toolz

Cruising down the lake on Sunday at about 3800 rpm, and my nice new 555 turned into a 7 cylinder. I pulled the heads last night to find the #1 intake valve head broken off. Two big holes in the chamber (ported iron Merlins) and a hole in the piston where the valve head passed through to the bottom end. I don't know the extent of the damage to the crank/rods, but hoping for the best. I can't find any indication of pistons hitting the valves. .625" lift cam with 9.5:1 JE pistons- shouldn't have been a problem. I can't imagine what would cause a valve to break off other than simply a bad part. What would you guys recommend for valves this time around? I will buy the best- I can't have this again. I've had Indy Cyl Head repair iron heads before, and since it would be really expensive to try to duplicate the port work, I will probably take the head there, unless someone here knows a better place. The block will need a sleeve, and 1 piston. Hopefully not too much more. Please let me know your suggestions.

Thanks

jpclear

If it had been an exhaust valve, (are you SURE it was an intake?) it's a common occurrence with hi-perf marine engines. You just HAVE to use the Ferria super alloy or Manley inconel extreme duty. I understand that REV makes a comparable valve also that is supposed to be as good but I have no first hand experience with them. Have seen this with other valves five times in the last four years, twice this year already. --- Jer

Mr Gadgets

toolz,
did you take a look at the lifters? I had a lifter clearance issue after my professional engine builder assembled a new crank with standard bearings and never micd the crank to find out it was ..010" under. When repaired I stuck two lifters and broke an intake valve. So sticky valve guide or lifter may have been the cause.. take a close look..
Sorry to hear your pain.. been there done that!

Dick

Panther

Sorry man, I hate hearing this stuff.

Vinny P

Along with everything that was said above, I just want to add checking the valve springs for a correct match up to the cam. To tell you a quick story.... i just built a 540 for myself. When I got my new heads from a very well known head company, the springs that they put on were not even close for me to run. Luckily for me, I took the heads apart and checked installed height and pressures myself.

toolz

Thanks for the responses. The valves are Manley, regular stainless as far as I know. I bought the heads complete from the engine builder. Every single part of the engine, including gaskets, were spec'd by me, with the exception of the head parts, as I bought them complete. My mistake, I guess. The broken valve was an intake. The springs were matched to the cam, and were not a problem. The lifter bores seemed just fine before assembly, but a sticky valve guide is a good possibility. None of the other valves have hit the pistons, but the broken one sure could have. Kinda hard to tell now, but a real possibility. Again, thanks for the help. I will look into the Ferrea valves. As I said before, I can't have this chit again.

Liberator21

Checkmate, I couldn't agree with you more about the heads! Seems any time I've ever had a problem, it was always because the builder didn't do what I asked him to with the heads. They always used their "Good Enough" spec! I even had one builder argue with me about setting the spring heights. He said because I was using a heavier valve spring, I had plenty of seat pressure, and didn't need to set them to spec. I guess he didn't care about the higher lift cam. Moron! Needless to say, I never used him again.
I now do almost all my own head work, and what I can't do, I send to a trusted friend to do. And I still take them apart to inspect before they go on an engine. Better safe than sorry!

toolz

I had a little time tonight to take a closer look at a few things, and- surprise surprise - the lifter for the broken valve won't come out of it's bore. The travel is more than the cam lift at this time, but it looks like it must have stuck enough at one time to make the piston hit the valve, snapping it's little head off. I haven't got the lifter out yet, so I don't know why it's sticking. At least I have a reason for the failure, and can hopefully prevent it next time. Thanks again for the help.

toolz

cig1988

The lifter is mushroomed and most likely you cam is trashed. Been there done that, Break Out Another Thousand (or several) At least its not the beginning of the season.

Mr Gadgets

toolz,
I had to cut the top of the lifter off and push it down into the cam area to get it out.. At least you found a cause, well a good starting point for it. Lifter clearance on a cold boat motor needs to be addressed..
If the bore is damaged, have them bushed by a reputable builder that has a 5 axis machine..

Good luck, keep us posted
Dick