ok I put .028 idle feed restrictors in the primary metering block. And I started it and it still had some lean popping out the exhaust with the fast idle on but it wasn't as bad as it was when it had the .025 ifr's in it, but it's definitely still lean. I found all 4 of the .031 idle feed restrictors that came in the carb. I am hesitant to run them because I am worried it will foul my plugs. But something I forgot to add, Back when my plugs were fouling with the .031 idle feed restrictors in it I was running a 1 inch 4 hole spacer and now I am running a 2 inch 4 hole spacer. Could that extra inch of spacer contribute to the engine being leaner in the transisition circuit?

I think you went backwards on some adjustments from the original post? I would use the original restriction and bleeds, they sounded OK. Check vacuum in gear and use a power valve that is 1/2 or lower than that, so if you have 10" vacuum, use a 4.5 power valve. Once the carb is set at your idle speed, pull the carb and check that the throttle blades are not so far open they are exposing the transfer slot. A small amount of exposed transfer slot (so it looks like a square) is OK. If the transfer slot is exposed, you may be able the crack the rear throttle blades a small amount. I don't know it the carb has an adjustable idle air bleed? I usually have to drill the throttle blades to allow a bit of idle air through with the throttle blades don't expose the transfer slot. I would then just work on adjusting your jetting and accelerator pump.

I read through the rest of the posts. As I mentioned above, make sure the throttle blades are not too far open at idle, then the idle screws can be adjusted for the correct mixture. The spark plugs might also be too cool a heat range for your combination causing them to foul easier than they should.

You should not be fouling plugs that quickly.

- 451 has a good point: what plugs are you using?
- 15 degrees initial timing may not be enough
- If the .028 front IFR's helped out on the lean idle, then that is your hint to keep going that direction and maybe one of the above items is the actual reason as to why you are fouling plugs.

My initial timing is set at 15 degrees, but I have my vaccum advance hooked up to manifold vaccum which adds another 15 degrees of timing at idle. So at idle I have 30 degrees from my 15 degrees of intial timing plus the 15 degrees of timing the vaccum advance Is adding.
I am running NGK BKR5E plugs and I have all 8 of my plugs indexed and they are gapped at .045. I know my ignition is up to snuff, it's a brand new crane cams hi-6 cd ignition with a crane cams lx91 ignition coil and my plug wires are brand new taylor thundervolt 8.2mm wires.
Distributer is a mopar unit built by don at fbo systems.
I agree I shouldn't be fouling plugs that easy ether, but this engine has always seemed to foul plugs easily for some reason. This engine was purchased brand new by my father in 2002 and I acquired it in 2010, it has around 20 thousand miles on it. I have done a compression test with the engine warm and carburetor all the way open and every cylinder is at 150psi. Which I am told is good for 4000 feet above sea level.
Is it possible maybe the 64 main jet and the .049 power valve channel restrictors were the culprit for fouling the plugs? I have some .063 main jets and some .045 power valve channel restrictors. I am going to put the .031 idle feed restrictors back in it tonight and see what happens, I will run the biggest idle air bleeds I have which are .072's. I'm going to order some .029 and some .030 idle feed restrictors tonight and a few different idle air bleeds. Maybe some .074's and some .076's.
There are no vaccum leaks on the engine, An my power valve is fine I checked it last night it is a quick fuel 9.5hg power valve, float level is half way up the sight glass with 6 lbs of fuel pressure at idle.
I don't know what was fouling my plugs back when I first installed this carburetor and was running the .031 idle feed restrictors. But I think adding this 2 inch spacer has leaned things down considerably, so maybe the .031 idle feed restrictors will be ok with this 2 inch spacer. I will let you guys know what happens when I install the .031 idle feed restrictors tonight. Thanks for everyones help with this.

