e30 M3 minor rust repair.

[xworks]

Haven't had much of a chance to work on the car lately, but, by way of a
small update to the thread I've routed out the last of the pic's for the
engine prep section.

One of the final items on the list to check were the valve springs...........



both the outer and smaller inner springs first had a quick check to make sure their
free standing heights were all equal.......





tolerance I'm using is 1.5mm, so, any spring thats over 1.5mm shorter
than it's brothers and sisters bites the bullet.
happy that none of the springs were deformed or "squashed" from previous use
the next check was to ensure each one was straight.........



tolerance this time around was 4mm, any spring displaying a drunken lean of
more than 4mm gets shown the door.
Before finally the poundage of each spring is checked using this little gauge......



Each spring is placed into the screw press and using the dial gauge each
one can be compressed the same distance while the force it takes to do
so can be read off the little gauge.........





The idea behind the check is to highlight any weak springs which may struggle to
control the valve when the engine rev's start to rise, and having seen in the last
section how close the valves run to the tops of the pistons the last thing you want is a rebel
valve doing it's own thing as the piston hurtles up the cylinder at warp
speed trying it's best to make shite of it.
Schrick list pressures in their catalogue so you can check each springs pressure at it's installed
height and at it's fully opened height (valve fully opened, spring compressed) to make sure they're
on the money.
However, when testing other makes of springs or even the standard BMW valve
springs it can be hard to track down this info and in this is the case each spring is just compressed to
it's installed height and it's fully opened height and the pressures are noted and all are checked to see
if they are within 10 percent of each other which is usually good enough to show up a weak
spring.

After this was done it was on to the coma inducing task of checking
valve spring installed heights.
So,
whats the deal here,
nobody asks.
Looking at the picture below you can see all the valve's in place and
and the springs pulling the valves tightly closed into their seats..........



The springs need to be pulling the valves closed into their seats just the right
amount. The smart folk that design valve springs do so in such a way that when the
valve is installed in the head, and it's spring is fitted, the valve spring is compressed
just enough to hold the valve shut with the right amount of force.
This is all bloody marvellous when the engine leaves the factory, but now we've had
a chance to screw around with things by cutting the valve seats and fitting aftermarket
valve springs we were going to have to check the new valves were going to be pulled shut
again just the right amount.
To do this we were going to have to measure the "valve spring installed heights". And
hopefully the diagram below should help to show what this measurement is........



As you can see above the valve spring is trapped between the lower and upper
valve spring retainers. The distance between these two retainers is the valve spring
installed height and Schrick kindly list what this measurement should be in their catalogue.
So next we need a way to measure what the installed heights were on my valves so
we can check it against this figure and below you can see what we use.
It's called a valve spring micrometers............



Basically the little tool is inserted instead of the valve spring and you rotate the
two halfs of the tool to extend it. When the tool is extended as much as the valve
spring retainers will allow you read off the little increments on the side to see
what the distance is between the top and bottom retainers...........




Unfortunately due to the nature of the design of the S14 cylinder head and the
shape of the retainers I'm using the little tool took some serious modifying to
fit into place and do it's job right. After a little bashing and much swearing
it worked and what it showed was that my installed heights were too large
as things stood which would mean the valve springs wouldn't be squashed
enough at rest to hold the valve shut with the right amount of pressure.
Thankfully the cure is rather straight forward. Some valve spring shims,
which are available in a variety of different thickness's, were purchased
and fitted below the bottom retainers to return the installed heights to what
they should be.

[xworks]

Basically you're just wanting to know when the piston has dropped 5mm, right?

Thats it in a nutshell, all your interested in is an accurate measurement
of when the piston drops 5mm either side of TDC. And having said that,
5mm is just a figure I decided to use, you can drop it 8, 10, 12mm or any
distance you want, so long as you drop it the same distance either side of
TDC.

When you fit the dial gauge, whether it be on the raised edge of the piston
or down through the spark plug hole into the dish in the piston, the first
thing you'll do is crank the engine over and back around TDC to find the
highest point the piston rises too. When you've found this point the dial
gauge is zero'd and it's using this zero that you drop the piston back 5mm
either side of TDC. Whether the pointer is on the rim or in the dish of the
piston will make no difference for this measurement, all your interested in is
the exact point the piston has reached the top of the cylinder.

[mnc2fan]

Question about finding the true TDC. When you were setting the piston to deck height you were measuring the high point on the piston, but when you put you gauge in through the plug bore after fitting the head you were measuring the bottom of the dish.

My question. Wouldn't that cause some variance between the two TDC measurements since your "zero" would allow the piston to be slightly higher in the dish, or does it not matter because you the piston set to deck height before fitting the head? Basically you're just wanting to know when the piston has dropped 5mm, right?

Amazing thread BTW. I've been watching this thread for over a year now. Good luck hiding from the credit sharks!

[alexdoubleu]

holy hell this thread is rediculous! nice job man, crazy detail!

[Car Addict]

Yes I just sat down and read this entire rebuild in one sitting only took 4.5 hours but so worth it.

xworks what you have done is truly sensational.

Can't wait for the next installment

[Zic]

f*ck me side ways this is brilliant.

[xworks]

many thanks for the kind words lads, it's always nice to see
at least some of this waffle is proving interesting.

Just another small bit on prep to go before the engine gets nailed together
and then we can stumble into the mystical world of little black boxes and engine
management. Wonder if there's enough room on the interweb.........

[Simon S]

I thought my Zen thread was formidable.. OP makes the Zen thread look like it was done by a drunken 4 year old..

Hats off to you, xworks. I’ve never before read a project thread with more detailed information and wit.. yes, wit – which is a word I never thought I’d use to describe a project write up.

Thank you for taking the time and care to compose it. I have a taste for what it takes to be constantly getting the camera out every step of the way – then loading all the photos – then generating post material. You have done so with remarkable skill – as you build a very remarkable car.

Also, this:

Restorations where the odometer should be set to zero are few and far between. You’ve earned the right to do so in spades.

[Massimo]

^^^

Some new euro support right there.

[JD_RFTR]

man, you`re cool....spechless...

[Oleg P]

i wonder how much just the parts cost you so far?
awesome thread by the way. cant wait till its done.

[Bartholomeo]

engine building for dummies, I'm learning so much with this thread.

Thank U for taking the time and effort to discribe it al to such great detail.

[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.

[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.

[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.