Plug Fouling Mama

[staggerwing]

Guys, I have a constant plug fouling problem and am pleadingly open for suggestions:
Here’s what I have and what’s been done:

1776
110 cam
Pertronix ignition
Dual Kadrons (new)
This is a fesh engine build and it has not been driven more than about 15 miles.

Stuff I’ve tried:
Valve adjustments; a couple were a little tight but they are all 0.006” as of a few days ago.
Timing; I’ve adjusted everything that will let the engine still idle from just over 6 Deg. BTDC at idle to 10 Deg. BTDC at idle. Timing advances smoothly to 25-28 Deg., respectively.
Mixture: Initially, “back the screw out in ¼ turn increments, pausing after each ¼ turn and listening for the RPM to increase until you reach the highest idle. Turn the screw in ¼ turn after reaching the highest RPM adjustment. Repeat on other carb, then repeat at least 1 more time on each carb. After fouling a couple of sets of plugs I just tried to lean the mixture adjusting each carb in ¼ turn then going for a test drive. I went all the way from 1 ½ turns down to ¾ of a turn, anything lower than that; she will not idle, period.

With a set of fresh plugs and the timing set at 8-10 Deg. BTDC at idle, she sounds like a clock, nice and smooth, no popping. 2 miles down the road the party is over.

I’ve tried Bosch Supers, Champions, and Bosch W8AC plugs with a gap setting of 0.028".

Obviously we’re up against the “she’s runnin rich wall”, right? I had the left carb off a few days ago cause 3 and 4 were fouling worse than 1 and 2 and stumbled across a plugged idle jet and thought that would be the end of my problems but it wasn’t. A new set of plugs and 2 miles down the road and we were fouling plugs again.

Here’s what the plugs look like after only a short run down the road, with the compression numbers I got Saturday:



I don’t know what the sizes of these main jets are but will be pulling carbs tonight to find out.

A guy mentioned to me that I might need to go up a grade at the fuel pump and that just doesn’t seem like a good solution.

Enough said, what do you guys think?

[GregR]

sounds familiar...or at least similar
http://www.texasmanxclub.com/bboard/viewtopic.php?t=992&highlight=
may need to go over the carbs again.....just a thought.

[staggerwing]

Yeah, read that one and there was another "similar" post back in Sept. 06 by Russhebert, but I've been over the carb adjustment thing too many times and I'm pretty convinced it ain't there. Thanks for the quick post anyway...

[MURZ]

First set your timing to 30BTDC at 3000 rpm. 25-28 ain't enough.

Second, check your fuel pressure 1.5-2.0 psi max with Kadrons at mid throttle. anymore and you will overpower the needles and seats. If you have a stock pump shim it up with additional gaskets or shorten the pushrod until you get 1.5-2.0 psi.

Third, set your best lean idle using a analog tachometer set to the low range or a vacuum gauge.(I like the tach) Do this with a hot engine. Linkage disconnected at each carb. Establish a base line for the carbs and then slowly turn in your mixture screw on one carb until you find the "sweet spot" where the idle will move up or down with the adjustment. Back it out 1/8 turn from the sweet spot. Repeat for other carb. Reattach linkage making sure that you do not disturb your settings.

Should do it.

Most important thing with kadrons though is fuel pressure. 2.0 psi MAX!!!!

MURZ

[staggerwing]

Thanks Murz:

Ran the fuel pressure check and came up with a little over 4 psi. Took a few minutes for the press. to max out. Need to pick up another set of plugs tomorrow and will probably spring for a press. regulator while I'm at it. So, the extra pressure is causing the fuel to "ooze" in places it shouldn't making for a rich mixture no matter what you do with the mixture screws? Does the engine really need to be at three grand to set the timing? Thanks again for the help...

[MURZ]

Do not use a pressure regulator. They are junk and will limit flow as well.(Most) Instead do as I said and install about three extra fuel pump gaskets to raise the pump. Put a thin film of ultra gray on both sides of the gaskets.

OR carefully spot face the flat end of your fuel pump pushrod slightly on a grinder and reinstall.

Remember 1.5 to 2.0 MAX!

