I have a 73 2.0L with stock weber 40idf carbs. I have heard that you can put different jets, venturis, and other internal parts in them, but I have no clue which ones to get. I want the car to have good performance with the carbs I have, but still be a good driver.

QUOTE (Gearren @ Mar 11 2005, 01:54 PM)

I have a 73 2.0L with stock weber 40idf carbs.

there were no stock carbed 2.0L !!!

in fact, unless you bought the car in europe, there were no stock carbed 914s at all.
certainly not in the US ...

now back to your question. yes, there's lots of different options for your carbs.
it depends on a whole list of things.

- is your engine modified? in particular, do you have a "hot" cam? any headwork done? header system? increased CR? increased displacement?

- what elevation are you at?

- do you race/ax or is it just street driving?

- how important is gas-milage to you?


Andy

I mean no work has been done on the carbs, but never mind that. The engine is stock except for the carbs, I just do street driving, and gas mileage is not really a factor, just so the car still runs fairly smooth.

Also I live in North Carolina.

If the car is running smooth, then there probably isn't anything you can do to the carbs that will increase performance ... But I'll let the real experts say so for sure.

QUOTE (Gearren @ Mar 11 2005, 02:13 PM)

Also I live in North Carolina.

You can get it running "smoothly", but an otherwise stock engine will run better with the stock EFI. Really.

That said, first do a valve adjustment, then double check the ignition system (timing, dwell, condition of points), and only then start fooling with the carbs. If the engine is running well now, leave it be. If you MUST do something, buy a Weber book to get diagrams of where all the parts are, then figure out what you have now. Come back with those numbers and ask for advice again.

Geez, I can't believe you guys are treating a new guy so terribly.
Gearren: You should do all the things above mentioned by Lapuwali good info there. And he is probably right by saying don't screw screw with the carbs until you are sure the rest of the engine is in good tune.
You said you wanted the car to run smooth does that mean it doesn't now?
Once your car is in good tune then clean the fuel system. One little particle of dirt will spoil the whole day. especially if it lodges in an idle jet or progression hole.
More than likely you will find rust and crud in your tank (they all do) unless you clean it and treat with something like POR-15 gas tank sealer.
Are you running an electric pump and a pressure regulator? what pressure are you running?


Now that all this is out of the way and you effectively used up your whole weekend. Drive the car around town below 3000 RPMS a few miles should do Check the color of the new spark plugs you installed. tell us what they look like. Now go for a ride above 4000 rpms try and stay on the main jets. 4th gear on the freeway should do it. 5th gear @ 4K rpms is flying low so be looking for the FUZZ. pull over at the rest stop try and shut the car off as soon as possible once exiting the freeway. coast to a stop. you sdon not want to confuse main gas burn with idle burn. What color are the plugs?

NOW we can tell you what jets you need if at all.

Is the car popping through the carbs? lean on one of the circuits
Popping out the exhaust? rich on one of the circuits.

Now isn't this fun? We can easily drain your bank account here. I have jets from 110 to 155 main gas, 35 to 60 idle. a whole assortment of air correction from 110 to 220. each jet is about 8 bucks times 4. Seems I inherit jets from each car I buy because the owner couldn't figure it out.

Have you figured out that Carbs are NOT cheaper than Fuel injection? Don't expect earth shattering performance from carbs if you have a truly stock cam.

Dang I can ramble I need a

Well said Joe.....another thing to consider for better performance that really does not cost...allot..is the ignition. A problem you will run into is when you spend 8 hours dialing your carbs--and then you fiddle with the advance curve or the total timing--you have to reset the carbs again--most likely not all the way indepth wise--but they will need to be rebalanced.

Before doing any carb work--I would suggest tinkering with your ignition. I have been doing much research on this and talked to many, many people, both here and abroad.

The word on the street is, for a carbed engine and the best bang for the buck is a well dialed in vacuum advance / mechanical advance distributor.

Seems that at normal cruising speeds the engine will tolerate as much as 50 degrees advance, depending on configuration. This is good for engine temps and fuel mileage. You mentioned you really don't care about mileage anyway--but this and cooler running go hand in hand--and a cooler running motor makes more power.

You can dial in as much advance as the engine will tolerate with the mechanical aspect--and yet fine tune it with an adjustable vacuum pot. Anytime you stomp on it you will get a retard from sudden lack of vacuum. This is good. too much advance when getting a slug of fuel streaming into the chamber is instant detonation.

