Dropped a valve

Old 11-15-2010, 03:51 PM
  #11  
contagious
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Took my time putting this together.Used adjustable pushrods to get the right length to get the roller in the center of the tips.they move from the center,forward about an 1/8 back to center,used dye to check.They were a little off center on the exh,but not any where close to off the tip. You never know when its up and running i guess,something was WRONG. :roll:
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Old 11-15-2010, 04:27 PM
  #12  
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Something has to be wrong and looks like the guys are already giving some good tips. I just wanted to add that sucks and I hate to hear anybody breaking parts. If the heads are aluminum they can be fixed no matter how messed up they are.
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Old 11-15-2010, 05:07 PM
  #13  
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Thanks,you are right something is not happy.!!!Built lots of engines,but i'm not a master engine builder,so posting problems and looking for ideas,thanks to all for advice,that's what i a'm looking for.Thanks again.!!!!!!
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Old 11-15-2010, 06:47 PM
  #14  
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YOU should set your pushrod length so that when you are at half lift the valve and the centerline of the rocker arm form a 90 degree angle. The roller tip won't likely be dead center when the lifter is on the base circle. On a BBC it will likely be toward the inside just a little,at least mine always are.Mine never start out centered up unless the pushrod is too long.




just my opinion I am far from an expert.
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Old 11-15-2010, 09:11 PM
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Just a NOTE, Tracy Smith dropped a valve at our RJ friends meeting at Byhalia in Sept. He broke the int valve head off on #2 cylinder about 1/2" up from the head. Luckly it went up into the valve pocket and didn't do a lot of damage to the head just a couple valve seats and some welding in the pocket. It didn't even punch a hole thru the piston, but beat it up pretty good. They were also Ferrea valves. I built the 388 short blk. but didn't install the heads. He was too tight on the valve to piston clearance. 6 holes was barely tapping the piston with the intake. I personally would not recommend less than .060 on the int. and no less than .100 on the ex valves. He says he checked the ex and they were around .080. Rocker geomertry was good according to him. He had .017 steel shim gaskets on a 48 CC head with flattop pistons, it's now costing him about $600.00 to put it back together, with .050 MLS gaskets. The short blk is a dirt cheap build, i mean less than $1,000.00 with cast steel crank, SIR rods and Hypereutectic pistons. Still in a 2950 lb Camero it ran best of 6.29 @ 108 MPH, with 1.27 60 ft times. (cam is special and i won't talk about it)
I'm not saying this was your problem, but i am saying that there may be a problem with some Ferrea valves.

Just making a point.

Zip.
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Old 11-16-2010, 05:12 AM
  #16  
TS1955
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My concern would be where it broke. I've seen valves break down around the head but never up around the top of the stem!

TS1955
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Old 11-16-2010, 06:42 AM
  #17  
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I forwarded this thread to my brother, an engine builder extrodinar, and here is what he said;

I'm gunna pass on this one (as far as posting), too many variables and the guys have already said the obvious. Sounds like a combination of improper valve train geometry and possibly piston contact - the exhaust valve is really strong down at the valve head but not so strong up the stem, may have hit the piston and loaded the stem up high to cause it to crack, then fail - the damage to the valve didn't happen at idle! Just happen to come unglued at idle.
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Old 11-16-2010, 08:42 AM
  #18  
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There is no contact piston to valve,did the math and checked with clay,over 100 thous on the exh and more on the int.The other seven cylinders and valves are clean ,no contact marks on pistons or valves.The Rocker geomertry need's to be checked very well as i'm the one that set it up as well,there was a little off center movment if i remember,but nothing off the tip.needs checking again for sure.Thanks for the help.!!
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Old 11-16-2010, 09:37 AM
  #19  
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The one answer that gives no satisfaction to the OP trying to find a cause is, sometimes things just break! Really sorry for your misfortune.

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Old 11-16-2010, 11:59 AM
  #20  
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sometimes things just break



It's all part of the game,if you have thin skin,this game is not for you.!!!!LOL!!!! :lol:
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