Yes fuel pressure can cause over filing of the float bowls and cause fuel to drip into the carb throats----creating in effect an extra idle jet

Three thousand is an absolute. The engine needs to rev until the advancing stops. On most 009's that is between 2500-2800 rpm so I say 3000 to be safe. If you just rev it to say 2200 the advance is not all in and set it your initial timing will be too much. If you are running 7.5-1 or 8.1 I would run 32-34 degrees total. More compression will not tolerate high degrees of advance...low compression engines need it.


Also, make sure you have a balance tube between the carbs. It has to be there.

Good reading here: http://www.lowbugget.com/help_section.html

[blackthree4me]

Murzi
Did you stay at a holiday Inn last night?
seems like good info and makes sence.

[staggerwing]

Got the fuel pressure where suggested (1.8 psi), set timing 31 BTDC @3K, set mixtures (carb linkage and balance tube disconnected), and set idle 950 - 960; she sounded pretty darn good but still plipping a little black smoke when goosed a little. Ran her down the road a bit. She started out pretty good although there is still something that just doesn't "sound" right. Started acting up again after about 3 miles. Pulled plugs after returning (and cooling off) and they are jet black and on the powdery side. Pulled both carbs to check main jet sizes (130) and idle jet sizes (looks like 91-55?) and look for traces of leaks and what-not. Looks good to me.

Looked down the intake port of the heads while the carbs were off and there is oil puddled in all four locations. Is that normal? Will post a photo of each side tomorrow. Any advise? I'll be calling the guy that built the engine tomorrow to ask him the same thing but wanted to see if anyone out there had any ideas. Thanks mucho...

[MURZ]

Call AJ Sims at lowbugget.com and order some 52 idles and 127 mains. Also I would "grap a holt" of a SVDA distributor from him.

But.....before I would do anything...i would run the bahonky out of the that engine seat the rings etc. Seriously, run it hard.

Also, with these carbs using a common plenumn it may be better to use a vacuum gauge to sync the carbs.....with the balance tube connected.

See if you can find a float setting on these things too. I would check that just to ease my mind. From the factory, most carbs are way off.

Good luck!

[staggerwing]

FYI for anyone following along. I hooked up with A.J. Simms and based on the engine setup I have he suggested:
140 main jets (why, when stock is 130?)
58 idle jets (why, when stock is 55?)
Fuel regulator (to get 2 psi)
The regulator seemed to help the most (prolonged the fouling a bit) but it still wasn't right. Soooo...
Drill left carb for vacuum port
SVDA distributor
It took 30 days to get the carb back from his shop and this dual Kadron setup is getting expensive!

Timing set at 32, mains are open 1/2 turn each, idle speed 900.

Why he sold me larger than stock jets; I have no clue, but I had to try something.

Now were getting somewhere. Drive time has increased significantly, but still way short of what it needs to be. Seems to run okay - maybe a little short on power, but feels pretty good. Still trying to "drive the bahonky out of it" and trying to get some break-in time. Driving around yesterday and things started to go South again with a pop or two and slightly rough engine operation. Pulled the plugs last night and found 1 and 3 with heavy deposits (dry and sooty), 2 and 4 look like new. That's better than before!

Okay Murz, I should have ordered 127 mains and 52 idles like you suggested to start with but I thought I'd go with what A.J. suggested "based on my set up" cause all arrows point to this guy regarding Kadrons! That being said, does it sound like we're getting close? What's up with 1 and 3, and does the orientation of the engine (tilting slightly towards 1 and 3) have anything to do with fuel distribution. Seems like a decent question to throw out there... Only other thing I can think of is that the carbs aren't synchronized, but I've read enough pros and cons about that to leave them alone and have also heard that as long as the mixture screws are adjusted properly and are the same "turns" on each side - "close enough".

I still don't have a float setting for the Kadrons but am planning on getting that when I call for the leaner jets.

I recently talked to a fellow that was having a similar problem and his solution was a CDI setup. I know basically nothing about CDI's other than they can shock you much more than "just a coil". Maybe that would have been the way to go but either way, we have both had to invest time and money to get the Kadrons to work for us. I think it's a good thing to get this information out there for others.

Thanks again for the help, I'm gonna go foul 1 and 3 and freeze my butt off!

[MURZ]

A CDI unit like a MSD is awesome and will prevent fouling plugs in almost all cases....but it is masking the problem. I would try synching the carbs with the vacuum gauge....linkage disconnected, engine hot. Get them dead on even...Then adjust idle mixture screws to highest reading on each and then GO back and adjust balance again. Reconnect linkage making sure that you adjust linkage to reach carbs and are not pulling throttle arms to reach linkage

As far as the jetting goes I would start leaning the idle jets down until you start get popping through the exhaust(lean condition sign) and then go back up a size or two.

