The trick with the compressed air is that the piston needs to be at TDC on a
compression stroke so that both valves are closed. Make sure you have the
crank set EXACTLY at TDC or the compressed air can spin the engine. Found
that out doing a leakdown test one time.
If you put it in gear and set the handbrake solidly, that would probably
hold it.
Gordon Glasgow
Renton, WA
> -----Original Message-----
> From: owner-datsun-roadsters@Autox.Team.Net
> [mailto:owner-datsun-roadsters@Autox.Team.Net]On Behalf Of Graeme
> Sent: Monday, December 04, 2006 8:18 PM
> To: datsun-roadsters@autox.team.net
> Subject: FW: Valve seal R/R U20
>
>
> "You can get a fitting or make one that will screw in to the
> spark plug and
> hook up to an air hose, the air pressue will hold the valves shut, much
> easyer than useing rope
>
> Mike"
>
> Hi list,
> An "inflatable spark plug" is a really handy tool.
> The limiting factor I have found is the sealing quality of the
> piston rings
> and valve seats.
> On a reasonably fresh engine, no problem.
> A squirt of oil in the spark plug hole first should also assist
> the rings to
> seal.
> I tried this method on a well worn Mini engine and it farted out more air
> than my compressor could supply!
> It turned out easier to take the head off and do the job conventionally.
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