New Zealand Datsun Club

i thought that stuffed valve stem seals didn't even make any smoke once the motor is running.. on start up a big puff of black smoke comes out the exhaust but after that no smoking is noticable. i know a few people that have built motors ad not run valve stem seals because of roller rockers or a bigger cam and there is no smoking once the motor is running.

I'm guess you could get away with no valve stem seals on a new engine, I think my guides would have too much wear to be up to it. Leave an engine idling that has worn valve guides and seals then give it a bootfull of throttle and you'll get a good puff generally.

Yeah definitely a new motor only kind of thing.
I've heard its quite common practice with race engines to leave the valve stem seals off on the exhaust valves as the extra lubrication keeps them cooler and stops them seizing in the valve guide
This was in reference to big yank v8's so bigger valve stems, more friction, more heat etc.

Valve guide seals aren't as important on the exhaust valves, as they never see the vaccuum that the inlet does. When you snap the throttle shut, the intake goes into high vaccuum on account of the cylinder drawing against the closed throtle blades. So this high vaccuum will draw oil past the stem of the inlet valves, especially when there is some wear in the guide. People often dispense with the seals where double or tripple valve springs are used. L series motor use the superior style of seal which has a spring loaded ring that holds snug to the valve stem.

Well, I have been slowly rebuilding my L16 for the coupe.

I have some pics somewhere I think, that I will upload later.

But today, I decided to test the fuel injectors that came standard with the L18E, and also some brand new injectors that I have that im not 100% sure what they're from.

I came up with a genius plan......built it.....then started testing.
But unfortunately, it seems my test rig didnt seem to give the right results.

There was a great variance in fuel quantities delivered, even from the factory injectors.
This could be due to the battery not being 100%, or the fuel pressure changing (I had no vacuum connected to the FPR), or simply dirty injectors (a few of them wouldnt spray anything at all until they had a few taps with a screw driver).

So I will take them in to the shop to get cleaned and then tested properly at a constant pressure.

anyway.....pics of my awesome test rig (that failed to get correct results)

It's not that expensive to have your injectors cleaned and flowed Dan. It's best to eliminate all the variables rather than try to get things running properly when there are variables that are all over the place.

yeah, as I said, I will be getting them cleaned and flow tested.

last time I think they were around the $10/injector mark for that? but that was years ago.

Does anyone else do them? only place I know is "diesel services" used to be on parkhouse road

you are thinking of diesel pumps ltd dan, they are on parkhouse. diesel services are on nga mahi rd, near royce clive engineering

ah right you are Dylan.
It was definately them.....will take them to Diesel pumps on parkhouse unless anyone knows anyone else?

I think caraid do them too. (wont cost anything to ring them and ask)