My '69 series 2 likes to miss under load at higher revs when it gets warmed up. Does not miss when I rev the motor in neutral. I sounds like one of the pistons may not be firing. Thoughts?

 

Hi John,
Based on previous posts I think you may have the same Engine/carb/distributor set-up as I have. Based on my experience your engine is not "missing", it's more likely to be pinking or pre-ignite. There are many causes but here are the easy ones: Fuel too low octane rating (combusts earlier), distributor too much advance (more on that below), incorrect sparkplugs or loads of carbon build-up in the cylinders. Over the years I dealt with all of them albeit not on my jag, it was with mg's and triumphs.
If I am correct you have the non-vac 41207 distributor. This one has a mechanical advance (only) which gives much more advance than on other E-types so it's really important you set the initial timing correctly. I don't know how you set the timing, but make sure you invest 20 bucks in a strobe gun and ensure you're at 10deg BTDC at 1000rpm.

Now, I could be completely wrong and your engine may indeed be "missing" - then it will most likely be an issue with the points/leads/sparkplugs. Do you still have the points? If so check gap and dwell. Adjust gap first and THEN adjust timing

Good luck with it - all are easy to check except the carbon build-up (check if it was EVER decoked) - so let us know what you find !

 

Try another coil....Coils tend to give out under load, but run fine otherwise, when they are going bad.....
If you haven't messed with the timing, it's unlikely that it has changed...
Of course, ignition parts like the rotor can also be troublesome....
There is a red rotor sold by several suppliers , that prevent arcing , due to poor quality control of the black "plastic" type rotors...It's the same rotor used in a TR-6.
Edward

 

If it only misses under load/higher revs, you may also have fuel starvation issues. Failing fuel pump, clogged fuel filters may be worth looking at as well.


Alfred

 

I agree that fuel starvation could be the issue, but the fact is that 90% of "fuel issues", are actually ignition....
Rotor and coil are easy and relatively cheap, new fuel pump is not.
Test the fuel pump , by disconnecting the line at the carbs, and dumping the fuel into a glass jar...Turn on the ignition, and see if fuel dribbles out or rushes into the jar.
Edward

 

I solved a similar issue with a needle change on my 3 SUs. For years I loved with it, I did all of the above recommendations to no joy. Then, one day on of the forums, I frequent, there was a mention of a specific needs P/N#. Thinking what the "hell" I purchased them made the change and wha-lah! No more hesitation or break down from approximately 3K Rs upwards. Might work for you, all else being OK...
Good Luck and Happy Holidays.....