Burnt exhaust valve rebuild

[Sleepin6]

Was just wondering what fail safe items I should replace so I don't burn a valve again. Doing a rebuild now and want to make sure everything that can prevent this is changed or fixed. Thanks.

[Sleepin6]

Anyone go through this on there rebuild?

[mxlplx71]

what tune, boost, and mods

[Mazdazilla6]

Have the head checked by a shop. The largest contributing factor to burnt valves is out of round seats on either the head or the valve or too large of a clearance between the valve stem and guide.

[Sleepin6]

Originally Posted by mxlplx71 what tune, boost, and mods

Ots stage 3,20-21lbs,fully bolted minus intake/exhaust mani's.

Originally Posted by Mazdazilla6 Have the head checked by a shop. The largest contributing factor to burnt valves is out of round seats on either the head or the valve or too large of a clearance between the valve stem and guide.

Ok it's going to get checked at the shop and will go through the full inspection and see what happened. It has rough edges on the head and a chunk of a valve is missing on the exhaust side cyl 2. That's why 0psi...I appreciate the response.

It was a Cobb ots tune and I'm sure that didn't help either. If there's anything else you guys can think of please don't hesitate to pm me or reply. Thanks.

[Sleepin6]

Originally Posted by Sleepin6 Ots stage 3,20-21lbs,fully bolted minus intake/exhaust mani's. Ok it's going to get checked at the shop and will go through the full inspection and see what happened. It has rough edges on the head and a chunk of a valve is missing on the exhaust side cyl 2. That's why 0psi...I appreciate the response. It was a Cobb ots tune and I'm sure that didn't help either. If there's anything else you guys can think of please don't hesitate to pm me or reply. Thanks.

You were right about the seats. He said I need to replace 2 of them in cyl 2 which was the cyl with the one burnt valve and another on the way out. Thanks.

[Mazdazilla6]

No worries. Happy you got it figured out!

[Sleepin6]

Originally Posted by Mazdazilla6 No worries. Happy you got it figured out!

Yeah...now I have to figure out how to not let it happen again. Keep it cool they tell me...I did purchase an aftermarket aluminum radiator overseas...

[Sleepin6]

Can I get away with std size valves when going aftermarket? I only want to upgrade the metal material if I can for heat reasons and strength. What are the advantages of oversized valves if i have the stock cams anyway? Thanks.

[mxlplx71]

Originally Posted by Sleepin6 Can I get away with std size valves when going aftermarket? I only want to upgrade the metal material if I can for heat reasons and strength. What are the advantages of oversized valves if i have the stock cams anyway? Thanks.

Aftermarket valves require valve seals and guides. Different diameter.

[mxlplx71]

Here's mine

[sheston]

That doesn't look like it works like much of a valve anymore. Did a piston hit it?

[Sleepin6]

Originally Posted by mxlplx71 Aftermarket valves require valve seals and guides. Different diameter.

Well the head shop said the guides needed to be replaced anyway so hopefully it works out. So supertech doesn't make oem size performance valves?

[mxlplx71]

Originally Posted by sheston That doesn't look like it works like much of a valve anymore. Did a piston hit it?

i think it just melted there was no damage any place else.

[Sleepin6]

Originally Posted by mxlplx71 i think it just melted there was no damage any place else.

My 2 exhaust valves in cyl 2 looked the same way.

[mituc]

Originally Posted by Sleepin6 My 2 exhaust valves in cyl 2 looked the same way.

So what did you use for replacement? I may be in the same boat.

I also want to go with stiffer valve springs, does anyone know the stiffness of the OEM valve springs?

[shaneski]

Originally Posted by mituc So what did you use for replacement? I may be in the same boat. I also want to go with stiffer valve springs, does anyone know the stiffness of the OEM valve springs?

The last post on the first page shows the stock valves are stiffer than the single spring rate of super techs, usually only need stiffer ones with a turbo that makes enough power to go over 7500rpm
Valve Spring Choices
I've been on stock valve train with my built set up for near 2 years and had zero issues

[Sleepin6]

Originally Posted by mituc So what did you use for replacement? I may be in the same boat. I also want to go with stiffer valve springs, does anyone know the stiffness of the OEM valve springs?

I went with supertech valves and kept everything else oem.

[Sleepin6]

Originally Posted by Sleepin6 I went with supertech valves and kept everything else oem.

O yeah I forgot port an polished also.