Vacuum Line re routing/cleaning up engine bay/carb line help

[daretzcouple]

Hey everyone couple of questions for everyone,

 

first does anyone have a vacuum diagram for the stock hitachi carb? I just rebuilt mine and well i forgot where everything went.  It doesn't help that i had a aftermarket cruise control setup in the vehicle so I have more lines and brackets than what are supposed to be there i think.

 

two) what is this? can it go? both top and bottom diaphragms

 

3) I know this is the backfire solenoid, where does it plug into? carb bottom? air cleaner? both??

 

4) see the bundle of wires? i know the red goes to anti dieseling valve, black goes to the one on the other side, yellow goes from the back but there is a fourth one looks blue? what does that go to ?

 

Also i couldn't get the truck to fire after rebuilding the car, i do not have to prime the float chamber do it? Im starting to  think i didn't rebuild it right?

 

thanks to everyone that can help me out!

[DanielC]

You got to tell us the year of 620 truck you have, they had L-16, L-18, and L-20-B engines in them.  Every year is different, and some years may have had changes mid year.

 

But every year of 620, and almost every other year and vehicle with a carburetor must have the float bowl full of gas to start.

[datzenmike]

L20B, has fuel return and no back pressure transducer valve on the EGR so '75- '77

 

In no order...

 

Disconnect anything vacuum or electrical to this... cruise control.

 

In the above picture look at the thick vacuum hose going over to the brake booster. See that uncapped fitting? Well that's a definite vacuum leak that need to be plugged or the proper hose on it.

 

The anti backfire valve simply dumps air into the intake on high speed deceleration to reduce that rumble and pop in the exhaust. You can leave disconnected but that small hose should connect to intake vacuum somewhere. So find and seal it off or check that it is connected properly and not leaking.

 

 

Red wire to idle cut solenoid

Blue to choke heater

White (may look yellowish with age) to the BCDD shut off solenoid. Looks like connected just follow wire.

Some of these wires are covered with a black sheath to protect them

 

Short black hose near the bottom should be connected to the brass pipe above it on the BCDD. (the thing with all the Philips screws on it)

The PCV valve (between small black hose and brass pipe looks like the block vent hose is off of it. Its the thumb sized grayish hose beside it open to the left.

 

 

[daretzcouple]

Correct it is a 77, 

 

1) I am going to buy new tubing for the brake booster line ( it’s old and brittle) just wasn’t shown in the photo. 

 

2) all wires are connected expect a 4th wire it appears greenish? Maybe just disregard that one? Cannot remember it being connected 

 

3) the first picture, the two diaphragms it is a a/c vehicle where do they go? 

 

4) off the throttle cable there is extra crap ?‍♂️ Can this be unbolted too? I assume it’s for the crusie control but not certain 

 

 

thanks guys for your help

 

also any particular way to prime the fuel bowl/ float chamber? Or just keep pumping the gas and turning it over. Sorry first carb’d vehicle