Subject: [TR] TR4A - Advance Created Noise

From: "G.D. Huggins" <[email-masked]>
Date: Tue, 17 Apr 2012 21:57:13 -0500

All,

I need some help and advice for an issue that has resurfaced after installing
a freshly rebuilt dizzy.

When the mechanical advance kicks in (I disconnected the vacuum advance)
around 2200 rpm, I hear a very noticeable buzzing/rattling noise.
This not only happens when advanced "up" (low to high RPM), but also when
stepping "down" (high to low RPM).
However, the engine suffers no performance loss, and there appear to be no
other symptoms.

This was happening straight away after I got the car on the road last
September, with a brand new pertronix dizzy.
When the rotor from it broke, I sent it back to Pertronix, and dropped in my
original Lucas 25D, and the sound went away.
I had the Lucas rebuilt, put it back in, and the sound is back.

Certainly this can't be normal, so something must be amiss.
Any suggestions?

Cheers,

Guy D. Huggins
1965 Triumph TR4A
CTC 63569LO

Online project diary at http://www.genfiniti.com/triumph

** [email-masked] **

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe/Manage: http://autox.team.net/mailman/options/triumphs/[email-masked]

---

From: "Randall" <[email-masked]>
Date: Thu, 19 Apr 2012 16:03:51 -0700

Guy,
Someone else reported a similar noise, which turned out to be part-throttle
detonation caused by too much spark advance for the engine/fuel combination.

I'd try backing off the initial timing by about 10 degrees or so (by turning
the dizzy, not with the vernier), and see what effect that has.  The engine
won't run very well, but just keep it running with your toe and it won't
hurt anything.  If the noise disappears, then the issue is detonation.

-- Randall