[Tom Vaught]

In 50+ years of playing with Pontiac Engines, I personally have seen only one case of a valve head coming off of a valve stem.

This was on Jim Brady's 64 GTO drag car many years ago at a race in Wisconsin.

Stock 2 Piece Pontiac Intake Valve.
Did a burnout in the water box, can out idled towards the starting line, engine locks up.
Turned out the valve head came off, flipped over and just shut the engine off. No major damage to the head or engine. new valve and maybe a Piston, but that was a long time ago.

Were these stock sealed power type valves? Some of these places might have had parts on the shelf for 25 years.

Tom V.

[ichabod]

I have run 100LL Av gas for over 20 yrs in both my cars. These cars were stored for 4-5 mo. (Maine Winters). As said AV gas is very stable. All I ever did when bringing them out of storage was pulling the coil wire and turning them over a few times. Replacing coil wire and starting within seconds of cranking. Your problem is not fuel related. Good luck.

[1968GTO421]

Originally Posted by grivera

Listen to the advice you've gotten here. Either the builder is incompetent or he is BS'ing you so he doesn't have to honor the warranty.

X2. I agree with everyone else on this. Best of luck getting it resolved.

[Schurkey]

Originally Posted by billkinney

#2 exhaust valve broke at the bottom of the stem. springs pulled the stem up.

Valve head pops off the stem? I'd be looking for valve seat-to-valve guide concentricity problems. Checking the other (non-failed) valves and seats could be revealing.

Could be a faulty welding of the head to the stem...but it would take some fancy equipment to determine that, after the head bounces around the chamber.

[geeteeohguy]

Originally Posted by Tom Vaught

My son has thousands of hours in Twin Engine aircraft engines that run 100LL gasoline. As was posted the gas is very stable.

The guy has no clue what he is talking about and was just grasping at straws (using the info you gave him) to try to back out of his poor workmanship and warranty on the engine.

Aviation Engines typically can go 200 hours or in car miles (35,000) assuming a speed of 175 mph on average with basically just oil changes and adding fuel to the tanks. AND they do not have valve issues.

Tom V.

This^^^. Absolute BS. The guy would have said ethanol caused it if you had told him pump gas. I have started and run many, many engines that have sat for 5-55 years without issue. The only stuck ones were where water got in.

[Bob Eiler]

Originally Posted by Schurkey

Valve head pops off the stem? I'd be looking for valve seat-to-valve guide concentricity problems. Checking the other (non-failed) valves and seats could be revealing.

Could be a faulty welding of the head to the stem...but it would take some fancy equipment to determine that, after the head bounces around the chamber.

X2

Tight valve guide clearance with excessive seat run out is a recipe for broken valves. Then the valve manufacturer gets blamed.

[3fastgtos]

Originally Posted by Tom Vaught

My son has thousands of hours in Twin Engine aircraft engines that run 100LL gasoline. As was posted the gas is very stable.

The guy has no clue what he is talking about and was just grasping at straws (using the info you gave him) to try to back out of his poor workmanship and warranty on the engine.

Aviation Engines typically can go 200 hours or in car miles (35,000) assuming a speed of 175 mph on average with basically just oil changes and adding fuel to the tanks. AND they do not have valve issues.

Tom V.

Actually they last around 1400-2000 hours depending on the brand and type (turbo or non-turbo).
SD

[hurryinhoosier62]

Originally Posted by 3fastgtos

Actually they last around 1400-2000 hours depending on the brand and type (turbo or non-turbo).
SD

Actually, it’s the FAA and the engine manufacturers that set the TBO (Time Before Overhaul) . It has nothing to do with brand; it has everything to do with the internal stresses of the engine. The Lycoming TIO-541 series of engines have TBOs ranging from 1200-1600 hrs based on what model is involved. Upgrades in materials usually extends the TBOs.

[3fastgtos]

Originally Posted by hurryinhoosier62

Actually, it’s the FAA and the engine manufacturers that set the TBO (Time Before Overhaul) . It has nothing to do with brand; it has everything to do with the internal stresses of the engine. The Lycoming TIO-541 series of engines have TBOs ranging from 1200-1600 hrs based on what model is involved. Upgrades in materials usually extends the TBOs.

Time Between Overhaul, but yea you're right.
We've had 1 Lycoming powered plane, and it had an IO540 with a 2000hr tbo.
A pair of Continental GTSIO-520N with 1600hr tbo
Several TSIO-520NBs with 1400
A couple TSIO-360-KBs with 1800.
Reaching tbo mostly comes down to proper maintenance and proper engine management in the cockpit.
But back on point, I've run Avgas in my cars since the '80s with no problems.
SD

[Tom Vaught]

Now I knew it was 2000 vs 200 but spent too much time thinking about the conversion to road miles vs making sure I typed the hours right, missed a zero there, DOH!. Back to post.

