Alright I lied, I’m not rich, but my 2.0 E spec 6 is doing pretty well for itself. I’m running out of ideas, and I’ve wasted a lot of time/money trying to figure this out , and I'd rather be driving.

The car runs great, pulls strong, the idle is solid, and no popping once it is warmed up, but I have to run the mixture screws out around 4 – 4 ½ turns to keep the engine running consistent. I’ve used PMO’s tuning instructions as well as Wayne’s, and every variation I have heard from others. Here’s the engine specs:

Original 914-6 engine rebuilt to E specs
Mechanical Advance Bosch Dist
Crane xr700 optical ignition
New coil, wires, NGK BP5ES plugs
Webers – 55 idles, 120 mains, 30mm venturies, 170 air correction, F1 emulsion tubes

The webers have been cleaned/rebuilt many times, pump volumes set at .6cc’s, float level set with the proper tool while the engine was idling. Carbs balanced at 1200/3000. Fuel regulator/guage showing constant 3.5lbs of pressure. I’ve tried 60 idles, but didn’t really help, and PMO said there was no reason I shouldn’t be able to run 55’s, and said my jetting was adequate for a 2.0E.

Valves adjusted, and the timing is set at 35 deg full advance at 6000rpm.

The problem when I lean it out:
The engine will idle when the mixture screws are 2 ½ turns out, but I get lean pop out the intakes, and once I rev the engine, it will not return to idle, it will just hang around 1800 – 2000. Once I get around 3 – 3 ½ turns and hit the throttle it will slowly return to idle, and at 4 – 4 ½ turns the throttle response becomes crisp.

What do I try next??? Has anyone else ever had this problem??

Thanks,
Justin

those are pretty hot plugs for 'E' compression.
170 looks a bit small for air correction, but that -shouldn't- be a big factor at idle ... venturiis sound big but i really don't remember what's in mine (stock pistons, E cams...).

are you SURE you don't have a vacuum leak? air coming in from sloppy throttle shafts or warped mounts could be a culprit...

if you don't have the '906' extended secondary venturiis, i recommend them, especially with those cams ...

beyond that i donno ...

Hi Justin,

As your description, having to turn the idle mixture screws out so much makes me thing that you might have an vacuum leak BTDT.

But first, did you make sure that the idle circuit isn't clogged somewhere. It's easy to figure out, do all cylinders react when you lean out (turn in) the idle mixtures screws one at the time. If they do, idle circuit seems ok. If not, check the offending one. Blow air in the idle jets (taking them out of the carrier). Take the mixture screw out and the idle jet. With a can of carb cleaner and a small tube, bend the end of the tube so that carb cleaner will take the small port at the bottom of the idle jet hole. Squirt carb cleaner and you should see it dribble out of the idle mixture screw port. If not, it's clogged and you will have to drill out the plugs and clean the passages.

Say that the idle circuit is ok. I'd bet for a vacuum leak next. . Could be a vacuum leak between the heads and the manifold or manifold to carb. The manifold/carb leak can be checked with propane. Get the idle steady and get the torch (unlite) near the base of the carbs. same thing at the bottom of the manifolds. If idle changes, you found the air leak. It happened to me with my 2.2. I didn't notice that an old gasket was still on the bottom of one port on a manifold.

If none of the above, it could be a sticky mecanical advance in the dizzy???

Good luck.

Marc-André

The plugs were PMO's recommendation for compression up to 9.1, I started with 27mm venturies, but was told 30’s were standard for a 2.0E. What is the best way to check for vacuum leaks, spray carb cleaner around the base and see if there is a change on the synchrometer?? What is acceptable movement for the throttle shafts??

Cylinders 1 and 3 seem to require more air than any others. Last time I removed the carbs, I pulled the manifolds and put new gaskets around the insulator blocks between the manifold and the heads and between the manifolds and carbs. Should I use the high temp RTV sealer on the gaskets, or is that just a bandaid?

My compression numbers were consistent, I just don’t remember the actual numbers, I think they are written down on my work pad in the garage.

Thanks,
Justin

Thanks Marc-Andre, glad to see you figured out the miss on your 3.0

-Justin

I vote for an air leak some where.....eliminate the obvious first.

