so here is the story i have an evo 8 with all the goodies and the best was my fully built cosworth head.. well about 2 months ago a bad tune caused my boost gauge to spike and my motor blew. so when i finally took the head off i needed new valves and resurfacing. here is where is gets depressing, it had 5000ths of an inch takin off of it so when we put it back on a new stock block it bent all the intake valves because just by shaving off that much it cause a clearance issue with the stock block. the only way i could run the head again is if i built a short block and have the pistons that will be able to clear it. so now i am having to put all the internals (cams, springs, retainers) into my stock head and use that so that it will clear the block and pistons... so now i will be selling it soon probably for a good deal and all the person will need is new intake valves, cams, springs and retainers and they have a fully done cossie head.... tonight the head is being taking off and being swapped.. i am very sad to see it unusable on my car now but stuff happens..... this thread is not a for sale thread just giving people an update

 

damn son! I am very sorry to hear that...that sucks.

 

just take you pistons out & get them fly cut to make the valve relifs bigger

 

Did the person who put the head back on check the PTV clearance?

 

Is that acronym actually used? PTV? Do you really say "piston to valve" so much that you need an acronym?

By the way, what is the proper way to check "PTV"? I heard you can put some clay on the pistons or something?

 

Would a thicker headgasket work?

 

that is what I was thinking...and if PTV was the issue, I would think the exhaust valve would be hitting. There is no way 5 thousandths made it a issue, we shave all of our heads 5-7..You could take 20 and in extreme cases 30 and still be ok.

Sounds like someone didn't time it right. If it were 180 out, the piston would chase the intake valve.

 

If a few thousandths of an inch was all that stood between the valves and piston, then it wasn't assembled correctly in the first place. I find it difficult to believe it was assembled with so little valve to piston clearance. What cams are you running. I might question how this conclusion was reached.

 

Don't all the cool people use acronyms? I just want to be cool

 

I'm with Ted B. Should be 60/1000 or so clearance throughout the cam/valve to piston cycle. 5/1000s would not do it if the clearances were set properly.

 

damn that sucks... I had a buddy that bought a fully built AMS 2.3l longblock and he ran a hafe manifold with a GT35r turbo setup, AMS VSR and his car blew up on the dyno while getting its C16 tune. He had barely even bought the AMS longblock he probably only drove it on pump for 1,800 miles
! : ( sh* t happens !

 

we did a leak down test and it was right there at the valves so we know it was a clearance issue... the timing was perfect.. so finally we did sum research and found out that a cosworth cnc race head is already pushing the limits with the clearance on a stock block with the pistons and valves so but resurfacing it caused it to just barely touch there for causing all my intake valves becoming bent and i just replaced all of the valves in it... and a thicker head gasket might work but doubt it and i have been waiting way too long to get my car back so i am just going to put all the internals from my cnc head into my stock head and try and sell the head.... but it just sux cause that head was bada**... but sh** happens so what can u do about it.... i mean it really wasnt changing much in my car since i am only running a fp white turbo... i mean the car was almost full done.. dp,tp,full race mani, 880cc precision fuel injectors, carbon ti exhaust, cnc head with 272 cams, gauges, boost controller and turbo timer, i had all the goodies i wanted and now i am having to sacrifice my head cause i dont have the money now to do a motor build

 

soo we have a conclusion, all the intake valves were bent, we rechecked the timing just to make sure and the timing was perfect, for some reason either the valves were not seated right when the machine shop put the new valves in or the clearance issue by shaving down the head and resurfacing it caused the problem either way it is a pain