Distributor question

[raygreenwood]

Its worth it to know that the 411's all came with D-jet. The 412's came with D-jet early and L-jet late. Except for the meteing controls...on the surface..the two systems looked very similar. They used the same basic auxiliary air regulator. The plenum on the 1.7 and 1.8 were the same in general. What you preobably have in the metal ceneter plenum...if it was larger and boxier...is a plenum from a 2.0 bus. The TB's can look very much the same...but are actually different art #'s. Slight variations. The throttle valve switchesfrom D to L jet were different. The temperature sensor on th air intake was the same for both injections...as was the cylinder head temp sensor. The fuel pressure regulator on D jet is adjustable fixed rate. It has a screw sticking out of the dome. L-jet is vacume variable. The D-jet has a fist sized aluminum gizmo that looks like a pump or something...off to one side...with asingle vacume line going to the manifold..and a four wire plug. That is the manifoldpressure sensor. It is the main load unit for adjusting fuel mixture. The L-jet has the AFC...which is the box wit the swinging air flap in it...as part of the air cleaner assembly. That is the main load and fuel sensor for L-jet. The fuel pumps were different. L jet I believe (memory here)...also fires all of the injectors at once. Since they were generally out of sync on two cylinders in D-jet...and it made little difference..they economized and got rid of that timing circuit. But...if you can make injection sequential...and control when in the timing cycle each injector injects...you can actually get much better throttle response due t not wasting the atomization from the injectors. Ray

[vwbill]

Its worth it to know that the 411's all came with D-jet. The 412's came with D-jet early and L-jet late. Except for the meteing controls...on the surface..the two systems looked very similar. They used the same basic auxiliary air regulator. The plenum on the 1.7 and 1.8 were the same in general. What you preobably have in the metal ceneter plenum...if it was larger and boxier...is a plenum from a 2.0 bus. The TB's can look very much the same...but are actually different art #'s. Slight variations. The throttle valve switchesfrom D to L jet were different. The temperature sensor on th air intake was the same for both injections...as was the cylinder head temp sensor. The fuel pressure regulator on D jet is adjustable fixed rate. It has a screw sticking out of the dome. L-jet is vacume variable. The D-jet has a fist sized aluminum gizmo that looks like a pump or something...off to one side...with asingle vacume line going to the manifold..and a four wire plug. That is the manifoldpressure sensor. It is the main load unit for adjusting fuel mixture. The L-jet has the AFC...which is the box wit the swinging air flap in it...as part of the air cleaner assembly. That is the main load and fuel sensor for L-jet. The fuel pumps were different. L jet I believe (memory here)...also fires all of the injectors at once. Since they were generally out of sync on two cylinders in D-jet...and it made little difference..they economized and got rid of that timing circuit. But...if you can make injection sequential...and control when in the timing cycle each injector injects...you can actually get much better throttle response due t not wasting the atomization from the injectors. Ray

Hey Ray, which sys has better perfoemanceLjet,djet? Is dual points better?
Do you think my 412 has a 1.7 djet because it was from the 411/412 transition or a transplant? Which engine and sys was the more perf.? Did the porche 914 engine set vary and was it a better performer? If the Ljet and 1800 was the later 412 series was it the better perf and reliability or is that mostly a engine cam/crank/head/ factor not air/dist/fuel? Thx Bill

[raygreenwood]

The D-jet made more Hp. Wether it was simply a better combustion chamber and piston design with better compression...or the injection....we will never know. VW never made the high compression 1.7 in the 412 with L-jet. But...D-jet is a bit more adjustable. That is to say there are also more adjustments that need to be made in setting it up...if things are way off. Its also a little more tedious. Its my experience that D-jet had much better throttle repsonse than L-jet no matter what. Parts for D-jet are a little more scarce. L jet is a bit simpler. The 1.7 with D-jet had 8.2:1 compression from the factory. It made better HP. It has a nicer head design...made to work with the dome pistons. But it has smaller combustion chambers than the 1.8. I'm biased. I happen to like the tunability in D-jet...but its not everyones cup of tea...and L-jet had better harness connectors. More dependable. I use them on D-jet no problem.