Post a picture of one of the fouled plugs A NGK 5 plug should not foul easily at part throttle,even at the hieght you are above sea level

The spark plug heat range sounds good too. That kind of leads me to think your throttle blades may be too far into the transition circuit?
I have found that at higher altitude, most carbs want a larger idle restrictor because there is less air pressure above the fuel, and the engine will also have less vacuum. I have never had an engine at this altitude (6,000 ft) that needed anything higher than a 6.5 power valve, usually I am using 3.5 to 5.5 power valves.
If you have a rear power valve, check it too to make sure fuel is not flowing past a blown power valve.

well I am confused but I think I might know what was going on before with the plugs fouling. I just realized that my idle mixture screws were 2 turns out on all 4 with the .025 idle feed restrictors. I was counting one full revolution of the screwdriver as 1 turn. I installed the .031 ifr's in it tonight and I put my largest .072 set of idle air bleeds in it and I fired it up with the choke on and while it was on the fast idle it wasn't popping like it was with the .025 and .028 ifr's, I thought I heard a few faint pops here and there but nothing really loud, you have to listen for them.
Anyways got it up to operating temp and I put the transmission in drive and blocked my rear tires. Then I set the idle mixture screws to the best vaccum reading. That ended up being 1 turn out on all 4 mixture screws and I noticed that the mixture screws are a lot more responsive now. 1/4 of a turn in or out makes the idle vaccum go down and you can hear a change in the idle. I also lowered my float a little bit because I figured going to the larger .031 ifr's might be too much, I lowered them down to the bottom of the sight glass instead of being half way up the sight glass.
Now my guess for the plugs fouling is because I forgot to put the vent back in on the primary metering block and I know it flooded the crap out of my engine. And my guess to why I fouled some plugs when I first installed the carburetor is because I think I left it running too long with the idle mixture screws being way too rich because iremember seeing black smoke coming from exhaust.
It seems to be doing a lot better right now with the .031 ifr's and the .072 iab's. I will run it for a few days and pull the plugs again and check them out.

I was thinking the float level is supposed to be at the bottom of the sight hole? To where it would just spill if you rocked the eng slightly. From your last post it sounds like you ARE making good progress

Nice job!!!
If you need to lean it out any more in the future, then just swap out the .072 IAB's for some .075/.078's or something in that area then reset your in D idle vacuum again and test again. Do what you can to keep the four metering screws between 1/2 - 1 turn out. These QF carbs don't like much more than 1 turn.

You now need to go out and drive it for a while to clean up those plugs. Have fun!

I am very glad to have gotten this some what figured out. I am going to invest in a wideband and I will get one in the near future. I just ordered 4 .030 quick fuel ifr's and 4 .075 quick fuel Iab's. And it looks like I wont even be needing them. I have some .032 and .033 quick fuel ifr's already. Should I try the .032 ifr's and see if that takes the lean popping sound completely away?
It only does it for a minute or so when you first fire it up and the fast idle is on, it has some faint pops in the exhaust here and there. Could that be telling me to go even bigger on the ifr's? Or smaller on the idle air bleeds?

Since you found improvement with the .031's, then retest with the .033's. You will need to reset your in D vacuum again.
Then test with the different IAB's that you have.

Since the IFR's and the IAB's work together, look at the IFR's as your "internal adjustment" and the IAB's as your "external adjustment". If you have three sets of IAB's, then test with all three to see if it makes a difference. If the three sets that you have do not give you the results that you want, then open the carb and change the IFR's then retest with the three sets of IAB's again if needed.
You usually want to change the IFR's in small increments (.002-.003" at a time). The IAB's can be changed in larger increments (.005" or so).

I would test your smallest IAB's along with the .033 IFR's. If your smallest IAB's are not small enough, then take a small wire and insert it down into each of the primary IAB's and bent the top of the wire so that it goes down into the carb body so it will not fall out. This will reduce the IAB hole and allow you to test a richer setup before buying more IAB's.

