e30 M3 minor rust repair.

[xworks]

along side this the custom gudgeon pins that accompanied the JE pistons also
helped the diet............



When the math is done the custom pistons and pins had managed to shave
over half a kilo (612.4g) off the rotating mass total.
The other items that came with the pistons were oversized piston rings.....



The reason they were oversized (too big for the cylinder bore) is as follows.
When a piston ring is fitted to a piston and then dropped into the cylinder
there is a gap in the ring as shown below......



the reason for that gap is to allow the piston ring metal to expand when the
temperatures start to rise in the cylinder with the engine running. The piston
rings main job is make sure all that rapidly expanding gas from the little explosion
the spark plug just started, stays above the piston pushing it down.
So, with that in mind, we'd really like if there was no gap at all in the ring when the
engine gets up to operating temperature. The rings that come with standard pistons
are designed in such a way that this gap is small when things are warm, but,
with customs rings you can get it a little smaller which should result in an even better seal.

The rings that come with the JE pistons are oversized, which means if you place them into
the cylinder as they are, they overlap. So you've got to file them down to just the right gap
which is usually specified by the ring manufacturer. Theres plenty of special tools out there
which you can buy to do this exact job and they range in price. But, seen as how I now owe
money to almost every known lending institution in the free world, I thought it might be best if I
knock up a tool from what I have rather than hitting e-bay.
What you see below is a Dremel with a narrow grinding disc and a little bent sheet aluminium table
for the ring to sit on.........



The pictures are fairly self explanatory I think. The grinding disc is set up so that
it only grinds the ring towards the centre as you don't want sharp edges on the
outside circumference of the ring that could scrape the bore. And the four little
brass thing-a-ma-jigs make sure the ring rotates squarely into the disc.......



so that you end up with a gap like below, so that when heat expanded together in the
engine the ends will be parallel to each other..........



the grinding process itself is a slow and meticulous one. The rings are ground a tiny
bit and then fitted into the block using a piston to sit them square.........



and then the gap is measured with feeler blades till you reach the required size.....



The whole process takes quite a while as you don't want to grind too much and
risk having to order more rings and start all over again. As is the nature of these things
you should just be getting the knack of how much needs to be taken off each ring when
your finishing the last one.
When all's done and dusted the rings are packed away for the final assembly........

[xworks]

After the rings were finished there was just two final checks to be completed on the
pistons. Check the volume of the dish on top of the piston to make sure our target
compression ratio was looking good, and finally, check to see if the valve relief's cut into
our new pistons were giving us a safe valve to piston clearance.

The dish volume test is the same as was shown a while back,
seal the piston with o-rings, fill with fluid, blah, blah, blah. The dish volume came out at
7.5cc, which is bang on the money. So we could move on to the valve clearance test.
For this we're going to have to pretty much build up most of the engine and fit and
time the camshafts, as we need to find out how much clearance there is between the
valves and the pistons at their tightest point.

One job thats needs to be tackled during this dummy build is the fitting and "timing in" of the
Schrick camshafts.
Theres no hard and fast rules for timing in a set of camshafts, lots of folk have their own method
of doing it and as long as the end result is the cams timed correctly then I suppose it's irrelevant
how you got there. It can however, be a little difficult to explain with pictures and words as opposed to
if someone was beside you watching it, so I've chosen a method here that hopefully should make
sense on paper.
First thing we gotta do is find "T.D.C".
What the f*ck is T.D.C?
TDC is short for Top Dead Centre and what it's referring to here is the position of the piston
in its cylinder. When the piston has risen to the exact top of it's cylinder this position is known as TDC.
For the purpose of camshaft timing you'll almost always be talking about the piston in number
one cylinder. If we want to time the cam's in accurately we've got to know where TDC is .

So, the crank is rotated till number 1 piston comes to the top of it's cylinder as
measured by the little dial gauge shown below..........



On most engines there will be a mark on the crankshaft pulley and timing case that align
to show you your on TDC on number 1 cylinder, and the S14's looks like so...........