The 1.7, 1.8 and 2.0 all used the same cam. Even in the 914. The 1.7 in the 411/412 and 914 are identcial down to the last part #. I think the 1.8 with L-jet could make as good or better power as the 1.7 with D jet ,with better compression. Better still...find some domed pistons and add those and the 1.7 heads to the 1.8 with L-jet. The compression will be close to 9.0:1...but it would be a runner! ray

[vwbill]

The D-jet made more Hp. Wether it was simply a better combustion chamber and piston design with better compression...or the injection....we will never know. VW never made the high compression 1.7 in the 412 with L-jet. But...D-jet is a bit more adjustable. That is to say there are also more adjustments that need to be made in setting it up...if things are way off. Its also a little more tedious. Its my experience that D-jet had much better throttle repsonse than L-jet no matter what. Parts for D-jet are a little more scarce. L jet is a bit simpler. The 1.7 with D-jet had 8.2:1 compression from the factory. It made better HP. It has a nicer head design...made to work with the dome pistons. But it has smaller combustion chambers than the 1.8. I'm biased. I happen to like the tunability in D-jet...but its not everyones cup of tea...and L-jet had better harness connectors. More dependable. I use them on D-jet no problem.

So if all the motors are the same why did they use two different injection systems? Why is the 1800 7.3:1/76hp? Does the dome and injection system matter over the 3mm to 12mm total volume. to the cyl. I guess its smart to use the best of both the designs, like you said! So is it the heads or injection system or dome? I guess its all down to getting all the performance from either system and motor you have! Like you said before, just the little stuff can cost hp. I think its funny to think that VW didnt just have one inj. sys and diff. bores for the 411/412/914 series. Why didnt they just change the setup programming or just heads? I always thought the Porsche design and setup would have been the best performer! I always love the sing rev of the pancake motor when its in the power curve! For a small motor it pulled! Like that roar sound of the waterboxer vanagon in its curve they sound bad to the bone! I put the dist in but it didnt pop. I have to start going over the stuff to confirm whats workin right! It should pop at least! I think it doesnt want to go till I get the frt end work done, lol! Thx again for the great info, Bill



The 1.7, 1.8 and 2.0 all used the same cam. Even in the 914. The 1.7 in the 411/412 and 914 are identcial down to the last part #. I think the 1.8 with L-jet could make as good or better power as the 1.7 with D jet ,with better compression. Better still...find some domed pistons and add those and the 1.7 heads to the 1.8 with L-jet. The compression will be close to 9.0:1...but it would be a runner! ray

[raygreenwood]

I will be a little more clear. The 1.7's were all the same ...with fuel injection. The carbed 411 engines in europe and the carbed bus engines were also identical in every way to the injected engines...except for the use of dished instead of domed pistons. That also gave extra HP. All the fuel injected 1.7's had domes and 8.2:1 compression. Same cam, same basic distributor etc. The 1.8...was a later engine. It used the same heads as the 1.8 in the bus and the 914. It also used L-jet in the 412 and the the bus.

The changes to the injection system were mainly due to making it simpler, easier for a dealer system to tune and going to a better connector system on the harness. You must remember, D-jet was the 1st production electronic injection system in the world. Its debut was originally on the type 3 in 1968. It came over here on the type 4 in about 70-71.

That being said, I tink L-jet is nice...but I also feel it does not adjust as encrementally. It also ...I feel is less sensitive to subtle changes in manifold pressure. At least not as sensitive as D-jet. That can be positive and negative. The problems with D-jet in this day and age will be keeping a working MPS and a decent harness. I have hadto put a project on hold...but the first 3 days in a row I have off....I will be offering replacement copper diaphrams for those MPS. I just got a new fixturing alloy in that allows me take make more than a couple at a time. Much more uniform.

All else is about equal in dificulty and price to get for either L and D jet. Sensors, connectors , pumps, TB's. Which is better? For ultimate tuning..if you are going to keep an original FI system like this.....and willing to really learn a few wierd things...D-jet. It is also a whole lot of work to get higher tuning out of...just a lot of tedious work. The L and D jet...just out of the box on thesame engine, will run about the same. the real differences in the 1.7 and 1.8 are the heads, pistons, valves and compression.

Remember these things: 1.7 liter ; carbed ,flat tops., 7.8:1 comp 37.5 x 33 valves. 68 hp@4500 with 93 lbs torque. Rarely if ever on this continenet.