I use carb cleaner or quick start (ether) and LIGHTLY spray it around the intake manifolds.....when the revs jump up...you found the leak.

okayfine on the plugs, maybe PMO pays less for pistons than i do.
8's the standard recommendation for 911E, i've been using 7's since i do so little highway driving. i'll use 8's for the track ...

in general, PMO's recommendations for carburation are WAY above the standard formulas shown in Bruce Anderson's books (and i'm at work, so i don't have any references with me ...) the 2,0 E was, of course, Bosch mechanical FI originally... Bruce figures maybe the newly redesigned PMO carburetors can handle MUCH larger throttle plates and venturiis than the original Webers, so - what have you got ? original 914.6 40-IDTP13C carbs, or new PMO's? (what size?).

i'll go take a snap gauge with me when i go get stuff out of storage this weekend and check my venturiis - i'm running bigger than stuck but i don't recall how much bigger...

for vacuum leaks you spray something combustible (so BE CAREFUL) areound the areas in question and listen for a change in the idle speed. a small amount of propane carefully directed to the intake port (cylinder head) and manifold/carb base areas (individually) should help isolate. maybe using one of those oxy-propane welding kits with the 14-oz tanks - harware store stuff - with the rubber-hose torch to direct the gas. don't use much, and beware of spark sources...

acceptable radial movement on the throttle shafts is zero.

when you say cylinders 1 and 3 require more are - air you tweaking thje idle mixture or the idle air bleed screws ? your first post made it sound like you were needed to add more FUEL with the idle mixture screws. now it sounds like you're actually tinkering with the idle air bleed screws (which should ALL be initially screwed closed, and then MINOR (if any, opinions vary) adjustments made to the cylinders that flow less.

but it could be that one carb throat base, or one manifold leg, has something stuck under it - like one too many gaskets, per Marc-Andre ?

Thanks Mike.

ArtechnikA -

I have 40-IDTP13C webers. When I start tuning the carbs all air screws are closed. When the time comes to pull out the synchrometer, cylinders 2 and 5 are the heavy hitters for their respective sides. #4 and #6 dont need more than 1/8 of a turn or so to balance with #5, but #1 and #3 need significantly more air to balance with #2. Thats why I replaced all the manifold gaskets recently.

Thanks for the suggestions guys.

-Justin

I use a propane torch for leaks.

I see that you are using insulator blocks. I have the same setup with my 3.0L. I had a huge vacuum leak between the heads and the insulator blocks. It was my fault as i didn't use the gaskets that came with the insulator kit. I used the 3.0L ones instead. They created a gap between the insulator and the head causing a vacuum leak.

I'd try to set the idle and it would sky rocket in the 2000 rpm rang or go way low (300 rpm) if i tried to ajust it with the idle stops. Took me several weeks to figure it out.

Might be worth taking the manifolds and carbs off as one unit and inspecting the gaskets.

The air leak that was under the insulator block will be hard to find as it's partly under the shroud.

For the 1-2-3 side. Are you sure that the throttle plates are all aligned and closing properly? #3 is on a seperate shaft than 1 & 2 and linked together with a small holder with allen screws (dont know the technical term for the thingy!). Make sure #3 operates with #1 & #2.

Marc-André

[ apologies if this posts twice, couldda sworn i sent this reply already, but it isn't showing up ...]

if i were going to look for a vacuum leak somewhere, #2 seems to be volunteering :-) ...

how's the balance side-to-side ? IOW - is it #2, or 1&3 that are the oddballs, compared with the 4-5-6 side ?

1 and 3 are the odd balls, 2,4,5,and 6 are consistent. 3 is the worst.

I guess I thought an air leak couldn't be overcome by running rich, so I went down the fuel pressure/float level path again.

I just need to find some time to check for a leak. I'm going to try both methods. The carb cleaner will probably work best for checking the seal around the insulator blocks and I'll use the propane around the carb bases.

I dunno about your mixture questions, but I would toss in my $.02 and agree with Rich about the plugs. I have always run 2 or 3 clicks colder than the 5's. My 2.2E (MFI) was usually running on the rich side too, and I don't recall any fouling issues with NGK 7's or the equivalent other brands. I have BP8's in my current 2.2 (carbed) which is more track (high-rpm) oriented and again it seems very happy with these plugs.

