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Paging Dr. Allis - D-17 Tune up specifications

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Topic: Paging Dr. Allis - D-17 Tune up specifications
Posted By: Clay
Subject: Paging Dr. Allis - D-17 Tune up specifications
Date Posted: 26 Jun 2011 at 11:31am
Dr. Allis
What are the tune up specifications for a 1962 D-17?
Dwell ____-_____
Spark Plug Gap _________
Timing ____ deg. BTDC
Point Gap _______

I am installing a new set of AC45XL spark plugs.

Thanks in advance.
Clay



Replies:
Posted By: DrAllis
Date Posted: 26 Jun 2011 at 12:11pm
I gap plugs at .025"....points at .020".....valves at .015" cold int&ex....timing is 25 degrees BTDC at full throttle.


Posted By: Clay
Date Posted: 26 Jun 2011 at 1:15pm
Thanks Dr. Allis.
Would you happen to know  the Dwell?  I can not find it in any of the literature I have on hand.


Posted By: Gary in Texas
Date Posted: 26 Jun 2011 at 2:19pm
 Clay
 The point gap and dwell kind of go hand in hand
 

The dwell is adjusted by setting the points gap to a specified distance at maximum opening. A narrower gap gives more dwell and a wider gap gives less. Taking it to extremes, excessive dwell means that the points close too soon after opening, cutting off the magnetic field collapse before it delivers all its energy. Too little dwell gives the magnetic flux insufficient time to build up to the maximum.

Both conditions give a weak spark which gets even weaker as the engine RPM rises and produces misfiring at normal operating speeds. The dwell, as well as spark plug gap, do have an effect on ignition timing. The later the points open, the later the spark comes and retards the timing. The earlier the points open the sooner the spark comes and advances the timing. That is why timing is the last thing to be set in a tune-up.

Don't know if this helps or not.
 
Gary in Texas


Posted By: Ed (Ont)
Date Posted: 26 Jun 2011 at 3:40pm
The dwell on a 4 cyl usually ends up at around 45 degrees if the points are correctly set but as the others have said more important to get points as accurate as possible. Also check that the dist shaft does not have a whole bunch of endplay.


Posted By: Brian Jasper co. Ia
Date Posted: 26 Jun 2011 at 8:33pm
I should see what the pertronix ignitor modules run for dwell. I'm pretty sure dwell being 30 degrees for GM V8 engines at idle and it changed with speed. When the HEI came out, dwell was fixed at 40 degrees. Been a long time since I've worked on anything with points other than a small engine...

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford



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