A bit of fine tuning

Well after the relative success of first engine fire I set about trying to get the engine running smoothly before making it all harder with the body on.

I bought a new timing light - this time one of the more advanced type that allows you to program in the advance required. Its so much easier than trying to work out where 15 degrees advance is with this gadget rather than guessing some point off the end of the pulley gauge. The unit I got also has a digital rev counter which comes in handy when setting the idle speed.

When I got the engine running originally, I managed to get the idle speed down to about 850 rpm as recommended, however I noticed there was fuel dripping from the venturi boosters which didn't seem right. Several hours of research later and the main reason appeared to be excess fuel pressure. Apparently these Edelbrock carb's don't like more than 6.5 psi. I'm running a Carter electric pump rated at 6psi so that shouldn't have been an issue.  Just to check things out I added yet another gadget to the portfolio with a Draper Vacuum gauge which also serves as a fuel pressure tester. This measured the Carter output at 5.5psi so well within the spec for the carb.

A bit more research suggested the idle circuit could be the culprit. If its not feeding the system suitably to hold an idle, you have to set the idle screw such that the throttle plates are open more than necessary, thus using the primary boosters to supply idle fuel. When I checked out my setup, the throttle plates were definitely open more than you would expect. So, approach I took was to disassemble the carb and used an airline to blow out all jets and passages including the idle mixture threads. While I was at it, I dismantled all the choke bits as they are completely unnecessary on these engines and just get in the way.
Anyhow, put is all back together and started her up - and good news - managed to set the idle down to 850 with the throttle pretty much closed and no drips from the boosters! Happy days!

After this success, I hooked up the vacuum gauge and measured the vacuum at 15"Hg which appears to be ballpark for a medium tuned engine.I played around with the idle mixture screws as per the carb manual until engine was running smoothly with no stumbling.

I think there's more fiddling to do with this setup in future but I reckon I now have a good base.