Thanks Chris, I was running colder Bosch plugs before PMO suggested I switch to the NGK 5's, and I never had a fouling problem. Based on what you and Rich have said I'll switch back to the colder plugs.

I was out of carb cleaner, so I tried the propane last night, and got no change in RPM, I picked up some carb cleaner this morning, and I'll try that tonight.

-Justin

may depend a little on what ignition you're running; i'm using a MSD-6AL with their hi-vibration coil. i think Chris has something similarly hi-po in his car. if you are too - or even just the OEM Bosch CDI - i'd say try a set of NGK or Denso Iridium in what passes for the NGK '7' heat range. (now that i've got my MFI dialed in i'm not having a fouling problem either ...)

as for the propane / carb cleaner test. maybe you -don't- have a vacuum leak.

i'm still a little confused tho on what it is you're actually adjusting.
did i last understand you to say that you have the mixture screws set somewhere plausible, and are adjusting the idle airflow balance screws to achieve equal airflow - on two cylinders - 1 & 3 ?

*if* that's the case, it doesn't sound like a vacuum leak - quite the opposite. it sounds like you have something choking the idle airflow to those two cylinders. pull the air correction / emulsion tube stack again and check v-e-r-y carefully for gunk or restrictions in that. also - check for wear or misalignment in the throttle butterfly valves. could be that one (my guess would be #2) is bent or worn beyond spec.

Yes that's correct. Here are my "basic" steps:

Close Air screws

Open mixture screws 2 1/2 turns

Start enginewarm it up to temp

Disconnect linkage at the carbs

Screw idle stop screws in evenly until hit the 1200 rpm range

Using the synchrometer, check and make sure the each bank is pulling equal air by using the measurement from the highest cylinder on each side (for me its 2 and 5). Adjust idle stop screw as necassary to achieve balance.

Adjust mixture screws - In until rpm drops - back until it levels out and then an extra 1/8 - 1/4 (repeat for all cylinders). At this point all cylinders are running between 2 and 2-1/2 turns out on mixture screws.

Balance air flow - 4,5,6 are almost dead even - 1 and 3 need significantly more air in order to match 2.

Connect linkage and blip the throttle - engine hangs around 1800 - 2000

This goes away as I make the mixture richer. Once it idles and transitions properly, I go back through the mixture screw adjustment, double check the airflow still matches all the way around. Reconnect the linkage, pull the hand throttle to run around 3000rpm's check synchronization again and check to see if I need any linkage adjustments.

I cleaned everything with compressed air and carb cleaner about three weeks ago, so if there is something blocking the passages, I'm guessing it's a deposit of some kind. Probably the butterfly valves.

I'll let you know what I find. Thanks again.

-Justin

I use the "end to end, side to side " method for sync.

With the engine running, disconnect the linkage to the driver side carb...at the carb. Check each throat on the pass side carb and note the highest flow. Sync each throat to that end to end using the air bleed screw(it usually takes very little air bleed adjustment). Do the same to the drivers side carb.

Reconnect the linkage....*use the barrel nut to align the linkage to the carb*(loosen both lock nuts on the barrel nut. It will expand or contract the lenght of the down link as you turn it). Back off the idle set screw on the drivers side carb, allowing the whole works to ride on the pass side idle screw only. Check flow...side to side. *Adjust the barrel nut* on the pass side to even out the side to side balance. I usually do this at around 1800-2000 rpms. Back the pass side idle screw off to get the idle to 900 rpms or so.......make sure the drivers side idle screw is still clear. Check balance....side to side. Now days, I can usually get this
on the first try.....but I know *my* carbs/linkage. If I had to do it on someones, it would take at least 2 run
thrus...maybe more. Now go back to the fuel metering screws and do that again....then check sync ......again.
*Don't forget to tighten them lock nuts*

Have someone press down the throttle pedal to bring the rpms up to 2500-3000.....check side to side, end to end. Remember, the air bleed screws are used *only* for end to end and the barrel nut (driver side) for side to side. Don't ak me why, but I get different numbers
at the pedal than by moving the cross bar.

