I need to ask you guys that know engines better then I do, I have a 440, believe its a mid 70's quite possibly from a motorhome, not sure just have a feeling it is, not sure of the internals although I was told when I bought it that it is a 440, 030 over bore, closed chamber heads, mild cam, not sure of what it is just told its a mild cam, Edelbrock intake and 750 Edelbrock carb, it has a fuel regulator and a large electric pump under the tank plus a mechanical fuel pump on the engine, stock cast performance exhaust, more then likely stock heads, they are cast also, I have been told by a mechanic that has worked with hotrods all his life that he suspects it is higher compression, 11:1 or higher, again a guess. I have tried using high octane gas and also used octane boost while it helps it still knocked once it gets warmed up and have now installed a Snow Performance water methanol injection that really does help and now no more knock but now when you get your foot into it hard it seems to be starving for fuel and will almost bog and actually died on me once, now when I feel this happening I have turned on the electric fuel pump for a couple seconds and all is well again. Now my question to you is this, is the mechanical fuel pump going or do I have a small leak somewhere, when the Snow Performance water methanol kit was installed you have to put a spacer plate in that has a port that you thread in a nozzle to spray the water methanol or windshield washer fluid into it. The electric pump can't be left on all the time as it pumps too much fuel and can't be regulated properly it is just used to start the car after it has sat for a few days and loses its prime, it has always done this so nothing different here. So what do you guys think could be the problem, sure would like to have it reliable and not doing this, thanks for any help and advice. Here is a picture of the engine too.

 

My suggestion would be to put a set of open chamber heads on the motor. I had a problem like that 30 years ago on a 383. Motor did not run on pump premium. So I swapped heads to fix the problem.

 

Hibred -

The purpose of the water injection is to allow you to advance the timing without pinging for greater performance or reduce pinging in an engine that is already pinging.

Before you added the water spray, have you tried:
Retarding the timing to a point where it stops pinging?
Used a fuel additive, specifically Techron to clean possible engine deposits. (It actually does work.)

After the water spray, did you change the jet size or A/F mixture. That's usually required.

A 440 with a "mild" cam shouldn't need more than a high-perf mechanical fuel pump, assuming you have at least a 3/8" CLEAN fuel line from the tank to the pump as well as from the pump to the carb.

BTW - nice looking engine bay.

Archer

 

Before making changes I would want to know cranking cylinder pressures and ignition timing, initial, total and at what RPM.

 

THAT is the first step...Cranking Pressure.....find out WHAT exactly you are dealing with first !

 

On the knocking..... Has the car always done that or has the knocking just recently started??????? I'm thinking with todays fuel the engine is lean.

As for the Dual fuel pump problem, I'm not a big fan of that type of setup but if it's been working, I'll just throw something out there for you to check.
You might be rite that the Mechanical pump is getting weak....
However on the electrical pump (which I feel is a restriction when not used, Just my 2 cents) I might be now that is has some years on it that the rotor inside the pump may not be turning free enough to let the Mechanical pump draw enough fuel threw it anymore.
I would try by passing the electric pump and see if that problems goes away.

Thought's ?????