426 dual 600 cfm - no power suddenly

[hofilbert]

I have a 426 Hemi with dual 600 Edelbrock carbs that are synchronized (I hope that's the right term) and has a MSD electronic ignition with a MSD Blaster for a coil. I went to a car show on the 4th - all went fine going there. On the way back home, I went about 2 blocks and suddenly I had very little power. I thought maybe I had popped out of gear, nope. I went another 2 blocks and made it to my country road home. I started playing with gears and gas then while driving. The car was slow at take off and never got out of 2nd gear. I stayed in 2nd gear all the way home. I tried changing gears and that all worked fine, even put it in neutral and the engine has a very slow power curve. It would accelerate, but very slowly...even in neutral. It was slow power like driving an old diesel Mercedes from the 60's.

You could stomp on the gas pedal and it would give a very slow acceleration. It didn't miss, or sputter or cutout...just a slow acceleration. I had a little less than 1/2 tank of gas, so that was good. I did have a very low battery from not driving it. After I was home, I took off the shaker and all hoses were attached. Had a new air filter. Everything looked good and connected. Checked all plug wires to ensure they were connected.
I did restart it cold later with the elec. choke and it ran fine for about 20-30 secs. I could get a good VROOM and it would go up nicely to 3500 rpms just fine. Then, suddenly it did this "low power" thing again and dropped to below 1K rpms and foot response was slow. Idle was just fine and no missing. My battery was very still low.

I've talked to a couple mechanics and they are both stumped.
Any help with ideas is appreciated. I'm not a full-time mechanic so I'll do my best to answer questions. Thanks! Phil

 

[Steve340]

MSD ignition will need a lot of power try a fully charged battery. Steve

 

[moparlee]

Just a thought, have you checked out your fuel delivery? Gas tank fuel pickup filter, fuel pump, line filter, dirty carb?

 

[DetMatt1]

Sounds fuel related to me as well although I have no experience with MSD. The 440 in my Imp began acting similar and after a while I discovered the fuel pump pushrods had worn down over a quarter of an inch.

 

[moparleo]

When diagnosing a running problem, always start with the battery. Especially electronic ignition systems. They require a fully charged battery to perform properly. Always charge the battery with a proper battery charger. Never try to recharge with the cars alternator. They will not recharge the battery. their function is only to maintain the state of charge. The battery should have at least 13.5 volts when fully charged. Also best to remove the battery from the car and charge away from the car. I have seen batteries explode when charging and you don't want that acid all over your car. If the car still runs the same, then you can look elsewhere. But you should always have a fully charged battery when operating your car.

 

[hofilbert]

Well, I don't think its the battery. I just went out a minute ago and after 3 days on a trickle charger and what sounded like a brand new battery, it cranked it over big time and fired up. The choke was fine and ran for a long minute or two then I revved it off. Idled fine, then I revved it again a few times. Revved OK for about 3 times, then she started the no power thing. I put my foot down to the floor and just a slow acceleration. Not much of anything.

I'm guessing now, it isn't getting enough fuel. I think its getting fuel, just not enough. It idles OK and doesn't seen starved or flooded or hesitations, or anything like that when I'm trying to rev it. It just doesn't want to perform.

 

[Steve340]

Is your fuel filter blocked?

 

[DetMatt1]

Maybe your coil is heating up and on its way out? I guess if I were you I'd do a repeat performance with the air cleaner off and see if You Can watch it run out of gas.

 

[hofilbert]

Fuel filter is now brand new. Nope. That ain't it either.
Air cleaner is off, and still does the same.
Ever heard of Herm Petersen? Famed top fuel drag racer that won the '73 Gatornationals? Guess what?...He's coming over in a few minutes to take a look at it. We'll see what he can figure out.

 

[hofilbert]

OK. Problem solved. I had Herm Petersen, famed top fuel drag racer ('73 Gaternationals winner) stop in and take a look at my car. It took him about 10 seconds to find the problem. The carbs are progressive and there is a little small screw on the linkage of the rear carb. The screw had come apart so the back carb wasn't working. The little screw and nut was down inside the tunnel humps of the intake so I didn't see them at initial inspection. I guess when you've done this as much as Herm its all easy to see.
THANK YOU HERM! All is good and I'm happy.
Thank everyone else for your ideas and the support.

 

[moparleo]

Great. Still make sure you have a fully charged battery.

 

[moper]

I was going to suggest first check the choke plate, then check the throttle linkage...lol. Not getting full throttle, or the cable sliding is really common.