Hello eveyone,

Not knowing much about carb tuning I thought I'd see if anyone here has seen this before.

While reving and sometimes when idling white smoke comes out the pipes. It’s not bluish and doesn’t smell like oil I don’t think it coolant.

Also, after the car sits over night and I start it up again in the mornings, it spatters wet carbon out the pipes – quite a bit of it.

I've got a 1404 Edelbrock – 292 with ’57 4v intake. I replaced the metering rod with the one recommended in the other old forum.

It seems to be running okay, but am I running it too lean or something? Can a carb adjustment improve this?

Thanks.

Ed

The white smoke you mention could also be condensate related but could also be an indicator of raw fuel passing through.  White smoke is common when the outside temperature is low enough for the hot exhaust to condensate right outside the tailpipe but I don't see that very often here in Texas where I reside.

Thanks Ted. I’ve already blasted my garage doors – they were nice and white. Now I’ve got two black spots.

Your last comment about the raw fuel is interesting. Last year when I first was playing with the new carb I was adjusting the mixture and got it to the point where white smoke was pouring out the pipes – that must be the raw fuel you mentioned. I had no idea what it was so I just dialed it back until it was gone.

So how do I know when I have the air/fuel mix adjusted right? Is there some rule of thumb that I can follow?”

Thanks again,

Ed

I typically just use a vacuum gauge when setting the idle mixture and adjust the mixture screws where the highest vacuum readings are achieved.  The exhaust should not smell rich.  I'll use the spark plug readings and/or mpg checks for primary fuel jetting.  Those times that I got that white smoke from raw fuel was from a carb that was really dumping in lots of fuel.  I was surprised it didn't flood the engine it was so rich but actually ran okay.  Just a good indicator that the ignition system was up to speed.

Thanks again Ted.

I tried to buy a vacuum gauge from the local parts store here and the guy didn’t know what I was talking about. I’m going to have to keep asking around for one.

I know squat about tuning a carb, so will do some research before I mess with it any more.

Thanks again for your help.

P.S. This weekend I’m taking the Merc on a 1200 mile road trip. It’s the first one since I did the frame off and probably the first one that car’s had in 30 years.

Wish me luck! : )

Ed

What rods are you using with the carb?  I have the same carb with a little warmed over cam, and the blue thunder intake, and it feels pretty lazy/unresponsive in the midrange.  Trying to figure if thats too rich or too lean, and which way to go with the rods.  I already changed the springs, which helped a lot, but still not as good as should be.  Any thoughts?

Thanks!

I don't know if this will help but I ran the 500 cfm Carter on my '55 for a good while before switching to the 525 cfm Road Demon Jr. and here's what I had in my notes.  I ultimately ended up using the 388/392 rod and jet combination.  If my notes are correct, the final jetting combination had an effective surface area of 0.002462 square inches.  Prior to that, I had been running 0.002490 square inches of effective primary jetting and the downsizing was worth an additional 0.3 mpg based on the average of twelve fuel checks with each jetting size change.

I went one stage lean - see chart on above page.

REF #    MAIN JET       METERING ROD      CHANGE FROM BASE
   6       1423 (.086)   1463 (067 x 055)     Rod

I still need to do some tuning. It's not quite right and I'm getting less than 10 mi/gal - I think it might be my timing or points or something, but it also seems to be running quite rich so even though I did follow the advice form another thread on the old forum, I can't say for sure that the above is the right choice for my application:

I've got a stock 292 with '57 distributor & intake and Edelbrock 1404 carb.

Your exposed jet area in cruise calculates out to 0.00228 sq inches which is about 7% leaner than what I ran.  The 500cfm Carter on my 272 with Isky cam would get ~17mpg in city and 19 on the highway with the T-85 overdrive.  The Isky cam is ground on 108° lobe centers but was installed at a 104° intake lobe centerline.  I played around with the valve lash and the engine liked it on the loose side.  You might check that the float levels are set correctly as either too high or too low will hurt the fuel mileage.  Ignition timing is also extremely important and the Y tends to like a lot of it, especially in cruise mode.  Make sure that the vacuum advance chamber on the distributor is functioning regardless of whether it's hooked up to ported or direct vacuum.

Thanks guys,

My timing is set a little above 8* BTDC. But, I did find something that may make a difference. After I had a closer look at my set up, found that I had the distributor hooked up to the fulltime vacuum and not the ported vacuum. I also set the points to .015 gap – they were closer to .018. I got this '57 distributor new from the parts store and that’s the way it came - points and all. So assume the vacuum diaphram is set up correctly as well. I really have no idea about this stuff, but am learning as I go. I’m going to drive it for a while and see if it improves. Any other suggestions?

If you set your timing at 8 degrees with the vacuum line connected, you will not have enough ignition advance for good performance and mileage.

John

I set the timing without the vacuum. So that should be OK. I'm beginning to wonder how well my carb is set up. Right out of the box and change the metering rods and set the idle, but how likely is it that I need to set the float level. I'm using one of the old fuel pumps with the glass top. Should I check/reset the float level. If so how is this done?

Thanks,

Ed