motor problems still...UPDATED...HORRIBLE MPG

[Chevy305]

is the only one that looks just like it...wouldn't taht be way to much for a 350????? don't i need a 600 or 650???could that kill my mileage????

http://www.holley.com/TechService/Library.asp

Go HERE:
http://www.holley.com/data/TechService/Technical/Selecting%20A%20Carburetor.pdf
That will give you a good indication on what cfm you really need. I think a 650-700 cfm would do you just fine.

 

[01maroonz71]

well, let the tuning begin tomm. i geuss...i wanna make this thing come alive!!!!

it pings like a mother !!!! i just drove it like 30miles round trip and pinged the whole way....

 

[Thunder]

Carb's not a double pumper. It just has dual feed.
That looks like an old Holley to me. Your gas milage problems are proabally a blown power valve. If it is blown it will run very rich all the time. All it takes is one backfire thru the carb to blow the power valve. Check the float lavel also.
But
That carb is a POS for off road. It will need an off road kit to even make it climb a little hill without flooding. I would not put a penny into it espically if you have to pay someone to work on it.
Personally I think you should get rid of it and get a 670 cfm Holley Truck Avenger. They are a good all around carb for trucks. It will save you many headaches and $$$ in the long run. You may have to tune it a little but its not hard. People here can help you out.

You could go the q-jet route also I think they are a better carb. But you will need an adapter to bolt it to your manifold. And If that engine is a 383 you will be in for some tuning/ jetting also.

IMHO a Holly truck avenger is your cheapest and easist way out of your problems.

Oh yeah hook up your vaccun advance if your dist is equipped with it. But be sure to hook it up to the right port on the carb. On holleys the vac adv port is on the right side of the float bowl.

 

[76zimmer]

http://www.amazon.com/Holley-Carburetors-Design-Dave-Emanuel/dp/1884089283

Read it, Learn it, Live it.

I would still like to know if you have ESP? I had trouble with my 85 retarding the timing from the computer. It was retarding about 15 degrees at any random time. I ended up bypassing the computer.

 

[Chevy305]

Carb's not a double pumper. It just has dual feed.
That looks like an old Holley to me. Your gas milage problems are proabally a blown power valve. If it is blown it will run very rich all the time. All it takes is one backfire thru the carb to blow the power valve. Check the float lavel also.

Personally I think you should get rid of it and get a 670 cfm Holley Truck Avenger. They are a good all around carb for trucks. It will save you many headaches and $$$ in the long run. You may have to tune it a little but its not hard. People here can help you out.

Good point on the blow out valve. Though all the new Holley carbs have blow out protection so 1 little backfire won't effect them.

Also if your truck is pinging then you still have timing issues. You should really get those issues solved before really digging too far into the carb.