Unfortunately for the purposes of cam timing this isn't accurate enough and the reason why
is, if you rotate the crankshaft a tiny bit to the right or a tiny bit to the left what you'll find
is that the piston doesn't move. The dial gauge still shows 0.00. The reason for this is
there's a sort of "dwell" period or dead period between the crankshaft pushing the piston
up the cylinder and just before it starts pulling it down the cylinder. The middle of this
"dwell" period is true TDC and it's what we need to find before we can move on.

So how do we find it? Well you need one of these known as a degree wheel..........



It's basically a large disc marked out with 360 points on it that you either bolt, glue,
nail or weld to the crankshaft pulley to allow you to accurately turn the crank to a
given position between anywhere on it's 360 marked degrees.
The other thing thats needed is some sort of pointer to line up with this disc so you
can see what position you've turned it too. For this we've used a simple M6 bolt
screwed into the timing case and cut a slit into the head of the bolt to act
as the pointer...........



degree wheel fitted to crankshaft pulley with the aid of two totally inconspicuous
welding magnets.........



and with number 1 piston "roughly" at TDC the degree wheel is aligned with the pointer
to read Top Dead Centre for the moment........



Then, onto the actual process of finding where the exact TDC is.
With the dial gauge pointer still resting on top of the piston and reading
0.00mm the crankshaft is turned backwards till the piston has dropped 5.00mm
exactly down the cylinder...........

[xworks]

At this exact point a reading is taken off the degree wheel and as you can see
below its at 23 degrees..........



Once the degree is scribbled down somewhere the crankshaft is rotated back
to TDC (0 degree's) again, and now the engine is rotated in the opposite direction
till again the piston has fallen 5.00mm down the bore..............





and again you take note of the point on the degree wheel, which in this case
was 27 degrees...........



Once you have these two measurements you find the exact halfway point between
them both and you have true Top Dead Centre position for number 1 piston..........



When we do the math to find the halfway point it comes up as 2 degrees after
top dead centre. So we rotate the crankshaft to align this point with the marker..........



Number 1 piston is now exactly at Top Dead Centre, so, using a socket and
pull bar the crankshaft is held dead still making sure it doesn't move,
and then the degree wheel is moved so that it now reads bang on TDC at this point..............



If your like me and f*ck up's seem to visit you with alarming regularity, it's not a
bad idea to run over the procedure again just to be sure you have it nailed.

So what the hell did we do all that crap for?
Well to time the camshafts in we need to be able to set the crankshaft to an exact degree.
In the case of the cam's we're using (Schrick 276 & 284) those points will be
106 degrees "after top dead centre" (ATDC) for the inlet cam
and 106 degrees "before top dead centre (BTDC) for the exhaust cam.
And now that the degree wheel is accurately set we can be happy that when the pointer
shows 106 degrees then it's on the money.
When it comes to timing in cams you've got to try to be as accurate as possible.
Sloppy cam timing can at best loose you a little horse power, or at worst, result in
bent valves.

[xworks]

I've shown the "finding true TDC" process with the cylinder head off to try and
make it a little easier to visualise what the hell was going on if you haven't done it
before. But as you can see from the pic's below, if your dummy building up
the engine to check valve clearances or if your nailing it together for real then it
can make sense waiting till the head's on to find TDC, for the simple reason
that it's fairly easy to disturb the degree wheel while your assembling the top end.

So, back to the reason we were doing all this. Checking valve to piston clearance.
The block has been fitted with a single piston in number 1 cylinder and now the
cylinder head is fitted (with old head gasket).........



One inlet valve and one exhaust valve were fitted to the cylinder head with
weak dummy valve springs over cylinder one and the head bolted down with the
old head bolts (just nipped them down, no need to hang out of them)............



after which the cam box got hammered on..............





now we needed to reattach the degree wheel and again find true TDC..........



and the procedure we used was identical to what was shown just a few
minutes ago.



Only this time instead of the little deck stand holding the dial gauge on
the face of the block, we use a modified long pointer for the dial gauge.........



I'm sure you can probably buy long pointer's but we just cut the ball from the
top of a normal screw in dial gauge tip, drilled a little hole into it and bonded a bit
of welding rod into the hole.
(starting to see the penny pinching sneaking into this thread?,
the credit card people finally found me)..............

