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| Carbs [or FI] for your Porsche® 912/912E |
Technical Blog:
For '76 owners, do you have the original Bosch L-Jetronic? A different fuel injection system? Back to carbs? New! 912 Registry Members can share technical information, add technical information, and access quality, up to date technical information on our 912 Wiki. |
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From:
Richard Shilling; I worked
on Porshes at Ralph Cutright VW Porshe in Santa Monica, California from
1967 to 1970. This meant I was right in the middle of the (in)famous 1968
912! Yesterday at the Los Angeles Porsche Literature Show I ran into
another mechanic from the same timeframe. We had a "discussion" about the
912. I'm sure I'm right, he's equally sure he's right. Which one of us
is "really" right? From: Heremans Benny; Hi all 912/912E people uptheir , I own a very nice Porsche 912E , and I love the FI, The fuel injection on the car is one of the reason that I prefer the 912E above the 912, and yes, their are some problems now and then , but that's all about vacuum leaks and/or fuel delivery problems , as I could find out on thise pages. I would like to keep it FI als long as possible, so if anyone could sell me spare parts like controle unit, boot for are intake, are other FI parts, a Thanks , and keep enjoying your Porsche. Benny Heremans , Belgium From: Chris Nicol; I found a good cross reference for 912e fuel injection parts. http://www.type2.com/library/fuel/fuelibo.htm ChrisFrom: ejk; hi I own a 912e and i still have the fuel injection system. It has performed quite well for me but i have one question. Right now Im getting some kicks or misfires from the motor while at high rpm's (say around 4500 rpm). Im wondering if thats a sign of a bad injector or a possible air leak. If anyone knows about the L-jetronic system or has had the same problem... i would greatly appreciate the advice. Thanks. From: Ben Charvet; I am currently using the original Bosch injection on my 921E. When it runs it runs well. I am having a very frustrating problem with occasional difficult starts. The injection system seems to be going to a full rich mode which floods it out. If I pull the wire off of the coil that stimulates the computer to fire the injectors and turn it over a few times it will catch and burn off the excess fuel. Then reattaching the wire usually will enable it to start. The throttle position switch is not shorted. Anybody have any ideas what could be causing this condition. I have had it happen on both cold and warm motor conditions? It is getting frustrating enough that I am considering switching to carbs, but I noticed that Performance and Tweeks no longer list the conversion kits. All suggestions welcome! Ben Charvet t 1976 912E 1333 From: matthew handscombe; ; I'm having tremendous trouble starting my 67 912 (w/Weber Carbs) and once started, keeping it from stalling for about the first 15 minutes. During this time it often feels as though the engine is playing catch-up with what I'm asking the accelerator to do - it all kind of bogs down. Sound familiar to anyone? Suggestions? Friom: taylor; I used an outfit in Richmond, CA. called: "Carburator Refactory: 815 Harbor Way South, #5, Richmond, CA 94804, Tel (510) 237-1277. Attn: Merrell Bright. Can rebuild entire carb. or in my case the bushings and butterflies. They did a great job. If you send check for the whole enchilada, they pay return shipping. Good Luck, Rocky Taylor From: Bill Todd; Hey! Just off a 2200 mile "Last
Road Trip" with my 912. It ran flawlessly! I had upgraded to the CB Performance Weber
40IDF Kit they came out with in January 2000. I did not supertune the carbs at
installation. My mileage was in the 28/29 MPG range overall, but I was averaging 70 MPH! From: Bill Todd; B- In "Hot VW's"
a month ago, a kit was advertised by CB Performance that upgraded the Weber venturri's and
changed the discharge configuration on the boost venturri's. You remove the old two piece
venturri set-up, and replace it with one single piece that is anout 6mm bigger in inside
diameter. You also have a cleaner airflow, since the old cast boost stuff is now replaced
with a single brass piece with holes drilled in the bottom. It's simply done and really
didn't require much effort. I also used new "Bugpack" base gaskets, #1556 for
the 40 IDF's. They are much thicker, and seal great. I match-mated them to the manifolds,
