JPIII

I am having trouble with 2 plugs fouling on my 2.7L, cyls 4 & 5. The plugs are sooty but dry and get progressivily more foul prone as the millage builds, till they no longer fire.
The last 2 went about 200 mi.

OK....running rich.

A quick description of the motor.
2.7L, Solex cams, 9.7 :1 compression, NGK BP5ES plugs, Permatune.Rebuilt the carbs myself (ah ah).....40IDAs, Throttle shafts are tight.
About 6/700 miles on the motor.

Things I have checked:
New cap, rotor.
Valves adjusted bout 400 mi ago.
OHMS on all plug wires are fairly equal.
(Don't know what the resistance should be,so I used clean running cyls as a guide)
Compression is 165 on the 2 holes.
Carbs synced & resynced, over and over.....
Float levels danm close to the same on all four bowls (note: 4 & 5 do not share a float bowl)
All idle circuit screws are open 1 1/2 to 1 3/4 turns...to highest rpm.
Air correction jets and E-tubes have been cleaned.....found nothin'during the operation. A more serious cleaning a few hundred miles ago...

The motor runs superbly at elevated rpms.....say above 4000. A soft launch(901 trans), then hard on the go pedal causes the tires to loose traction around 5000 rpm in first gear, so I assume the problem is in the idle circuit.
To my way of thinking, I am somehow getting *extra* gas into those two holes, but am at a loss to explain from where it is comming.
Somewhere in the accelerator pump , perhaps....?

I'm really stuck and have wrapped myself around the axle on this.....I need help!!!

JPIII

magistro

Assuming the problem is fuel delivery related, I would plug the idle jet with a broken off wooden toothpick on one of the rick running cylinders (4 or 5). See what the effect is regarding plug fouling, expect it to run poorly down low, however this should let you know if it is carb/idle curcut related.

There is a chance this is not a fuel delivery problem, but perhaps a mechanical problem e.g. a broken oil ring (bottom of piston). If you only have 600 or 700 miles on engine on a fresh rebuild, this could be a consideration.

JPIII

There's a thought.....albeit, noy a pleasent one......something I hadn't thought of.

The motor doesn't smoke, except at start up.The plugs are sooty, but not oily or wet. The carbon build up is not thick, but they really don't stay in there all that long.
This problem started within the first hundred miles...and I admit to not being real gentle with it during break in.

Is there any way (short of a tear down) to check for a broken oil ring? The after market pistons do to tend to rattle around a bit, but quiet down after the engine is warm.

Think I just took another turn around the axle, but thanks anyhow.

RoninLB

I don't know the answer, but I am curious. Logic tells me to look at that carb. Is right bank and left bank in sync. Do you have air fuel monitor. The left and right carbs are suposited to lift off the stop screws at the same time.Adjust that w/throttle drop links. That gets adj after you adjust idle stop screws. I'll be watching this, I want to know the answer...........Ron

Steve Weiner-Rennsport Systems

JP:

Plug fouling during the first 3000 miles can be caused by many things. Here is some stuff to check:

1) Plugs- Those plugs are kinda cold for break-in. In short they will foul easier if there is oil or excess fuel in the combustion chamber. Sometime the rings do always seat in the cylinder at the same time and you have very few miles, yet.

2) Oil consumption- Exactly what IS your oil consumption? Fuel fouled plugs smell like unburned gasoline and oil fouled plugs are usually kinda wet. I would have to see them myself to be sure,......

3) Ignition- This MUST be working perfectly before troubleshooting this whole thing. This is truly a "keeping the cart behind the horse" sort of thing. There can be no issues here. You must have nice big fat blue spark on each cylinder when cranking and if you do not, then plug connectors, the coil and even the Permatune can be suspect. Check these things very thoroughly!!!!!! The Beru plug connectors are quite troublesome and are usually found "open", when they fail.