[xworks]

after that the dial gauge is rigged up on the cam box so the long pointer reaches
down in through the empty spark plug hole and rests on top of the piston,
just like before.............







and again the same procedure as before is followed to get the degree wheel bang
on the money.............



With that done, we could move on to dropping the cam's in, but before they
can sit into place the cam followers and shims need to go in under them.
The one's pictured below are not the standard followers from an S14 engine
but instead are after market and are generally known as "shim under" followers.
The reason for the name is unlike the standard follower that fits in first and then a large shim
sits on top of it, these ones have a small "top hat" shim that goes in first sitting
on top of the valve stem...........





and then the follower sits on top of this shim........



These "shim under" followers are recommended when your using high lift cams (292+)
or a high rev limit, as the shim that sits on top of the standard follower can get
flung out when used in these situations causing widespread destruction.
Whereas with these "shim under" style the shim is safely tucked in under the
follower and is less likely to head off for a wander when the going gets tough.
These aren't strictly necessary for the cam's and rev limit this engine is being
built for at the moment but I plan to change cam's down the line so it seemed
to make sense to fit them now. (plus they were purchased before the credit card embargo)

With the shims and followers in, the cams were next to be fitted, but before they
could drop in we had to do one little job on them first. The standard cams come with
a little notch on them to help you align them when fitting, Schrick cams don't have this
mark. So we needed to transfer over this mark to get us in the ball park when fitting the
new cams.
Two cams are laid out on the bench, new Schrick on the left, standard S14 cam on the right............

[xworks]

making sure the lobes on each cam are mirroring each other as they sit........



and then a guide mark is made on the new cam in the same place as the
notch on the standard cam........



With the marks transferred to both new cam's they were laid into the
cam box with a wee dab of oil on the bearings........



with the marks facing upwards at 12 o'clock.........





then the cam caps were bolted down.........



making sure each cap went in it's right place.......

[xworks]

probably worth mentioning at this stage if you were nailing this engine together for
the final time, and all the valves and proper springs were in place there would be
a fair bit of resistance as you bolted the cams down as some valves are going to
be pushed open by the cam lobes. When this is the case the cam caps are tightened
down very gradually and evenly till everything is tight, other wise you run the risk of
snapping that lovely new camshaft in half.

For this dummy build however there is only two valves fitted with very weak dummy
springs so the cams just fall in.
With all the caps in place you could now see how the marks on the cam's lined up
with the slots on the number 1 cam caps...........





Next to go on were the cam pulleys. We're using adjustable pulleys
as they allow you to fine tune the cam timing to get it just right, which
is helpful when your switching away from the standard cams. The pulleys
are available from the main dealers under the part number 113 113 11781,
and they are similar to the standard pulley only the bolts holes are machined
out to a slot rather than a round hole............



first to sit on is the inlet pulley..........



making sure theres no slack in the chain between the crank and cam pulley
as its fitted.......



after which the exhaust cam pulley is thrown on.........



and as we're only doing a dummy built at the moment two bolt are enough
to secure each pulley (if you were on the final build all six bolts would be in
each pulley along with the little locking washer tab thingy behind them)........



One thing that's probably worth mentioning at this stage is that if your using
the slotted BMW pulleys, the standard retaining bolts are a little long as the
pulley is slightly skinnier than than the stock item. If you use the standard bolts
to secure the pulley they protrude out the back of the pulley and jam in the
cam box..........



Probably not great for performance. A quick lick of a file and a thread or two
removed see's them fit to go again.
With the two pulleys fitted the final item to go on was the chain tensioner.............

[xworks]

which screws into the side of the head.........



and pushes against the large and small chain tensioners, both of which press against
the chain to take the slack out of it and keep it tight,
and,
cost you a f*cking fortune to replace when they wear out ..........




Threads on the tensioner are fairly fine and the threads in the head are only
aluminium, so if you bull it in arseways and cross thread it you need only look
in the mirror to find the person responsible for the world of shit you just stepped into.......





