390 Valve problem?
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Joined: Jun 2001
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390 Valve problem?
Got a 69 390GT. Rebuilt the engine. got a valve job. The problem is that the valves won't seat. When the runners are bolted down the valves don't seat, but if the runners are unbolted a little they seat. Same pushrods and rocker ratio. The cam is the same cam but reground a little. can anyone help? please. Engines been decomishened for 2 months now.
Laughing Gas
Joined: Oct 1999
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From: yes
390 Valve problem?
ok, by wont seat, do you mean none of the valves are closing? cause in this case you probably needed shorter pushrods when the engine was rebuilt, it sounds like they milled the heads and deck and didn't think about this lowering the pushrod length. If it's just some of them going down this is normal since some valves will be open with the engine just sitting there. another reason why it's good to run a engine every now and then.
Senior User
Joined: Apr 2001
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390 Valve problem?
The problem with the lifters is easily checked. Put the engine at top dead center, then take off the left valve cover. Both lifters at the forward cylinder should spin freely but not so free that they move up and down a whole bunch. Generally, all lifters on closed valves should spin freely. Most parts stores still carry the lifters in long, standard, and short lengths.
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