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Discussion Starter #1
Ok..nova owners,throw some opinions at me...I adjusted my total timing yesterday and after finished,the car ran ok and throttle response was good.However ,after car was warmed up,it started to stall at idle.It did seem to chug a bit while at cruise speed.
I didnt have a dial back timing light so I measured the harmonic balancer to get the 36 degrees. Is it possible to have this condition if the timing is advanced too much? If I start it cold w/choke it will stay running though..Any ideas? Thanks in advance..
 

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1.) Where was your timing at originally before you adjusted it? Looks like you set it to 36 degrees total, where was it before? (i.e. 32, 38, 42)

2.) How old is your harmonic balancer? Its possible it has slipped and your 36 degree mark may actually be something else now, causing your readings to be off.

3.) What do you mean by chug at cruise speed? Was it surging or bucking? Sometimes if you have too much timing it will do this. My car did this when I had too much vacuum advance at part throttle (went from 15 to 10 and it was fine after that)

4.) Does it only stall when warmed up? Sounds like your choke is operating correctly but when it pulls off your car will stall.

5.) Check your idle speed and mixture. Maybe when you changed your timing you reduced it, causing your idle speed to drop which might cause it to stall now if it wasn't stalling before.

Let us know what your original timing settings were (both initial and total) and what your timing settings are now (what is your initial, you stated only 36 total).

I had an issue with stalling at lights when warmed up and it turned out to be a bad module and other components in my distributor. Basically an ignition problem. But if it wasn't doing it before you changed your timing, I'd see what the deal is with your timing first.
 

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Discussion Starter #3
I purchased a dial back timing light on ebay and I'm waiting till it arrives to try anything. The car ran fine before changing timing and I didnt disturb anything else.It just didnt have the throttle response I thought it should have...Right now I'm waiting for the UPS guy..Thanks for the info.!
 

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Discussion Starter #6
ok...Set timing at 36 degrees with dial back light,then increased curb idle and it runs ok..no stalling at idle..except when cruising it has a little surging sensation also some hesitation at times when accelarating.I have a new holley 670 avenger carb with stock jet size.I would like to get wire looms to separate plug wires better..
 

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1.) Surge at cruise - could be too much vacuum advance. Try limiting your vacuum advance to just 10-12 degrees. Some cans put out as much as 20-25 degrees. My car used to surge a little at cruise, backed my vacuum advance can down from 15 to 10 degrees and it was fine after that.

2.) Hesitation - can be caused from too little initial timing. You might be running 10 degrees initial and 26 mechanical for 36 total, and the total may be good for your car, but the initial might be too low. Sometimes recurving your distributor so you have less mechanical advance helps so you can increase your initial timing. For example, 16 initial and 20 mechanical is the same 36 total, but you'll have much better response with 16 initial vs 10 initial. This is assuming an aftermarket semi-aggressive camshaft. With a stock cam 10-12 initial is probably about right.

Off idle hesitations are sometimes just lack of accelerator pump shot. Sometimes you just need to make an adjustment for more pump shot, or sometimes change to larger shooters so the carb squirts in more fuel off idle. I had to change from stock .035" shooters to .043" shooters in my Edelbrock 800 and between that and some timing adjustments, my off idle hesitation is long gone! :)

I need to do something myself to clean up my plug wires, they're all over the place currently. Might do that sometime next spring, think I'm about done for this year. Just going to enjoy the car through the fall until winter hits and when the snow flies, it hibernates in the garage till spring. :(
 

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Discussion Starter #8
CDAHL,Thanks for the suggestions,I am going to check my initial again to see where I'm at with that.It could be the problem..Are you using the lightest springs in your distributor?
 

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Discussion Starter #9
ok...initial at 18 degrees,total {36 degrees} coming in at 3,00 rpm..throttle response is far better but I have some surging yet to address...If this is a vacum problem,will an adjustable vacum canister solve this? I'm using a 270/470 cam w/10:1 comp in a 355..How does this timing sound to you guys?
 

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18 initial + 18 mechanical = 36 total sounds pretty good to me. All in around 3,000 RPM should be good too.

Im running an MSD pro billet distributor using one light silver and one light blue spring, kind of the equivalent of one medium and one light spring from a curve kit. Brings my timing all in around 2,500 RPM. If I use two light springs the timing jumps around at idle as the springs aren't tight enough to pull the weights all the way back in at idle.

The surging is probably too much vacuum advance at cruise. If you dont already have a vacuum advance can that is adjustable, you can buy one, several companies make them. Crane makes a nice one, Accel makes one, and there are several others. You can also just buy a basic stock replacement type that is preset for 10 degrees. You have to look up part numbers and stuff though.

There are two types of adjustable cans though. The one I had with my old distributor just required an allan wrench for adjustment, you put it in the port, turn it to the right or left and physically limit the amount of degrees you got. Others like the Crane do the same thing, but that only adjusts the rate of when the degrees come in, and you have to physically limit the travel of the rod with a limiter plate. Whichever one you choose, make sure you understand what you have and how it works, and then try to set it up for 10-12 degrees max. That will most likely cure your problem.

But before you buy anything, just do a quick test. Unhook your vacuum advance and plug the port at the carb and take the car out for a drive. See if it surges then with no vacuum advance hooked up. Obviously if it stops then you know the vacuum advance is putting out too much timing. If it continues to do it, you have a problem elsewhere.
 
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