RE: Compression tests

["Santamaria, Joseph (Joseph)" <jsantamaria@domain.elided>]

Hey, Mike and others - thanks very much for the reply.

Re my distributor advance - the centrifugal advance is fine - the previous
owner decided to disable the vacuum retard unit only by cutting of the
actuator stem - I've seen this on a lot of Aust. Stags so it must have been
some twisted idea of either the local distributor or some local expert at
the time. Maybe there was a good reason.

Re another response from PGA Howells and Frank.M Wichita - thanks for your
responses. 

Frank, I've tried thje method of trying maximum advance and waiting for
pinging but on this low comp engine by the time you get audible pinging at
low revs the engine pings dangerously at high revs but I have found this a
good method on my 2500 PI.

Another question was why does the mainteenance maual ask for 2 degrees ATDC
as the dynamic timing at idle - is this meant to be done with vacuum advance
conne4cted or not. This setting really tends to kill performance. Any input
here? Was it just to satisfy emission control specs.

Don't get me wrong my car is not a snail of the start but at least the
2500PI kills it up to 2500 Revs.

Does anyone know the cost of injection from Harts or any other source and
the best source for the headers.

I'm still also waiting for anyone with experience or info on Electron soft
tops.

Once again thanks for all; the help 		- I might as well get all
the questions out of my system this week and leave you all in peace.
Joe Santamaria
* Lucent Technologies Australia Pty Ltd
Professional Services
*Tel:   +61 2 93529287
*Fax:  +61 2 93529287
* mailto:jsantamaria@domain.elided

> ----------
> From: 	Mike Wattam[SMTP:MikeWattam@domain.elided]
> Sent: 	Sunday, 16 May 1999 10:03
> To: 	Santamaria, Joseph (Joseph)
> Cc: 	TSR Mailing List
> Subject: 	Compression tests
> 
> Hi Joe
> 
> With a low compression engine assuming all the spark plugs are out,
> accelerator wide open, fule pump disconnected, a good starter and plenty
> of
> volts at the battery, you should get about 140-160 with a good engine, and
> below 120 is suspicious.  If you get a variation of 30 between cylinders,
> do something about it pretty soon.  After the 'dry' test, squirt some oil
> in the cylinders and you may find some cylinders which were low before
> have
> suddenly got their compression back.  In this case suspect piston rings
> but
> if ther is no improvement suspect head gasket or valve seat problems.
> This
> will probably root out your cold start problem and tell you something I
> suspect you don't really want to know!
> 
> You say the distributor advance and retard is fixed - it may be the cam is
> seized on the spindle.  The Stag should pull quite well from 1500rpm
> anyway, the distributor may be responsible for the sluggishness if not an
> engine problem.
> 
> Tuning is a different matter.  If youe engine is a bit sick, just don't
> attempt to get it to take more performance or it will break.  
> 
> The Stag engine does not respond fantastically well to performance tuning,
> but try this;
> 
> K&N filter element (Jag XJ6/TR7/Sprint type) in standard air cleaner
> Multi-branch exhaust header kit (available from many sources but quality
> often suspect) is the one thing to give a substantial kick to performance
> careful blending of all manifold and head inlet passages, exhaust port
> throats, exhaust manifold
> meticulous attention to fuel and ignition tuning
> 
> if engine is stripped;
> static and dynamic balancing of crank, rods, pistons, flywheel
> high compression pistons (UK specification)
> TR7 inlet valves with seats and port blending
> bronze valve guides but expect shorter life
> above together should give close to 200bhp with high compression engine
> 
> Fast road cams shifts power up rev band but standard ones are pretty good
> anyway, also engine life will suffer at high revs.
> 
> Ultimate power mod is fuel injection with manifold as supplied by Hart
> Racing, not cheap but very good and may allow fast cams to work better -
> Hart Racing only can advise on this.
> When uprating your motor, always uprate suspension and most importantly
> brakes.
> 
> IMHO - Mike Wattam
> Chairman - Triumph Stag Register
>