In a nutshell, even with a fi cam in it---if you really want to maximize its potential--spend the time, two full days maybe, and dial it all in. I just do not agree that a stock engine with dual webers will not make anymore power, than with the stock non adjustable-tamper proof fi, with out numerous and honestly expensive upgrades to the fi system, if you do not have the original fi stashed someplace. Carbs, especially dual webers, are just so adjustable, and they work, and once they are set, you can forget about them. Think carbs are costly?? Try keeping a 35 year old electronic system in top notch--better carry two of everything as a spare in your trunk--just look at all the posts on here about people having nothing but trouble from thier fi.....things to ponder

If you can take it to a chassis dyno shop for some pulls you can do it all in a day--I know you will be pleasantly surprised at the results when you are finished--and those shops are very reasonably priced. Therre you can fiddle with ignition and jetting to achieve some realistically startling results.

Go to the aircooled.net website and look at the tech articles on the links at the bottom of the home page--this will help you out tremendously--

Bottom line is--do it your way--and do it good

QUOTE (jwalters @ Mar 11 2005, 06:04 PM)

just look at all the posts on here about people having nothing but trouble from thier fi.....

yeah, but that's because most people don't understand how the FI works ...

once you know what each D-Jet component is doing, it's easy to diagnose and fix.
after a initial overhaul, my 1.8L D-Jet ran without a problem for 3 years and now mueller is running it. still going strong.

now my carbs on the other hand ...
Andy

QUOTE (SirAndy @ Mar 11 2005, 06:14 PM)

QUOTE (jwalters @ Mar 11 2005, 06:04 PM) just look at all the posts on here about people having nothing but trouble from thier fi..... yeah, but that's because most people don't understand how the FI works ... once you know what each D-Jet compnent is doing, it's easy to diagnose and fix. after a initial overhaul, my 1.8L D-Jet ran without a problem for 3 years and now mueller is running it. still going strong. now my carbs on the other hand ... Andy

Well said and spot on Governor!! HIP HIP AND CHEERIO. People around here (my lacality, not this club!)thingk I'm nuts for putting the injection back onto my dads car, but it is the best option for a 1.7 that is intended to be a weekend cruiser in the country and the mountains. Alot of people are afraid of F>I> cause they don't care to get to know it. Yes for easy performance carbs are the best but for driveability I says F.I.

After a few years of driving my 72, I pulled my stock FI 1.7 out to fix the oil leaks from the tubes.

Started driving my other 914 and never did get to fixing that 1.7, so I left it in the back of the garage just as it was when I pulled it. You now without any storage prep at all!

Last year I got a 73 914 with a blown engine. I knew that the 1.7 engine ran fine, it was just leaking oil when I pulled it. So I changed the oil, flushed the injectors, replaced the plugs, points, cap, rotor and wires. And the FI worked great. I drove it all last summer, to the Mid west classic, and sat in the summer hot sun idling in traffic at the Woodward Dream cruise.

The year I pulled that 1.7 from my 72 914? ..............









1979 ! It sat in a michigan garage for 25 years.

I have would never switch to carbs.

O, and never did fix the oil leaks, It's a little worst now.

2 weeks ago I bought a rebuilt short block 1.7 from a fellow club member. I will be building it up with the tins and FI from my oil leaker.
For some reason I guess, I never will replace the seals on that old 1.7. So I will just slide it to the back of the garage, again!

Please keep in mind that I am relatively new to this forum and my knowledge of the FI is limited at best. W/ that said - if one is not knowledgeable would it be "cost" effective just to convert to CARBS?

My 72, 1.9L, that I just found out does NOT have the stock CAM has been giving me all sorts of FI problems.

JWALTERS came by and helped me on other issues, and after throwing some ideas back and forth, reading many of the threads on CARB vs FI -

I've come to the conclusion that for a STOCK engine FI is just straight forward after you get it up and running, but if you have a mod like the one mentioned above - CARBS are the less PAINFUL route.

I'm going under the impression: STOCK ENG "FI," MODIFIED ENG "CARB."

I'm doing research to find a 44IDF kit. I've spent an efin amount of money of FI and I can't get my car running right. I have TWO of every 1972 FI part available and it's just efin hopeless.

just throwing my two cents out there. regards

first, if you've never delt with webers before buy Bob Tomlinsons' "Weber Tech Manual". how they work is important to know before you slap a pair on, and the trouble shooting guide in bt's book is a great resource. aircooled.net has a good setup article too. buying a set of GOOD, KNOWN carbs isn't cheap. add in a GOOD linkage, new fuel pump, a fuel presure regulator(if the pump dicates the need for one), and the pice starts to jump. you can expect ok mileage. i got nearly 27 mpg on the drive to california on some easy cruising sections. lawful speed, hiway cruising, just under going to the main jet circuits does the trick. it got to the point i could tell exactly when the transition was happening. zipping around town is another story. i never quite got the carbs are bad arguement. there are a lot of 911, 912, and 356 cars driving with carbs. screwed up f.i. is just as bad as a set of poorly dialed in carbs. maybe worse, you may have to limp in with a plugged jet, but with a t.u compoment in the f.i., it's a tow.