For the mains do the same thing...lean them down until you get a lean surge in third gear mid throttle...a surge, surge, then go back up a size or two.

If that don't work...get some 40 IDF's and really see that engine come alive!!!!

[Buggy1]

Just a thought, you do kow there are diff lengths of push rods for fuel pumps right? Did you install a new pump or chane the rod .........that can cause some problems also. Too long, to much fuel push into the carb.

Neal

[David O']

If the engine is always just running for short distances, and they have electric chocks on them. You're not running the engine long enough to get the chocks to get off.
I would not worry about the 30 degree thing on the timing, the pullys can be off by 5 degrees.
I've never seen these carbs give anyone that much trouble....there has to be someting else going on.
Note, if you are getting black smoke from the engine every time you try to accelerate the motor....shorten the pump movment on the accelerator pumps...they could be putting too much fuel in on the take off.
Also, the vac. signal on duel carbs is HALF that of the single stock setup, just keep that in mind when you try to get the vac. distributor to work.

[staggerwing]

Hey guys:
Still fouling 1 and 3...
I talked to Mr. Sims Friday and it was an interesting conversation. I'll save the details for the round table. Basically it was "remove the balance tube (hint: it's colse to 1 and 3), retune the carbs, take her for a spin and "see what you get". After reading some tuning stuff on the lowbugget sight - AGAIN - I thought I'd pull the carbs, check everything again but this time check the accelerator pump linkage. For what it's worth, one was WAY off. Here's what we changed over the weekend:

Removed balance tube
Accelerator pumps adjusted
Put the stock jets (130/55) back in (makes since cause we're still way rich)
Readjusted mixture and idle
Cleaned plugs

Took her for a spin and there was a considerable improvement! Better acceleration, better cruising, and better sounding. Probably a combination of stuff but I'm thinking mostly jets. When I talked to Mr. Sims we discussed jets a bit and it was obvious that when someone orders jets from lowbugget.com, they "start you off" on the rich side. I guess they have to do that to avoid burning up engines because there are so many different applications out there. They have it set up so that if buy their jets and you end up rich/lean, just send the jets you bought back with an s self addressed stamped envelope enclosed and they will send you they "next size" lower/higher as many times as it takes to get you "tuned".

I wish I had mentioned this in an earlier post but a guy at work saw the car for the first time and he made a comment about the smaller air filters I stuck on there to replace the larger stock air filters that didn't fit under the back of the body. I suspected their size a long time ago when I bought them. Although they "breath" well, a second run with them removed made a difference as well, subtle, but obvious especially under power. Okay, we need to do something about air cleaners and jets.

Now I'm thinking I should have listened to Murz a long time ago about jet sizes and we could have saved a bunch of time but I would have missed out on all this fun and education. The stock carbs came with 130 mains and 55 idles; lowbugget had me but 140 mains and 58 idles in there along with:

fuel press. regulator
drilled left carb. for vacuum
SVDA
remove that balance tube
he has a different linkage to sell me but I ain't ready yet...

So as far as selecting the next set of jet sizes, obviously Murzi's initial suggestion of 127 mains and 52 idles will make things better but will it be enough is the big question. I guess it's the safe thing to do and from here on we should approach a leaner running engine with caution. Mr. Simms at lowbugget says one should lean till one gets detontion, then go back up a size or two.

I'm mailing jets today and hopefully we'll have something to try by this weekend...

[MURZ]

Carb balance is very important...don't discount it or the car will run like pshaw.

Do this before you do the jets. Pinch off or plug the balance tube.

Disconnect the linkage at the carbs, back the idle stop screws all the off the throttle arms, now run each one in about 3/4 of a turn from just touching the throttle arm.

Start the car.

Now attach a vacuum gauge to each carb . reading? They should be almost dead on equal to each other. Adjust the throttle stop screws to get the same reading on each carb.

Reattach the linkage to ONE carb and THEN adjust the linkage so that the arm just reaches the throttle linkage.

Carbs are synched!!

NOW For Jets....
Do the idles first by themselves. If it is too lean it will poot, sputter and crackle through the exhaust...doubt it will. Then do the mains.