And then, finally, with everything in place we were ready to time the cam's in.
As mentioned earlier, "hopefully", the following method is one of the easier ways
to grasp, although I'll most probably make it sound f*cking awkward as usual.

The following method uses the "maximum lift" points of the camshaft to time them in. Basically,
the cam manufacturer gives you certain degree you turn the crankshaft too and the cam lobe
should be pushing the valve fully open at this exact point. To allow us to know when the valve is
fully open we set up a dial gauge that rests on the cam follower, as shown below............



The dial gauge is set up at the same angle as the valve so you get
accurate readings. When the camshaft lobe isn't touching the follower
at all (like in the pic above) and the valve is fully closed, the dial gauge is
zero'd. Then as the engine is rotated the cam lobe starts to rotate and
slowly pushes the follower down opening the valve. As the dial gauge
is resting on the cam follower the figures will rise as the follower is pushed
down, and, eventually, the after the valve has been fully opened the cam lobe
will start to let the follower come back up again and the valve starts to close again.
The point we're looking for is where the dial gauge figure was greatest, the point
where the valve was fully open, the "max lift" point..........



As you can probably see the dial gauge plays an important part in all this.
And in times gone by I've spent an age setting up the dial gauge
to rest on followers, only to sneeze, cough or fart during the measuring
process and have the dial gauge move on you, meaning you had to first remove the
hammer from the garage roof, or, apologise to the dog for verbally abusing him and then start all over again.
However a little while back I managed to buy a tool that makes this whole
job a lot easier in a group buy over on www.S14.net. The tool was designed and
sold by a forum member named "Jake", and it's worth it's weight in gold........

[xworks]

The tool bolts down on top of the cam box like so..........



and then the dial gauges that were supplied with it with extra long pointers........



simply sits into the angled holes drilled in the tool............



which hold the dial gauge just at the right angle to allow the pointer
to sit on the follower............





and when all the mounting bolts are nicked up you can now cough, sneeze, fart or
experience a minor earth quake and the dial gauge won't move. The dog loves it.

So with the dial gauge fitted and resting on the follower, the first thing to do
was zero the gauge with the valve fully closed. A quick look to make sure the
cam lobe isn't pressing against the follower and that the valve is actually fully
closed (as the cams were installed with the little marks lining up with the slots
in the cam caps then the number 1 inlet and exhaust valves are closed at this point)..............



and then the gauge is zero'd.........



The engine is now turned over clockwise while the dial gauge is watched to see
the valve being pushed open. It takes the best part of 3 quarters of a full revolution
for the cam lobe to start opening the valve from this point. And then the dial
gauge starts to move, as the cam lobe starts to push the follower down and open
the valve. We keep rotating the engine watching the dial gauge rising, rising, rising,
then holding still for a moment and then falling as the cam lobe goes over it's max lift
point and starts letting the valve close again. At this point the engine is rocked back and
forth a little so you can zero in on what the max lift figure is on the dial gauge.
For this engine, with these cams and their valves clearances that figure was 11.31mm.........

[xworks]

Turning the engine either way from here results in the dial gauge figure dropping.
So, the dial gauge is zero'd at this point.........



A quick look down at the degree wheel shows us this max lift point is taking
place roughly at 107 degrees after top dead centre (ATDC)



Probably worth just taking a quick second to explain "before top dead centre" (BTDC)
and "after top dead centre" (ATDC) if you've never come across them before.
In the pic below you can see the degree wheel is split into two colours, red and blue.
The little arrows around the outside show the direction the engine turns (clockwise).
All the degree points on the red side are referred to as "before top dead centre", as,
when the engine is turning these points will be reached before the top dead centre (0)
point is. And likewise, all the degree points in the blue half are reached after you pass the
Top Dead Centre (TDC) point, so, these are referred to as "after top dead centre" (ATDC)........



So, back at the ranch, we had found out that our max lift point on this inlet cam,
as things stand at the moment, was happening around 107 degrees ATDC.
The reason I say "around" is because just like the piston at TDC earlier the cam
hit's max lift and has a sort of "dwell" period where the valve stays fully open for
a few degree's before starting to close again. And again, we're going to have to find
the middle of this "dwell" period to find out what degree the cam is hitting true max lift at.

