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Picked up a 1 owner 73 that is all stock, it is running like it has a huge vacume leak. Checked the manifold, card, and pcv with brake clean and there's no difference in the idle. Was thinkin about rebuilding the card OR going the other way and throwing a weber on it. If I go with the weber should I remove the air pump and all the other smog stuff or just leave it alone?? What would the best thing to do??

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Well for one thing use carb cleaner.Brake cleaner has different chemicals.Check vacuum lines for visible cracks.Check plug wires are on correctly.Did you look at the points and see if they are pitted. Did you put in new gas? Did you check the fuel filters?Did you check the air filter? Is the condenser ok?

Replaced the plugs, wires, cap, rotor, points and condensor, fuel filter, air filter, pcv, and checked all the vacume lines. Also did a smoke test through the carb and there are no visible leaks.

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Doesn't your 73 have two fuel filters? My 75 has one at the tan and one right before the carb. Did you check the volume on the fuel pump?

Didn't check volume but checked the pressure wile running and it was fine. I think that the truck had two filters at one time but the lower one has been eliminated. I'm meaning towards the card just being bad, I rebuilt it a few months ago and it ran okey for a wile and now its starting to brake up. Maybe time to just go with a weber.

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99% of carb problems involves dirt plugging some tiny passage somewhere. After a carb is properly tuned and set up nothing should ever change except---dirt in a passage. Four cylinder vehicles are much more prone to this because of the very small passages involved in the carb.
Try this-----remove the idle mixture adj screw and using a carb cleaner spry can with a plastic nozzel, stick it all the way into the hole and blast some spray into there. Worth a try.
Be sure and count the turns out from seated position before start so you can put it back in the same place. Usually about 2--3 turns out from seated position.

Might cap off the brake booster line and see if that helps. Or does a 73 have a booster...

Carbs do wear around the throttle shaft and can get loose and leak around the base. Spraying with just about anything over those areas should have shown some change in RPM/smoothness.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Pulled the carb and manifold, surfficed the manifold and pulled the carb apart, there was a little sediment in the bowl but all the ports and passages seemed to be clear. Going to put it back together tomorrow and hopefully it will run like I should..... if not all the smog stuff is going in the trash and its getting Weber carb in Monday.

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+1 on the Weber, best thing I did to my pretty stock '72. The Hitachi is just not very good, and no matter what you do they just aren't very good. I also did a Pertronix conversion, so no more points to set, and the thing runs like a champ when my fuel filter isn't clogged with rust. I need to get my tank re-sealed but drive it infrequently so haven't done it yet.

Weber conversion works fine with the stock mechanical fuel pump, no pressure regulator needed for my 72.

Does the 73 have the dual points distributor? That was a ridiculous emissions idea that I think didn't work too well. I unplugged the switches that made it switch points in 3rd and 4th gear and set the timing for the primary set of points. Otherwise the advance changes unpredictably. I think it's supposed to retard the timing in 3rd/4th part throttle but it never worked right on my truck. The Pertronix conversion for the early motors uses a 74-75 distributor which is only a single set of points.

You might try setting the timing using a vacuum gauge rather than a timing light. I think you can give it a little more advance than the shop manual says.

I have a weber 32/36 sitting on my shelf that was going to use for another project but I think I'm going to just get an adapted and put it on the Luv. Should I leave all the smog stuff on the truck (air pump and EGR) or pull it off and cap it off???

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Is there really any argument for keeping the smog stuff on, aside from difficulty finding the correct caps, etc? Seems like more of a liability to keep it than to cap it.

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75 Mikado G180/4sp Desert Tortoise

So after banging my head against the wall for a all g time I found that the idle fuel mixture relay was bad, a simple $6 relay and its running like a swiss watch again. Took it for a 800 mile test drive all over California. Thanks to everyone who offered there advice.

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just to comment on the emissions stuff, I try to leave the EGR valve if at all possible. Without it I've found you have to retreats the timing or run higher octane gas. It is also some slight protection against burnt valves as it keeps combustion chamber temps a little lower.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good