Hydraulic Lock Up?
Thread Starter
Instructor
Joined: Aug 2009
Posts: 112
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From: Caledon Ont
Hydraulic Lock Up?
any one hear of hydraulic Lock up. My buddy blew the head gaskets on his 81, and had his brother and him replace the gaskets and sent out the heads...the car runs well for about 3 min starts to sputter, back fire big bang through carb then stall. If you let it sit for about 30s and starts right back up and does the same. runs great for the first few minutes.
Timing is fine I figure he tightened the valves down to tight and when the iol pressure builds up in the lifters some valves aern't closing...Any ideas?
Timing is fine I figure he tightened the valves down to tight and when the iol pressure builds up in the lifters some valves aern't closing...Any ideas?
My thoughts exactly, I'm going to run over towmorrow and give them a hand..thanks for the info.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
I would view hydraulic lock up as when a cylinder fills with a fluid and it cant be compressed.
If the rockers were tight and holding valves open that cylinder would be low on compression but should kill it that bad..
Carb flooding , ign prob , plugged exhaust ?
If the rockers were tight and holding valves open that cylinder would be low on compression but should kill it that bad..
Carb flooding , ign prob , plugged exhaust ?
Instructor
Joined: Apr 2007
Posts: 184
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From: Atlas is shrugging KC, MO area
Anyone that's ever adjusted hydraulic lifters w/ engine running will remember that if you tighten too fast, the engine will stumble 'til the lifter bleeds back down. So sounds like it could be some lifters that are too tite.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
They would almost have to be so tight that the pushrod is bottomed out in the lifter. Thats a full turn too tight. The lifter travel is around .140. Gm says the prime spot is .070 down (middle) and thats 1 turn down. If they were adjusted down at .120 the engine wouldnt know the difference. That would leave .020 for heat expansion before a valve would be held open.
Le Mans Master
Joined: Jan 2004
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