Technical HELP with fuel pump AC Delco SBC

The pump I am using now is a ac delco has a # on the pump k323r40987 which I was told is a 40987.Called my parts guy and he says it is now a 40725?All I know is I want to install the right pump the 1st time.Years ago I went to replace the org. pump and installed some kind of aftermarket one and all it did was flood my carb so I installed the old one till now.Need to replace as it is now leaking.Will the new ac 40725 work? web site says 6.5 pounds and the dealer told me to use a 40987 which is 9 pounds?Stock 1970's chev 350 with a 600 elderbrook carb and a mild cam?Thanks

 

Carter part number M4685 will work for you.

 

9 lbs is too much fuel pressure, keep it under 7psi and you will be much happier.

 

He sent me the ac delco 40725 told me it was a 6.5 pound and will work on "most sbc motors" Hope it does, anyone else use the same pump on the same motor as mine?

 

That number comes up as the standard to to number for the majority of small blocks that run a pump with the inlet and outlet and no byp*** line and use 3/8 lines.

 

Don't think the carb will be happy with that much fuel pressure. Read on the edlebrock site and I think you will see this. I put a new Carter fuel pump and an Edlebrock card. Used a pressure regulator. No problems so far.

 

Why not go ahead and plumb in a regulator so if you ever need to replace the pump on a road trip you can use anything available and drop the pressure? Cater and old AFBs don't like anything above 5.5 LBS or so.

 

Not at home right now but I recall my eng. block starting with 397****x can someone tell me what fuel pump came on that motor stock,also running a eldelbrock 600 carb,was it a gm# 6470779?Thanks

 

I'm running 2 different cars with that carter pump I mentioned above both with edelbrock carbs and both without regulators.

 

So one last question I am now running the 40987 which if I read right is for 9lbs and it works very well yet I am told that 6.5 lbs is better which I think the 40725 is,so maybe I should be using the 40725 instead of the 40987?

 

Could the old 40987 have been so worn out that it worked with my edelbrock 600? The motor originally came with a 2 barrel carb,does a 2 barrel require a 9lb pump?Thanks

 

I'm using the same pump on my 400 HP 355 Chevy with a Holley 700 DP, pressure is at 6 lbs and it runs fine. Summit has them if you can't get one locally. You have to watch the tube size, the M4685 is for 3/8" tubing and their M4513 is for 5/16" tubing.