1.7Liter w/ D-jet domed pistons , 8.2:1 comp 39 x 33 valves , 82 hp@4900, 99.5 lbs of torque

both enines had the same cam, same heads, same ignition except for the advance unit.

There was also the EB series smog engine in california
1.7 liter, dished pistons, 7.3:1 comp, 39x33 valves, 72 HP @ 5000 , 90.3 lbs torque.

1.8 liter. UK edition. 8.6:1 compression, 41x34mm valves, 85 HP @ 5000 rpm. Domed? pistons? On the 412 these used twin solex 40's

1.8 liter UK edition 7.8:1 comp., 41x34 valves, 75hp @ 5000 rpm

USA edition 1.8l Dished piston, injected l-type, 7.3:1 comp, 41x34 valves, 76 HP@ 5000 rpm.


The real correlations are this. In all of the engines wether 1.7 or 1.8, the larger valves allow a higher rpm powerband...or it can make power to a higher rpm with free er breathing. The lower compression really keepsr specific power low. So..its in the total configuation. I know this much, on a stock 1.7, because of the small size of the combustion chamber, and the shape...which is made to work well with the domes, you can raise compression ungodly high, very quickly, with minor mods. .030" of extra dome and the ommission of the gasket will bring the compression up to about 9.0:1. The high compression works well...maybe 8,8:1. But the small combustion chamber will become a restriction above about 93mm. It may also not be the head for a stroker (the 1.7L). I do believe its one of the most tunable...as long as the engine volume is kept sane. All of the type 4's benefeit greatlt from decent port work, larger valves and a decent cam.
So.......if the 1.8 in England made 86 HP with carbs...whyt would I want Fuel injection? Simple. It took larger pistons and larger valves and 100 more rpm to gain 4 HP...and only half the throttle repsonse...andabout 15-20% less gas milage. Imagine an L or D injected 1.8 wwith 8.6:1...and larger valves. That would be about 90 HP. With better valves, port work, tuning, cam, and compression...you can achieve 100 HP on a 1.7L. Sorry for the length. Ray

[vwbill]

I will be a little more clear. The 1.7's were all the same ...with fuel injection. The carbed 411 engines in europe and the carbed bus engines were also identical in every way to the injected engines...except for the use of dished instead of domed pistons. That also gave extra HP. All the fuel injected 1.7's had domes and 8.2:1 compression. Same cam, same basic distributor etc. The 1.8...was a later engine. It used the same heads as the 1.8 in the bus and the 914. It also used L-jet in the 412 and the the bus.

The changes to the injection system were mainly due to making it simpler, easier for a dealer system to tune and going to a better connector system on the harness. You must remember, D-jet was the 1st production electronic injection system in the world. Its debut was originally on the type 3 in 1968. It came over here on the type 4 in about 70-71.

That being said, I tink L-jet is nice...but I also feel it does not adjust as encrementally. It also ...I feel is less sensitive to subtle changes in manifold pressure. At least not as sensitive as D-jet. That can be positive and negative. The problems with D-jet in this day and age will be keeping a working MPS and a decent harness. I have hadto put a project on hold...but the first 3 days in a row I have off....I will be offering replacement copper diaphrams for those MPS. I just got a new fixturing alloy in that allows me take make more than a couple at a time. Much more uniform.

All else is about equal in dificulty and price to get for either L and D jet. Sensors, connectors , pumps, TB's. Which is better? For ultimate tuning..if you are going to keep an original FI system like this.....and willing to really learn a few wierd things...D-jet. It is also a whole lot of work to get higher tuning out of...just a lot of tedious work. The L and D jet...just out of the box on thesame engine, will run about the same. the real differences in the 1.7 and 1.8 are the heads, pistons, valves and compression.

Remember these things: 1.7 liter ; carbed ,flat tops., 7.8:1 comp 37.5 x 33 valves. 68 hp@4500 with 93 lbs torque. Rarely if ever on this continenet.

1.7Liter w/ D-jet domed pistons , 8.2:1 comp 39 x 33 valves , 82 hp@4900, 99.5 lbs of torque

both enines had the same cam, same heads, same ignition except for the advance unit.

There was also the EB series smog engine in california
1.7 liter, dished pistons, 7.3:1 comp, 39x33 valves, 72 HP @ 5000 , 90.3 lbs torque.

