i have an 85 c4 that has been switched to a 4-barrel. everything is there and working. i have 2 questions though. i feel i have tuned it properly yet i smell it running rich. there is no blow out from the mufflers and it isnt backfiring. i have an out of tank 4-7psi fuel pump running straight in with no regulator/return line. any thoughts out there?

 

Check float levels, adjust idle mixture, check power valve opening if it is a Holley.

 

If it was TPI the computer would take care of that. To bad somebody changed it.

 

ya ive been on the fence about going back. float levels are to specification idles a turn and a quarter past "stutter" and its a edel.

 

she runs fine, hard cold starts. and fine with wot

 

check the timing also

 

havent done that yet, its a new hei dizzy, may be off a tooth.

 

Hey dude those are sweet wheels in your pic over there----|
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If it runs fine then leave it. Carb motors are going to stink a little in comparison. Do you have cats on it still?

 

nothings been removed, all stock except for air & fuel delivery

 

A carbureted car is always going to run richer than a fuel injected car. It is dangerous to go lean, especially on a carb. If there isn't a fuel pressure gauge installed on the carb I would strongly suggest adding one, since going above 5psi will cause most carbs to just dump fuel down the intake. Also, if you haven't checked the timing at all that is the first place I would start. Timing is way more important than adjusting anything on the carb. Factory timing settings are at 8* before tdc at the lowest you can get the car to idle at, but make sure you have the vacuum advance disconnected from your distributor and plug the line going to the carb, otherwise you will get false readings. Personally I have my base timing set at 12* before tdc, which is fairly common for a carbureted 350.

 

if im reading it correctly its at 10*

 

Thank you

 

Mkay, then as long as the vacuum advance and mechanical advance are working properly you should be fine. The vacuum advance should be hooked up to manifold vacuum, which is easy to test. Just have the car running then pop the line off the distributor, if you put your finger up to it and feel vacuum, it is hooked up properly. A way to test to see if the vacuum diaphragm that doesn't taste good is fairly easy. With the line hooked up to the distributor, pop the other end of it off the manifold vacuum port and suck on it, or you could use a vacuum pump and see if it holds... whichever works for you.
Mechanical advance can be tested by just revving the engine with the vacuum advance disconnected. If you see the timing advance, it is at least functional.
Also a good way to tune the idle circuit is by hooking up a vacuum gauge to manifold vacuum. Try to get the most vacuum you can at your desired idle speed, by adjusting the idle mixture screws.

But really though, if it is running correctly I don't really see a need to test all of it. If the ignition timing was off even by a little it would have all sorts of issues. You could check vacuum and try to adjust for more to get the idle mixture as good as you can. If you want to get it tuned to perfection, have it dyno tuned by a shop that knows how to tune a carburetor correctly.

Edit: Also if you are worried or just curious about your air/fuel ratio, you can buy a wide band oxygen sensor with gauge from vendors like summit racing for fairly cheap, along with a gauge pod of some sort.

 

i went and replaced a bad cap and cleaned out my pickups and put on a new rotor and got the internal vacuum as high as i could (around 60 on my vacuum gauge.) and at the moment i have no dash gauges so all i have is a small aftermarket water temp. so im kind of in the dark. thank you very much for your help.

 

What cfm edel. carb are you using?? What rods, front and rear jets are you using?? My carbed 84 was running too rich even with the stock 1405 .100 primary jets, .095 2ndy. jets and .070 x .047 rods. I have a WB AFR Comp gauge and am now running .095 front jets with the stock .070 x .047 rods. Running 12* initial timing. Large valve 72cc cast iron Summit/Dart heads, ZZ4 intake, and Isky 228-228 @.050 solid lifter cam.

 

650cfm manual choke 4 barrel double float single inlet with 100 primes with an ambient pressure of around 5/7psi.

 

You might want to try a #1456 .073 x .047 or a #1459 .075 x .047 rod. Will lean it out at idle and low power cruise mode. Rods are about $12 and take 5 minutes to install. Pull your rods and read the size that is stamped on them before you order new ones.

 

Did the gauges stop working when you went with the carb set up. Can you use the factory gauges with a carb setup

 

they work fine aslong as you keep your computer plugged in, your fuel mileage gauges wont work, just as long as you re connect the tach to the new hei and re install the colllant temp sensor youll be fine