[6pack] Pinging Engine

[Tomislav Marincic]

Rob,

Always good to hear your advice.

I had my damper rebuilt as part of the engine rebuild by the "damper dudes."
I'm inclined to believe that the marks are correct: it idles sweetly at an
indicated 10-12 BTDC, manifold vacuum starts to drop off above that, and
when I retarded it to an indicated 4BTDC, my header wrap was smoking and my
idle exhaust CO went to 10%. 

You have 9.67:1, a GP-3, and only 5 psi more than me. I may be a little high
then, or it might just be testing conditions and compression gauges
providing the variation.

May I ask what you use for timing/ignition on that car?

I have a spare distributor on the shelf set up for 0 advance at idle and a
full 13 distributor/26 crank degrees at 2800 RPM. The car was pinging with
that distributor when I contacted Jeff, so I assume the one he built me is
milder, but I'm just guessing there.

Good writing is like a windowpane. 
George Orwell


-----Original Message-----
From: Robert M. Lang [mailto:lang at isis.mit.edu] 
Sent: Monday, April 09, 2012 2:52 PM
To: Tomislav Marincic
Cc: 6pack at autox.team.net
Subject: Re: [6pack] Pinging Engine

Hi,

As a point of reference, I have a similar setup on my street car and I also
have a race motor with a lot higher compression ratio. The static
compression in the 9.67:1 motor is in the 195-200 range. That's with a GP3
cam. The 12.3:1 motor compression is more like 245 lb.

Regarding your pinging, you should verify TDC is correct. You might be
chasing your tail if the ring on the harmonic balancer has slipped and we
all know that DOES happen from time to time.

On both my motors, I run 10 BTDC at idle and I have a total of 33 degrees
advance (so the dizzy gives me 23 degrees on top of the 10 static).

No pinging on either motor, the street caar get 93 octane, the race car gets
110 octane race fuel.

Let me know if this is helpful.

regards,
rml
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Bob Lang              Triumph TR6!!            |  This space for rent
Former NER Solo Chair                          |
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