[MURZ]

Updates????

[staggerwing]

After a two week wait, a friendly phone call was placed to lowbugget.com to remind them that I hadn't seen the jets I requested a couple of weeks ago (127/52's). They told me that the jets were sitting in the out-box and they would be promptly mailed. Three weeks to the day they showed up in the mailbox. For some reason lowbugget.com sent 135/55's, still larger then the stock jets that are in there now! I decided to go eat some more party food to try to relax and let my blood pressure go down a bit before taking a baseball bat to the engine.

A note enclosed in the package of jets read the following:
Fuel Pressure?
Bad Float?
Bad Needle and Seat?
Engine Size, 1776?

All being good questions I guess, I'm bascially where I was 6 months ago when the problem first came up, but only 3 and 4 are fouling instead of all four. I'm thinking about setting up a bench test to look for leaks and to verify fuel pressure, AGAIN. Really irritated with the whole thing but am hard-headed enough not to throw in the towel just yet.

These are new carbs, they shouldn't have all these problems, should they? The engine is new too, if we can factor that in while we're at it!

I appreciate the interest in helping me solve this thing. I can't wait to celebrate a victory over the issue I'm having with fouling. Thanks for the interest - and the help, I can't think of anything else I'd rather be doing... well, except for driving the car around without all that popping and fouling.

[MURZ]

call Lee at Action Imports in Shreveport, he will have those jets to you in two days.

[staggerwing]

Okay, will do. Thanks Murz... BillK has told me the same thing but I haven't really needed anything until now.

Maybe a dumb question - Since we've removed the balance tube ("common plenum") that connects to the back side of the intakes of each carb, consequently where the intake ports of cylinders 1 and 3 are (and over the 2 plugs that are fouling), could it be that the holes that are drilled in those two areas are acting as "disrupters" for the air/fuel mix that's on it's way to cyclinders 1 and 3? Maybe it would be good to weld them holes shut and give the fuel/air mix an unobstructed path.

Just thinking out load here. I took the tube off cause A.J. Simms suggested it and I have a motor head buddy that asked about the "balance tube" and his reaction was "get that thing off of there now, you don't need it".

Gathering parts for a test-rig...

[staggerwing]

Lee's a nice guy! Jets are on the way (127/52's).

[staggerwing]

Just got back from a record 10 mile "trip" and she's running very well! Made the wife go with me and I swear I saw a smile on her face more than once! Don't know what it was but it was a combination of:

-bench test with carbs off car to check for leaks (no leaks to speak of, even at 3 psi)
-tweaked regulator press. down from 2 to 1.7ish
-readjusted accelerator pumps (backed the "squirt off just a hair)
-polished intakes
-black silicon between gaskets at top of intakes
- cleaned idle jets REALLY good

Reinstalled carbs on car and there was a significant increase in idle speed; didn't check it with a tach but it was up there. Went for a test drive to heat things up and check the mixtures upon return. The buggy ran really well so I ventured away from the house a bit sort of in celebration of the new turn of events! Upon returning, reset idle speed, checked the mixtures (they were good), and made a supltle adjustment on the linkage to make sure the carbs were synchronized.

Whatever it was (a partially clogged idle jet all this time?!) it's not there anymore. If it was a partially clogged idle jet all along, Murz was right in a previous post - after you clean idle jets; CLEAN THEM AGAIN. If it was something else, or a combination of a couple of things, I hope it's gone for good cause as hairless as I already am, I was ready to pull some hair.

When the jets we ordered (me and Murz) come in the mail (127/52's), I probably stick those to see what we gain/lose and go from there. Right now I'm really happy and can't wait to go for another ride...

Thanks for all the tips and suggestions along the way, you guys are great and we're looking forward to meeting everyone.

[MURZ]

hey snappy, how about an update????

[staggerwing]

Still waiting on the jet sets from Action Imports! I don't think I've ever checked the mailbox this regularly! I'm betting that they show up today.

[staggerwing]

Just got back from the mailbox - NO JETS!

Did get to do a 20 minute run-about, cause the weather is so nice right now and I can't walk by the buggy without it calling my name. Does that happen to everyone? It's like, "Hey Richie, wanna take me out for a spin"? Do these cars talk to their owners? Anyway, things are still on the up-and-up, she's runnng great and I'm pleased as punch.