cam 180 deg from tdc when engine cranked... fubar or usable

[noobschool]

So, purchased a 1.6 turbo head to throw on my 1.5l block.  When I picked up the head they said that it was already set to TDC so I never questioned it or paid attention to the lobes, just the mark on the end of the camshaft.  Put it all together and started to crank it after getting everything all TDC and timed (I thought the cam was TDC at this point but it was really 180 degrees from it, just didn't click in my head because all of the valves are closed in this position still).  It obviously didn't start, but would doing this mangle the valves?  It seems like everything would just be backwards to me (exhaust valves opening when the intake valves should be on the 1 and 4 cylinders, thus the engine would just be smothered.  I know I am dumb for overlooking something so simple, but hoping I can escape this with just my pride damaged.  Any input?

[rallydiesel]

If you can still turn it by hand then it's probably ok. You may want to pull the head and spin the camshaft to make sure the valves aren't bent and binding before re-timing.

[noobschool]

Yep, took off the head in frustration earlier once I realized that it had been backwards.  Everything rotated fine, all the valves operated appropriately it seemed.  Curious though, mechanically speaking, is it plausible that the valves didn't didn't get touched being 180 degrees off time?  I wish I could revert to checking out the pistons for marks but the reason I bought a new head is because the tensioner pulley came loose and the valves got smashed on the 1.5 head and the pistons were already punched.  I was told that the pistons were still usable for a time, but I am also in the process of building up a new block

[rallydiesel]

Well at 180, the bottom end would still be at TDC, so there was probably no contact. You would have just filled the intake manifold with unburnt fuel. Did it actually fire up for a second? If so, you could have damaged the compressor wheel/broken the shaft. If it didn't fire up at all, I really wouldn't worry about anything.

[noobschool]

nope it never cracked over or even sputtered.  I figured that I was putting fuel in on the exhaust stroke, so there was fuel just sitting on the piston on the compression stroke that wouldn't combust.  Am I thinking correctly?  In my mind the valves couldn't strike the pistons when 180 deg out sync.  the head is just going to be opening the intake valve when it needs to be opening the exhaust valve and vice versa, right?  Dodging bullets I hope... Can anyone validate what I am thinking.

[noobschool]

thats exactly what my mind was thinking but my words weren't saying.  Good to know.  I just wasn't sure if maybe the was a difference in when the valves opened (exhaust vs. intake that is).  Oh well.  All this inspired me to build up the block this next couple of weeks in my spare time.  Got a TD block freshly bored, just need to pick up some pistons and make sure the crankshaft is true.  Any other advice on what to do with the head or block while they are all disassembled?  I was thinking about getting new valves and installing them myself but it seems like you have to have all of the special tools and time and space.  Fun stuff.

[Rabbit TD]

The two valve strokes are not opposite each other but rather next to each other.  Both valves are closed for the other two strokes.  The order is power stroke, exhaust stroke, intake stroke, compression stroke.  Whenever #1 is at TDC on the power stroke, #4 is at TDC on the intake stroke and vice versa.  #1 and #4 are both at TDC when the correct mark is showing on the flywheel.  The only thing that determines which is on what stroke is the position of the cam at that time.  Same deal for #2 and #4, but their crank TDC mark would be 180° of crank (90° of cam) away from THE TDC mark.  That situation happens several thousand times per minute on a properly functioning engine so no harm can come of it.

Considering the spec of .001 for piston to cylinder clearance, my machinist insists on having the pistons in hand before boring the block.  

Be sure to replace the intermediate shaft bearings and the oil pump shaft bushing.

The only special tool needed for replacing the valves is a valve spring compressor that will work with these springs.

Andrew

I was going to make a compressor for these but I found out an oxygen sensor socket with a regular C-style compressor works real good.

[Rabbit TD]

thats exactly what my mind was thinking but my words weren't saying.  Good to know.  I just wasn't sure if maybe the was a difference in when the valves opened (exhaust vs. intake that is).  Oh well.  All this inspired me to build up the block this next couple of weeks in my spare time.  Got a TD block freshly bored, just need to pick up some pistons and make sure the crankshaft is true.  Any other advice on what to do with the head or block while they are all disassembled?  I was thinking about getting new valves and installing them myself but it seems like you have to have all of the special tools and time and space.  Fun stuff.

I'm wondering the same thing Andrew is.  Did you have the block bored yourself without having pistons or was it already bored when you got it and what hapened to the pistons if there were any?  I'm wondering about if the clearance possibilities also.  Another thing about oversize pistons is that some of them are .005 shorter from wristpin center to the crown alowing you to surface the block and still be in the same range for the head gasket or very close.  The ones I just got from Parts Place were like that so I had it surfaced when it was bored also just to make sure everything was as flat as possible.