1.8 liter. UK edition. 8.6:1 compression, 41x34mm valves, 85 HP @ 5000 rpm. Domed? pistons? On the 412 these used twin solex 40's

1.8 liter UK edition 7.8:1 comp., 41x34 valves, 75hp @ 5000 rpm

USA edition 1.8l Dished piston, injected l-type, 7.3:1 comp, 41x34 valves, 76 HP@ 5000 rpm.


The real correlations are this. In all of the engines wether 1.7 or 1.8, the larger valves allow a higher rpm powerband...or it can make power to a higher rpm with free er breathing. The lower compression really keepsr specific power low. So..its in the total configuation. I know this much, on a stock 1.7, because of the small size of the combustion chamber, and the shape...which is made to work well with the domes, you can raise compression ungodly high, very quickly, with minor mods. .030" of extra dome and the ommission of the gasket will bring the compression up to about 9.0:1. The high compression works well...maybe 8,8:1. But the small combustion chamber will become a restriction above about 93mm. It may also not be the head for a stroker (the 1.7L). I do believe its one of the most tunable...as long as the engine volume is kept sane. All of the type 4's benefeit greatlt from decent port work, larger valves and a decent cam.
So.......if the 1.8 in England made 86 HP with carbs...whyt would I want Fuel injection? Simple. It took larger pistons and larger valves and 100 more rpm to gain 4 HP...and only half the throttle repsonse...andabout 15-20% less gas milage. Imagine an L or D injected 1.8 wwith 8.6:1...and larger valves. That would be about 90 HP. With better valves, port work, tuning, cam, and compression...you can achieve 100 HP on a 1.7L. Sorry for the length. Ray

I just think its funny they didnt just go with a 1800 big valve fi motor all around by the time the had work it on the t3's. Lots of diff. setups fuel wise from carb to fi....Must be alway for diff uses maybe or just the natural progression of the motor. I think the dist without the points seems simpler and reliable.. I wish they would put a test led on all the componant and a main sensor reading light too...Just look at the light and move on... I want to go to the problem easy...lol! They need to make a board to show you the connections on the fi sys. Maybe a radioshack project lol. I just want to find the adj. problem. Does changing the weight springs in the dist. to a diff metal help drive the power or is that just a fuel reading on the manifold? I was thinking about that when I had it apart. I put different springs on a monza and it helped the power curve.
But I'm sure if the fi is right it will meet the demand. I cant believe I dont have it back running with the parts I had. If its right it will start on the dime. I think Im on to the struts and the boots are gone..... I have it back to the backing plate off and painted. do you pull the strut with the ball joint? I have nos inserts and ball joints. am I gonna find a zero strut mount,lol. It was lookin like I should do the tie rod end now too...
Thanks wahoo with all your stuff and the info!! Bill

[raygreenwood]

Aaaah...you have hit on several points of interest. The engine in the 411/412...you will have to remember...was very young compared to the bug. It had only really been in existance for about 4.5 years when the 1.8 liter ctarted coming about. Unlike american cars, the Germans tend to think of efficiency before just "larding" on the cubic inches and the weight like the V-8 USA crowd. The 1.7 size...and the engine design...and the fuel injection...were monumental improvements over what the bug had in it. The 1.8 was mainly an amswer for the american market. With the new smog laws...we had to lower NOX. To do that, they lowered compression and changed the deceleration characteristics with both different vacume retard units and slight changes to the advance curve. But...in order to keep the HP more "type 4 ish" they used larger valves and displacement.

You have to keep in mind that compared to the bug and type 3....the 1.7 with its smallish valves (compared to a 1.8 or a 2.0 porsche.....bt large compared to a 1600)...more than satisifed a big jump in HP...from what...54 on a bug...maybe 60+ on a type 3 (not including the high compression euro type 3)...to 82 on the 1.7 with injection? Thats stinkin great! Until the american market (THE main market)...brought up th emissions issue, there was no need for the 1.8. I feel the 1.8 was a "quickie" answer. With correct tuning...read that as R&D and testing time...the 1.7 could have been 90 HP in thw next year...yes with bigger 1.8 valves, and 100 easy with combustion chamber and cam work.

