"Dialing" in a Camshaft.

[Boydie]

Recently there have been some discussions on how to set the Fuel Injection Pump (FIP) to 10 degrees BDTC. Considereing my limited experiences I think anyone attempting this should first consider checking the position of their camshaft prior to setting the FIP at an increased injection angle.

When I recently re-built the top and front end of my 300TDi after I boiled it enough to cause the head to warp beyond salvagable limits (unless I used a head saver shim plate) I found that the camshaft was about 3 degrees out of the design (blue-print) setting, not enough to prevent a diesel from running but it concerned me all the same, enough to reset it.

In order to "dial" in the camshaft you will need:-

Two Dial guages 0-1" IN .001" increments with extended screw-on probes of at least 100 mm long fitted to a magnetic base(s).

A replacement cylinder head gasket. Use the new multi-plate style.

Inlet/exhaust gasket.

Rocker cover gasket.

8 off valve stem caps. Please dont try to save money by re-using these, they take a hell of a pounding so retire them at every opportunity, ie. every time you re-set your tappets.

A replacement camshaft oil seal,

Crankshaft oil seal,

Crankshaft "O" ring.

4 off new injector "O" rings.

Timing cover oil seal.

A torque angle guage,

A new set of head bolts.

A 250mm long dial torque wrench.

Okay, remove the head, injectors, glow plugs etc. and the front of the timing cover, rotate the engine until, using one of the dial guages on the crown of the piston the No.1 cylinder is at Top Dead Centre (TDC). Pin the FIP and the flywheel. (Number the injectors and replace them back into the same cylinder)

Remove the timing belt, if its in the least bit worn buy a new one and consider replacing the sprockets as well, Bripart do a reasonable kit.

Remove the cam followers and rollers -- remove them in order and later replace them in order, that is No.1 exhaust into No.1 exhaust, No.1 inlet into No.1 inlet. DO NOT MIX THEM UP.

Locate the dial guages so each one is sensing the cam lobes on No.1 cylinder. Turn the cam shaft CLOCK-WISE until you can see the point where the inlet vave is fully closed and the exhaust is yet to open, There is a "flat spot" at this point, measure the rotational distance, you want to be at the mid-point. Set the dial guages to zero and rotate the camshaft several times to satisfy yourself that the camshaft is indeed at this dwell point.

With a scribe and steel ruler incribe a mark on the camshaft and the sprocket (the new one if you're replacing it) and onto the inside face of the timing cover.

Repeat this for the remaining three cylinders, -- remove rhe flywheel pin first - if the camshaft dwell points differ from No.1 cylinder the camshaft is either pooly machined or worn, in either case you should replace. Mine at 254,000 kilometers wasnt so I wouldnt expect yours to be either but it needs to be checked. Replace the flywheen pin on TDC for No.1 cylinder, again, check that the piston is at TDC, zero it --dont rely on cast-in timing marks

Next, refit the timing belt and torque it to the correctly, this is where you need a 250mm long torque wrench with a dial indicator so you can see that the belt is set correctly to between 14 and 16Nm, a "clicker" isnt any good as you need to be able to look at the guage and see that you are applying the torque correctly to the timing belt, I got my wrench on Ebay.

LOOK at the marks you scribed on the camshaft, camshaft sprocket and timing cover. If they are not fully aligned then the camshaft is not set correctly.

If it isnt loosen the retaining bolts and while the sprocket is held in location by the timing belt move the camshaft to re-align the mark on the camshaft to the one on timing cover - use your steel ruler. If you cannot align them you will need to remove the timing belt and with a rat-tail file elongate the bolt holes so that the bolts will fit. Mine were out and the holes needed to be elongated by around 2.0mm.

Re-fit the bolts, fit and torque the timing belt and remove the flywheel and FIP pins, rotate the engine at least two rotations and again check the marks at TDC on No.1 -LOOK at your piston dial guage if you hav'nt moved it it should be back at zero and the FIP pin should slip into place and the scribed mark on the camshaft should align with the scribed mark on the rear of the timing cover. If it doesnt investigate why and repeat the previous steps until it realigns.

If it is happy days, remove the timing belt, remove the camshaft and have the camshaft doweled to the camshaft sprocket. You can do this in a home workshop or at your nearest machine shop. I drilled mine with a dual material (Steel and stone) carbide tip drill in a vertical bench drill, I used a 6mm drill and a 6mm dowel in the camshaft with a 6.5mm drill hole in the sprocket. Hint, DONT heat the camshaft with a flame to get the dowel into the hole, freeze the dowel for around 4 hours in the ice tray and then immerse the camshaft in boiling water for around 10 minutes, the dowel will slip in perfectly, incidentally a 6mm dowel will be a "knock-in" size diameter wise for a 6mm hole but the col/heat method is better than applying a hammer to the camshaft.

