NC-car-guy

How buttercup got her groove back

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Pull just the head with the issue.  Once out a better determination of repair can be made. Yes, new head gasket and intake gaskets. Reuse the head bolts. 

Edited by avgwarhawk (see edit history)

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Benefits of AACA Membership.

20 minutes ago, JohnD1956 said:

Before tearing it down  have you considered pulling the valve up and charging the cylinder with pressurized air? Might just be a broken spring on that valve. If the seats were addressed when you had the heads off previously I don't think a seat could be ruined with what little use it has had since then.if the air holds that valve in position, changing that spring might be enough to get her back in the groove.

Seats were not previously addressed.  At 13k miles that thought did not cross my mind.  Unfortunately I cant pull up on the valve, hence stuck.  Matt Martin told me that as little as 1 liter of bad fuel in an entire tank can gum up the valve stem and cause it to bend like this one.

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When I had our 54 Super, I had one valve that was stuck down causing zero compression.  I knew it had a miss right off the bat when I drove it off the trailer.  It turned out to be the valve guide that had worked its way down a bit.  Pretty sure it had stuck inside the guide and took the guide with it when initially started.  I pulled the head, removed the valve, tapped the guide back in place, reinstalled valve and reassembled the head.  Problem solved.

stuck_valve.jpg

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3 minutes ago, Smartin said:

When I had our 54 Super, I had one valve that was stuck down causing zero compression.  I knew it had a miss right off the bat when I drove it off the trailer.  It turned out to be the valve guide that had worked its way down a bit.  Pretty sure it had stuck inside the guide and took the guide with it when initially started.  I pulled the head, removed the valve, tapped the guide back in place, reinstalled valve and reassembled the head.  Problem solved.

stuck_valve.jpg

Inspiring!  I sure hope that's all I need.  But even if I need another valve....I've  got a ton of used valves and a few boxes of new ones.  Just all the extra work sucks.

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Yeah it's a pisser, but you can have the head off in an hour.  You got this!

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So in a few months it will be 24 years since I got my first classic car. Pretty sure I've run a lot on bad gas and never had a problem.   Karma? Just the odds? 

Edited by NC-car-guy (see edit history)

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2 minutes ago, NC-car-guy said:

So in a few months it will be 24 years since I got my first classic car. Pretty sure I've run a lot on bad gas and never had a problem.   Karma? Just the odds? 

 

Just a lot of sitting without being ran would be my guess. 

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Matt Martin commented on my facebook post that one cannot lap in a replacement and they must be ground and that I should replace all the valve guides and the exhaust valves since they tend to break.  

I think I'm going back to Ford products after this.  I've run a worn out 300 inline six on duct tape and coat hangers for tens of thousands of miles...  these GM engines are too needy!

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4 hours ago, JohnD1956 said:

Before tearing it down  have you considered pulling the valve up and charging the cylinder with pressurized air? Might just be a broken spring on that valve. If the seats were addressed when you had the heads off previously I don't think a seat could be ruined with what little use it has had since then.if the air holds that valve in position, changing that spring might be enough to get her back in the groove.

Take the rocker assembly off and apply some penetrating oil at the valve stem/valve guide area.  Tap with a small hammer and the valve may pop up, if it does follow up with some light oil; replace rockers and crank.  Not uncommon for valves to stick on a long dormant low mileage engine; OR of the heads were at a machine shop they will see the valve to guide clearance too tight (chevy specs).  Buick specs:

valve stem clearance in guide:
0.0025 inlet
0.0030 exhaust

If you replace one valve you need to set the valve stem height the same as the others or:

1.525 to 1.550 measured (in inches) from valve cover rail to valve stem tip.

 

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3 minutes ago, old-tank said:

Take the rocker assembly off and apply some penetrating oil at the valve stem/valve guide area.  Tap with a small hammer and the valve may pop up, if it does follow up with some light oil; replace rockers and crank.  Not uncommon for valves to stick on a long dormant low mileage engine; OR of the heads were at a machine shop they will see the valve to guide clearance too tight (chevy specs).  Buick specs:

valve stem clearance in guide:
0.0025 inlet
0.0030 exhaust

If you replace one valve you need to set the valve stem height the same as the others or:

1.525 to 1.550 measured (in inches) from valve cover rail to valve stem tip.

