Author Topic: Tuning 440: Hold at 2500 rpm, rotate distributor, etc: Plz repost!  (Read 2318 times)

Offline DocMel

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Tuning 440: Hold at 2500 rpm, rotate distributor, etc: Plz repost!
« on: February 24, 2011 - 07:47:14 PM »
I cant find the post where someone said rev engine and hold at about 2500 rpm or so, Rotate distributor till you get the highest idle, then back off slightly.

If someone could repost the steps, Id appreciate it:  I used that technique, and it worked GREAT.  But I have since removed my distributor, and cant find/remember the

Thanks




Offline Bullitt-

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Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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Offline DocMel

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Re: Tuning 440: Hold at 2500 rpm, rotate distributor, etc: Plz repost!
« Reply #2 on: February 25, 2011 - 02:30:42 PM »
I appreciate the help, but not the exact post I was looking for. 

The one I was looking for was even simplier in steps   Basically it said:

Rev up to and hold at 2200 or 2500:  Then rotate distro until highest rpm is acheved, then back off slightly

The points I cant remember:

1.  If rpm held was 2200 or 2500
2.  If vacum hose was attached or detached/plugged while you do it

Offline Bullitt-

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Re: Tuning 440: Hold at 2500 rpm, rotate distributor, etc: Plz repost!
« Reply #3 on: February 25, 2011 - 03:01:51 PM »
I've seen the same thing said a few different ways but I can't imagine it much simpler, same basic thing MoparAL had me do to my small block.  If you don't have a timing light use your ear for detonation & back off till it stops. Vacuum advance at 2500 will be all in so you want it attached if using it.

The engine spend 90% of the time running at full advance above the advance curve so it is more important to have the timing set there than at idle. Most engine want more intial advance at idle than the factory curve will allow

Set the timing between 36-38* above 2500 rpm
[ I usually turn the idle speed screw up to keep the rpm steady]with the vacuum hooked up , if it is over advanced you can hear it pop/ misfire in the exhaust.
I f you do not have a timing lite with the advance feature you can put a mark or cut into the damper 2 3/8" clockwise form TDC this is 36*

Now reset the idle speed & now try advancing the timing at idle , if the idle speed picks up it wants more initial timing so you need to shorten the curve.

You can put a small allen wrench into the hose nipple on the vacuum advance unit & turn counter clockwise to reduce the amount of extra advance the vacuum gives you & shorten the timing curve  [it will turn approx 14 turns total & will not hurt anything if you unthread it too far]

Now reset the timing above 2500 RPM  & try again at idle until it runs best both at idle & above 2500 rpm

I f you completely disable the vacuum advance & the engine still wants more advance at idle with the total timing set properly  the only option is to disassemble the dist & put a small tack weld in theslots for the advance weights which will shorten the curve even more

You will probably be surprised how much better the gas milage , response & power you will be adjusting the timing this way


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Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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