Howdy,

Working on a 240z that has a 280z motor, N42 block and N42 head.

Car runs just kinda OK, but seems to not be right. Thought there was a burnt valve, but compression is good.

All  valve timing alignments with the cam looks good.

Replaced the distributor cap and had the whole thing out. At TDC,  I looked at the distributor drive, and it looks to align directly with the mounting bolts. I am getting older, but my memory is that the "line" should be off the left edge of the upper bolt with the angle.

I have attached a picture.

So, am I off or should I drop the oil pump and take it over one "tooth"?

 

Any advice is appreciated.

Thanks

Bob
 

Edited January 6, 20232 yr by 70z4fun

In my serv.man. it says: (page EM20) it should be on 11:25 hour and smaller bow-shape should be facing towards the front.. so.. it looks good!

Why a engine does not run perfect, there are a lot of reasons..  change the sparkplugs or the wiring or the distributor, use fresh fuel.. these days the fuel can be the problem as there is some E10 in it and cause misfires? lots of reasons...

Distributor and ignition coil original or aftermarket (junk? oeps...😢)  Old contacts or no contacts but aftermarket eh... "replacements"?

Yeah, i'm a fan of original ignition.. with contacts.. as i'm driving only 1-2,000 km a year..  last year i renewed the contacts on my 240z after over 20000km.. was still good but replaced them.

Looks perfect. Put a timing light on it. I would suggest 12 to 17 degrees BTDC compression stroke.

Looks like the mounting pedestal is backwards.  The clamping screw screw should be to the front.  Might be some other things not quite right.

It's funny how hard it is to find a simple good picture of how the drive quill should be oriented.  Probably why so many people have problems with it.  Nissan never really got it right throughout ll of the years of the FSM.  1978 isn't bad though.

7 hours ago, 70z4fun said:

Working on a 240z

But, if you're using the 240Z distributor maybe the clamping screw is on the back.

Thanks for the feedback.

Yes, I do run a 240z distributor, so that's why it look like the mounting looks that way. The current distributor has electronic aftermarket in it, but I do have another one with points. Need to clean up the vacuum plate on that one.

we do use ethanol free fuel, and will install some new plugs. I have been running at 10 degree BTDC

I will try to go up to 15 degrees and see if that helps. 

So like for now, I won't pull the distributor drive.

Thanks for the advice

Enjoy

I "ran" to my 240z and took a look.. Your distributor is on like mine.. plate (with degrees) in front and mounting bolt at the rear .. so okay..

Change the inner electronics first with the mech. contacts from the other distributor.

Always change one thing and test, so we all know what the culprit was! 😉 

Always test with a warmed up engine.

On 1/6/2023 at 12:56 AM, 70z4fun said:

Car runs just kinda OK, but seems to not be right.

You didn't say much about what's not right.  Your picture just shows that the distributor is in the hole the right way.  Could be many other things not right.  Firing order, stuck mechanical advance weights, stuck vacuum advance, loose advance mechanisms flopping around, carb problems.

On the initial timing, you need to know what's in your distributor and if it's working right.  Looks like Nissan used a different distributor for emissions engines, according to the FSM.

When you have your timing light on, watch the mark as you rev the engine.  Estimate how high it goes above about 2500 RPM.  It should rise to well above 20 pretty quickly.  If you have a dial-back light you can get an exact number.

p.s. also not uncommon for the old damper/balancer rubber to be bad.  The timing marks might be incorrect.

Here's the 1972 tune-up specs.

 

 

Edited January 7, 20232 yr by Zed Head