 

 

 

This is a sound plan of attack.   

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14 minutes ago, old-tank said:

Take the rocker assembly off and apply some penetrating oil at the valve stem/valve guide area.  Tap with a small hammer and the valve may pop up, if it does follow up with some light oil; replace rockers and crank.  Not uncommon for valves to stick on a long dormant low mileage engine; OR of the heads were at a machine shop they will see the valve to guide clearance too tight (chevy specs).  Buick specs:

valve stem clearance in guide:
0.0025 inlet
0.0030 exhaust

If you replace one valve you need to set the valve stem height the same as the others or:

1.525 to 1.550 measured (in inches) from valve cover rail to valve stem tip.

 

How does one measure from the valve cover rail to the valve stem tip? Is this the gasket surface?   Also how does one "set the height" without grinding metal off?

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1 minute ago, NC-car-guy said:

How does one measure from the valve cover rail to the valve stem tip? Is this the gasket surface?   Also how does one "set the height" without grinding metal off?

Gotta grind. Yes, gasket surface.  If you do this, put a straight edge over the valve stems and they should be pretty close to the same....just match that height.

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1 minute ago, old-tank said:

Gotta grind. Yes, gasket surface.  If you do this, put a straight edge over the valve stems and they should be pretty close to the same....just match that height.

I don't have the equipment or the know-how for grinding valves.  Sounds like an expensive trip to the machine shop.

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2 minutes ago, NC-car-guy said:

I don't have the equipment or the know-how for grinding valves.  Sounds like an expensive trip to the machine shop.

You should be able to find a machine shop that will do one valve, but do it yourself:  lap the new valve with grinding compound and carefully grind the stem with your  bench grinder to match the others.  You worry too much.:rolleyes:.

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10 minutes ago, old-tank said:

You should be able to find a machine shop that will do one valve, but do it yourself:  lap the new valve with grinding compound and carefully grind the stem with your  bench grinder to match the others.  You worry too much.:rolleyes:.

Ha Ha Ha!  Your are right about that!  I do worry a lot. Some people I talk to would have me believe if I sneeze while the valve cover is off it will implode on next start up 😳😳  I've never rebuilt a buick engine.  Ford 302s and international inline 6s I've built in my kitchen lol. Heck even my cadillac is a patchwork of junkyard parts in her 425 and I run that car in two modes, stop and full throttle ha ha ha. I don't worry about it and that's probably why its my favorite right now.

Edited by NC-car-guy (see edit history)

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The manual shows how to handle the lap, etc.  With luck it is just a valve stuck in the guide and a minor repair. 

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7 hours ago, NC-car-guy said:

Barring any damage to the head or piston, can I just lap in a new valve? Should I replace head gaskets again? Should I replace the head bolts?

 

Yes, you can lap one valve in. You must definitely check the stem height and set it correctly because Buicks do not have selective length pushrods. The lifter preload and rocker arm geometry on a Buick depends on the valve stem height being at a predictable dimension, then no other adjustments are usually made. Also measure the valve spring installed height. It is much less likely to be a problem, but check it.

 

Again? The heads were already off?! If you have to pull the head, use a new gasket. Get the same brand and type` the other side has.

 

Bolts are not torque-to-yield, and are not normally replaced on these old engines unless there is some obvious problem. If you are worried about it, measure their length and look for stretched ones. I'll bet you don't find any.

 

7 hours ago, JohnD1956 said:

Before tearing it down  have you considered pulling the valve up and charging the cylinder with pressurized air? Might just be a broken spring on that valve. If the seats were addressed when you had the heads off previously I don't think a seat could be ruined with what little use it has had since then.if the air holds that valve in position, changing that spring might be enough to get her back in the groove.

 

Good plan.

 

6 hours ago, NC-car-guy said:

Seats were not previously addressed.  At 13k miles that thought did not cross my mind.  Unfortunately I cant pull up on the valve, hence stuck.  Matt Martin told me that as little as 1 liter of bad fuel in an entire tank can gum up the valve stem and cause it to bend like this one.