and removed any air restriction and flow interrupters. From: Rudy Santo; I have been searching for a source to purchase the Solex P40II carburetor throttle shaft bushing kit. Automotion does not carry this kit anymore. Does anyone know of another source? Thank you, Rudy Santo, 68 912 From: Martin Eddleston; I've just bought my
first Porsche 912 after years of driving boring modern family cars - never can I go back
to driving such rubbish after experiencing a Porsche ! From: McCoy Family; ; Anybody have some good advise on the proper way to adjust the idle on IDA (?) Weber Carbs? I'm thinking about drilling a vacumm tap on each intake runner so I could use 4 water manometers ( like motorcycles do) to balance the Idle mixture better. Rory From: David Cardone; Hi there..... my 912E has been
modified to a 32/36 carb. This is a horrible replacement for the injection and I am
looking to go original or to a dual carb set-up when I find the right parts for the right
price. If anyone has a big bore kit, dual webers or the factory injection for sale, let me
know. From: Mike; The brazilian solex might work. most machine shops can rebush your throttle shafts for a reasonable price. Try this guy Dave owner/manager Barts Parts, Phone# 1-661-327-5501 Its in Bakersfield Ca but they are the best shop for imports and work with mostly VW and porsche. Hope this helps Sincerly, Mike From: Scott Ball; I have a 1968 912 with its original solex carbs which are worn and leaky. I cannot afford to replace them at the moment, nor even the cost of a new set of webers. Are there any economical solutions for these old solexs? Mine leak air through the throttle shaft bearings and through other worn areas. Can you suggest a good rebuilder? Are there alternatives to droping $1000 on a set of Webers that I do not know about? Thank you, Scott, Atlanta, Ga From: Andy Daniels; Hi Rick I recently bought
a '66 912 which I found on your 912 for sale page. I will register it with you soon. In
preparation for buying the car your site was invaluable and I am delighted with my
purchase. Keep up the good work! From: Michael Winter; I'm another of those who had a miserable cold starter, and it idled either racing at 1750 or 400 rpm! Mine is a '68 912 and I live in the state of Washington, so we have to go through emissions (all the original emission stuff had all ready been disconnected). I took the carbs apart this past winter and the first thing I found was that three of the four accelerator pump jets were plugged. That's why it would only barely start on one cylinder. Clearing those made it an easy starter, what a pleasure after the past struggles! The idling problem I had previously worked on for months, adjusting jets, mixture screws, etc. For the emission test it can't idle higher than 1100 rpm so it was a real pain. I considered the possibility that it was the advance on the distributor, but decided to do the rebuild of the carbs first. After the rebuild, when I re-installed the carbs, the fast/slow idle was as bad as ever. So I removed the carbs again and I discovered the throttle plates on the right hand carb was not closing all the way.......I could just see a "sliver of light" when looking down the throats. It turned out the accelerator pump adjustment had been tweaked so far it was interfering with the plates closing all the way. I was also suspicious that I had a slight leak around the manifold to carb gasket. When it was idling, I could place my hand over the throat opening and the idle speed would increase slightly. So when I reinstalled the carbs, I put a little bit of pliable sealer to both sides of the gaskets. When I went to start it, to my AMAZEMENT it purred, and with almost no tweaking idle at 800-900 rpm. It runs perfectly! After all the months and struggles and cussing and puzzlement, these two things solved the problem and now I have a gentle, docile idler. From: Bill Schmidt; ; I've got rebuilt Solexes on my '66 912 currently (sans any rebushing work). Although I suspect some air leakage around the Throttle Shafts, the carbs seem to be performing satisfactory. I picked up a used engine from a '67 Euro 912 two years ago, as my original engine came with a cracked case at the Oil Cooler. There were 44 Webers installed on this engine - so I tried them initially. Above 3000 RPM they were great - knocked you in the back seat! Below 3000 RPM, I literally fouled out plugs at stoplights! Additionally, the linkage was never correct with the Webers installed. The Thottle Travel seemed to be roughly 2./3 of the Solex's, and I promply bent the Throttle Rod with the first brisk acceleration. Was there a Linkage Kit that I was supposed to