Cam tuning

[Tomoturbo55]

Mk2 owner 1.6 TD ic 80hp engine,

Turbo k24 20 psi+ Ducato intercooler
2.25' downpipe all the way and Remus muffler
N/A pump with fuel turned up and gov mod.

The car has a good bottom end and no high-end power after 4k, turbo spools faster than it should, in my opinion, and full boost at first gear no problem.

The top speed is 111 mph. Before the intercooler, and small exhaust it was 100 mph.

I can put it in fifth and drive at 500 rpm without it shaking or dying. All timing is set at zero but my worry is that I should retard the cam timing a little.  Maybe the previous owner installed the flywheel wrong so I have no top end?

Has anybody played with Cam timing on these engines cause I can't find any info.

[fatmobile]

When you say all timing is set at zero you don't mean injection pump timing right?
That should be at 12BTDC.

[ORCoaster]

With a standard N/A IP, you are not getting additional fueling at boost.  So of course you will be high end limited.  No fuel, no speed.  Simply that.

Get a turbo pump on it and see what it will do. 

[Tomoturbo55]

I mean set at all timing Marks the Cam the pump and crank

[Tomoturbo55]

Fuel is turned up and governor mod is done so i have fuel, very light haze of black smoke at 20 psi

[fatmobile]

With a standard N/A IP, you are not getting additional fueling at boost.  So of course you will be high end limited.  No fuel, no speed.  Simply that.

Get a turbo pump on it and see what it will do. 

A 9mm pump will pump what a 9mm pump can.
 The LDA only reduces fuel when there is no boost.
It doesn't add more fuel than a regular 9mm pump when there is boost.

Sounds like you don't know what the injection pump timing is.
 That's usually found with a pulse detector and timing light.

I once got my cam timing off by about 1/4", not sure which way,
it reduced power in the midrange.

[ORCoaster]

Fatmobile, IF

The LDA only reduces fuel when there is no boost.
It doesn't add more fuel than a regular 9mm pump when there is boost.

Then why is there a taper to the control mechanism?   The pin that everyone wants to shave to make it have a steeper slope.

Does not that allow that pin that rests against the cone to push against the metering internals and allow more fuel to be placed into the secondary stage of the pump? 

Wait a minute I think I just answered my own question.   I see what you mean, given that the pump will push the fuel into the injectors no matter what.  There is no way to get more fuel into that part of the system unless you pressurized the first stage of the pump, correct?

So does that LDA boost controller reduce the force being placed on the fueling spill collar and allow it to stay open longer than it normally would?  Is that what is going on when we feel that increase of speed as the boost pressure goes up? 


TomoTurbo55, lining up the cam to be flat with the head is correct. Lining up the IP with the pin in the hole is correct.  Lining up the IP mark on the bracket or whatever is only a starting point for getting the timing to where it needs to be.  You have to either use a dial gauge to measure the amount of lift of the cam or as Fatmobile says measure it with a system that will tell you the degrees of advance that the fuel is being delivered to the injector.

I use the dial gauge to do a dirty set and then break out the little adapter that goes in the glow plug hole and a means to convert that light signal to an electronic one that my timing light can be triggered with.  I also have a couple of Snap-on meters that use the flywheel pickup and read the degrees from that directly.  It just is real fussy and I have snapped off the pick-up head on one already. 

But yes do a proper timing on it by moving the IP forward or backwards to retard or advance the fuel delivery.  On Turbos you need to get it a bit earlier than NA as the increase compression can light it up earlier than later.  For me that means running 135 mm of advance to get it to fire at 10 degrees TDC.  I was running at 95 for a while and didn't know it and wondered why I didn't get much for performance out of the 10 lbs of boost.

[Tomoturbo55]

I timed my pump by ear. I push it till it starts to clatter and then back off a little bit, it worked so far on a few engines.

The only thing I can think of is a weak vane pump not giving enough advance.

If I hit the regulator it had trouble starting until it builds case pressure I guess.

I have a TD regulator and TDI large spring and cap to get more advance but I guess the spring is too stiff and the pump is worn out or is it?

I will have to play a bit with this before Winter comes.

[ORCoaster]

Timing by ear is only a "get it running" sort of adjustment.  If you want to get it running correctly you need to time it at least with a dial gauge.

