exhaust valve sticking in guide

[6burg]

Dart platinum iron head 215 runners ported at rons porting in St. louis on cnc machine . 5/16 valve stems ,manley valves. after 20 laps #6 exhaust valve siezed in guide,tagged piston and bent. paid to replace valve and repair . machinest said he would cover labor and I pay for parts. O.k. next night 12 laps #8 exh valve same deal. machinest replaced all guides with cast iron,brass sleeved guides set clearance at guide clearance at .023 . 6 laps #7 siezed. Raised jets 2 sizes, moved hvh spacer back 1/2 inch . not lean. plugs yellow and exhaust ports black and sooty. this all done before #7 siezed. Told machine shop to set valve stem clearance to 4 thousands, made him mad and says way to much clearance but he would. he replaces them a 3 thou. any thoughts or opinions. manley has been sent all valves and guides for inspection and have upgraded me to severduty valves. apparently mine were mid-grade. manley and machine shop have been excellent to deal with and I have nothing bad to say about them. just want problem fixed. engine always brought up to temp and runs 185-200 . Is 4 thousands to much? should be done and ready to pick up thursday

[let-r-eat]

Yes that's too much. Is this an alky engine or gas. Are you sure the valve train geometry is proper. Look at the witness mark where your roller is contacting the valve. Is it narrow? Is it in the center?What is the runout on the valve job?I'd find somewhere else to do the machining. Just my opinion.

[diggindirt]

Check your EGT's and fuel curve. Mine did that for a while, had to make adjustments to the metering blocks to get the fuel curve where we wanted and then tuned to EGT's to get the temps down. She was a bit fat at idle, but was spot on at wide open throttle. Keep an eye on your plugs as well to make sure you don't have any detonation while working with the curves and EGT's.

[andy16]

sounds fishy? i would say optimum valve stem clearance is around .0012 . .002 is a little big imo. .004 is extreme to me? machinist may need to check his tooling maybe guide has taper in it ? may have a new guy or apprentice working on it... ive seen it... maybe your valves have mixed up valve stem sizes like some stems are .001 bigger o.d. than the others. then when machinist sets tooling to the smaller o.d. stem its too tight for the mix match bigger ones? he prob set tooling to #1 valve specs then honed them all to fit it. i would def. investigate plus rons porting is a pretty decent place imo??

[let-r-eat]

Do you have water lines plumbed from waterpump on both sides to center exhaust ports and each side of thermostat housing front to center to back? Ron's is good. Nothing he done I wouldn't think. My guess is you need additional plumbing if you don't have it already.Carb could be the problem as well. What did the plugs look like?

[WRH]

Dart platinum iron head 215 runners ported at rons porting in St. louis on cnc machine . 5/16 valve stems ,manley valves. after 20 laps #6 exhaust valve siezed in guide,tagged piston and bent. paid to replace valve and repair . machinest said he would cover labor and I pay for parts. O.k. next night 12 laps #8 exh valve same deal. machinest replaced all guides with cast iron,brass sleeved guides set clearance at guide clearance at .023 . 6 laps #7 siezed. Raised jets 2 sizes, moved hvh spacer back 1/2 inch . not lean. plugs yellow and exhaust ports black and sooty. this all done before #7 siezed. Told machine shop to set valve stem clearance to 4 thousands, made him mad and says way to much clearance but he would. he replaces them a 3 thou. any thoughts or opinions. manley has been sent all valves and guides for inspection and have upgraded me to severduty valves. apparently mine were mid-grade. manley and machine shop have been excellent to deal with and I have nothing bad to say about them. just want problem fixed. engine always brought up to temp and runs 185-200 . Is 4 thousands to much? should be done and ready to pick up thursday

.004 on a 5/16 stem...hell yes that is wayyy too much. .002 is loose on a 5/16 stem. First thing I would check is that your timing marks are right on your dampner. Install a piston stop and find the true TDC and see if it lines up with your marked TDC on your dampner. Having retarded timing will cause excessive ex temps and will stick valves in guides. If that is ok double check your timing light... borrow a known good one and see if it reads the same as yours.

[perfconn]

I second what WRH says.Too low on timing will cause very high exhaust temperatures,causing exhaust valves to stick.

[6burg]

Picked up heads from machine shop, took to another shop and disassembled and inspected . Found guides were smooth type, not spiral to help with oiling and he had button style sleeves and they were trimed 1/4 inch short in guides, the 16 new valves sent free of charge by manley were installed on old seats that still had carbon on them. two of the intake valves didn't seal properly. we installed spring locators , did valve job and installed guides correctly. won heat and FINISHED feature in 7th place. Learned that big money on heads doesn't always get quality work. Got to give credit to Tripp Manley for going above and beyond ,he upgraded valves and overnighted all parts and payed for old valves and guides to be overnighted to be inspected. Valves still have not been returned to manley as of today. wonder why?hmm

[Chico]

Who did the work?

[6burg]

shop in bathalto illinois, Ron's porting did porting, performance automotive set up and assembled heads. in my opinion the problem was due to only one valve being checked and clearances being set for all valves on that measurement. His statement was "I've always checked only one valve and probably always will" I am not a machinest but assumed all were being checked. He didn't charge any labor, only parts and gaskets first time. next 2 times he paid for parts and labor. just replaced damaged valves each time. I was satisfied with that since he was still trying . I 'm sure he was frustrated and threw it together last time . That's when I thought another shop needs to inspect his work. the 4 thous. clearance came from Billy Fischer works for howards cams. Hell I would have sacrifised a chicken and shook it over the roof if it would have fixed it after 3 times