install along with the Webers? Properly jetted, I believe the Webers would be a great carb - definately easier to maintain than the original Solexes. I'd also like to make contact with any other Michigan 912 owners out there! Thanx in advance - From: Mark Price; ; Rick, I bet there is someone doing injection for the early 912s, most of what I have seen in hunting for future Bosch replacement is based on the Weber IDF flange design. Lumenition ( an English Co.) makes some really fine looking FI throttle bodys that mount on these flange shapes. This may be one way to improve the emissions and driveability on some of these older cars as modern sequential FI is much more emissions friendly than carbs or even early injection like L Jetronic. I think CB Performance could probably taylor something for these cars also. Cheers, Mark Price From: MPrice; ; I still have the L-Jetronic FI on my 912E. It works very well as long as there are no air leaks. I have found it pays to replace all vacumn lines about once a year and to check all the hose clamps for tightness about once a month. I found out the hard way ( about $850 worth) that most Porsche repair people know virtually nothing about this system. All early Bosch injection systems are relatively easy to figure out if you have the Bently book on them. My car squeeks through the emission tests ( with out thermal reactors ) but you really have to lean it out to pass. You can't beat FI for driveability. From: "Christophe"; Yes I still have original Solex carbs on my 912 (year 1969), it cost me about $500 to renew it and have an engine running fine. For air filters, I used Ford Transit filters which are exactly the same. From: Greg Bryan; ; I put a set of
Weber 40mm carbs on my '68 912 about 10 years ago after the Solexs finally gave up the
ghost. I had rebushed the Solexs, rebuilt them and fiddled with them endlessly but good
idle quality just wasn't possible to achieve. I bought the Webers from ********** in the
******** area and when I installed them, I was obvious that they were jetted for a VW
engine. I increased the venturis to 30mm and enlarged the idle jets and finally got
it to run pretty well, but it could be better. I wish I had gone to the 32 mm venturis
like in the Solex, but I was given advice from another Weber "expert". The
manifolds and linkages that came with my kit fit well, but the front plugs are a little
harder to get in and out because the manifolds are slightly bigger. From: brian reynolds; Dear Rick, my 912e is still all original with injection in place, very economical system. Gets great mileage per gallon and runs consistent. only problem running wise was bad head temp sensor. as for racing , not here! but i practice dodging pot holes. michigan drivers are the best at this, every road in state is a new coarse. great web site and keep up the good work. brian From: Kanas, Jon B; ; Hello all, I still have my Solex carbs on my 1969 coupe. Over the past 10 years I have worked with a number of local enthusiasts on carb problems, and my opinion is to keep the Solex and do whatever is necessary to keep them operating properly. With the assistance of a local small parts machinist, I had composite Bronze and Teflon bushings pressed into the throttle shaft openings at the throttle lever. This has resolved my throttle "wobble" satisfactorily. Regards, Jon B Kanas From: Jason Terada; ; My '66 912 was fitted
with solid-shaft Solexes. The two throats of the left carburetor were way out of synch,
and are impossible to balance, so I replaced both carbs with used split-shaft Solexes from
Best Deal in Stanton, CA. After rebuilding both of these carbs and some fiddling, the car
runs great (at least for now). I briefly entertained the idea of replacing the Solexes
with one of the Weber kits from a catalog, but the prices scared me. I also wanted to use
the original air cleaner housings to keep the car looking stock. From: BJOswald; I have a '66 with SOLEX carbs; a car which I've owned for only a few months. Another version which I owned some years ago had WEBERS...which I found to be relatively bulletproof and very dependable. However from what I've seen so far I'm not sure I can afford the conversion anymore. What's the solution? From: David Malan; ; My 68 912 still has it's original Solex carbs, I have recently had new butterfly's fitted which has made a big difference. They still need to be adjusted every 6months or so to keep idling speeds consistent. Besides being a little temperamental they seem to do the job reasonably well. Please tell me about the "throttle shaft air leak" is this a common problem? Thanks for a great web site. David Malan ( All the way from South Africa ) From: Eric Nichols; I ran Weber