Vanes may be worn and they are not building good internal pressure.  Does the pump have a problem drawing fuel from a bottle or jar into the pump?  A good test of that side of the pump is to remove the line going to the fuel tank and measure the outflow at 1000 RPM.  Kind of hard to do with an engine that won't hold an idle but otherwise you should get a liter of outflow in 90 seconds.

If you don't get that volume then you need to tap down that pin in the front of the pump, near the inlet until you do.  Tap it a bit at a time and if you go too far remove the whole assembly tap it through and start it all over again.  Measuring the depth of the pin to a reference before you start is a good way to keep track of your hammering progress. 

Internal pressure is what moves the piston under the pump to provide an advance to the timing.  You may find that once you get proper static timing you will need to adjust it back once your flow rate is up to 1 liter. 

If you have a large LDA on top of the pump the spring under the cap is what can be adjusted to push up on the diaphragm.  Turning that star wheel up increases the amount of pushing up it does.  So put a mark on it and twist it down and the boost will act sooner. 

When you take the cap off note there is a dot generally on the rubber diaphragm. Note where it is pointing, 12, 3, 6 or 9 o'clock, on a face of an old style clock.  Now look at the pin itself, see the tapered side of it?  That should point to the dot.  If not loosen the nut and twist it around to make it so.  You want to use that dot as a reference too but you may need to set the pin proper in order to do so. 

Inserting the pin into the hole maybe a hassle if the tiny pin at the bottom of that hole has moved outward.  Just use a skinny, long screwdriver to move it to the left and it should go back together properly. 

So where was the steepest part of that pin pointing?  If it was towards the tiny pin at the 9 o'clock position you were at max boost setting.  Most pumps I see when I tear into them have that pin at the 3 or noon position.  Those give the least or mid-boost settings.  6 is like noon so a mid position too. 

Is any of this making sense to you?  You might print it out and then go disassemble the top of the pump and see how it is put together.  I think there is a post here someplace with the diagram of the LDA.  IF I find it I will add it later. 

[fatmobile]

 With a 9mm pump like we use on these old diesels.
 There are limits to how much fuel it can push.
 Putting an LDA on top doesn't change that.
 I haven't done side-by-side tests to prove that an NA pump will push as much as one with an LDA.
 It's something the local bosch service center guy told me.
They were designed to reduce smoke when the boost is low.

 When you hit the internal pressure regulator it will advance the timing.
By causing higher internal pressure earlier and moving the timing piston.
 Basically it moves the starting point but the line stays the same.
I say line because the timing graphs I've seen were pretty linear, pretty straight.
 Might be why it made it hard to start.
It's like rotating the pump and advancing it.
Too advanced and it will fire before TDC, which makes it hard to start.
Along with using the cold start to hear where timing should be.
 Using the cold start lever to find out where the engine likes to start and using that info to adjust the timing works pretty good too.
 Especially good if there is cold weather to really find where it likes to start.
Sometimes you pull the CS and it turns slower. I've heard on the MK2s you are supposed to let the engine speed come up and try to start before pulling the CS.
 I haven't messed with the TDI timing piston stuff.
 I usually shave 2mm off the end of my piston so it can move farther, give me a little more advance at high RPMs.

[Tomoturbo55]

On the past i had lda on N/A pump without remowing limiter pin, with TD throtle Springs, governor mod and agresivne side on the pin i had fuel for 30 psi on k24 turbo probubly could have more but i was woried that was too much, blinding road behind, but i guess without limmiter pin fullcrum lever can travel few millimiters further meaning more fuel.

About pump regulator when i hit it few times it Would jump timing and i could hear clatter, that is when i set out flow od fuel by haggar 0.5 liter of fuel in 1 minute.

Then i readjust pump timing by ear again, when i try to start after some time i need couple of revs to start witch i dont Like, if i turn it off and immidietly on its good

Fells Like preassure drops after some time inside pump with couple turns its Back to set preassure so timing moves and everything is good for propper running, or could be dirty or bad vane pump not drawing fuel right away.

[fatmobile]

 What are you seeing for EGTs?
 I consider an EGT gauge to be a handy tool for figuring out if there is enough air for the fuel.
 I try to provide enough air to keep it below 1200F.

[Tomoturbo55]

I dont have egt gauge but i have verry light black haze at 20 psi, intercooler piping is pretty cold so i don think egts are to high.