No timing vacuum advance-good or bad? - FSB Forums
 
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post #1 of 10 (permalink) Old 08-03-2010, 04:15 PM Thread Starter
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Bronco Info: 1978 Bronco,400m,c6,d44,custom d60 rear,np205,410's,ox locker front&rear,33" bfg's,hd bumpers
No timing vacuum advance-good or bad?

Is it going to cause any damage to my engine,not having the vacuum advance hooked up. I had my engine rebuilt and the shop that put the engine back in could not get my truck to stop knocking under load. They said they tried everything to get the timing set right. They unhooked the vacuum advance and the issues went away and they told me I didn't need the vacuum advance anyway. I'm just wondering if this shop really knew what they were talking about.(supposed to be a reputable shop) I've been driving the truck for a while now and it seems to run good when warm, with lots of power. However it seems to be running a little rich even though the carb is set up right, plugs are pretty black after only 5000 miles, it's hard to start if it sits for a couple days or after its sat for about 15-20 mins after its been at operating temperature. Could this be the fact that the vacuum advance isn't hooked up or do I have a fuel delivery issue?
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post #2 of 10 (permalink) Old 08-03-2010, 05:41 PM
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you don't need the vacuum advance.....but it will maximize your efficiency.which leads me to believe that it was malfunctioning.i'm no mechanic mind you, but i've owned quite a few fords...all of them had the vacuum advance.
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post #3 of 10 (permalink) Old 08-03-2010, 06:21 PM Thread Starter
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Bronco Info: 1978 Bronco,400m,c6,d44,custom d60 rear,np205,410's,ox locker front&rear,33" bfg's,hd bumpers
I should probably add: the engine was bored 30 over, heads decked 20, mild cam, 4 barrel carb, 4barrel edelbrock aluminum intake, if any of that makes a difference.
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post #4 of 10 (permalink) Old 08-03-2010, 06:37 PM
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It would bother me from someone that is a reputable engine rebuilder could not find the reason for the problem and the only solution is “you don’t need a vacuum advance anyway”. There has to be a solution to the problem. Maybe there is a problem with the distributor or the vacuum line to the distributor.



Torque it down till it strips...Then back it off a quarter-turn!
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post #5 of 10 (permalink) Old 08-05-2010, 04:27 PM Thread Starter
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Bronco Info: 1978 Bronco,400m,c6,d44,custom d60 rear,np205,410's,ox locker front&rear,33" bfg's,hd bumpers
I guess maybe I'll have to look at getting a new distributor?
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post #6 of 10 (permalink) Old 08-05-2010, 05:20 PM
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Or a used Duraspark.

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Originally Posted by InfoFord View Post
if you still can't figure it out put it back together and take it to a mechanic
"Under my plan electricity prices would necessarily skyrocket" BHO

Truck was stolen & sold for parts Wheat Ridge Colo Black with Red 2 tone. About $20K in the truck. VIN U15HLEC0170
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post #7 of 10 (permalink) Old 08-05-2010, 11:59 PM
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Originally Posted by bronco ox View Post
...... it's hard to start if it sits for a couple days or after its sat for about 15-20 mins after its been at operating temperature. Could this be the fact that the vacuum advance isn't hooked up or do I have a fuel delivery issue?
The hard starting when warm could be from the fuel percolating into the
carb after it's been shut off. You can check this by removing the air cleaner
and looking into the carb to see if fuel is dripping into the venturies.

Was the vacuum advance connected to the timed/ported nipple on the
carb, as opposed to straight manifold vacuum?

1978 Bronco Ranger XLT, Trailer Special with FreeWheeling Package, 351M, NP435, Ford alloys w/BFG 31's, MAC/IMCO hybrid exhaust.
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post #8 of 10 (permalink) Old 08-06-2010, 04:57 AM Thread Starter
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It was hooked up to the manifold. There was a plastic nipple coming out of the front of the manifold with a vacuum line running to the distributor. Should it be hooked up to the carb directly?
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post #9 of 10 (permalink) Old 08-06-2010, 08:48 AM
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yes it needs to be hooked up to the timed port on the carb. Also get out your timing light and check you total timing. The issue Im having with mine is Im getting too much mechanical advance. I get about 30-32 deg from mechanical alone. So you add in your initial and thats what you get. You only want a total of around 32-35 deg. For me I cant run more that 2-3 deg initial timing with out it pinging really bad.

You can take the distributor apart and get down to the weights to see what the value is. There are 2 slots for mechanical advance. Each one should have a number stamped on it like 12L and 15L. Take that number and multiply it by 2 and that should be the mechanical advance. Also you can turn down the vacuum advance by getting a 3/32" allen and inserting it into the vacuum port on the advance module. Turning it counter clockwise will decrease the vacuum advance applied.

Heres a good write up for ya.

http://www.fordmuscle.com/archives/2...ng/index.shtml

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post #10 of 10 (permalink) Old 08-06-2010, 04:32 PM Thread Starter
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Quote:
Originally Posted by ZOSO View Post
yes it needs to be hooked up to the timed port on the carb. Also get out your timing light and check you total timing. The issue Im having with mine is Im getting too much mechanical advance. I get about 30-32 deg from mechanical alone. So you add in your initial and thats what you get. You only want a total of around 32-35 deg. For me I cant run more that 2-3 deg initial timing with out it pinging really bad.

You can take the distributor apart and get down to the weights to see what the value is. There are 2 slots for mechanical advance. Each one should have a number stamped on it like 12L and 15L. Take that number and multiply it by 2 and that should be the mechanical advance. Also you can turn down the vacuum advance by getting a 3/32" allen and inserting it into the vacuum port on the advance module. Turning it counter clockwise will decrease the vacuum advance applied.

Heres a good write up for ya.

http://www.fordmuscle.com/archives/2...ng/index.shtml
That's great, this link was really good at explaining it all. I guess I have some work to do playing with my timing now. I think if I turn back the vacuum advance and fine tune it a bit it should be good.
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