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Old 09-13-2017, 01:14 PM   #1
Licensed to kill
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Default Point cam

So, I'm just checking everything on my engine to make sure that settings are correct and was checking the ignition timing. Found the point a tad tight so set them to .020 but noticed about 5-10 degrees of free movement in the cam when turning it with a screw driver on the locking screw. Everything under the cap looks new but this movement in the cam doesn't seem right. How can one ever set the timing and keep the timing right if the cam is free to move back and forth several degrees?. Theoretically the rotation of the engine should keep it all the way over one way but should t not be free of any advance/retard play??. Also, could be related but I find very little difference in full retard to full advance on the lever as far as how the car runs. Lots of movement on the plate but would expect a more noticeable change in the engine for the amount of timing difference.
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Old 09-13-2017, 01:43 PM   #2
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Default Re: Point cam

What you are experiencing is the play in the distributor drive linkage from the camshaft up to the distributor. When you set the ignition timing you must compensate for the backlash. There are some Youtube videos on How to set the ignition timing and also on (abarnyard.com)
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Old 09-13-2017, 02:03 PM   #3
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Default Re: Point cam

I watched a couple youtube videos as well as read a writeup on abarnyard.com but they said nothing about compensating for the backlash.
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Old 09-13-2017, 02:39 PM   #4
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Default Re: Point cam

Try the following link. It tells you how to get time the A and account for the slop.

Timing the A
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Old 09-13-2017, 02:48 PM   #5
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Default Re: Point cam

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Originally Posted by Licensed to kill View Post
I watched a couple youtube videos as well as read a writeup on abarnyard.com but they said nothing about compensating for the backlash.
This is from Marco's site (abarnyard).
"Begin tightening the screw. This removes the backlash in the system and the cam should remain as close to touching the rubbing block on the points as possible without opening the points. This may require multiple efforts to get it ideally positioned."
Also see B in the picture.

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Old 09-13-2017, 03:34 PM   #6
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Default Re: Point cam

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Originally Posted by Licensed to kill View Post
I watched a couple youtube videos as well as read a writeup on abarnyard.com but they said nothing about compensating for the backlash.
Seems like all the things I have read, whether it is in Les Andrews' book, the Les Andrews Youtube "seminar", or the instructions for the Nu-Rex tool, all have not only mentioned the backlash, and the Nu-Rex instructions even go so far as to tell you to make two complete clockwise revolutions (against the normal rotor direction), presumably out of an abundance of caution to compensate for that play. For me it was a totally new concept because I had never run into this with a newer car, but it seems that if you always set the rotor position after rotating clockwise to take out the play, you will always be correct.
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Old 09-13-2017, 05:33 PM   #7
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Default Re: Point cam

Nu-Rex tool X 2
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Old 09-13-2017, 05:55 PM   #8
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Default Re: Point cam

Thanks for all the replies.
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Old 09-13-2017, 07:44 PM   #9
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Default Re: Point cam

Yes to setting the points to .020" first.
Then once the timing is set correctly counting for the backlash, there should a big difference between full retard and full advance. Full retard should allow for a low idle speed and the timing will sound late as it should. 1/2 advance will/should have a nice slightly faster idle speed. Full advance the engine idle speed should start to 'roll' a bit.
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Old 09-13-2017, 08:05 PM   #10
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Default Re: Point cam

Got the timing set and the points gapped to spec, found and fixed a vacuum leak and tightened up exhaust eliminating slight exhaust leak. Runs pretty good but still backfires through exhaust on deceleration. Been playing with the gav but even with it closed all the way, the plugs show rich (and wet). Should i not be looking for nice tan plugs like in other cars??. When in open the gav a bit (about 1 turn) it does seem to run a bit better but those plugs??!!!!!
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Old 09-13-2017, 08:56 PM   #11
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Default Re: Point cam

I got reprimanded by an expert on here once, when I stated that mine does not run happy at 1/4 turn open. Mine seems to run best at about 1/2 to 3/4 turn open. I adjust mine while driving at about 25 to 30 miles an hour and it smooth's out at those speeds and idles perfect. I have heard of others who do the same thing. Just my 2 cents. As for the plugs,,,,,,,,which ones are you running?
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Old 09-13-2017, 09:08 PM   #12
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Default Re: Point cam

