I'm currently having a little problem with my ute which is a "Miss or splutter" at about 6500 to 7000rpm. I have cleaned out the carbs, changed the points but it is still there. I am starting to wonder if it could be the coil or spark plugs or the float level?? I'm pretty sure its getting enough fuel as it is runing an electric fuel pump and holley regulator. Im just wanting a few ideas before I go start wasting money on parts i don't need.
Thanks

Check your ignition timing?

Hey NZ,
do you run a tacho ? Electrical mysteries are often supplied by tachos ! I too had a mystery misfire in my coupe at the same revs and it disappeared once I bypassed the factory tach - must have been acting as a rev limiter!
Good luck.
Cheers

1200 tachos are an induction loop. I doubt that would cause a problem in the ignition circuit. Are you sure R-fast that was the cause?

I'd look at the ignition coil or points.

We are talking very high revs here. Way out of factory spec

Maybe the 12v feed to the coil is not getting a clean 12V or (resistor fed 9v) due to a dirty ignition switch or engine bay loom connector.


Chris

Yeh probably coil,
Oh, and u might wanna check the resisitor above the coil and even plug leads.

Just my 2 cents

I have had similar situations with all of the following being the cause:

1. Timing too far advanced.

2. Spark plug wires burnt through or shorting out somewhere

3. Old or bad spark plugs

4. Cap/rotor might need replacement

5. Lean condition caused by improper fuel jetting or a clogged or worn part in the carb(s)

6. Valves out of adjustment

7. Not enough voltage to the ignitionl (bad alternator, dead or dying battery, bad voltage regulator, or bad or corroded electrical connections)

Everything listed here is easy to check for and/or cheap to replace or fix. Grab each spark plug wire with the car running and see if you get zapped. Take it out at night in the darkest spot you can find with all lights off and watch the engine running and revving up to look for sparks arcing where they shouldn't be. Should be an easy fix!

Hey datodude,
it doesn't seem to make sense but it is true. We were constantly chasing a high rev misfire at the track and through past experience we generally suspect any tacho (usually aftermarket though) if an electrical problem arises. It felt like a rev limiter was installed - the car would rev up to about 6500 - 6800, misfire a little, then struggle on up the rev range with small, intermittant misfires. Came off the track, disconnected the two tacho wires and plugged them into each other to reform the loop and back onto the track. No misfire up to the "I think she's gonna blow" max rev shiftpoint. Regardless of logic, all these components are 30 years old now and like all mass produced items, can be prone to problems maybe even from new . If all else fails, try the tacho. Cheap to check - disconnect and then test (on a closed road by a professional drver under controlled conditions of course ) If problem persists, reconnect tach and move on to next suspect !
Hope you find it.
Cheers

I've found the problem or how to fix it, The motor runs fine when you use a full 12V on the coil. Any Idea why this might be? could i be using the wrong spark plugs? The ute runs so much better too!