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How could intake valves bend?

 
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Old 05-09-2011, 02:21 PM
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How could intake valves bend?

Recently sold some closed chamber 4V Cleveland heads to a guy for his Mustang, and we've been keeping up, and he just got word from the machine shop that not only were ALL of the valve seats bad, but 4 of the intake valves were bent.

I ran this engine for no more than 300 miles before it blew a head gasket. It was bought from a member here and the list of problems has continued to grow from day one, but this one involves me possibly screwing over someone else.

300 miles by me, and I was told that they were JUST newly rebuilt, so they have 300 miles and a break in on them....

What would cause an intake valve to bend?

AleX
 
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Old 05-09-2011, 02:55 PM
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Timing chain slip would be my first guess, second incorrectly installed timing chain causing piston to valve contact.
 
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Old 05-09-2011, 03:09 PM
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73fomo is right on the money.....piston to valve contact, plain and simple. Either improperly installed timing chain, gear, cam gear, whatever....but the end result is the same. Piston contact will bend a valve every time.
 
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Old 05-09-2011, 04:30 PM
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Well I mean of course if a piston slams into a valve, but is that the only thing that can do it?

I need to be sure because if they HAD to be like that before I ran it, then I just got screeeewed.

The timing chain was installed retarded one or two teeth, when I had been told it was straight up.

I did blow a head gasket through under one of these heads like I said, but the engine kept right on running. Is there no way that that bent the valves?
 
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Old 05-09-2011, 04:47 PM
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Pretty much PTV contact. The timing chain being off two teeth could definitely be the issue.
 
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Old 05-09-2011, 04:56 PM
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Geez. I'm probably still not going to put the guys name out there, but literally he did everything wrong. I paid 1100$ for this engine. The head gaskets were never right, either torque, type, or they were put on dirty or something. The guy used a water pump gasket to back the timing plate. He had no idea what he was doing installing the timing set. There was old gasket and like, some type of metal material in the pan, thank god I drained it. The intake manifold was installed so badly that it leaked INSIDE the engine and sucked oil into the chambers.

The shortblock seems OK. I've put several hundred more miles on it recently, but god this is stupid. Now I screwed the next guy.

I didn't see any obvious contact on the piston surface though, or on the valves, and they looked normal assembled when I took them off?
 
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Old 05-09-2011, 06:52 PM
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You said seats were bad, yet it has 300 miles, and 4 bent valves? Wonder what kind of rebuild job was done on those heads? If not bent bad, they could have been bent all along, like before you bought it even.

Did it run smoothly or did it miss? Did you ever have a vacum gage on it?
 
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Old 05-09-2011, 07:11 PM
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Right that's what I'm thinking. The heads are at Jasper Engines right now being built, so I pretty much trust them/the guy who now owns them.

Ya they certainly weren't bent bad. I gave everything a good looking over, and cleaning, and even pushing/budging, and didn't notice anything obviously wrong. The heads were super clean, valves, chambers, everything, so you know it could actually be the shop that screwed the guy before me....

I had a vac gauge on it and there was steady vacuum, and I think I remember it was strong. I never got it to run right, but that could have been anything. It was driveable, but it did have a very hard time idling, getting warmed up, and was seriously underpowered for the beast it should have been...

The engine had a .595/.595 lift roller cam and these were Cleveland 4V heads on a 400 with flat top pistons. With all the other mistakes this guy made, I wouldn't be suprised if he never even checked the clearance. I found Chevy 1.7 ratio roller rockers in there too.
 
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Old 05-10-2011, 10:16 AM
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Originally Posted by nothercrash View Post
Right that's what I'm thinking. The heads are at Jasper Engines right now being built, so I pretty much trust them/the guy who now owns them.

Ya they certainly weren't bent bad. I gave everything a good looking over, and cleaning, and even pushing/budging, and didn't notice anything obviously wrong. The heads were super clean, valves, chambers, everything, so you know it could actually be the shop that screwed the guy before me....

I had a vac gauge on it and there was steady vacuum, and I think I remember it was strong. I never got it to run right, but that could have been anything. It was driveable, but it did have a very hard time idling, getting warmed up, and was seriously underpowered for the beast it should have been...

The engine had a .595/.595 lift roller cam and these were Cleveland 4V heads on a 400 with flat top pistons. With all the other mistakes this guy made, I wouldn't be suprised if he never even checked the clearance. I found Chevy 1.7 ratio roller rockers in there too.
Wow...with everything you said, the person that assembled this motor was not very meticulous. Engine building takes patience and attention to detail if you want it to last. I would almost guarantee that clearances were not checked and with a .595 lift cam, flat top pistons, 1.7 rockers, and the TC two teeth off you had PTV contact.
 
 
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