help on tune up and carburetor issues

[El Dorado Jim]

Originally Posted by davepl

They're a bit of a fire hazard. Good that you can see, to be sure, but maybe only as a temporary tuneup measure to see what's in the tank. Steel doesn't burn, break, or crack.

(Sound of glass filter on cast iron itake)
..tink... ...tink... ...Crack!... ..splash... ...WOOF!...

At a very minimum keep it securely zip-tied somewhere that it's not banging or resting on anything hard. But I'd replace it once your other issues are sorted out.

I used to run those glass filters, until I smelled gas one day, popped the hood with engine running and saw gas spraying out like a fan from a length wise split in the glass, don't know why my truck didn't catch fire...luckily, had a piece of steel tubing with me in my toolbox, so I removed the filter and temporarily installed the tubing to get me home, will never use another glass filter again..

[samlsn]

I was recently in the same boat and while my dist had been upgraded to hei, I still had the original resistor ignition wire running from the hei to back of my fuse panel. Also had platinum plugs and copper core plug wires which both serve the hei poorly (I've been told) correcting those issues did improve my situation, along with the new holley 670 S/A carb

[Gromit]

Accelerator pump diaphragm looks like it is leaking - which could mean it is torn as well.

Also the air filter to carb gasket is missing so if run like that long enough the carb could pull in a lot of dirt.

I'm a fan of these Quick Fuel super rebuild kits - they come with all new bolts and screws and springs..

Here is the page from their catalog - should be less than $50 - I don't recognize your carburetor but it is a vacuum secondary with side bowl floats and balance tubes - maybe someone will chime in but it looks like the list number is ..3343920? (number on the front) But I've never seen one that didn't have the word "list" in front of the number...

Anyway; doing the rebuild isn't that bad; remove, disassemble, (take lots of photos), clean, match up the old parts with the ones in the kit; and reassemble using an inch-pound torque wrench using toque specs attached below in the pdf

There are lots of videos on youtube where they show step by step...

[centuryhouse]

Originally Posted by samlsn

....I still had the original resistor ignition wire running from the hei to back of my fuse panel

Can you elaborate on this? What would the original (and I presume wrong) wire be like, as opposed to whatever should be there?

[swamp rat]

Originally Posted by centuryhouse

Can you elaborate on this? What would the original (and I presume wrong) wire be like, as opposed to whatever should be there?

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=

[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.