Some general stuff:
IDTs have an odd shaped fuel metering screw having a radiused taper rather than a straight taper like IDAs.
In 30 odd years, these two types get ...intermingled. make sure all yours are the same. IDTs are all 30 years old or more. Throttle shafts wear out the bores.
The bores suck air.....the front ends (1 & 4) go first.
If it's bad, they need to be repaired (bring money) or they will never run right.

IMO, Fuel metering screws should be between 1 1/2 &
2 1/2 turns open....maybe more ...up to maybe 3 1/2 for IDTS. More than that and the idle jets are too small or sumthin' is fucked up.

Long distance Weber tuning is a bitch.....particularly when one doesn't know what else may be ....not up to snuff. Dizzy/ ignition system, et al....

Alright, does not appear to be a vacuum leak. No change in rpm with propane or carb cleaner.

So who can I trust to recondition my webers, I'm thinking throttle shafts and maybe remove lead plugs and clean the passages?? JP said, "Bring $$$$", What kind of $$$$ am I looking at?

Is the lead plug removal and passage cleaning a DIY job or not??

-Justin

Eurometrix.

there are others who can do it, but i'll let the people who have had really good results with them chime in. Mike Ginter had it done and wasn't completely happy with the experience although his major problem (not unlike yours) did get resolved IIRC.

extracting the plugs shouldn't be a problem, donno who you'd go to for new ones tho; maybe get to know the guys at the shotgun reloading sites pretty well - although lots of them have gone to stainless, bismuth, and tungsten for environmental reasons ... if compressed air, Berryman's B-12, and pipe cleaners don't address the issue, it may be your best path. i donno - never been there myself.

if spraying carb cleaner / squirting propane around the throttle shaft bores didn't change the idle, you do not have worn shafts and the expensive rebush process may not be needed.

i'd think it's still possible to get the shafts, butterfly discs, and screws new, probably from Redline (possible...) or more likely PMO. if you're ordering parts, let me once again recommend the '906' extended preatomisers (secondary venturiis)...

ya know - a missing butterfly screw might produce these same symptoms - might be time for a full rebuild and an opportunity to "look for the obvious" as well as an up close and personal with more pipe cleaners and Berryman's ...

but i think that's the best i can suggest long-distance ...

good luck ...

Wait before drilling out the lead plugs.

If the shafts had alot of play, they would have picked up propane and the idle should of changed. If the shafts are lousse, they are sucking air, so if they suck air, they will suck propane also.

You have insulators and the gasket setup should be like this:

A- Head
B- Gasket from insulator kit
C- Insulator
D- Gasket from insulator kit
E- Manifold
F- Gasket
G- Carb

Finding a vacuum leak for ''B'' is pretty hard. The gasket is hidden under the shroud. As this cost nothing, i'd suggest removing the carb & manifold in one unit. You will be able to check the carb afterwards if gaskets "B'' are ok.

If you want to check the idle circuits here is an easy way.

Take to top part of the carbs off and put it aside and remove the floats. As compressed air will be used, you don't want to dammage the floats or the needle valves.

Leave some fuel in the bowls. Take the idle mixture screw out and shoot compressed air via the idle mixture screw hole, while blocking the idle mixture port in the carb body. Fuel should squirt from the e-tubes like 3 feet high. If it barely comes out, or dribble, something is wrong. Recheck and clean every part in the circuit. you should be able to isolate where the blockage is if there is one.

Here is a diagram of the idle circuit:



Check for blockage in 22 and 21.

Lead plugs can be drill out by yourself (that what i've done). For new plugs, small lead pellets were pounded back in and secured with a bit of JB-Weld.

Marc-André

Thanks for the recommendations, there is a lot of great info here. I have not tried pipe cleaners yet, and is Berrymans B-12 carb cleaner or something stronger?? Normally I use carb cleaner and compressed air only.

I had the manifolds and insulator blocks off this spring, but I'll check again and make sure I didn't miss anything. Thanks for the blockage test procedures, I will try that in conjuction with pipe cleaners and see where I get. I plan on exhausting all possibilities before sending them off to be refurbished .

Thanks again , I never get this many responses on the PP911 board when I ask engine questions (unless it's local NoVA guys responding), I think they see "914" in the screen name and just move on .

-Justin