68 327 - Engine Surges at 3/4 throttle

[benchrgw]

Hoping for some help on my '68 - lately at approx. 3/4 throttle I'll get an engine surge much like I'm running out of gas, if you back off it will smooth out and run fine until you put it under moderate load again. Odd thing is it doesn't seem to always do it. Am I having fuel pump failure as I assume a fuel filter problem would do it all the time or is it something else entirely? How would you test? Anyone else had this experience?
Thanks

 

[petes74ttop]

Hi benchrgw, my guess is low float level, but I would change the fuel filter and check the pump pressure first, PG.

 

[wishuwerehere82]

A sticking mechanical or vaccuum timing advance can produce those symptoms, as well as timing that is too far advanced. A bad vaccuum hose to your distributor vaccuum advance might do it too.
Check to see if your timing is 36 degrees at 3000 RPM with everything hooked up.

 

[petes74ttop]

Good point, that's a few more things to check, PG.