help on tune up and carburetor issues

[Boog]

I'm with wrenchbender. It sounds like the ignition is not advancing properly. You replaced the normal electrical ignition parts but if the centrifugal advance is n't moving freely it will have next to no pulling power. The weights and springs under the rotor cap need to be clean and move freely. Twist the rotor by hand. It should move but spring back when released. If it doesn't the distributor shaft is likely gummed up down in the housing. It can be disassembled and cleaned or you may elect to go with a new or reman'd unit. 12 volt power supply and it should be good to go.
Most tuners agree, get the ignition right first then the carb.

[centuryhouse]

A little additional info.

The carb is a Holley 4160 (List 1850-2 2731) 600 CFM unit.


And this is the thing (not sure what) on the brake booster:

[im4darush]

Lots of things going on in this thread. Take a step back and go through everything step by step. That holley needs to be rebuilt. Buy a complete kit and go through it. If you cant, or don't have the desire, you can get a rebuilt qjet for under $200. As mentioned, your HEI needs 12 volts. If the resistor wire is still used, you are getting 9 volts. Don't assume the individual who installed the HEI used a new wire. Check it. Get a timing light and make sure you are where you need to be. 8 btdc is a good place to start. And make sure there are no vacuum leaks anywhere. Things look really old in those pics.

[samlsn]

Originally Posted by swamp rat

What he means is there is a resistance wire or at least in my 72 K20's case what's ( I thought all our trucks had one) called a ballast resistor in line to that wire that cuts voltage to about half where the newer electronic systems require 12V to operate correctly. It looks very much like what is in this link and its mounted to the firewall above and off to the side the distributor

https://www.motoparts.net.au/cat/ele...ors?&position=

There was a white wire running from the bulkhead to distributor with a woven fabric insulation, instead of the usual color coded plastic. I think it had fewer strands of copper, which limited the amount of electricity allowed to run through it, for the lower amperage(or voltage, I'm unclear) the points style distributors required . With an HEI, that needs to be replaced with the regular 10-14 AWG copper wire. You'll find threads on this forum that describe that better than I just did.
I attached the best pic I had of mine before replacing the whole shorted out rat's nest. It's mostly hidden in the shrink tubing

[Gromit]

If that choke flap arm is just free to pivot or loose (like it appears in the photo) then vacuum may pull it closed and you would be driving with the choke on full.

It would be preferable to install the manual choke linkage as 70Stovebolt pointed out above, but for purposes of tracking down your problem or if you don't have the choke linkage you can temporarily fasten the choke flap so it stays open.

You can use a 3" to 4" long piece of wire installed in the locations where the choke cable normally goes (forward end the through the hole in the barrel nut and other end of the wire under the square washer on the vacuum secondary housing). I've used coat hanger wire for this and it is the right diameter.

[centuryhouse]

A minor update. I took whatever that thing pictured below is, off. And the truck seemed to run either the same or slightly better, hard to tell. No idea what it was, or what it was there for.

Also, I took the cap & rotor off and looked at the internals underneath. Everything seemed to move freely as it should.

Next is probably procuring a timing light. I don't see any timing marks though, so I may be looking in the wrong place. The last time I messed with timing was 25 years ago on a Mustang, and it seems like the marks were on top of the harmonic balancer.

Originally Posted by centuryhouse

And this is the thing (not sure what) on the brake booster: