cars of that time period, I don't see the logic in spending thousands of dollars in cylinder heads just to drive the car.

I mean, I love my 67 and drive it daily but I also want it to be reliable if im going to continue to invest in it.

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Re: dropped valve seats?
Posted by: JimBrandberg ()
Date: November 24, 2019 06:21AM

Part of the problem is the old aluminum loses temper especially when overheated. I would guess the no problem heads have not been overheated. That's why you wonder about the other 11 when one comes out.
I think #5 has more issues because of the fresh air duct especially if the hose is bad and there's a big cooling air pressure loss.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: dropped valve seats?
Posted by: Timothy Shortle ()
Date: November 24, 2019 09:40AM

To Ron62: I believe also the same reason some folks live to over 100 and some don't make it to their first birthday.

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Re: dropped valve seats?
Posted by: American Mel ()
Date: November 24, 2019 02:11PM

JimBrandberg Wrote:
-------------------------------------------------------
> Part of the problem is the old aluminum loses temper especially when overheated. I would guess the no problem heads have not been overheated. That's why you wonder about the other 11 when one comes out.
> I think #5 has more issues because of the fresh air duct especially if the hose is bad and there's a big cooling air pressure loss.


I would tend to agree with that theorem.
I have lost a #5, and a #2 seat.
The #5 dropped going down a hill after a rather spirited run on a nice country back-road.
The #2 dropped while just cruising along home on a cool evening after the Northwest Econorun at Harrison Hot Springs.
It has been suggested that the #2 may be due to the proximity of the oil cooler.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, '62 Monza Wagon, '63 Spyder, '65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dualy, approaching 400K
17'Terry

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Re: dropped valve seats?
Posted by: alan_smithee ()
Date: November 24, 2019 03:40PM

my turbo is currently in the shop with a #2 and #3 cylinder gone. Whats the likelihood of that happening all within a matter of a few days of one another?


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