Author Topic: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C  (Read 17175 times)

keiken01

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Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« on: June 26, 2008, 08:16:01 PM »
What is the correct steps to adjust the fuel mix and hot engine idle?
My book says set mix screws at 1 1/2 turns from closed and start the hot engine idle at 1 1/2 also. 

Also, my car was running fairly smooth, but not perfect.  It has a Pertronix II Ignitor and Flamethrower II Coil.  I noticed a leak at the donut section of the exhaust on the driver side and tightened it up to seal it, which it appears to have worked.  But now my engine runs rougher, so I decide to go back through the steps to adjust the timing and carb from scratch, but it still runs more rough than before I fixed the leak.

Any ideas?

Soaring

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #1 on: June 26, 2008, 09:49:32 PM »
I have been rebuilding Motorcraft 2100 carburetors for several years now, and I always set the idle adjustment screws to 2 1/4 turns out initially.   The correct way to adjust them is by using a vacuum gauge, but I just use my ear. 

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #2 on: June 26, 2008, 10:01:21 PM »
Ok, so 2 1/4 turns out to start.  The the book says adjust the screws IN... but I could swear last time I did it, I used the vacuum like you said and adjusted out until I got the max vacuum.

It was at a vacuum of 15-17, something is making it float up and down.  Using the tach method dropped it down to 13-15.

Would it matter that the horns are broke off?

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #3 on: June 27, 2008, 10:36:26 AM »
  Yes, you need to have the horns.  Snap a pic of the top of your carb so I can see what damage has been done. 

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #4 on: June 27, 2008, 01:33:09 PM »
Attached a pic.

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #5 on: June 27, 2008, 01:53:47 PM »
Open the butterfly so I can see the damage to the horns.  If you can unscrew it from the body, then I can send you a new set of horns, or if you can't get it out, I will just send you a carb. 

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #6 on: June 27, 2008, 02:39:39 PM »
Sorry for the confusion, I should have said the 2 vent stacks that come up from the top of the carb... but here's a pic of the inside...

I paid $80 to a fella a couple years ago for a new carb and duraspark II setup, but he got into some serious health problems and I've never heard back from him.


keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #7 on: June 27, 2008, 04:14:30 PM »
Correct me if I'm wrong but the correct method to set timing is to remove and plug the vacuum advance and then adjust to 6 BTDC then reattach the vacuum.  Right? 

I'm going to take another look at my plugs in case they fouled, but can't image they have with driving less than 500 miles in the 3 years I've had it.

Do you adjust the mix screws OUT or IN or anyway it takes to get the max vacuum?  Going to give it one last shot before I start looking at other options to get it running smooth.


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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #8 on: June 27, 2008, 04:57:09 PM »
Yes, you take the vacuum advance tube off at the dizzy and plug it before you set the timing.  I know the book says 6 degrees BTDC, but it all depends on your altitude.  Here in central Texas at about 3K feet, mine is set at about 8 degrees BTDC.  Others have theirs set at even 10 or 12 for optimum performance.  The problem is that the higher you set it, the hotter your engine runs.  Try to find a medium setting.  Use timing light to set the timing and your ear to know when it is right.  Set it at 6, then drive it and go WOT for a block or so.  If it doesn't ping, then set it at 8 degrees, then repeat the WOT thing.  Anyhow, keep doing this until you get ping then back down to the next degree. 
Your horns look good, and those tubes don't need to stick above the plate, so you are good to go there. Just make sure your gasket doesn't cover up the opening of them. 

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #9 on: June 27, 2008, 05:53:53 PM »
What about the mix ?  In or Out? or whichever? for max vacuum right?

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #10 on: June 27, 2008, 06:04:35 PM »
Yes, once you get your timing right, set the carb to max vacuum.  I just do mine by ear, but for an untrained ear, I would go ahead and set it at max vacuum.  You can't go wrong with that setting. 

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #11 on: July 21, 2008, 03:23:04 PM »
I ended up removing and replacing the intake gaskets.  This increased the vacuum up to 18-20" but still have the fluctuation.  Better, but not steady.  My carb has a vacuum port on the pass. side that leads to the vacuum switch atop the thermostat housing.  There's another rubber line that runs from the exhaust manifold to the rear corner of the carb on the pass. side above the metal line also running to the exhaust manifold. 

How necessary are these lines?

Oh and an interesting thing with the intake... the numbers C8AE-9425-B appear to be from a 68 289/302 2v which tells me whoever swapped the engine decided to swap the intake also.  The intake end ports, that I believe are for coolant, do NOT line up perfect to the heads.  The gasket fits the rest of the holes.  I was told this is a common thing because of so many changes that occurred with engine components.

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #12 on: July 21, 2008, 05:06:59 PM »
That's strange, because the vacuum tube coming from the passenger side of the carb right under the choke housing should go to the distributor.  You have a vacuum switch atop the thermostat housing?  WTF is that for?  The thermostat opens and closes without the assistance of vacuum. 

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #13 on: July 21, 2008, 06:54:30 PM »
It's the distributor vacuum control valve and is supposed to adjust the RPM of the engine if the engine is too hot.

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #14 on: July 21, 2008, 07:08:10 PM »
Attached pic.

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #15 on: July 21, 2008, 08:22:53 PM »
That's correct, but here is what you said.  >>>>My carb has a vacuum port on the pass. side that leads to the vacuum switch atop the thermostat housing.  <<<<<

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #16 on: July 21, 2008, 10:39:41 PM »
Yeah, sorry for the confusion.
Makes me wonder if it might be something else.  If memory serves, my compression averaged like 151#.
FYI-I'm also going to test a "mister" and a "water4gas" HHO jar to see what they do to the MPG.

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #17 on: July 22, 2008, 04:03:25 AM »
OK, let us know how that water burns.  Hydrogen may be the fuel of the future. 

keiken01

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #18 on: January 03, 2009, 08:30:08 PM »
Hey, just thought I'd let you all know that I did the water 4 gas and it increased my MPG from 11 to 14.  My MPG still sucks, cause I can get 18 MPG from my 2001 4.6L F150, so I'm open to ideas on that problem.  Wondering if a new carb is in order... maybe upgrade to a 4 barrel Edelbrock manifold/carb???   Thoughts??

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Re: Adjust 68 2v 2100 Carb w/ Auto Tran & A/C
« Reply #19 on: January 03, 2009, 09:47:17 PM »
Did you turn the idle misture screws all the way in then out 2 1/4 turns then check the vacuum; and adjust for maximum vacuum from there?  Also, spray some carb cleaner around the intake gasket area, and if the RPM's pick up, you indeed have a vacuum gasket leak.  Start a new thread on that water for gas subject and tell us what you know about it.  It sounds very interesting.  If you are going to seriously consider a 4V carb system, be careful about the CFM's you get.  That stock 289 (A code) originally had a 480 CFM Motorcraft carb (4100) so  going too much over that will cause washout, meaning some of the fuel won't get burned and will wash out the cylinder walls.  In other words, a huge waste of gas, and no benefit for performance.  Also consider a dual plane intake manifold as opposed to a single plane.   

 

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