Phew that's quite the list of things and places to check, thanks folks! The more I work on this truck, the better I'm getting at guessing socket sizes
. Hopefully this weekend I'll have the time to get out there and hunt for the noise.
@thedudeabides86, I followed the steps in Edelbrock's tuning guide, I have an AVSII. Not sure if the Holley will be different. I've pasted the steps I used below. Well, mostly used. I did it roughly by ear for now, but once I have the time I'll properly do it.
Based off the steps below, using the idle mixture screws I found max RPM (honestly leaning it out at first upped the RPMs which was a bit odd), then leaned it until the rpms dropped a bit, and lastly I upped my idle speed back up. Still not the happiest sounding engine at idle, but she revs nice. (On my carb, turning the screws clockwise leans the carb)
1. Fully warm engine and ensure choke is fully open.
2. Air cleaner in place.
3. Set desired speed with the idle speed screw.
4. Adjust the IMS on ONE side to get the maximum possible RPM. Do not go rich beyond the
maximum speed point.
5. If the above changed the idle speed more than 40 RPM, then readjust the speed.
6. Adjust the side OPPOSITE of that in Step 4 to get maximum RPM.
7. Reset the speed.
8. Carefully turn each IMS to again get the maximum idle RPM.
9. Go leaner just enough to get a 20 RPM drop in speed.
10.Reset the speed to the desired RPM.
11.This is a Lean-Best Idle Set. Setting richer than this will not improve idle quality or
performance, but could tend to foul plugs.
https://advertising.edelbrock.com/Li...Guide_0348.pdf Page 4