Tom V.

[hurryinhoosier62]

Originally Posted by 3fastgtos

Time Between Overhaul, but yea you're right.
We've had 1 Lycoming powered plane, and it had an IO540 with a 2000hr tbo.
A pair of Continental GTSIO-520N with 1600hr tbo
Several TSIO-520NBs with 1400
A couple TSIO-360-KBs with 1800.
Reaching tbo mostly comes down to proper maintenance and proper engine management in the cockpit.
But back on point, I've run Avgas in my cars since the '80s with no problems.
SD

Did any of the "N" model GTSIO-520s make TBO? Ours never did. Usually started making metal around 1400hrs.

[3fastgtos]

Originally Posted by hurryinhoosier62

Did any of the "N" model GTSIO-520s make TBO? Ours never did. Usually started making metal around 1400hrs.

No, had 4 different pilots flying the 421 and that's hard on them. They seem to last better in the 404's though. I've been told the added load actually keeps the gearbox from making so much metal. We finally traded it for another 414. Loved the extra power but the maintenance was to much.
Now we mostly have C90A King Airs. Two with Blackhawks. Night and day difference.
SD

[hurryinhoosier62]

Originally Posted by 3fastgtos

No, had 4 different pilots flying the 421 and that's hard on them. They seem to last better in the 404's though. I've been told the added load actually keeps the gearbox from making so much metal. We finally traded it for another 414. Loved the extra power but the maintenance was to much.
Now we mostly have C90A King Airs. Two with Blackhawks. Night and day difference.
SD

The -135s turn the C90As from “OK” to “HOLY S$&T!”. I never liked the-21s; I preferred the-28s on the E90s..

[U47]

Originally Posted by hurryinhoosier62

Actually, it’s the FAA and the engine manufacturers that set the TBO (Time Before Overhaul) . It has nothing to do with brand; it has everything to do with the internal stresses of the engine. The Lycoming TIO-541 series of engines have TBOs ranging from 1200-1600 hrs based on what model is involved. Upgrades in materials usually extends the TBOs.

With our 1820's and 3350's we went by the manufacturers recommendations, but certain conditions changed those circumstances that the Navy would indicate, so the interval varies , but is generally between 700-1,000 hours. I understand the US Forest Service used to set 1,700 hours as a TBO on R-3350s, but would allow extensions if an engine met certain specs and was in an oil analysis program. I do not know if their engines were turbo compound like we had in the navy because they are only using 100LL and we were using 145 / 115, I ran as a steady diet in my 65 VW Beetle using day old fuel samples.
From 1992- until the 9/11 attack closed most airports without a pass I always used 100LL in my 455 LeMans.

[dataway]

Any chance the engine ingested something? Sometimes a object can get trapped and hold the valve open, piston smacks it, breaks off the head. Unlikely to happen on a one piece valve where it would just bend.

[Transamric]

I'd say it's time to lawyer up! Don't let the ship off the hook, they owe you.

[hurryinhoosier62]

Originally Posted by U47

With our 1820's and 3350's we went by the manufacturers recommendations, but certain conditions changed those circumstances that the Navy would indicate, so the interval varies , but is generally between 700-1,000 hours. I understand the US Forest Service used to set 1,700 hours as a TBO on R-3350s, but would allow extensions if an engine met certain specs and was in an oil analysis program. I do not know if their engines were turbo compound like we had in the navy because they are only using 100LL and we were using 145 / 115, I ran as a steady diet in my 65 VW Beetle using day old fuel samples.
From 1992- until the 9/11 attack closed most airports without a pass I always used 100LL in my 455 LeMans.

3350 turbo compounds rarely made 700 hrs in service. Too complex and way too many fire warning lights!

[STEELCITYFIREBIRD]

It's amazing how fast someone does the right thing when you send a demand letter, via certified mail.

[U47]

Originally Posted by hurryinhoosier62

3350 turbo compounds rarely made 700 hrs in service. Too complex and way too many fire warning lights!

For you maybe. I liked them, working on them, and put many hrs. in the air with them.
http://vp23.org/gallery_gen/f639849f...2c_gallery.jpg

[HeliTech]

I've been maintaining aircraft and engines since 1966. There are too many details concerning the differences between 100LL Avgas and automotive fuels. Suffice it to say running 100LL will not break a valve, but Avgas burns slower than automotive gas. For those of you that claim you have run 100LL for years, I'm guessing you don't drive in cold climates as avgas makes for much harder starting in cold weather. It is also incompatible with legacy (old) seals an o rings.

Do you really want to know about fuel choices? Here is one of the best sites I've run across: http://www.superchevy.com/how-to/car...-about-octane/