Exhaust temps... what do they mean?

[BSB67]

As per OP his description the cylinders with high temperature are #6 and #7.



IF he is using a dual plane manifold like a Edelbrock Performance (RPM) those cylinders are on the "Low" "rear" section...the passenger side of the manifold.
So that section probably has a different mixture compared to the rest, probably very lean as that causes a higher temperature.
As they are both on the same "port" of the manifold the likelyhood there is an issue with the valves seems very small.
Maybe check the carb settings and ensure all idle screws are set the same, or a idle circuit port could be blocked with dirt?

You are correct, #6 & 7 (not 5&7). And your points are correct.

In fact, it was common to jet-up the driver side secondary throttle bore (i.e. stagger jet that one higher) on dual plane intakes.

Also remember you're only measuring it at an idle and no load. If you have 4-corner idle mixture, simply adjust accordingly.

Going down the road will be different.

 

[Canadian1968]

It is the edelbrock performer RPM.

The carb is the classic 750- 3310 with a rear metering block added so I can adjust the secondary fuel a little bit more . I have been thinking of upgrading to a carb with more adjustablitly but it's just not in the budget right now.

Yes the temps are surface temps taken with a optical thermometer .

By the sounds of it, it's seems to be normal

 

[Wietse]

It is a distribution issue as mentioned already.
If you have 4-corner idle screws you may want to adjust the respective corner to provide a bit more fuel and check again what the temperatures do.
You will have to find a balance between temperatures and idle quality if you want to reduce the temperature differences.