Outer Limits 4x4 Board

Hi, I am trying to improve a flat spot that I have from 1500rpm - 2000rpm. TB42 Petrol only.

I have new plugs, points, timing is at factory standard - 10 I think.
Today I have put Pacemakers and a 2 1/4 sustem on it.

Would it be worth putting it on a dyno and get a good tune?

What are the causes of this happening normally?

Ignition
Timing
Carby?

Cheers
Eric

Have same flat spot... 240,000 kms. Extractors, sports pipe... Unknown how old plugs and stuff are.

Interested to hear...

some things you could try are:

1. close the plug gap a bit maybe .1 or .2 mm. I had a car that i increased gap by .2 and in the top rev range it went hard but had trouble idling,would often stall.

2. adjust timing manually.Fuels aint what they used to be.try advancing and retarding the timing a bit and see what happens.You could put an alignment mark so you know where you started from

3. is the air cleaner restrictive.Im unsure of the setup for a petrol patrol

But remeber if you fit a bigger exhaust you have to loose some power somewhere ussually.everything is a comprimise.
These couple things wont cost anything so i would try these first.Good Luck

Probably not getting enough fuel on transition from idle to main jets. Try raising float level a couple of mm.

Bazzle

Check to see if the advance is working correctly, the transition from vaccum to mechanical advance may not be working correctly (broken spring & the like).

Nissans can carbon the jets & as Bazzle said it might not have a smooth transition into the main jets. This can be rectified a number of ways. I have had good results with slightly increasing the primary main jet sise to slightly increase the mixture.

Before you get int doing this though you need to make sure your ignition system is spot on & there are no vacuum leaks.

Cool I will try a couple of these ideas.

Bazzle, how do I adjust the float?

Put it on a Dyno. As you have done the exhaust etc it is not running right in the midrange due to carby tuning.
CJ

cool, sounds like a plan