40IDF's for a few years of active autocrossing in NoCal. I had experimented with
many jetting combinations with the Webers, all using 28 mm venturis. They worked well, and
were easy to tune, but I eventually switched back to the Solexes for a more original look,
and better performance. From: JMarg7000; In 1982 when I bought my 912E I immediately had a problem with the L-jetronic FI. A call to Porsche Mail-order in Calif. (I have no idea if they are still in business) and I had a Weber 40 idf setup for a 914. All I had to do was put it on backwards. To make a long story short, we torn the engine down, put in a Sig Erson cam, balanced the rotating assembly, the rods & pistons, put a three angle valve job in, ported the heads to match the new manifolds, and viola! 123 hp on the Stuka, 34 mpg on the highway, and plenty of grunt when needed. I was a VW freak at the time, and I call it my Type 4 Karman Ghia. I'd never go back, but now it's the only auto I own which isn't FI auto I own. From: Leland J Olsen; I still have my original Solex's, they are in a box. I converted to Weber...the conversion was easy as Motormeister provided a no brainer conversion kit. The linkage and fuel line modifications required were done by a local Porsche mechanic. Lee Olsen From: Jim Gissel; ; I still have the original L-Jetronic system on my 1976 912E. I is working just fine so I am not going to touch it. Last summer it developed a "flat spot" at 2200 rpm which required a new air box to fix, other than that it performs just fine. Jim Gissel VIN# 9126000777 From: Neil M. Fennessey; ; Hi Rick: I still run Solex
PII-4 carburetors. About 8 years ago, I had an opportunity to purchase a pair new carbs
from Stoddards at a good price and so I jumped at the chance. To have new carbs, with
passageways free of accumulated crud, for just a few dollars more than the cost of
rebushing my old ones was the incentive. I especially like the original Solexes because
they work well in my motor and the stock air cleaners fit, which results in a quieter
motor than K&N air cleaners on top of Webers for example. From: Kai Schueler; ; My car is a 1968 912, short wheelbasse, 4speed, almost completely original. When I bought the car it was still equipped with the original Solexes (all numbers match). The car was very difficult to start, and it was virtually not possible to adjust a steady idle. Also, the engine was smoking a little bit when cold. After following the various Porsche mailing-lists on the net (356talk, etc.) I decided that Webers were the way to go for me. I decided on Weber 40 IDF, and I bought them from Italian production because they are by far the best of all Webers. I purchased a complete kit from a very reputable 912/356 specialist in Germany. The kit came complete with two new manifolds, air-filters (sprint) gaskets, sealant, fuel hoses etc. and an o.k. instruction-manual. The manual recommended to pull the engine if the conversion is done on a 356, but on a 912 it would be possible to do the conversion with the engine in the vehicle. From my experience I say: DONT do it with the engine in the vehicle. It is SO MUCH easier with the engine out, that I would never bother with the small engine compartment. The switch was a snap exect for one thing: I stripped the thread of the third screw that holds the driver side manifold to the cylinder head (the smallest of the three screws). The thread is cut directly into the soft alloy of the cylinder head, and it can easily be overtorqued (ask me how I found out...). So I had to interupt the carb-conversion for a couple of days to have the cylinder head repaired with a helicoil repair-thread (don't know if thats the correct word?). The repair can only be done with serious equipment, because the thread goes into the head at a slight angle, not perpendicular. And because the screw is approx. 3.5 inch long you have to drill very precicely. Anyway, after that was taken care of the rest was a snap. The whole conversion can be done in maybe 4-5 hours, when the engine is already out of the car. And the results: A lot easier starting, stable idle, quicker engine response, overall very pleasing results. I highly recommend it. Maybe in the longer future I will rebuild the Solex carbs myself and sometime switch back to them for originality reasons. But from a drivers standpoint: A big change for the better. Regards, Kai. From: Trenholme, ; Hello all.
