New Carb adjustments

[jebner]

I just bought a Holly remanufactured Motorcraft 2100 carb for my 77 Cherokee. I have not been able to successfully adjust the air and gas so that it will run correctly. I timed it perfectly, but there still seems to be a problem with the carb. At first, it would start and run if I gave it enough gas, but would not idle. I adjusted the gas flow and now it will not start. Any tips on getting the air/fuel mixture correct. Thanks for you help!

Jeff
'77 Cherokee Chief
360 2bbl
Urban Camo paint

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by jebner:
I adjusted the gas flow and now it will not start. Any tips on getting the air/fuel mixture correct<HR></BLOCKQUOTE>

Jeff, start with the mix screws about 1.5-2.0 turns out. That should at least get it running unless something else is botched. Let the motor get to normal temp. Hook up a tach or vac gauge(ported vac). I like the vac method because my el cheapo hand held tach needle is too bouncy.
Set the idle screw to idle speed then SLOWLY turn one of the mix screws till you get the highest rpm/vac reading. Reset the idle if needed and do the same with the other mix screw. Reset idle and keep going back and forth between the two mix screws till you can't get any higher rpm or vacuum. Reset the idle and rehook the vac hose. That's as good as it gets.


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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8

[RudyC]

Joe you mean manifold (full time)vacuume. Ported vacuume is not on at idle when the throttle plates are covering the slots. There is a manifold vacuume fitting someplace on the carb base, it's the one sucking air all the time.

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1979 WAGONEER, 360, TH400, Q- TRAC. 3" ADD A LEAFS, 31" MUD T/A'S (PEP BOYS CLONES).
" Go farther, it only breaks on the street"

[Ralph]

Several months ago, "Dave_S" posted a pretty good message about adjusting a carb without fancy instruments:
http://www.ifsja.org/ubb/Forum2/HTML/000605.html

[BPMeenan]

You know, I was just messing around with this. It looks like the only two things that run off the ported vacuum are the distributor and the air injector pump. I rerouted both of these to full time manafold vacuum and I think I'm seeing better performance. The concern I have is that as of right now, I have nothing making use of the ported vacuum; it's just plugged. Can anyone give me a reason I shouldn't be doing this?

Thanks,
Brian
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90 GW, all stock, running fine.

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by RudyC:
Joe you mean manifold (full time)vacuume. Ported vacuume is not on at idle when the throttle plates are covering the slots. There is a manifold vacuume fitting someplace on the carb base, it's the one sucking air all the time.

<HR></BLOCKQUOTE>

No Rudy I do mean ported vac. There is always some ported vac even at idle but it may not be accessable on the far side of a CTO valve. As throttle/rpm increases so does ported vac.
Manifold vac decreases as the throttle opens/rpms increase.
I usually just pop the hose directly at the dist and plug the vac gauge there. Granted the eng must be at operating temp or the hose at the dist will be running off man vac till the CTO switches it to ported after 165*F.


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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8