Spit and sputter fixed...need "expert" advice

Ok, just on a whim (or semi-educated guess) I decided to swap the metering rods in the carb and see if the power loss when the secondaries kicked in might be the carb "drowning". I used the .070X.037 originally, and it was losing out as discussed in previous threads.

I swapped down to .073X.042 rods, and almost all of the sputtering disappeared. So, I tried the .073X.047, and then the stock rods .075X.047 and it is running MUCH better now. Just a tiny bit of hesitation when the secondaries kick in which a passenger would not notice, but I do when driving (could be psychosomatic )

I originally changed to a richer mixture due to my spark plugs running very clean, almost white like new. The .070X.037 was finally used because it was as rich as I could go with just a metering rod change, and not having to swap jets (a little more work, rods are 30 seconds each to change), plus it gave my plugs a light brown color.

Now that I am back to stock, I am guessing my plugs will clean up and I will be running what I used to call "lean" (ie. clean white plugs).

Since it is running better now, should I try other jet/rod combinations to go even leaner and see how it runs?

How accurate is the "spark plug color" test at measuring a/f ratios?

Would my plug gap add to the equation, if I am running them a little bigger than stock, like at .045, or would I be messing with too many variables by even thinking about the plugs right now?

Any suggestions for how to further tweak this, and which direction, if at all?

By the way, there is and never has been any pinging, regardless of how far advanced I put my timing. I can turn it until the dizzy hits the radiator hose and it will just look like 20 or 25 degrees initial timing on the light, and run just fine. Just wanted to mention this in case the white plugs are not an issue unless pinging is involved.

 

Glad u got it fixed. I read somewhere that because of the oxegenated fuels coupled with additives of today that the plug reading test wasnt so accurate. But of coarse thay alwats recomend an a/f ratio meter preferably a wide band to tune with. I always use the ol' dragstrip method. Jet it up untill it slows down and back up one, or two on the street.

 

Even on improved ignition, I still run .35 plug gap. I don't think the plugs will get better, although you may be able to clean them, pull them and sand them, or a method me and my cousin use, idle it up (at least about 1500rpm) and trickle water into the carb. Works wonders for carbon deposits and such. Just think of how clean a piston/head is where a headgasket has blown.

As for the spark plug color, I'm not the best at guaging AF ratio, but it is reliable. Personally, I'd probably do the water trick, maybe pull the plugs or just replace them, anything, and drive it as is for a while and see what she does.

As for the timing, just don't go over 38* total and let it go, over 38* can lose power.

 

I keep getting mixed messages...is 38* total determined with or without a vacuum advance hooked up. I am currently taking the vacuum line OFF, timing it to 38* at 2500-3000 rpm (it gets to a point where advance stops advancing without vacuum assist) then bolting it down with and installing the vacuum line. If I hook the light back up with vacuum attached, it will appear to be advanced to up over 50 or 60* when revved. Timing at idle appears 15-ish with or without the vacuum line hooked up, so I have it on the correct port.

I think I might mess with the rods at the track (if it ever opens back up) and just test it to see if it makes a noticeable difference. Maybe mess with it this weekend and just see if it FEELS different with different combinations.

 

always set timing WITHOUT vac adv hooked up. i think i said that before.

 

When I started running my Duraspark/Chevy/TFI ignition, I initially left my plugs at .35. After 3,500 miles the electrodes looked to me to be wearing prematurely. Gapped the plugs to .50 and haven't noticed them wearing anymore since, and I seem to recall the car felt like it had a little more power at take off after regapping them.

 

I thought you were running points?
If so, .045" sounds really wide for plug gap.
Dave

 

i am running at 36* at 3000 rpms.. i dont have vacuum anything on the car except the line from intake to tranny...

i would not recommend going too lean... you will run hot and burn up pistons.. richer is better, but not too rich.. you should have a slight coloring of the plug after one run at the track.. i have tried to read my plugs... but i dont know what i am looking at.. and they are so dang hot after one run that i hate getting my hands near them headers at night in the dark... i will do it one day when its light out... and not burn my hands up.. heheh

i was running the following setups on my 600 carb

stock .100 and .94 with 70x47 rods
went to .104 and .100 and 75x43 rods

now i am at .100 and .098
and 70x47 rods.. (it passed emissions with flying colors on this setup)
it will stay this way until i get to iowa.. then i plan on tweaking it at Cordova track in Iowa.. i leave in 1 week

 

manser, a little cheat for the heat. bring one of your wifes old oven mits and use that to get the #1 plug (always the easiest to grab).

 

One problem I have found is that alot of the plugs today have a shiny almost chrome appearance. Used to be that they were cadium plated and you could actually read the heat on the plug but now they changed and are harder to read.You can weld in a O2 sensor and read it with a voltmeter , thats the easiest way I have found or invest in a high dollar setup like Innovatives, it has datalogging capabilities and makes it nice to read RPM vs Mixture.

 

igo, not that I am not listening (even though all my teachers said so, never mind that I always wore TWO HEARING AIDS!!!), but my question is not "setting" the advance, but checking total advance. I "set" it with the vacuum line off (14* initial, 38* total), but then put the line back on and check again (14* initial, and 55* total). So, when I put the line back on and start driving, what is my total, 38 or 55?

I am just confused on if you take into account the vacuumed addition to the centrifugal advance when naming it "total".

To clarify, I do ALL "setting" with no vacuum.

 

There was a little motor on a dyno, timing was set at 38 degrees TOTAL. After the little motor was warmed up it was loaded and opened wide open. Total horsepower was recorded. Timing was backed off 4 degrees for a total of 34, The little motor was warmed and loaded again and opened wide open. Horsepower was once again recorded. Lo and behold 60 horsepower differnce in the second pull. Timing is not a set number for any engine. It depends on a lot of varabiles. But it has been a unspoken rule that anything over 38 total is a waste of power. Although during cruise with no load on the motor 60 + degrees can and will improve fuel milage. The eec IV system on a mustang somtimes advances timing above 60 degrees. But without computer control you probaly cant do it and make it run correct. Also rembember its really not vaccum advance its vaccum retard. To answer your question 38 degrees should be the most timing your motor sees with no vaccum advance. If you feel that there is no pinging or any other problems with the vaccum hooked up, By all means run it. But itnital set should be performed without the vaccum. PS. to give you an idea of what timing will do, Under boost on a normal pass i run 18 degrees total timing. If i need to speed up ill add 4 degrees, This little bit of timing usually will better my 1/8 mile time by 3+4 tenths and usually 4+5 mph. If i need to slow down i take timing away. Hope this helps.

 

Scott; go to a parts house, and get a new vacuum advance can. I think yours is bad. The arm could be bent, or the diaphram is bad. Look on the inside of the distributor for a loose or worn out connection to the vacuum adv. arm. Age can get to them after a while.

 

and the adjustable one is only around $15-20

 

Adjustable one for $15-20 sound good to me. I figured it was OK as the entire unit is fairly new. May as well dump the points while I am at it, and duraspark it.

$60-70 and I have a "new" distributor.