If your timing is correct the usual causes of backfiring on deceleration are:

Mixture too rich

Mixture too lean

Burned valves
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Old 09-14-2017, 08:49 AM   #13
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Default Re: Point cam

Loose connection where the down pipe on the muffler meets the exhaust manifold will let in air and re ignite the excess un-burned fuel in the exhaust. Air getting in at the intake gasket or further down at muffler can have the same effect. These are the details that are the extension of what barnstuf said above.
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Old 09-14-2017, 08:50 AM   #14
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Default Re: Point cam

You can KNOW if your timing is RIGHT!
1 Spark up, should have a smooth, rhythmical sound, like TADA-TADA-TADA-TADA.
2 Spark 1/2 way down should have a FASTER, SMOOTH idle.
3 Spark FULL down should have an even FASTER, but somewhat "rolling" idle.
IF YOU HAVE ALL THESE, THEN IT'S PERFECT!!!----NOW, you can "TUNE" yo' HORN--LOL
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Old 09-14-2017, 09:21 AM   #15
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Default Re: Point cam

Quote:
Originally Posted by zzlegend View Post
I got reprimanded by an expert on here once, when I stated that mine does not run happy at 1/4 turn open. Mine seems to run best at about 1/2 to 3/4 turn open. I adjust mine while driving at about 25 to 30 miles an hour and it smooth's out at those speeds and idles perfect. I have heard of others who do the same thing. Just my 2 cents. As for the plugs,,,,,,,,which ones are you running?
They are new Autolites
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Old 09-14-2017, 09:26 AM   #16
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Default Re: Point cam

Quote:
Originally Posted by BILL WILLIAMSON View Post
You can KNOW if your timing is RIGHT!
1 Spark up, should have a smooth, rhythmical sound, like TADA-TADA-TADA-TADA.
2 Spark 1/2 way down should have a FASTER, SMOOTH idle.
3 Spark FULL down should have an even FASTER, but somewhat "rolling" idle.
IF YOU HAVE ALL THESE, THEN IT'S PERFECT!!!----NOW, you can "TUNE" yo' HORN--LOL
Bill Ear
Patrick L said that the idle should "roll" with full advance also. Don't know what that means??. Also, the horn doesn't work at this time. The ammeter jumps when the button is pushed but no blow. Be getting to that once I get it running right so, yes, once it's running satisfactorily, I will "TUNE" the horn
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Old 09-14-2017, 09:39 AM   #17
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Default Re: Point cam

Quote:
Originally Posted by Licensed to kill View Post
Patrick L said that the idle should "roll" with full advance also. Don't know what that means??. Also, the horn doesn't work at this time. The ammeter jumps when the button is pushed but no blow. Be getting to that once I get it running right so, yes, once it's running satisfactorily, I will "TUNE" the horn
"ROLLING" means the idle speed goes UP & DOWN---Like a YO-YO!
Bill Rollingaround
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Old 09-14-2017, 09:57 AM   #18
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Default Re: Point cam

The picture that Bob C. posted from Marco's site,,,,,,will get you very close on timing. Just make sure your retard lever is all the way up. Then if it is timed properly,,,,you should notice a definite difference in RPM's when the lever is retarded and advanced up and down. Both of mine do not like to run at full advance around town. Half way down is where the sweet spot is on mine and that's where I normally run them. Good luck with yours.
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Old 09-14-2017, 10:46 AM   #19
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Default Re: Point cam

New Autolites but what heat range. They may be too cold for short trips where you don't really get the engine up to temp.
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Old 09-14-2017, 08:07 PM   #20
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Originally Posted by wmws View Post
New Autolites but what heat range. They may be too cold for short trips where you don't really get the engine up to temp.
I drive with GUSTO, to keep my plugs clean Everyone sez, "You're not REALLY 81, are you"?----"YEP"!
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