Loss of power @ 4000rpm's -- Help!

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440-VS

440-VS

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Well, Here's what's happening with my 440...
Starts and runs fine up to, right at 4000 rpm's. No matter if i'm half throttle or wide open, when it hits 4k, it starts spitting, sputtering, backfiring, and losses power. That sucks.
I have a new Edelbrock 750cfm carb, fairly new plugs, 8.8 wires, the HP ICU and electric fuel pump.

Any ideas? Thanks everyone in advance for your help. I really want to black the road this weekend!!

440-VS
 
If it's not the ignition, you are too lean on the jetting/rod combo

What is the total timing set at and at what rpm is it full advanced?

Is this a stock/mopar distributor?
 
1wild&crazyguy said:
If it's not the ignition, you are too lean on the jetting/rod combo

What is the total timing set at and at what rpm is it full advanced?

Is this a stock/mopar distributor?
Click to expand...

'73 motor built to '69HP spec's. I bought it after the build. I'm OK at most everything... except the engine. Best of my knowledge, Mopar distributor. I don't know the answer on the timing. It was set to run the street on 93 octane, told me where to set it for race fuel, but I wasn't going to be doing that for a while and since forgot.

The car ran strong through 5-5500 rpm's untill late last year. That's when it starting doing this and I parked it for winter interior mods. Got it out the other day and the problem's still there.
 
440-VS said:
The car ran strong through 5-5500 rpm's untill late last year. That's when it starting doing this and I parked it for winter interior mods. Got it out the other day and the problem's still there.
Click to expand...

verify the timing 1st, if decent 'like 34-38* or 'in the relm', then basically make sure the ignition is function properly wires/plugs.
It might be the ignition box is on it's way out, if you had a spare to swap that'd be nice.

once the easy stuff is outta the way, look at the valve springs and how old they are.

Thats kinda how I'd approach it.
 
Valve spring is the first thing that popped into my head. Any noise around the valve cover at all?

Its not to bad to pull the covers and take a look.
 
440-VS said:
How would I know if it IS the ignition breaking down?
Click to expand...

Much of the time ignition is load sensitive, so you can get it to the "fail" point and play with the throttle. More throttle= more popping, banging.

Flat exhaust cam lobes can throw you fer a loop, as can an open intake valve
 
More throttle DOES equal more popping, backfiring...

Local friends are telling me to just put an aftermarket ignition on it. MSD or equal. That's out of my "safe" zone, and have no idea where to start... or if I even should.
 
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