lean or rich?

[dustbag]

when i rev the engine up around 5g it starts to sputter and cant rev past it, what does that mean

[ozconnection]

A word of advice mate, you cannot possibly expect a solid answer to this question. Let me give you an example;

"Doctor, my stomach aches and can you tell me why?"

He'll be able to answer you after a bazillion questions but it will take some more effort from you to help him help you.

We really would like to help you with your question but you really need to give us a lot more information such as:

What car/engine is it?

Have you worked on the engine or is it standard?

Does it do/doesn't do this all the time?

Have you had your car assessed by a professional or at least seen by someone who knows our cars and given you some tips?

Fresh fuel?

Solid spark and timing?

and on and on it goes.....your turn mate.....info please.

Good luck.

[dustbag]

Sorry about that

Its a 70 L24, i got the 240 about a month ago and haven't been able to drive it much but every time that i had, in every gear when it starts to rev a little past 5000 it sputters, losses all power and probably wont go past 5500. Its not burning oil and the motor and carb was rebuilt a few years ago. ill have time this weekend to check the spark plugs for what the mixture is but i just wanted to see what you guys thought before then.

[sparegolfer]

What kind of carbs do you have? What kind of ignition do you have? Are you using an electric and mechanical fuel pump, or just one? Who did the rebuild?

[Nissanman]

The crank/cam relationship may very well be 1 or maybe 2 teeth out.

So typical if a non L series aware mechanic did the job:stupid:

Had this very experience on an L28, wouldn't do zip over 5000rpm, hit a brick wall:angry:

[Gary in NJ]

I have a couple questions on the 5,000rpm ceiling:

1) Is this ceiling in neutral and all gears?

2) Does it only happen under heavy load (acceleration or climbing a hill)?

3) What happens if you slowly apply throttle to WOT while in neutral?

4) What is the condition of the fuel filter?

5) What is the condition of the ignition system (points, condenser, cap, rotor, wires & plugs)?

[dustbag]

Everything on the car is the is still original except it has a 5spd instead of the 4, i'm pretty sure the attachment pic i got is the same kinda carb. I think its a mechanical fuel pump but i'm not sure, how can i find out? I'm super new to the whole datsun thing but i been reading through tons of threads trying to learn as much as i can but i know a whole bunch of you guys are crazy experts. i don't know who rebuilt the engine but if the cam is off by 1 or 2 teeth can advance or retard the timing it get it in sync or does that not matter?

1. The ceiling is in neutral and all gears.

2. Its a little worse when under a heavy load.

3. It still does it

4. fuel filter is in okay shape ill get a new one this weekend.

5. The ignition system is in good shape.

Thanks for all this help

[Nissanman]

The crank/cam relationship is dictated by the number of cam chain links between the two, i.e. it is an assembly step.

That doesn't mean it can't be easily corrected but it does involve some strip down to check and/or adjust the cam pulley position.

There should be 42 links between the crank pulley timing reference mark and the mark on the cam pulley, counted on the tension side, exhaust/inlet side of the engine.

The Advance/Retard adjustment range on the distributor only affects the spark timing in relationship to the crankshaft position, it won't and can't remedy the crank/cam physical relationship.

Edited December 3, 2010 by Nissanman

[Gary in NJ]

The reason I asked the questions about loaded/unloaded conditions is that carburetors will behave differently under load then when lightly loaded. The fact that this doesn't effect the 5,000 rpm ceiling leads me to think that this is an ignition or engine timing issue.

Do you own a timing light? It's time to take some measurements.

[FastWoman]

What Gary said! I'd bet it's one of the following:

* your distributor's centrifugal advance is frozen

* the power feed to the ignition module is weak

* the ignition module is going out

[ncolz]

Sounds like you have the stock distributor - have you checked the ignition dwell?

[Zed Head]

What Gary said! I'd bet it's one of the following:

* your distributor's centrifugal advance is frozen

* the power feed to the ignition module is weak

* the ignition module is going out

I think he's running points, if he has an unmodified L24. So ncolz might be on the right track. If dustbag can't measure dwell, he should at least check point quality (pitting, burnt, etc.) and make sure the gap is set right. Then re-time the engine.

To your first item though FW, if it is an old distributor, he should check the advance mechanism as you suggest. I just recently have taken two distributors apart, a 76 and a 78, and they both had gummed up bearings, with broken bearing holders. The breaker plates would move but I'm sure they weren't moving the proper distance.

dustbag, you should probably just pop your distributor out and give it a good examination, and some maintenance. You can clean it up, make sure everything works right, and replace/reset the points with it off the engine. Then pop it back in, set your timing and know that it's right.