k

So obviously there are good points and bad points to each of these---

Agree on the limp home or tow---a tow down here from "a to b" can be as much as 400 dollars---

I just like carbs--plain and simple--cause they are plain and simple--once they are bought, modest cash outlay at best--over the next 20 years of never ever having to buy or put on another induction part will more than recoup the expense--many times fold--

And we have all seen the engines that Jake builds--even he loves carbs

Yo fernando--got the finish coat on it today and started replacing all the electrics--you need to move closer to me-- Even I am still amazed we kept you from pulling a head the other day--talk about LUCKY!!! See, if it was me, and my ride--that would not have happened--I would be pulling the head Hows it going on the search for the gasser beasties??? oh, and if I forgot to mention--thanks for the brew! J

QUOTE (jwalters @ Mar 12 2005, 04:37 PM)

I just like carbs--plain and simple--cause they are plain and simple--once they are bought, modest cash outlay at best--over the next 20 years of never ever having to buy or put on another induction part will more than recoup the expense--many times fold--

There are D-Jet systems out there still operating just fine after 200K miles and more than 30 years. How reliable to you want? The system in my Type 3 is 36 years old, and all it's required is some cleaning to free up a stuck fast idle valve. It's never needed tuning of any kind. The Webers on my 914, however, have been a constant source of irritation and problems. They're substantially less than 36 years old, and have needed three full rebuild kits to finally get them working even halfway decently, and I still have so much trouble with them, I'm pulling them off to put on a fuel injection system. Prior to the 914, I had an Alfa that had L-Jet on it, which had been working just fine for 20 years with zero maintenance.

If you bother to learn how fuel injection works, you find it's very plain and very simple. Andy's point still stands: the trouble most people have with EFI is they don't understand it, and have decided NOT to understand it. EFI system failures are almost never due to parts that cannot be replaced by the side of the road, like the ECU, but nearly always wiring problems that can be solved IF they can be worked out. Carbs also have parts in them that cannot be replaced by the side of the road (care to try to find an IDF accelerator pump diaphram in Barstow at 2am?).

Yes, there are carbs that operate trouble-free for years and years. There are also EFI systems that operate trouble free for years and years. That EFI systems provide better fuel control is undeniable (automakers wouldn't be using them today if they didn't), so I'd prefer to stick with the superior system.

superior!?! James what have you been ???

Sounds like your carb problems are due to you not understanding them or not wanting to..

How long you gonna keep it on the car?? Till it hits 50 years old??

Have you REALLY not done anything to the fi except a carb spray on a stuck idle valve??
that is hard to fathom...

Just giving you a hard time there bud..

QUOTE (jwalters @ Mar 12 2005, 05:39 PM)

Have you REALLY not done anything to the fi except a carb spray on a stuck idle valve?? that is hard to fathom...

I've only had the Type 3 a few months, and the fast idle valve was unplugged, so it was always a "slow" idle, much like a set of Webers...An afternoon of futzing got the valve unstuck so it more or less works now.

The previous owner didn't understand the system, and hadn't touched it out of fear. He had a big stack of receipts showing servicing records back to 1980. The engine was rebuilt a few years ago, but no mention of any EFI related problems; just one case of the trigger points being replaced. The system is maintenance free except for the trigger points, so there's not really any need for it other than age-related problems. The fuel hoses are all getting pretty old, so I'll likely touch the system again to replace them before the car goes up in flames. Not exactly an EFI v carb kind of issue. For all I know, the injectors could all be dirty and need a good cleaning, but it starts and runs well, and gets exactly the mileage it's supposed to, so I'm leaving them as is.

By the standards of EFI, D-Jet is fairly mechanically complex, with a mechanical MPS and the trigger points, as well as the injectors and the fuel pump. L-Jet is mechanically simpler (no trigger points, no MPS, but add a flapper airflow meter). LH-Jet is simpler still (delete flapper, replace with solid-state MAF meter). Sensors can age and fail over time, esp. those in direct contact with water or oil, but this often takes 20 years or longer, and replacing them is simple and inexpensive. In most cases, a sensor can be replaced by a fixed-value resistor to get the car to run again, which is a roadside fix if there's any place nearby that sells resistors. On D-Jet, only MPS failure will really stop you completely, with little hope of finding a workable replacement part locally.

btw, as for the $400 towing, get AAA. Anyone relying on an old car to get anywhere should have it. In the last 15 years, I've only needed two tows (once for a carb'd car :-), and one of those could have been fixed on the road if I hadn't been dumb enough to leave home with no tools at all.

Man I have always loved the T3's--which one you got--square, fast, or notch??

If you say notch I am going to die--those things are just about unobtanium--

Man, if only they put K-jet on it---ohh boy--what you can do with that!!

Got any pics of it???

