I've finally got my cruiser idling fairly well ('73 fj40 with a rochester carb) and it seems to be running a little bit rich. I've got a fuel regulator set at 3 PSI right now and it does a little better, however it is still rich. On the rochester, there are two screw adjusters on the front of the carb. Can someone fill me in on what they adjust? Also, when I give it some gas, it hesitates a little bit before taking off. Is this a vacuum leak problem? If not, any ideas as to getting it to be more responsive?

Rochester 2Jet running rich on a Toyota engine? SAY IT ISN'T SO!

:p

How rich? Rich enough to blacken the plugs? Or do you just see black spots come out when you start it up in the mornings?

While I would be one of the last ones to defend a Rochester on a Toyota engine, you should also consider that a carb will have the appearance of running rich if the ignition system is not strong enough to spark and burn all of the gas being delivered.

The two screws you mentioned should be idle mixture screws. If the carb and the engine are otherwise working properly, then turning the screws in either direction should have the effect of smoothing out or roughening the idle.

As far as the hesitation goes, it COULD be the accelerator pump in the Rochester, but I wouldn't rush to judgement on it. Many other things to consider first.

For starters, what's your vacuum reading at idle?

Hth

Mark A.

Not much blackness....just some puffs as it idles. I'll mess with the mixture screws and see what happens. Also, I'll check the plugs to see if they are wet when I remove them. The thing hasn't been run for a while, so it might just need some time to clean everything out. Also, based on your comment in regards to the ignition system...maybe I'll try new rotor, cap, wires and plugs to get the spark a little more active. Maybe I'm just being over-sensitive and am comparing it to the emissions on my Honda Accord :) Thankfully, I live in an area where I don't have to worry about smog checks.

As far as your second question......Now my Newbie inexperience is going to show.....I don't have a vacuum guage (however, I'm sure they aren't that expensive/difficult to get) and I wouldn't know how to measure the vacuum pressure if I got one. Any suggestions???

So get a gauge. ANY decent autoparts store will have them. While you're there might as well get some more vacuum hose. You'll want a few feet so you can set the gauge down in a convenient, visible, spot while you tune and you might as well get enough to replace your current vacuum lines unless yours are shiny and new. And a "T" fitting unless the gauge comes with one.
You want to measure your MANIFOLD vacuum. So look at your intake manifold. You might have two small (about 1/8") threaded holes on the top of the manifold. One fore and one aft of the carb. You might have a little (maybe an inch tall?) hexagonal gizmo threaded into one. This gizmo probably has several brass tubes sticking out, these tubes hopefully have vacuum lines on them. Maybe some of these vacuum lines go to a little black box mounted on the driver's side of the engine bay. Maybe, if you've got a rochester, not. Anyway, you want to attach your new vacuum gauge, somehow, onto the intake manifold, maybe by plumbing it in with a "T" fitting or finding an unused port. Once you have the vacuum gauge in-line, you're ready to go. Fire it up and see what it says.


I am a real fan of the vacuum gauge...like 'em so much I mounted one in my dash for everyday use.

Also, to get a more active spark, you might want to look into one of those Pertronix Ignition systems...Super easy to install (easier than a vacuum gauge) and they really work.
Maybe someone here older and wiser than I knows where you can get a good deal on one correct for your distributor.

Actually, I believe I have a pertronix ignition on the cruiser. It came with it when I bought the rig, but I had one on my old '56 Ford F100 (390 big block). Before that, I had some high performance mallory points.....impossible to keep up with. I must say, that was the best $75 I ever spent on that truck. I'm definitely a big fan of pertronix.

I know that I have some ports on the top of the manifold as well as some coming out of the carb and right below the carb on the mounting bracket (i believe that one is for the brake booster). However, no vacuum lines hooked up to anything. I'll see what I can do over the next day or two and give everyone here an update. Thanks for the help.