Sounds like "sticky gas" could be one factor, but easy to fix.
m.
----- Original Message -----
From: "Gordon Glasgow" <gsglasgow@comcast.net>
To: <hallosb@juno.com>; <datsun-roadsters@autox.team.net>
Sent: Saturday, October 03, 2009 5:07 PM
Subject: Re: [Roadsters] Engine test results, help please
> Since the engine is out, why not pull the head and take a look?
>
> If the car has been sitting for 15 years, one obvious question is, did you
> drain the gas tank and lines before you stored it?
>
> Gordon Glasgow
>
> -----Original Message-----
> From: datsun-roadsters-bounces@autox.team.net
> [mailto:datsun-roadsters-bounces@autox.team.net] On Behalf Of
> hallosb@juno.com
> Sent: Saturday, October 03, 2009 2:32 PM
> To: datsun-roadsters@autox.team.net
> Subject: [Roadsters] Engine test results, help please
>
> If youre following my previous post, I decided to pull the motor so, I
can
> have the engine bay painted when, the rest of the car is refinished.
Please,
> read this long post, I need help.
>
> I thought I would tune up the engine then, run compression and leak down
> tests
> to check the health. If I have any issues, the time to correct would be
> while
> the engine was out. The engine was rebuilt 20 years ago. I put maybe 5,000
> miles on it, then it sat dormant for 15+ years. While it was dormant, it
was
> garaged. I routinely squirted oil in the cylinders and turned it over by
> hand
> to keep it from seizing up.
>
> I set my dwell and timing, balanced the carbs, and went for a spin.
Results
> were fantastic. No hesitation. Pulled hard. Idled nicely. With accurate
> timing, it was running much cooler, also.
>
> Next, I ran the leak down test while the engine was hot. Initial results
> werent bad but, I ran out of time. Next day, I fired the engine up to get
> it
> warm, again for another test. Its running like crap. Backfiring through
the
> carbs on occasion. Lots of hesitation. I drove it around the block to get
it
> warm then, ran another test. Results looked good and were repeatable.
> 1. 100/93 (7%)
> 2. 110/94 (6%)
> 3. 100/96 (4%)
> 4. 100/96 (4%)
> During the leakdown tests, all the air was escaping from the crankcase.
> Absolutely nothing out of the carbs or tail pipe. Sounds like my valves
are
> sealing nicely. While it was hot, checked all the valve clearances,
0.017.
> All in spec.
>
> Took a break. Warmed up the engine again and ran a compression test.
Results
> were sporadic, no consistency. I ran each test several times and never got
> the
> same answer. Heres a sampling.
> 1. 170, 160, 145
> 2. 160, 140
> 3. 165, 150
> 4. 180, 170, 160
>
> Im thinking my valves are sticking open. The leak down test may have
forced
> the valves fully closed and any goo on the stem is now causing me
problems.
> I
> did try swapping plug wires to see if it made a difference. Nothing. I
> didnt
> have a spare cap and rotor.
>
> So. What do you think?
>
> Thanks,
> Dan McHatton
> 66 1600
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