Bill,
If the valve stuck open for a bit, there'd be enough clearance for the push
rod to drop out. I've heard that the silicon-bronze valve guides are more
likely to cause this. Don't know if that applies here or not.
Bob
WILLIAM B LAWRENCE wrote:
> ----------------------------------------
>> From: ynotink@msn.com
>> To: healey-bounces@autox.team.net
>> Subject: Things that make you go Hmm!
>> Date: Tue, 14 Oct 2008 23:25:43 +0000
>>
>>
>> On the way to the parts store in my BN1 yesterday I had a sudden failure
> complete with popping sounds and power loss and hissing noises. I thought I
> had blown another head gasket, but unable to reach my wife to bring a tow
> vehicle I limped home.
>> I started to disassemble in preparation for repairing the gasket, the head
> and block surfaces if needed etc. but I only got as far as the valve cover
> when I discovered the problem. The pushrod on the #3 exhaust valve had become
> disengaged from the lifter and rocker.
>> I pulled the rocker shaft and retrieved the pushrod to discover that it was
> perfectly straight and undamaged. When i reassembled the rocker shaft and
> checked valve clearances the setting was correct. (I run a 3/4 race Isky cam
> and the recommended valve clearance is 0.018"). I ran the other valves and
> found no discrepancies. After reassembly she started and ran with no problem.
> I was not revving the engine very high and 4,000 RPM is about as tight as I
> wrap it.
>> Despite the noise and the terrible miss there was no harm done and the
> repair was pretty simple, but I would like to avoid this in the future.
>> Has anyone had this experience? Are there any ideas as to what would cause
> this to happen? Is 0.018" enough slack to allow the pushrod to jump out of its
> position? I know that some people use bucket lifters that might have helped
> avoid this. What lifters and pushrods do they use?
>>
>> Flummoxed!
>>
>>
>> Bill Lawrence
>> Albuquerque, NM
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