Hi John,
That might simply be "Olde Fashioned" advice. Certainly, the valves should
leak little, but that isn't a real world test. With an engine operating at
3500 RPM, figure out how long each valve is in contact with the seat,
contacting 1750 times per minute, or contacting a little over 29 times a
second. Does overnight tell you a lot?
I didn't see stated that you had new valve guides installed at seat and
valve grind time. That needs to be done in most cases, too. Lapping is no
longer needed with today's precision machinery for grinding seats and valves
along with new guides. Can't control valve angles and contact points by
lapping them in with likely a pretty coarse compound.
Later, Paul A
----- Original Message -----
From <John.Deikis at med.va.gov>
To: <spridgets@autox.team.net>
Sent: Wednesday, July 28, 2004 1:10 PM
Subject: Valve job question-- No political content
> Noticed in an engine book the other day the advice to fill the combustion
> chambers in the head with a solvent to see if your valves are sealing
> properly. No leakage into ports over night means all okay.
>
> I tried it with some kerosene on a head I recently rebuilt. Two chambers
> emptied into the intake ports over night. Since the intake valves and
seats
> were done on a NewWay cutter and the exhausts on a Sioux grinder, I
figured
> maybe they needed some lapping.
>
> Did the suction cup and grinding paste thing on all 4 intakes. Now all 4
> leaked over night!
>
> Should I use the head as-is or seek professional intervention? (I guess
> going to the list does approach "professional" in some cases).
>
> JohnD
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