To do this we use a method very similar to how we found true TDC earlier on.
With the dial gauge still zero'd at the maximum valve lift point.......



we turn the engine backwards........



till the valve closes by 0.50mm......



and note the degree this happens at (83.5deg.).......



(quick word on turning the engine backwards to take a measurement,
never just turn it back to the point your looking for, go back past it and
then come forward again to reach the point. ie. here we were looking
for the point the valve closed 0.50mm, go back till the valve closes
maybe 0.60mm and then come forward again to 0.50mm)

After we noted down this point the engine was turned forward till
the valve was fully open again.........



and now this time we turn the engine forward..........



till again the valve closes 0.50mm

[xworks]

and again noted down the point this happened at (132.5deg)...........



and now with these two figures we can work out the exact max lift point
of the cam as it's now fitted, as it's right smack bang in the middle of these
two figures...........




So, as you can see above the inlet cam was now timed for max lift at 108 degrees ATDC.
But, when we look up the Schrick spec's for cam timing we can see that they want
the max lift or "peak timing" point to occur at 106 deg............



So, we gotta adjust the cam timing a little. We can do this thanks to the slotted
holes in the adjustable pulleys we've fitted, but, first we gotta figure out which
way we need to swing the cam to get max lift happening at 106 deg..........



To figure this out it can help if you try and visualise things on the big degree
wheel. We want the cam to "hit" max lift at 106 degrees (red line) but as things stand
it's hitting it at 108 degrees (blue line).........



As you can see above the cam is 2 degree's late coming on max lift, so, we
gotta swing the cam forward to get max lift happening earlier.........



To do this we return to the two marks we found a few minutes ago while
finding where the max lift point was........



well, because we want to bring the cam forward we align the degree wheel
with the forward one of these two marks (83.5deg).........



and again the dial gauge is showing the valve closed 0.50mm at this point.........



As we want to bring the max lift point forward 2 degree's we now turn the
crank forward 2 degrees from 83.5 to 81.5 degrees.........



Now when we checked the dial gauge it was showing the valve
had closed 0.59mm........

[xworks]

So we gotta adjust the cam to get this reading 0.50mm. To do this the cam
pulley bolts are loosened off a little bit to allow us to swing the cam without actually
moving the cam pulley. With the bolts loosened enough a spanner is placed on the hex on the
camshaft..........



and the cam is swung forward till again the dial gauge reads 0.50mm.....





With that done the cam pulley bolts are locked up again, and it's time to
redo the max lift check all over again to see where max lift now lies.

The engine is turned over a couple of full revolutions to let things settle and
then you find the point where the dial gauge shows the valve to be fully open again........



and then repeat what we done earlier, turn the engine backwards till we find the
point the the valve closes 0.50mm.......







and then forward...........







and then do the math to find out the mid point between these two degree's.......



and what we find is that the cam max lift point is now timed to happen at
105.75 degrees, which for the purpose of this write up I'm going to call 106 degree's.
If you want to find that last 0.25 of a degree then knock yourself out.

After that the exhaust cam was timed in the exact same way.
Rotate the engine to find the max lift point of the exhaust valve and zero the
dial gauge at this..........



Swing the engine each side of this till the dial gauge shows the valve closing 0.50mm.........



and what you'll probably notice is that your working on the other half of the
degree wheel now because the exhaust cam is timed at 106 degree's BTDC......



again the two points the crank stopped at are noted (136 deg. BTDC)..........



and 85 degree BTDC .........

[xworks]

and when we do the math to find the centre point between these two points we
get 110.5 degrees BTDC.........



So as things stood our exhaust cam is timed for max lift at 110.5 degrees BTDC
and we want this to be happening at 106 degrees BTDC.
Time to look at the big degree wheel again and figure out which way the cam
is going to need to be adjusted.

In the pic below you can see that over on the BTDC (before top dead centre)
side of the degree wheel, 110.5 degrees comes before 106 degree's.........