Just changing the springs has a lot to do with both the fuel and advance curve onb the 1.7 with injection. Start by simply tightening up that long loop in the smaller spring, before you go anywhere else. Also...bear in mind, when you add a tad more timing than stock...which helps of the line...you are also pulling the injection timing out of line. So if you advance 3 degrees on timing...slot the trigger plate..and retard that 3 degrees. You will notice better stability in the fuel pressure...because the augmented vacume signature has a tendencey to cause pulses that change the injection duration. Keeping the injection timing as close as possible helps keep it smooth. Ray

[vwbill]

Hey the vacuum can looks like the one on a porsche 924 78-81. except the one on the 205P has a set-screw/locknut adjustment. Think it would work? Why do they have the adj. set screw in it? Have to find a djet dist. I have all the ljet stuff off a 1800fi. LOl. Thanks for all the info, bill

[raygreenwood]

The 205 P unit is the most desireable. When you compare advance units, of course they have to physically fit the distributor....but the main thing is the # stamped on the arm. The one with the locknut and screw is a 917. The adjustment screw is 100% necessary on 411 and 412. In fact....on all type 4 in my opinion. The advance rate is quicker on the 917 unit. So it can greatly overadvance you without the adjustment screw.

What you need to do, is find a junkyard or shop that has lots of old, but working advance units. Many are almost identical to the 917....except for the adjustment screw. You need to take a small hand vacume pump with a guage and a dial caliper to the junkyard. Write down the # on the arm of a unit you test, pull vacume slowly and measure how far each inch of mercury will move the arm. Make a list. When you find one close...I can tell you at a later point how to install an adjusting screw.

Vacume retard. Do you need it? Well....it is an emissions device. But on D-jet, it is also a bit of a safety device depending upon the model. If you are also using the deceleration valve, retard is not really that necessary. What happens to an an engine with D-jet and no decel valve, isthat on long high speed engine overrun...like a freway off-ramp in 3rd gear, the throttle is shut. Vacume is high, enrichment is very low....but with rpm high, advance is way high...see the potential problem? The decel valve ...contrary to what the books say, works just a bit opposite. It bleeds a little air past, allowing a small amount of part throttle enrichment. Yes...you also get a little from the rpm signature in the ECU, but depending upon compresion, advance level etc...that may not be enough. Retard, coupled with a decel. valve really constitutes and emmissions package. But with the decel valve, retard is really redundent in the performance scheme of things.

That being said.....there is also a single advance unit used on 411/412 in europe. It is still fairly available and common. I will get the arm # and aprt # to you when I get home . It also needs aset screw installed. Ray

[Guest]

The 205 P unit is the most desireable. When you compare advance units, of course they have to physically fit the distributor....but the main thing is the # stamped on the arm. The one with the locknut and screw is a 917. The adjustment screw is 100% necessary on 411 and 412. In fact....on all type 4 in my opinion. The advance rate is quicker on the 917 unit. So it can greatly overadvance you without the adjustment screw.

What you need to do, is find a junkyard or shop that has lots of old, but working advance units. Many are almost identical to the 917....except for the adjustment screw. You need to take a small hand vacume pump with a guage and a dial caliper to the junkyard. Write down the # on the arm of a unit you test, pull vacume slowly and measure how far each inch of mercury will move the arm. Make a list. When you find one close...I can tell you at a later point how to install an adjusting screw.

Vacume retard. Do you need it? Well....it is an emissions device. But on D-jet, it is also a bit of a safety device depending upon the model. If you are also using the deceleration valve, retard is not really that necessary. What happens to an an engine with D-jet and no decel valve, isthat on long high speed engine overrun...like a freway off-ramp in 3rd gear, the throttle is shut. Vacume is high, enrichment is very low....but with rpm high, advance is way high...see the potential problem? The decel valve ...contrary to what the books say, works just a bit opposite. It bleeds a little air past, allowing a small amount of part throttle enrichment. Yes...you also get a little from the rpm signature in the ECU, but depending upon compresion, advance level etc...that may not be enough. Retard, coupled with a decel. valve really constitutes and emmissions package. But with the decel valve, retard is really redundent in the performance scheme of things.

That being said.....there is also a single advance unit used on 411/412 in europe. It is still fairly available and common. I will get the arm # and aprt # to you when I get home . It also needs aset screw installed. Ray

Hey Ray, the vac. arm has two numbers 979,917. 917 runs accross the tip looking at the end clip the other runs to the tip along the edge from the can to end. Thx, bill