Replace the camshaft oil seal and re-assemble the cylinder head starting with replacing the cam followers and rollers into the correct cam lobes, then the head gasket, torque the new bolts down using the torque wrench and torque angle dial guage.

I believe its best to allow at least 10 mins between each torque angle step to allow the bolts to rest. Torque angle tensioning literally stretches the bolts so its best to allow a pause for this stretch to take effect. Incidentally this is why it's false economy to re-use the same bolts, even though the manuals say they can be reused in my experience all diesel engine head bolts are a one use item.

Fit the manifolds (incidentally even with a brand new cylinder head it's a good idea to drill, tap and fit stainless steel HELICOILS in the alloy cylinder head as these are stronger than the original alloy manifold threads)

Fit the new crankshaft oil seals, "O" ring, timing belt (re-torque), new sprockets and crankshaft oil seals, NOTE if you dont have a short torque wrench torque the belt BEFORE installing the head! If you dont the thermostat housing will get in the way.

Refit the front timing cover and crank pulley, NOTE the position of the timing mark for future referance, it may be out, mine was perfect.

Refil with coolant.

Hint, to remove all the air from the head, first fill the system up to the top of the radiator and fit the radiator brass plug, fill the overflow tank to just a bit below full, have the brass plug hand tight and with the pressure cap off blow into the overflow tank, the water will push out all the air, when coolant is flowing from the brass cap, and with your mouth still over the reservoir, reach over and screw the thermostat plug down, if the system is air and water tight the level in the overflow tank will not change, if it rises you have a leak.

Finish assembly, re-fit such ancillaries as injectors and start your engine.

[landroversforever]

Something to be stashed in the tech archive I think!

[piper109]

Wow, taking the head off etc seems like a lot of work to be doing for that. Could you not do the checking at least, by putting a full circle protractor on the crankshaft pulley and using your two dial indicators on the rocker adjustment screws or similar? You only have to remove the valve cover to do that.

Steve

[Boydie]

As I said Steve, my cylinder head was off anyway as it had to be replaced as it was warped beyond recovery.

The other three considerations are that :-

1.) The cam followers and rollers need pressure to remain in contact with the cams, and my dial guages wont apply that sort of pressure so they are best removed and for me it was a case of "Oh well while the head's off...."

2.) As for measuring the cam at the rocker adjustment, yes, it would be possible if you first set the tappet gap to zero and then found a location to fix the dial guages, the magnetic base wouldnt be useful on the alloy head so a fixture mounted on one of the rocker shaft/rocker cover bolts would need to be fabricated.

3.) The third thing is if the camshaft is out of true as mine was (even though I assume within tollerance) and needs to be re-set to be exact and then doweled to the cam sprocket the camshaft has to be removed from the block and to do that all the cam followers and rollers need to be removed and to do that the head has to be removed.

[piper109]

OK Boydie,

1 if you have the head already for other reasons, I would certainly agree that that makes a big difference but for someone who has their head on, with a good gasket etc but none the less has an insatiable desire to check their valve timing, your method does seem a bit labour intensive.

2 With two bits of ten thou gauge you can take care of the valve clearances, keep the followers in place and get the valve clearances set all at once. What a deal!

3 To blueprint an engine to that degree you have to be a true blue enthusiast (pun intended). The venerable 300tdi however has fine characteristics which place it high indeed for an engine that is a small but important step away from a tractor engine. Other engines have valve timing that varies with rpm. Most camshafts then are a compromise of engine needs for idle to max speed but are probably not entirely optimal for any particular speed.

How do you know that by setting your camshaft to that degree of accuracy, you are improving the gas flow for an engine speed you actually need while driving, rather than just improving the idle?

Its a well written write up, very comprehensive and represents a lot of time and effort and you should receive applause for that !!

cheers right, mate.

Steve

[Boydie]

You got several things right, one being that I'm anally intentive and I enjoy building engines perfectly, it's a fad I guess, like going through a crate of pistons to find just four that were identical diameters and then using a toolmakets grinder to ensure all were exactly the same weight, that the con rods were identical in length and weight (static and dynamic) as well as the crank ballance etc.

Sure there isnt anything refined about the 300TDi but I've had fun making sure its the very best that it can be and knowing that it will be still fine in around 400,000 kilometers just because of the additional effort and fun in the assembly

But my point is still valid, you cannot dowel the camshaft without removing it -- unles you want to dry drilling it in situe, and good luck with that idea!

[redneck]

You got several things right, one being that I'm anally intentive and I enjoy building engines perfectly.

Interesting post, but your assuming the manufacturers cam timing is the optimum.

Unfortunately cam timing is all about compromise, advancing /retarding the cam alters the torque and horsepower, and where the torque and horsepower peaks in the rev range. Changing the timing can improve your vehicle depending on your driving style and requirements.

You can say you've set it perfectly to the manufacturers specification though.