 

 

4 hours ago, NC-car-guy said:

So in a few months it will be 24 years since I got my first classic car. Pretty sure I've run a lot on bad gas and never had a problem.   Karma? Just the odds? 

 

Ugh. So have I, always getting rid of most of it first, but never worried to much about a little residue back in the day. Then one day some bad gas stuck a bunch of valves in an an old Mercury (390 Ford) I inherited from my dad. The gas wasn't even that old, maybe a couple of years. No more than four.

 

It bent a bunch of pushrods, and ran so badly It would not drive. I pulled the valvesprings to change the seals using the cylinder full off rope method. The stuck valves were stuck so badly I couldn't believe it. Lots of penetrating oil and brake cleaner, and still I had to whale on them repeatedly with a brass hammer to get them unstuck, and then repeatedly wash out the guides with more brake cleaner and penetrating oil. These were not new tight guides. The engine has over 200k miles. Once clean, they were about as loose as you would expect them to be, not horrible but definitely loose compared to new. Modern gas rots fast. I think this is probably the new normal.

 

The nailhead valves are at such an angle compared to the pistons, I can't help but wonder if yours is bent. If it isn't bent, you can probably fix it from the top if you want.

 

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1 hour ago, Bloo said:

 

Yes, you can lap one valve in. You must definitely check the stem height and set it correctly because Buicks do not have selective length pushrods. The lifter preload and rocker arm geometry on a Buick depends on the valve stem height being at a predictable dimension, then no other adjustments are usually made. Also measure the valve spring installed height. It is much less likely to be a problem, but check it.

 

Again? The heads were already off?! If you have to pull the head, use a new gasket. Get the same brand and type` the other side has.

 

Bolts are not torque-to-yield, and are not normally replaced on these old engines unless there is some obvious problem. If you are worried about it, measure their length and look for stretched ones. I'll bet you don't find any.

 

 

Good plan.

 

 

 

 

Ugh. So have I, always getting rid of most of it first, but never worried to much about a little residue back in the day. Then one day some bad gas stuck a bunch of valves in an an old Mercury (390 Ford) I inherited from my dad. The gas wasn't even that old, maybe a couple of years. No more than four.

 

It bent a bunch of pushrods, and ran so badly It would not drive. I pulled the valvesprings to change the seals using the cylinder full off rope method. The stuck valves were stuck so badly I couldn't believe it. Lots of penetrating oil and brake cleaner, and still I had to whale on them repeatedly with a brass hammer to get them unstuck, and then repeatedly wash out the guides with more brake cleaner and penetrating oil. These were not new tight guides. The engine has over 200k miles. Once clean, they were about as loose as you would expect them to be, not horrible but definitely loose compared to new. Modern gas rots fast. I think this is probably the new normal.

 

The nailhead valves are at such an angle compared to the pistons, I can't help but wonder if yours is bent. If it isn't bent, you can probably fix it from the top if you want.

 

Thanks for the info. I also appreciate the story...misery loves company!

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2 hours ago, Bloo said:

 

 

Again? The heads were already off?! If you have to pull the head, use a new gasket. Get the same brand and type` the other side has.

 

 

 

Eventhough they are brand new?

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Never reuse a head gasket...unless it's made for it.  That is usually a race application.

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24 minutes ago, NC-car-guy said:

Eventhough they are brand new?

Might work...might not.  It stinks to buy a gasket set for $100+ just for one head gasket.

Did you use the low or high compression gasket?  Let me know...may have some extras.

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6 minutes ago, old-tank said:

Might work...might not.  It stinks to buy a gasket set for $100+ just for one head gasket.

Did you use the low or high compression gasket?  Let me know...may have some extras.

I'm not entirely sure.  Its what centerville sent for my car and they are the "fiber" type not the plain metal...  When I get it out I'll look up the part #.

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I think they use "Best" brand....I imagine Russ would sell you one if you needed it.

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7 minutes ago, NC-car-guy said:

I'm not entirely sure.  Its what centerville sent for my car and they are the "fiber" type not the plain metal...  When I get it out I'll look up the part #.

Fiber type. I purchased from Centerville as well. If I'm not mistaken it was Felpro.  

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