[Roadsters] Was Engine test results, suspect distributor

[Gary and Cindy Ault]

Ron,

His dwell is fine.  The  standard dwell value for roadsters is variously 
stated in the Nissan manual as 50-54 degrees, 49-55 degrees and 50 to 55 
degrees.  These values are consistent with a point gap of 0.018 to 0.020 for 
the Hitachi distributor.  I try for the lower end of the range since the 
dwell increases as the rubbing block wears.

Gary
----- Original Message ----- 
From: "Ronnie Day" <ronnie.day at gmail.com>
To: "Roadster List" <datsun-roadsters at autox.team.net>
Sent: Monday, October 05, 2009 11:17 AM
Subject: Re: [Roadsters] Was Engine test results, suspect distributor


>> Dan McHatton
>>
>> I think my problem is my distributor. I found another cap and rotor then,
> went
>> to grab my coil wire from my old Chevy to have a complete set of fresh
> plug
>> wires. While I was there, I checked the play in the Chevy distributor
> rotor.
>> When you twist it lightly and let it go, the springs snap it right back 
>> to
> the
>> home position. When you try the same trick on the Datsun distributor, the
>> rotor has lots of slop in it.
>>
>> I'm thinking my distributor is worn and causing my backfire problem. The
>> engine idles smooth as glass. Engine timing is 16 BTDC on the nose. Dwell
>> angle 51 degrees. As soon as you rev it up, it misses and backfires.
>>
> First, I'm pretty sure even without checking that your dwell is way off.
> IIRC, it should be around 30 degrees and it should be set before you set
> timing. Then the timing mark should remain stable at any RPM as you rev 
> the
> engine. Yes, it should move (smoothly) as RPMs increase but any time you
> hold an engine speed  the mark should not jump around, but stay in one 
> spot,
> until you change engine speed again. There are a number of reasons for
> timing instability, including play in the distributor shaft or drive 
> gears,
> a breaker/advance plate that's worn out, etc.
>
> HTH,
> Ron
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