I spoke too soon it looks like. Since changing to the .031 idle feed restrictors and .072 idle air bleeds I noticed I have some black smoke coming out the exhaust when I have it idling in park and I give it some gas. I'm guessing this is because something is too rich and I think its the ifr's and iab's. I will pull my plugs and find out if any of them are fouled.

I would definitely get the LM1 & get the systems spot on in order. The carb tech given here is extremely good

"I spoke too soon it looks like. Since changing to the .031 idle feed restrictors and .072 idle air bleeds I noticed I have some black smoke coming out the exhaust when I have it idling in park and I give it some gas."

Did you reset your metering screws?
(Note: .031 IFR / .072 IAB is not what I would call a rich setup, it is more lean if anything.)


What size pump cam/squirter do you have?

Note: It sounds like you may have a component adding too much fuel at/or off idle. If the above seem normal, check to see if you have any rotation in your power valve assembly. Hold each end of your PV with each hand. If you can spin either end of your PV, then IT WILL LEAK even if the engine is not even running [if the fuel level in the bowl is at or above the PV level]. QF gave me this advice a few months back and I found my existing QF pv and one of my spare Holley pv's could twist. Don't use a lot of force, but just see if the PV assembly is intact.

Well I'm pretty sure I have fouled a plug or two because the exhaust at idle is super rich smelling and the idle doesn't sound right out of the exhaust.
My power valve is brand new so I don't see why it would have an issue or be leaking, but I will check it out when I tear back into carburetor. The .030 ifr's and .075 iab's I ordered wont be here until Friday. I double checked my timing tonight and it's at 16 degrees initial 34 total, vaccum advance on manifold vaccum adding another 14 degrees at idle.
My ignition should be more then enough to fire my plugs it's a crane cams hi-6 cd ignition with a crane cams lx91 ignition coil. My wires are brand new taylor thundervolt 8.2mm. This is so frustrating it seems like no matter what I do I'm fouling plugs some how some way, even with the .025 ifr's I fouled some plugs. I don't know what to do to eliminate this issue, but I think it is fuel related because my plugs are black and sooty looking like a chimney when I do foul them.
I have some different plugs I am going to try if I have fouled some plugs, they are NGK V-power zfr5f11's and they are a little bit longer then the ngk v-power bkr5e's that I am running now, the zfr5f11's look like they would run a little hotter since they go down into the combustion chamber a little further.
I am going to install the .030 ifr's and .075 iab's when they get here and these different plugs.
I'm running an orange accelerator pump cam in the number 1 position and I am running .035 accelerator pump squiters with the hi-flow accelerator pump nozzle screw. Can an accelerator pump foul plugs? I have never heard of that before. But if it's possible I can try some smaller squiters I have a .031 and a .033 squirter.

And yes I re-set my idle mixture screws. I put it in drive and blocked my tires and I set it to the highest vaccum reading, which ended up being about .075 to 1 turn out on all 4 mixture screws.

"" I'm running an orange accelerator pump cam/.035 squirter"
- The ORANGE cam is the second largest 30cc pump cam. It is very aggressive off idle and "could" cause the black smoke at the blip of the throttle. Try using a less aggressive pump cam (white/black).

Check your power valve as noted. My NEW 10.5 QF power valve was bad and QF is who told me to check it!!
Double check that you tightened down the IFR's. If they are not tight, the fuel would leak past them. I know that they are small but just make sure that they are snugged up.

I am still guessing that "something" is leaking on you that is causing the fouled plugs since you have seen this since running the .025 IFR's. You have found that .025 & .028 IFR's are too lean, so maybe the .030's might help out a bit.

Check the power valve gaskets to make sure they are seal up against the metering plate correctly, it is very easy to get the gasket cocked, out of round, and make it leak I have done that I now install the power valve with the gasket holding the metering block with the jets pointed up so I can watch the gasket seat squarely agianst the sealing surface on the metering block Once you have it seated properly tighten it down well, not lightly

What Cab said, most people tighten PV's too loose and jets too tight

Pv torque= 100 inch/lbs (not foot/lbs).