4) Carb Setup- Fuel pressure should be at 3.5 psi and the floats set to spec at that fuel pressure. Idle jets should be 55 or 60 with 34 or 36mm main venturies. Idle air bypass and then mixture screws must be adjusted correctly and all barrels should flow the same airflow at idle (900 RPM) using your Syncrometer or Unisyn. Idle jets and their passages are very very easily obstructed and the jets should be removed, the main jets removed and clean air blown back and forth to ensure that this system is clean. A rough idle and some popping in the exhaust usually is one good tell-tale than all is not healthy in the idle circuits on Webers.

5) Oil ring breakage is tough to detect with a leakdown test, but I would certainly recommend doing one right now to see that all cylinders ar within 2-4% leakown of each other. The result of this will help determine whether you will tear it down or not. If the oil rings or compression rings were not installed properly, then you will have oiling troubles in those holes.

I hope these suggestions help in some way and feel free to call me if you get stuck and need further suggestions.

JPIII

This has been reposted from the Pelican 911 website.

OK....got it.
I have never been so relieved while being proven to be inept.....
The answer is coil bind.

Anyone familar with webers knows of them little springs on the idle circuit(mixture) screws.
I have 2.....maybe 3 different length springs (or a different number of coils). The longer springs just happen to be on cyls 4 & 5.....you got it......turning in the screws
did not seat the needles, rather it became coil bound but the needle was about 1 1/2-2 turns from closing. Simple, no? Running rich cause that's the way I tuned it.....or more to the point, not runnng at idle cause it was too rich, but running when more air became available, but still rich......Gawd.

Today,the diagnostic process was my usual
chaos.....my first clue was when, with a new plug, #5 wasn't running at idle..well it can't be lean...gotta be rich....grabbed a screw driver... as the idle screw bottomed
out, it lit off.....keerist....more of the same on #4.

Those springs are going to get shortened. The temptation to do it with a BFH is almost overwhelming.

I've fighting this for months. Just goes to show ya that if you are stuipd it helps to let the world know.

Thanks for all the replies. I'm sure if I'd
told ya that I am an ignorant #*$&@^$(* and inept to boot, someone would have told me to just look at the damn things and see if somethin' is odd. Mikey came closest cause he knows me best.

If you'll excuse me, I have to go tell a couple more web sites how dumb I am, just in case they don't already know.

JPIII
Humble pie for dinner tonite......yummie.

BTW had a guy on another list get all het up cause my plugs were too hot. Said I was gonna lunch my pistons.....I'll go with Steve, thanx.

RoninLB

JPIII
Humility doesn't have to be self mocking. What you have accomplished is a timeless story in history. Some would say the ordinary man is involved in action, the hero acts........Ron

JPIII

Thanks again for the replies.
The engine is running fine as frog hair
and, hopefully, will be till I start tuning on it.....

Even took a picture.

JPIII

JGriff

Don't feel too bad, I bought my 1973 914 2.0 in the middle of May, and I'm still trying to get the dual Webers properly adjusted.

Granted, I haven't spent a lot of time monkeying with them... just a quick tweek here and there, hoping that a small adjustment would make the difference.

Unfortunately, it's going to take a bit more effort (and free time, which I haven't had lots of over the past couple of months) to get it right. I've toyed with the idea of bringing it to the local Porsche specialty shop to have them work some magic, but I've decided that I'd like to try to get myself more familiar with them before giving up.

As frustrating as it is, I think I'll be better off if I first try my best to figure it all out. As the saying goes "what doesn't kill you makes you stronger"!! The learning experience would be good for me (not to mention the $$ saved as well), now and in the future.

Glad to hear that you got them adjusted and working properly. Did you finally manage to fix it yourself, by shortening the springs etc. as you mentioned, or did you end up having someone else do it?

Jim

JPIII

As with many of my past fiascos, the tough part was identifing the problem. A pair of sidecutters fixed the problem......snip...snip,all done.