Just an update as promised - my 204Z is finally back with the Datsun Spirit 3.1 stroker installed.
The engine starts with difficulty, and the car was bogging down under acceleration or even just cutting out entirely even under power. I nearly got rear-ended at a roundabout on my first breaking-in drive when the engine cut out completely.
This has been a good learning curve for me! I've posted some pics to help others who are (like me) completely new at this stuff and may end up doing this.
So please bear in mind this thread is for newbie inexperienced guys like me tackling stuff they don't understand, not for you mechanics
LOL but it may help someone.
The engine arrived with this crank timing setup from the tuner who felt the engine was too advanced. He felt the sprocket markings were incorrect. What prompted him to check this and make the changes was that the emissions seemed wrong when he did a basic tune.
So here's where it was set to:
When I explained this to the engine-builder, he got pretty worried that the engine could now be severely retarded as a result of moving the chain up a link (18 deg), plus 3 degrees at the sprocket (total 21 at crank). He asked me to send a photo with sprocket removed so he could compare with a mockup of the build he made, as well as the photos he took of my engine during the build process.(Simply amazing service by the way). He said "I suspect you will find the dowel and the market positions to be almost exactly like this (undeniable evidence that the valve timing is now severely retarded and that how I had it was correct)." Here's the picture he referred to from my engine build album:
Here's my sprocket dowel markings for comparison:
So the builder told me the car would be dangerously lean, and advised me to change it to this immediately and not to run it until reset, which I did:
This involved making a chain wedge to stop the timing chain-tensioner from popping out (a bad thing apparently) and to immobilise the crank, so that I wouldn't be working to the wrong crank timing.
Here's the tensioner made from some blue 1" plastic scrap:
Here's the chain tensioner in place about to be pushed down (it goes pretty far down). The cords are so you can pull it out again. You really need to push it down hard all the way until it can go no further or you will be in serious trouble - probably have to remove the front engine cover to reset everything unless you have surgeon-hands...
Here's a view down the chain so you can see the curved path it takes when under tension. Hopefully you'll see what I mean by pushing it all the way down.
The car is now driveable and still bogging down a bit running lean on the idle circuit. ordered some 55F8 jets then 60F8 which are starting to solve that problem. Engine is running lean higher up in the rev range but I'm going to leave that for a bit to see how things settle in.
I thought I should check the valve clearances (because the tuner said number 2 exhaust was too wide and he adjusted that), and the engine manual says they should be same for exhaust and intake, namely 0.08" - 0.2mm which they are now - what a PITA that was to untighten the locking nuts. I need to find some as I rounded off a few and messed up a spanner getting there.
I bought a timing light with dial and I'm still playing around with the timing. Also got a Gunson colortune which helped me set the idle mixtures. Used ear for synch then got a synchrometer. Turns out ear is just as accurate, and free.
Jobs to do: The carbs need work. I levelled the floats (all over the place) but I need to install vibration dampening mounts with Thackeray washers.
Oh yes - some of you wanted to see the cam, well seeing a took the sprocket off to move the chain one link I took a pic of the cam:
PS: Any fellow Z owners in Norwich? Keen to compare notes!