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Plugs fouling, left side only
1 Attachment(s)
After many attempts to jet my webers, and always ending up with oil/fuel fouled plugs on the left bank only, I think I need to cure the fouling before any further jetting changes. Intake gaskets have been changed ( the old ones WERE leaking on the left side only) Valve seals have been changed to vitons ( old ones were teflon) Oil fouling is less, but still there. Thinking of going to hotter plugs, presently autolite AR 3924.
Any thoughts/input appreciated. Thanks, Ted |
Oil
Bad intake gasket, did you use Felpro pin seal? I have had issues with those.
Jon |
Hello Motörhead
Need you to check the synchronization between left side bank of carbs and right side bank using synchrometer tool I know your idle is probably all in synch but what is the synch like at steady 1500 rpm and steady 2000 rpm If there's difference between left bank and right bank then you have a linkage problem to adjust that is causing engine to run richer on one side bank and fouling that side of plugs at cruising RPMs |
Quote:
smell the plugs.....will tell you oil or gas fouled. hell taste em' if you have to... if oil then its the gasket, if fuel its the sync. whats that old joke? smell it, feel it, taste it.....ok now we know not to step in it.... |
Don't mask the problem 24s are hot enough this is a one side issue. Usually oil has a little shine on the plug at end of the threads on the rim. Gas is dull and rubs off easier. Did you check for head intake alignment. How was the previous gasket leaking. Rule out oil first that's the bigger problem
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Jon:
The leaky gaskets were a special thick laminated part designed to compensate for "gaposis"when milled heads and intake don't match up. I replaced them with felpro 1246S-3's, which are for a 428FE (bigger ports) with a steel center so they don't distort, plus custom shims to close the head to intake gap. Intake runners are now free of any oil. |
Carmine:
I do have a linkage problem. The throttle arms are the same length, center of shaft to rod attaching hole, and L & R rods connect to a single pivot arm, but if you adjust the rods to have throttle plates closed at idle, they will be out of sync at wide open, and vice-versa. I synced them at idle figuring I would be driving mostly in the 1k to 3k rpm range for the initial jetting of the low speed circuits so it should be close enough. Evidently I was wrong, and I will ck the sync to 3K and see how that is. I had planned to totally re-do the linkage anyway, so I'll have to pursue that. Couldn't find the pieces I need to do it. Ted |
As it turns out, the AR3924's ARE the top of the heat range, so no help there.
I re-vamped the carb linkage and got them synced @ 2 & 3Krpm, swapped the idle jets from 65 to 70, and drove it. Ran the best it has yet, aside from too rich (afr's 11.3-12 from idle thru 5krpm) thought "all I have to do now is tweek the mixture leaner in the low/mid range and I'm done ! Wrong ! I just had to pull the plugs and take a look. Still the same: left bank black and oil fouled (although I had no miss as before) and rt bank lean to normal, with some oil present. Guess i'll have to put an o2 probe in the rt exhaust to make sure I don't get to lean on that side. Still can't figure why I'm getting the oil in the plugs, unless it's rings. Engine only has 7-800 mi on it. |
Hello Ted
The cause that I have found to this out of sinc problem is that the hole drilled in the center of the intake that holds your center pivot bell crank has been drilled aprox 1/4 inch out of center to the carbs. Had same problem on my carb sync and that's what I found was causing that problem. If your using air fuel gauge with o2 sensor 11-12 air fuel readings is what you want to see at idle Anything higher tends to cause lots of popping and lag on transition What idle air corrector are you running? On your water pump, what water pump pulley ratio are you running? Eg) one to one or underdrive ratio as compared to crank pulley. If underdrive I have found that more cooling happening on one side bank head than the other and gave me richer reading plugs on one side vs the other. |
Hello Ted
Another thing to check. I see your running a stroker motor. The crank throw being longer can dip into the oil in pan and whip oil to underside of one side of pistons and cylinder walls under more pressure and oil rings becoming overwhelmed with excesive oil. The oil pans on most motors calibrated for fill based on stock crank throw. When running stroker crank that usually means about half to one quart less oil to allow for extra aprox 1/4 crank throw dip in. |
Carmine: Good info, thanks!
Right now I'm running the 70 idle with a 100 holder. (65 was too lean) 2k to 5k (in 2nd gear) yields 11.3-4. No smoke that I can tell. I have a 428 crank, so it's not a lot of stroke, can't remember the numbers. Aviad road race pan with windage tray. Think I'll ignore the oil for now, and continue to tune the upper power band and see what that looks like. Ted |
Hey Ted
With those cubes you should be closer to 75 idle jet x 120 air holder If well ported heads and intake matched I would bet closer to 80 x 130 air Might smell little rich but that's just during warm up Webers like heat Helps vaporization process 195f or 92c thermostate helps with this process Hope this helps Beautiful work on the kirkham Carmine |
Motorhead, like I said in a earlier post, the oil problem is a problem. You might be able to fix the rich condition especially on the left bank but oil contamination is going to mess up your observations and sensor readings.
You said oil on both sides. It took me a year to figure out my oiling problem, I took it in steps, [I was still driving the car a lot], and eliminated one thing at a time. Rings would have been my worst situation and I was saving that for last. I checked: Plugs, two sets intake runners from carb to valve to see if it was some or all {big cams and open plenums can fool you} PCV even eliminated it and went with two breathers Intake Gaskets twice Intake to head angle Valve Guides Intake Rocker arm studs. It turned out to be rocker arm studs. On ported SBF heads they are tapped into the intake runners. I tried to seal them with ARP thread lube, and it just turned to grey goo, I tried blue loctite, and that was ok. I changed to Ultra grey after a through cleaning with break cleaner and a small amount of Blue Loctite and problem solved. I never thought oil could wick through those studs. I had my intake off so much I could make the change in a few hours. |
Lou: Thanks for the input.
I've been thru the intake gaskets and angle matching as posted above. Changed out the left bank valve guide seals, and the FE doesn't have rocker studs, but any bolt hole could be a potential leaker if the ports were opened too much.Strange thing (to me anyway) is the valve stems are called 3/8", but actually measure 0.370" and I used Comp Cams 515-16, which are shown .002" oversize at 0.372", yet they fit the stems snugly. 'Bout the only thing left is rings, but I'll give them more miles before I go after that. Ted |
Carmine:
Looking at *13's spread sheet on weber jetting by CC members, it's interesting to note that all the 427's listed (8) 7 are running 60-65 idle jets, and (5) of those are the 482 c.i. The one difference that jumps out is they are, all but one, running the 40 chokes, with one 454c.i.(my displ) with 37's, while I'm running 45's. Ted |
Hello Ted
45 choke to big for the street For your cubes I would suggest no more than 38 or 39 You'll give up a little up top but idle circuit where you spend most driving will be nice and crisp Buy from reputable weber supplier I've seen lots of nice looking shiny crappy parts for these weber coming out of china I'm aware of some people on that chart that haven't up dated there settings Carmine |
Spread sheet
Where can I find this? By the way, I am running 45 chokes on a 435ci fe and runs great!
Jon |
"I am running 45 chokes on a 435ci fe and runs great!
Jon" Hello Jon Where talking webers with independant runners From what i understand your running 2 x 4barrels probably with progressive linkage and common plenum style manifold. Please correct me if im wrong. Carmine |
Webers
No, I'm using 4x 48ida's on a blue thunder intake....
Where can I find this spreadsheet? Jon |
Hello Jon
To find chart Do a search for (weber jetting survey) page 5 45 chokes with 435 cubes would be off the charts |
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