Stopped up to a friends house yesterday to help him break in his new engine, and had big troubles. Looking for possible clues that might help.

Its a 10 to 1 360, flat tops, basic bottom end, has Magnum R/T heads (cast iron), and hydralic flat tappet cam (i do not know the specs, but it too is mild mannered-- around .500 lift).

3 minutes into break in at 2000 rpm, a dreadful noise started and he hit the key off immediatly. We pulled the valve covers didn't see any thing that caught our eye as we rotated the motor over by hand, ended up putting it together, tried starting it again. It ran quiet for about 30 seconds and the noise returned---again key off right away.

Well, to make a long story short, #4 intake pushrod got bent. then we noticed #4 intake valve hanging open a bit, around half lift. Tried tapping it with a hammer and no movement at all--its stuck. Rolled #4 piston to BDC and used a bore scope to look in and looks like no piston damage, or it at most it just got tagged (older bore scope, was a little hard to see), but the valve relief notches appeared to be ok and the piston top seemed ok too. Could not get it to bend enough to see the condition of the valve.

Sooo, assuming the valve isnt bent (although i am not ruling it out), what do you think would hang the valve open and seize it that quick? It has plenty of retainer to guide clearance on it in case anyone was wondering. Plenty of oil on top of the motor, everything was running great untill this happened.

The heads are not pulled off yet, not sure when they will be as he is pretty dejected right now about it. Were actually going to just pull the engine back out and put it on a stand when he is ready to work on it again.

Most likely the valve guide siezed on the valve stem. Unusal to say the least, but quite possible. The valve STEM could have been bent to start with, or a piece of debris got in there. Were the heads reworked? If so, they may not have had enough clearence between the guide and stem.
Another possibility is sommething is stuck between the valve head and the valve seat or the valve seat has came out of the head and got cocked sideways. I would pull the one head first, not the whole engine.

Brian

Another possibility is the pre load was light and the
push rod came out and slid in close to the shaft
giving you alot more lift and it hit... check with
him to see what the P to V clearance was... also I
wouldnt pull the engine(yet)... I would pull that
head then roll the engine over so the piston starts
down and then push on the piston to see if it moves
down to check for a bearing issue

Yup, has guide plates and stock style rockers, like a SM chevy. Plus the pushrod holes in the head are really close to. It bent below the head deck. I wish i could tell you some of the specs about it as far as P to V clearance and VG to retainer clearance, but when i asked yesterday, he didn't know as he had it all mocked up by a machine shop in another state several years ago, and the assembled the short block for him. I looked and it looked like plent of VG to retainer clearance though so i would say that is ok. To me it looked like a set of KB 107 flattops in there, and i know the valve notches on those are pretty forgiving as i had a set years ago myself.

The reason we were thinking we wanted to pull it was to A) check for any loose pieces of epoxy that may have come loose from the pushrod pockets (they had to be opened up a little to clear the p/rods and were mighty close to the intake ports). So we wanted to pull the pan to check if any got down there as it looks like some may have come loose. And B) while the pan was off, check the bearings just to verify all is well. You can not get the pan out in the car, its in a 80's Cordoba and the K-frame is only about a half inch from the pan and it copmletly surrounds it pretty good on the front half. Plus its easier just to check all the stuff on the stand anyhow.

But that is what i would do and i would have had it out already, but like i said, he is pretty dejected at this point and doesn't want to touch it. So we'll see what i can get him to do, i told him just to walk away for a few days and take a breather.

MR P, he did say the preload when he checked that was .060" with the p/rods he used. He had another set that put the preload at .125" so he went with the lighter preload. It seems to me that would be an adaquate preload at .060" though.

"You can not get the pan out in the car, its in a 80's Cordoba and the K-frame is only about a half inch from the pan and it copmletly surrounds it pretty good on the front half. "

Not true, I have pulled small block pans out of Miradas before. It wasnt fun or easy, but they do come out. Heres a tip, Lossen the motor mounts and lift the engine a little bit

Kasey, i here ya about the nervousness. We all try to build stuff to the best of our ability, but sometimes it just happens. This was a first for me, never had a break in go so wrong. The worst i ever had were oil leaks or coolant leaks. It sucks, he even talked of pulling the engine and putting the car on the trailer and letting it sit. I would hate to see that happen, so i'll let him be a couple of days and see where he is at. Just seems like a rash of bad luck running around lately from what i see. MAybe i'll wait untill next year to fire mine up.

B5sixpackbee, i am not saying it absoluty wouldn't come out, but being a milodon deep 7qt pan, its WAY tighter than the stock one is---had to make a slight notch in the K for the sump. So with all the effort to get it out in the car undoing the mounts, whats a few more bellhousing/flexplate bolts and then its out. Even if you could get it out in the car checking 1/3 and 2/4 bearings would be a B!t(h. And then all that nice shiney an clean parts dont get all scratched to heck either. I hate trying to fix newly painted parts, but thats just me.

Mine is a fully roller engine, Nothing nasty, but its in the 570 lift. Im not really gonna do much of a break in really, but just nervous because its taken me 5 yrs of collecting parts, and getting enough cash to get it inn. Mine should be a nast piece, but I couldnt afford new rockers, so I got a good deal on a slightly used set off a buddy. Harland sharps, so I shouldnt have any issues.

Kasey

Man, that's too bad. I hate to hear things like this. It's tough enough nowadays, and to break things on a start up is hard to tolorate. I agree with you, I would bite the bullet, pull it, and check everything. If a guide was too tight, that shows an assumption on the shop that did the head work. It will be money well spent.

Pull the carb and run the bore scope thru the intake port, you should be able to see the valve and seat