Re: [DML] An Epiphany

[Martin Gutkowski <webmaster@xxxx>]

Hi Rich

Okay, I've done the chains, and taken photos, but I'll explain in words 
because I'm not at my flat (going home tonight where my camera lead is!).

You get the crankshaft rotated to the keyway points to the RH camshaft. 
The timing mark which is on the middle sprocket on the crank points 
roughly skywards. Put the chain on so the single timing mark aligns with 
the timing mark on the middle crankshaft sprocket. Then by slotting the 
camshaft sprocket into the chain so the timing mark on that lies between 
the double marks on the chain, you can rest the camshaft sprocket on the 
end of the cam and rotate the crank till the camshaft sprocket slots 
into its locking slot. This last bit is how I do it because no matter 
how hard to try, you never get the blasted pin lining up on the camshaft 
sprocket! Now put in the chain guides and you can forget about the RH 
chain.

Now rotate the crankshaft so the timing mark (NOT the keyway) points to 
the lower oil pump mountig bolt - roughly half-past-four. This does not 
have to be accurate. Now drop the chain over the middle sprocket so the 
single timing mark on the chain aligns with the mark on the sprocket. 
Now drop the camshaft sprocket into the chain so the two marks on the 
chain sit either side of the mark on the sprocket. Again by resting the 
sprocket on the end of the camshaft, you can rotate the assembly around 
by turning the crankshaft, till the locking pin drops into the slot on 
the camshaft. When you see the pictures, you'll see that by this point, 
ont he engine I'm working on today, the timing mark on the crank end has 
already left the crankshaft sprocket. Now put the chain guides back in.

When I first did the job, I spent ages getting the camshaft slot to line 
up properly so I could put both chains on with the marks as they appear 
in the manual. The problem is it's a pain in the arse to turn either the 
crank or the camshaft to the left - you always end up unscrewing the 
nut/bolt - and you can't just spin it round 350 degrees because you run 
the risk of hitting a valve on a piston.

THEN, reassemble the oil pump chain and sprocket, timing cover, pulley 
and crankshaft nut. Now, an explanation: There are two timing marks on 
the pulley. We only use one of them. The camshaft rotates once for every 
two rotations of the crank. You need to get it so cyl #1 is in firing 
position. This means that the valves are both closed on cyl #1. For the 
valves to be closed, the rocker arms that control them will be clear by 
0.1mm (inlet) and 0.25mm (exhaust). If you wiggle them by hand, they 
will rattle slightly. The inlet valves are in the middle of the "V" and 
the exhuast valves are on the outside. Explanation over.

Now take spark plug #1 out. Drop a long screwdriver down the hole and 
gently turn the crank so you can work out which timing mark hits 0 on 
the timing plate when piston #1 is at the top of its stroke. When you 
have worked this out, and the mark is on "0" - watch the rocker arms on 
cyl #1 and turn the crank first to the left by a few degrees and then to 
the right by a few degrees. If when turning to the left, you see exhaust 
rocker arm start to move, and then to the right of TDC, you see the 
inlet rocker move - this is when the arms are "on the rock" and this 
means the piston has just finished exhausting, and started induction. 
This is 360 degrees out from TDC on firing stroke. Spin the crank by 360 
degrees, and you should now feel play the rocker arms on cyl #1. You can 
NOW drop the distributor in so the rotor arm points to the mark on the 
body of the distributor. Make sure you get it so you can adjust the 
dizzy either way - you won't get it spot on, but you'll get it on the 
right "tooth" on the drive gear. Lock it down as near as you can judge 
it, and put the cap on.

While at TDC on firing stroke, the following valve clearances can be 
adjusted:

Inlet 1 2 4
Exhaust 1 3 6

Now rotate the crank by 360 degrees, and adjust

Inlet 3 5 6
Exhaust 2 4 5

When adjusting the valve clearances, you have to get snug fit with the 
feeler guage - not too tight and not too lose - you will get a feel for 
it after a while. Too tight, and when you're adjusting it you will start 
to open the valves. Too loose and the valves will not open fully and for 
less time, and will rattle.

Now reassemble everything else. Adjust the fuelling so the injectors 
"crack" when the metering flap is down by a millimetre or so. Jump the 
coil with 12v. Get a friend to turn the key and you reach down to the 
vacuum advance diaphragm on the distributor and while it's cranking, 
start moving the dizzy around. You should hear a point where the engine 
is trying to fire. It may not. If not, try turning the misture 
adjustment screw another 1/2 turn to the right. The conditions required 
in getting this sucker started for the first time may be vastly 
different from what it'll merrily run at once it's fired up for 30 
seconds or so - eg over-rich and over-advanced.

Okay, I can hear my girlfriend buzzing the timing cover bolts on with 
the air-wrench from here, so I'd better go and check she's got the right 
sized bolts in each hole..... will post the photos later

Martin

PS no idea what "cylinder overlap position" is :-)

cruznmd wrote:

>As usual, a fellow DML'er handed me an epiphany, well sort 
>of...something I had been considering but didn't want to admit.
>
>Consider: 
>
>An engine with new head gaskets that had the timing chains and 
>sprockets removed, now assembled cranks exceedingly hard. New 
>starter, new, larger capacity battery.
>
>Timing light indicates 13 BTDC. That's only electrical timing though. 
>I am absolutely certain that the pistons have not struck and bent any 
>valves (engine was handcranked first) but could I still be off on my 
>valve timing?
>
>If the valves weren't synchronized properly, then the engine is 
>fighting itself right? It has also occurred to me that I don't here 
>any of the "sighing" that the air makes when expelled or inhaled. I 
>don't know about the PRV but I'm used to this in other engines.
>
>Help me with valve timing terminology:
>
>What does "on the rock" and what does "overlap position" mean when 
>referring to the valve positions? Open, closed or what?
>
>I have everything else. Fuel, air, good, hot spark. Starting fluid 
>changes nothing. New fuel pump, CPR, injectors, fuel dizzy, filter. 
>All tested sat.
>
>What else could it be besides timing, given the symptoms?
>
>Thanks,
>
>Rich
>#5335(The Zombie DeLorean)
>
>
> 
>



[Non-text portions of this message have been removed]