It seems, I remember 1406 being 600 cfm with auto choke.
where as the 1405 being 600 cfm with manual choke both being square bore carbs....
2x Go Holley
orich

 

Yup. The jetting is also different between the two.

 

I would recommend the following:

1. Install the orange step up springs.

2. Replace existing rods with 71/47 rods.

3. Dial in your idle using a vacuum gauge. Connect vacuum gauge to the manifold port on carb and adjust both screws to the highest vacuum reading.

Just my 2 cents.

Lance

 

Lance

What size jets would you recommend?

 

Don't change the jets; use the jets that came with your carb.

 

Well its been awhile..But with that said..get rid of the AFB style carb #1...there crap in my book..you will never get the right vacuum setting with it out of timing..rebuild of the motor without an at least rebuilt carb is well..Just asking for problems.. I have always ran Holley and always will because of there simplicity and they get the job done far better than any other carb on the market..JMO of course.. If you choose to get a holley and either have it rebuilt or a remand one..turn both the air/fuel screws in all the way to where they seat..with a small screwdriver..and very lightly at that..dont want to damage the points on them..then back both out a turn and a half..good starting point..then work on your timing once fired.. Good luck...

 

Special thanks to Lance Hogan, and everyone else that chimed in.

Sorry it took so long for me to get back to it. Had some family issues.

Here's what I did:

Installed the 71/47 metering rods and orange springs. Also, adjusted the idle mixture and moved the accelerator pump one notch closer to the carb body.

Made a huge difference in driveability. Now just a matter of fine tuning.

 

I am glad to hear you have dialed your carb in a little closer. One thing I like about Edelbrock carbs is that once you get them dialed in, you don't have to touch them again (or very rarily).

Lance

 

Well this could be part of the problem. I'm gonna need help diagnosing this one. The only thing I did not do on this rebuild is the valve guides. They didn't seem too bad. Needle rapidly moves between 15 and 8 at idle. The truck drives pretty good now. But, obviously something has gone wrong. What do I do now? Compression check? Help...

 

gauge reading vibrating excessively at idle but steady as engine speeds up indicates worn valve guides.

gauge reading vibrating excessively at all speeds indicates leaky cylinder head gasket.

 

That's gonna suck, if its a leaky head gasket. Here's a better video. With engine revving, etc. Does this paint a clearer picture? What do I do now? Could it be a bad gasket? Warped head? Where could it be leaking from? There's no water in the oil or steam from the exhaust. Leaking between cylinders maybe?

 

My guess is between two cylinders. You could do a coolant system pressure test to verify. Are you getting bubbles in the radiator when you rev it with cap off? Be careful if it's hot.

 

I don't have a tool to test the pressure. But, wouldn't I have steam coming from the exhaust?

 

I would start with a compression test first and see if you can narrow it down to which cylinder/cylinders

 

The compression test reads 120 lbs on all 8 cylinders. Spark plugs look good. My brake booster has a leak. But, that was disconnected during the vacuum test. There's no bubbles in the coolant when I rev the motor. Next I'll pull the valve covers to make sure everything looks good. Don't know what else to look for.