L18 cam timing nightmare!!!

[NickandM 72 240Z]

Hey guys, just looking for any info you could give me on what the cam settings are meant to be on my motor.
I'll start at the start, about 3 weeks ago now I decided to change my twin 40mm DCOE webers to a single and do the head gasket on my L18 I have in my 1600.
I hadn't taken the head off one of these engines before so totally forgot about the chain tensioner, so it sprung out and wouldn't go back in for 2 weeks, it now sits about 2cm out, normal?.
Before taking the cam sprocket off I scribed a mark on the chain and the sprocket then tried to keep constant tension on the chain by using a bungee cord between the chain and the bonnet release handle (on the bonnet) so as not to slip a tooth on the crank.
My problems began when I had to move the cam slightly clockwise when refitting the cam sprocket, I didn't understand why I had to do this to make the scribe marks line up when nothing moved while it was apart.
So after numerous rough starts and short, bad drives I got the carb rejetted.
Carb goes back on only to find it's just as bad.
So me and a mate moved the cam sprocket over several teeth each way until it ran smoothest, turning it over by hand first to make sure no valves would hit.
At the setting we came to it still ran like a pig and had no power at all on the road and died if you tried to rev it up quickly.
I have now set the cam timing so that when number 1 is at tdc and the third notch on the crank pulley (coz it had white on it) is lined up with the pointer, the cam notch is lined up perfect with the grove in the cam bearing support.
And yes you guessed it, still runs like an amputee.
So what I'm asking is this, which grove should I line the crank pulley up with when number 1's at tdc? and has anyone els had problems similar to this, surely you have?
Spark timing was not touched during head R&I and carbie jetting should be spot on now.
Any help appreciated.
Cheers. Nick

[tortfeaser]

You need wood. All I know about L series is that you need to jam the wood in there good.

Someone will be along with more datto specific info, but I'd find TDC accurately (google any number of methods) then make sure No 1 is about to open the exhaust valve and line up the cam sproket with the mark, then put the chain on.

[NickandM 72 240Z]

Yeh I know about the wood, I ended up using a valve spring from an fj20 to hold the bastard in.
Why would number 1 be opening it's exhaust valve?, I thought you were meant to find tdc on 1's compression stroke? (both valves closed)

[lxb02]

Thats not the way to do it, for a normal cam (not reground) the simple way is to put the motor on TDC, the on the CAM sproket u will see three triangular notches, depending on how much the chain has stretched and how much the head has been shaved u need to select whether to use notch 1, 2 or 3. Two should be safe, then u get that notch to line up with and indent on the plate that holds the CAM on, generaly the centre of the V to the passenger side end of the notch.

If you have a special CAM u need to do this by finding when valves on no. 4 are rocking (with a dial guage) down and then set to TDC, this gen requires special CAM sproket.

[tortfeaser]

Number 1 about to open exhaust valve 'cos its just fired, number 4 valves on the rock like lxb says (ie exhaust just shut, inlet about to open).

[buzzard]

Originally Posted by tortfeaser

Number 1 about to open exhaust valve 'cos its just fired, number 4 valves on the rock like lxb says (ie exhaust just shut, inlet about to open).

If #4is rocking the engine needs to turn a good 100 or more degrees before #1
exhaust valve opens.(exhaust cam centerline dependent )

May I suggest you obtain a workshop manual to verify the correct procedure and once the cam is installed correctly perform a compression test to ensure no valves have been bent.

Also verify correct spark timing.

Chris

[NickandM 72 240Z]

ok I just checked the spark timing and it's about 10 dgrs advanced which is near enough, I have the cam sprocket on the number 2 hole and the notch lines up perfect with the indent when the pointer for the crank pulley is pointing to the third notch on the pulley. still crap.
I'll do a compression test to see if I buggered any valves and let you know.
Thanks for your help guys keep it coming.

[NickandM 72 240Z]

Just moved the cam sprocket to hole number 3 and it runs alot smoother at idle, took it for a spin and it's almost drivable. It dies at low revs when I try to give it a bit but slowly takes off as the revs get higher, I think now it's just the carby, maybe float level?

[afifield]

If you think it's just down to the carby now, check to make sure the pump jets are squirting when you open the butterflies. Sounds like a symptom of either blocked pump jets, or the pump diaphragm is weak/leaking.

[NickandM 72 240Z]

ok thanks afifield will do. That makes sence I guess, coz even when I try to rev it up quickly it dies and will loose revs until I back off then it revs up. I'll test the pump jets out tonight.