Some good advice here, but I question one statement:

QUOTE

You mentioned you really don't care about mileage anyway--but this and cooler running go hand in hand--and a cooler running motor makes more power.

I don't think this is the case. I was taught that a hotter engine develops more power due to greater thermal expansion. The upper end of the heat range being limited by the potential of burned valves, detonation and possible breakdown of the oil. Colder engines produce less power because they're not extracting as much expansion energy out of the fuel due to less optimal air/fuel ratios, cam overlap or spark timing.

Isn't this correct?

I have dual 40's w/ FI cam. Did not plan it that way. Once I got the linkage working and the timing set it runs great and gets good gas mileage. When I do another rebuild (hoping to be way off in the future) I will think about a different cam or Raby engine kit.

QUOTE (Carl @ Mar 12 2005, 11:33 PM)

Some good advice here, but I question one statement: QUOTE You mentioned you really don't care about mileage anyway--but this and cooler running go hand in hand--and a cooler running motor makes more power. I don't think this is the case. I was taught that a hotter engine develops more power due to greater thermal expansion. The upper end of the heat range being limited by the potential of burned valves, detonation and possible breakdown of the oil. Colder engines produce less power because they're not extracting as much expansion energy out of the fuel due to less optimal air/fuel ratios, cam overlap or spark timing. Isn't this correct?

you ARE correct--if it is a water cooled motor---A hot water cooled is equal to a cold air cooled--most performance minded w/c use a 160 thermostat--cool water and hot oil are best for these engines--160 x 2 = about normal head temps at speed on an aircooled--optimal for these engines is cold oil and hope the air in the atmosphere is cool ..

QUOTE (jwalters @ Mar 12 2005, 08:29 PM)

Man I have always loved the T3's--which one you got--square, fast, or notch?? If you say notch I am going to die--those things are just about unobtanium-- Man, if only they put K-jet on it---ohh boy--what you can do with that!! Got any pics of it???

It's a Square, I wanted a pack mule for hauling parts. No pics, and it's nothing to write home about. Panels are different colors, paint's oxidized, but it runs very well.

Take a look at The Samba for Notch's. They never officially imported them to the US, but there are a good many here in California.

QUOTE (jwalters @ Mar 12 2005, 08:45 PM)

QUOTE (Carl @ Mar 12 2005, 11:33 PM) Some good advice here, but I question one statement: QUOTE You mentioned you really don't care about mileage anyway--but this and cooler running go hand in hand--and a cooler running motor makes more power. I don't think this is the case. I was taught that a hotter engine develops more power due to greater thermal expansion. The upper end of the heat range being limited by the potential of burned valves, detonation and possible breakdown of the oil. Colder engines produce less power because they're not extracting as much expansion energy out of the fuel due to less optimal air/fuel ratios, cam overlap or spark timing. Isn't this correct? you ARE correct--if it is a water cooled motor---A hot water cooled is equal to a cold air cooled--most performance minded w/c use a 160 thermostat--cool water and hot oil are best for these engines--160 x 2 = about normal head temps at speed on an aircooled--optimal for these engines is cold oil and hope the air in the atmosphere is cool ..

Speaking strictly thermodynamically, a hotter-running engine is ALWAYS more efficient. There's a fixed amount of energy in a gallon of gas, and any of that energy taken up by the cooling system is wasted, since it's not being used to propel the car. However, the materials used now all melt at combustion temps, so they all need to be cooled. There are very high temp materials available that would completely remove the need to cool them (primarily ceramics), but work is still being done to make them durable enough to last and cheap enough to manufacture in volume. If that particular nut is ever cracked, the efficiency (mileage and power) will rise by 30% or so just from that alone. No air cooling, no water cooling, no cooling at all.

In practical terms, one can't really generalize, as peak efficiency v. running temp is highly variable from engine to engine, based on all kinds of factors like exactly how efficient the cooling system is, the combustion chamber shape, the materials used, etc. Saying generally that air-coolled engines MUST run cooler isn't true. Some air-cooled engines may need to run cooler than some water cooled engines for best efficiency. The Type 4 may very well be one of those engines that needs to run relatively cool to work best. You can't extrapolate that to a general rule, however.

OK. I gather we're pretty much in agreement, then. If a perfect system could be designed and built then 100% of the fuel energy would be used to power the engine and no heat would be expelled from the combustion chamber. In that case the engine would be cold.

In support of the earlier statement that I questioned, I suppose that if an engine was running in a more optimal condition so that a higher percentage of the fuel energy was converted to engine power then it would run cooler externally than one that was less efficient. Temperatures inside the cylinder of the more efficient engine, however, would be higher because the air/fuel mix would be closer to optimal.

Regardless, we're not going to get there with our present hardware so we'll have to go back to tinkering with fuel injection and carbs in the hopes of balancing power against fuel economy with heat as waste. That's OK, though, we still need to defog the windows.