So our max lift point is now actually happening 4.5 degree's to early. We needed to adjust the
cam to bring this point backwards 4.5 degrees.
Again. the same process we used to adjust the inlet cam. Remember the two "rocking"
points we just used to find the where the exhaust cam is currently timed........



well because we want to bring the max lift point backwards we use the
rear point (85 degree's) and go back from here 4.5 degree's.
Which brings us to 80.5 degree's...........



had we wanted to bring the max lift point forward we would have gone to the
front point (136 degree's)........



So with the crank now lined up with 80.5 degree's we just need to swing the
cam backwards to get the dial gauge again reading 0.50mm at this point........



again cam pulley bolts are loosened so that the cam pulley doesn't move and
the cam is swung slightly backwards..........



till the dial gauge again reads 0.50mm.........



With the adjustments made, cam pulley bolts are tightened up and the engine is again
rotated two full turns to let things settle.
And we recheck to see where max lift is now occurring.

Find max lift on the dial gauge........



swing to 0.50mm each side of this......



note the degree's you hit 0.50mm at (80.5 and 132)......





Do the brain work to find the true max lift point which is exactly between the two
points.......



And bingo, the exhaust cam is now timed to 106.25 BTDC degrees,
which is good enough for me.
All of which will probably make f*ck all sense unless you have an engine
in front of you to play with.

[xworks]

And finally, we get around to what we actually done all this for,
checking the valve to piston clearance.
As mentioned earlier Schrick recommend a minimum of 1.5mm clearance
between the valves and the pistons at their tightest point. Thankfully we don't have to
rotate the engine to each degree on the wheel and check the clearance, as the tightest
point between the exhaust valve and the piston will usually occur somewhere between
15 degree's before top dead centre and top dead centre (green area below).
And for the inlet valve the tightest point will be somewhere between TDC and
15 degree's ATDC (yellow below)...........



So we only need to check the clearance in these positions.
We started with the exhaust valve. The degree wheel was lined up with
15 deg. BTDC..........



The dial gauge was showing that the exhaust valve was open at this point,
but we're not really interested in that. What we are interested in is the clearance
between the valve and the piston at this point. So, the dial gauge is zero'd......



And we use the special "valve depressor tool", which looks suspiciously like
a large flat screw driver with some soft cloth tape wrapped around the business
end so as not to scratch the cam follower...........



and thanks to those weak dummy valve springs we fitted earlier we can now
push the follower down till the valve GENTLY hit's the piston......



When it hit's the piston and can't go any further, the distance it travelled is
read off the dial gauge.............



And thats the exhaust valve to piston clearance at this point. It's noted down
and then the crank is turned slightly to the next point, 14 degrees's before TDC.
Again the dial gauge is zero'd, the follower is depressed with the screw driver till the
valve butt's up against the piston and the clearance noted from the dial gauge.
And this is done with the exhaust valve for each of the 15 degree's to TDC
where upon we ended up with the following figures.........

15 deg. BTDC - 2.28mm
12 deg. BTDC - 1.98mm
11 deg. BTDC - 1.95mm
10 deg. BTDC - 1.93mm
9 deg. BTDC - 1.90mm
8 deg. BTDC - 1.93mm
7 deg. BTDC - 1.93mm
6 deg. BTDC - 1.95mm
5 deg. BTDC - 2.00mm
TDC - 2.46mm

And from this we were able to tell that our tightest piston to valve clearance on the exhaust
valve was at 9 degree's BTDC and it's 1.90mm, which is comfortably in excess of the minimum
recommended 1.50mm, and hopefully should provide enough clearance to upgrade to more aggressive
cam's down the line.

The exact same process was used on the inlet valve and it was checked at each degree between 15 deg. ATDC
and TDC and the minimum clearance came in at 2.24mm.

And that, ladies and gentlemen, is where we wrap up tonight's episode.

Till next time.............

ps.
nope,
I tried, but I've nearly bit clean through my tongue,
Top End Performance suck's at supplying piston's.

[Massimo]

^
That is a good method I have always seen the playdough method to calculation valve clearance which seems some what not very accurate and could potentually damage the valve.

Cheers much appericiated.