I just went through a simmilar situation. The valve was sticking in the guide. In my case the valve hit the pistons, but it still could happen if the valve just sticks. We when back to stock original o-ring seals and removed the aftermarket positive seals. Problem solved. It now gets enough oil to lube the guide.

 

I was thinking the same thing. Insufficient oil in the guides or clearance too tight.

 

These are just as tight as new ones-in fact they are new from 2 weeks ago.
Yes I just went out and put the wood end of a hammer on top of the valve-the intake I can compress and hold down about half way-The exhaust will go down about 1/4" and stop-something is bent on this one,its the one with the busted stud.
Here is my thought on the sticking and you guys tell me if this makes sense.I think the valve stuck trying to close which left the rocker and pushrod loose as a goose-pushrod comes out of ball seat-piston closes valve-cam comes up-valve is bent and cant reopen-stud breaks--why is the pushrod not bent?What caused the intake rod to bend?

 

We could keep putting in the skull sweat over "out there" causes for this...but I think it's "lemon law" time. I think we'd all agree it shouldn't do this and maybe it's time to just settle up with the builder and walk away. You bought a builder's engine to drive your 'vette - not debug what has to be a design/assembly error somewhere.

 

Wonder if someone has stuck some .003 over size walve stem
valves in it. can't remember how big the oversizes ran on valve.
stems been to many yrs.

 

The owner of the car just left and agreed with you he's done with this builder.He said he is going to try to return the motor and get some of his money back.He wants to put in a crate motor.I think I will start a seperate thread and ask you guys to go over some crate motors and the changes to be made with me.
Back to this abortion for a moment.I really think Blue Juice was on to something.Can one of you explain why the 2 front cylinders are sensitive to lack of coolant flow? They seem like they would be first off the water pump.Is this a head thing? If someone pushed one of the front freeze plugs into the block and it fell inside would this be enough to slow the flow? I just want this to make sense if possible for future reference.Thanks for all the responses.

 

I'm pretty sure you have valve to piston clearance problems. Dismantle the engine, put some clay on it, turn it around for a revolution of 4 and measure how thick the clay still is in the tightest spot.

 

I thought so to the first time it bent pushrods on #2 but the builder said it wasnt even close. He also said the valves he was using were very thin and if it would have hit the valve it would have bent and the cylinder wouldnt show good compression.The cyl comp was good.Could a valve hit hard enough to bend a pushrod and not bend the valve?

 

I have seen this before without bending valves. Remember that the material valves (especially exhaust valves) are made from is really tough. Take of the heads and check the v-p-clearance with clay. You will directly see where the problem is. Sometimes you can correct the problem with a piston pocket filer (a valve with a file on the head and create clearance this way) but remember that it could upset the balance of the engine.

 

"DWncchs: Back to this abortion for a moment.I really think Blue Juice was on to something.Can one of you explain why the 2 front cylinders are sensitive to lack of coolant flow? They seem like they would be first off the water pump.Is this a head thing? If someone pushed one of the front freeze plugs into the block and it fell inside would this be enough to slow the flow? I just want this to make sense if possible for future reference.Thanks for all the responses."

for the older engines, the coolant flow enters at the front of the block and travels from front to rear around the cylinders. there are small holes or orifices in the head gasket that "meter" the flowrate of coolant to the heads. the gasket manufacturer is trying to balance coolant flow to areas in the heads this is one reason why they have different gaskets for different applications. the coolant flow then makes its way to the front of the heads, through the intake manifold passages under the thernostat. if the front coolant holes in the gasket were opened too much, then too much coolant would "short circuit" back to the thermostat without cooling the rear of the engine and heads. the gasket manufacturer is also trying to force more coolant to areas in the head that require more flow, like around the exhast valves, and also depending on head design and material.

Originally Posted by S489
can you compress the springs by hand in any way?

"DWncchs:Yes I just went out and put the wood end of a hammer on top of the valve-the intake I can compress and hold down about half way-The exhaust will go down about 1/4" and stop-something is bent on this one,its the one with the busted stud."

i don't think you should be able to compress the spings by hand with no mechanical advantage. i've got an old 350 with 150000 miles sitting in the shop with the factory springs, and i can't budge them by pushing as you did. i can open them with a mallet, so they are not stuck (and the engine was running when pulled). to me this indicates that the springs could have suffered from heat damage. this will cause the valves to "float" at much lower rpms, even as low as 2-3k.

one last question (if already answered in thread somewhere, sorry): did you check the clearance between the top of the valve stem seal and the bottom of the valve spring retainer at full lift with the valve lash adjusted? i ran across a case this summer where the machinist didn't check this and the interference caused bent pushrods and eventually some bent valves.

 

With the valve and rocker down completly I can see the shiny valve stem.The bottom of the retainer is not coming down and pinching the seal against the stud boss.

 

of course i don't know for sure, but if a freeze plug were left in the block it would likely not cause the problem that engine seems to have. anyway, a freeze plug in the engine would only affect one side; it would probably settle to the bottom as well. typical corrosion and sludge probably have more impact than a lost plug would (just opinion).

installing the wrong head gasket would be an error most likely made by a careless builder (with many gasket types on hand) or maybe a first time builder type mistake. i'm not sure if it is possible to cause the problem symptoms with wrong gaskets, but i do know different gasket mfgs have very different philosophies about how to cool heads. i know that isn't a solid answer, but is getting to the end of what i know and can think of. the springs still sound way too weak. if you could borrow a borescope perhaps to look for evidence of a crash between the pistons and valves, that might help . . .