Engine overhaul (help needed) - 240z with a 280z block

Graeme - CZ

Club Member
Hello folks,

So i've almost completed my body and interior restoration and it's now on to the engine and suspension. Engine first. I'm hoping that some kind people on this forum might be able to help me work out a) what it is I have and b) what parts I should order before sending it to the mechanics to breathe some love on the engine. It's running pretty rough at present, despite changing the spark plugs, leads and distributor cap. I'm also open to any other advice about getting my beloved 240z running and driving better. I'm attaching a load of pictures of the engine bay area, most of which is stuff I know little about.

Many thanks everyone, Graeme

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Graeme - CZ

Club Member
I've also got a couple of ignition related items which I do not know what they are for. Suspect they belong to a 240z ignition, as i had previously wrongly ordered some 240z parts, only discovering later that what I needed were 280z parts.
 

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Mr Tenno

Digital Officer
Staff member
Site Administrator
What's the block / head combo? The numbers are cast into the side.
 

jonbills

Membership Secretary
Site Administrator
What's the block / head combo? The numbers are cast into the side.
The head cast number is below spark plug 4/5 I think, and the block type is above the sump on the exhaust side.
N42 block I'd guess.

Why do you think you need parts? Can you describe the problems?
 

Graeme - CZ

Club Member
The head cast number is below spark plug 4/5 I think, and the block type is above the sump on the exhaust side.
N42 block I'd guess.

Why do you think you need parts? Can you describe the problems?

Well, I have a guy who can do the carb strip down, clean and rebuild - this feels like my step 1. Given the hassle of getting parts, i'd rather be prepared - especially if there are obvious parts i should replace. The problems: it's seems to be running very rich (very strong fuel smell in the cabin when driving, unpleasantly so). It's coughing and spluttering when I drive it, with the occasional back fire. Feels like it needs a good re-tune.
 

Graeme - CZ

Club Member
Are you keeping the K&Ns or going back to the original set-up? I see both in the photos :D

Part of the smell in the cabin is coming from the escape filter on the rockar cover - one of the reasons why i switched back to stock. The old filter is back on now, though I do need to replace the filter - though not sure if it's a 240z or 280z one i need.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
There is a need for you to go back to basics but I'm guessing it may be beyond your knowledge.

Compression test
Ignition timing
Fuel filter clear of rubbish
Fuel at the carbs
Balance of throttles
Mixture settings
Spark at each plug
Valve clearances

etc

You need to find an old school mechanic who needs some beer money. Shame I don't live closer.
 

Graeme - CZ

Club Member
There is a need for you to go back to basics but I'm guessing it may be beyond your knowledge.

Compression test
Ignition timing
Fuel filter clear of rubbish
Fuel at the carbs
Balance of throttles
Mixture settings
Spark at each plug
Valve clearances

etc

You need to find an old school mechanic who needs some beer money. Shame I don't live closer.

Hi Rob, you are exactly right. Safe to say all of that needs done regardless. Datsun specialist a bit few and far between in Scotland. G
 

jonbills

Membership Secretary
Site Administrator
Hi Rob, you are exactly right. Safe to say all of that needs done regardless. Datsun specialist a bit few and far between in Scotland. G
You definitely don't need a Datsun specialist Graeme, just someone who knows carbs and points and engines from the 60/70s. This stuff was common with British sports cars from that time.
 

SacCyclone

Club Member
Given the description of how it is running, first make sure your chokes are completely off and then make sure your main jets are fully in the up position. Place your finger under each main jet and push up to make sure the jet is fully seated and not in the down position....this usually will clean up the running rough and sputtering part if the main jets were sticking open.
 

Farmer42

Club Member
The rough running could also be caused by duff points and condenser in your dizzy. It looks like you have a mechanical dizzy so you would need those extra ignition items you previously mentioned. Poor ignition will give you unburnt fuel and hence the rich fuel smell. The way to tell if you have a mechanical dizzy is to take off the cap and look to see if you have points. If so i would recommend replacing those and the condenser to start with. Make sure you set the points gap correctly then set the timing. The Haynes manual will give you instruction on how to do this and it is relatively easy even for a novice. I would recommend checking this before you start on the carbs.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I'm guessing that Graeme isn't able to do the jobs that people suggest. To someone who works on mechanical parts these tasks are easy but to others they aren't. So checking main jet heights and replacing points may be something for someone else to do.

I think that's how I read the situation.

It's like asking me to rebuild a PC.
 

Graeme - CZ

Club Member
Whereabouts in Scotland? I know a chap who would be able to support.
I'm guessing that Graeme isn't able to do the jobs that people suggest. To someone who works on mechanical parts these tasks are easy but to others they aren't. So checking main jet heights and replacing points may be something for someone else to do.

I think that's how I read the situation.

It's like asking me to rebuild a PC.

You read it very well. I work in IT. I'd find rebuilding a PC easier ;) Happy enough with bodywork, interior and big stuff like suspension - but when it comes to engine or electrical stuff, i am a rank beginner.
 
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