Well here in California all 66-69 912's are now smog exempt (all cars through '72), so we
can run what ever we like on our engines. I recently removed the original Solex carbs and
installed Weber 40 IDF carbs on my 68 912. I did this because the carbs idled poorly,
although they ran great from 2000 rpm on up to the redline. I also have been requested to
not use Webers on my 356 race car as they are not vintage correct for racing. So I
proceeded to swap the carbs on my 912 and 356. My set of Webers has the larger 32mm
venturis and I have 135 main jets, which makes them very similar to the Solex 40. I also
removed the engines from both of my cars as I needed to swap the manifolds as well as the
carbs. I really don't know how else you could really swap these parts without removing the
engine, and it is probably the quicker way to go. Installing the Webers on the 912
required removing quite a bit of smog related equipment. I vented the heads and the
crankcase to a plastic radiator overflow bottle that I mounted in the engine compartment.
I used barbed hose fittings and installed them directly into the vent holes that were
already present on my heads. The air injection pump was gone and the injection ports on
the heads had been previously plugged. I also spent quite a bit of time cleaning up my
engine and the sheet metal. When I got through my engine looked real sharp and I
know my car was happy with the engine as reinstalling the engine went super smooth and the
motor just popped back into place without any hesitation. Once the engine was
reinstalled and I got the engine started (after correcting the incorrectly installed spark
plug wires!) I went about adjusting the linkage and balancing the carbs. Funny thing
though, the engine would still not idle! It was as if I had not changed anything, and the
Webers were working perfectly before I removed them from the 356. I tried every adjustment
that I could think of without any luck. I then turned my attention to the original
distributor in the car as I suspected the advancing mechanism was not working properly.
Well I completely disassembled the distributor and lubed things and everything looked fine
but after reinstalling it in the car it would still not idle! The engine would either be
barely running at 400-500 RPM or it was racing at 1700-1800 RPM. Sound familiar? I
finally took the new 050 distributor that I use on my 356 and installed it on the 912.
Viola! My idling problem went away! The car now purrs at idle and will start instantly in
the morning with a pump or two on the gas pedal. I don't think that the car has any more
power or accelerates any better but my engine looks at lot cleaner without the large 912
air filters and associated hoses. So be aware of your distributor making perfectly good
solex carbs appear as if though they are worn out. If you are still running your original
distributor it is probably seen better days anyway. A new 050 can be had for $80.00 (JC
Whitney even has electronic ignitions that will work on 912's for $100.00) and takes about
5 minutes to install. The cost to rebuild your Solex carbs (full rebuild with new
bushings) will run you $500-$800 and a good Weber kit goes for around $600.00. It is
amazing how fun these cars can be when they are running great, I commute to work in my car
everyday (75 mile round trip) and can't From: Chris Smith; ; I have a '76 912E and I live in California. Unfortunately this leaves no options but to run the stock L-jet unless I want to dismantle the intake system completely every two years. It's very strict in CA, including the visual test, although most people don't know what some of the L-jet componets look like. I've gotten away with keeping my thermal reactors off because most people don't know what they look like either and the funny thing is my car runs cleaner without them. Sorry...back to the issue at hand....I had to spend quite a bit of time getting my L-jet back to original performance(312K miles on 'er) but most of it has related to vacuum leaks and/or fuel delivery problems. I've found that once you've replaced all of the vacuum lines, gotten the injectors clean, and the fuel pressure, burn, and timing adjusted to where my car runs good the L-jet has been fairly trouble free. I get about 27 miles to the gallon and run on regular gas without any problems although I had to advance my timing a bit to get my car to run better with the Bursch headers. I used to run dual carbs on my older cars and the syncing them every so often didn't really bother me but overall it seems Porsche didn't do too bad with the L-jet as long as everything is in order. Parts are still available although I'm thinking about buying a complete used replacement at Parts Heaven for down the road when the parts might not be available anymore. -Chris New! 912 Registry Members can share technical information, add technical information, and access quality, up to date technical information on our 912 Wiki. |
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