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Topic: Cutting out under load

in Forum: C3 Engines


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Cutting out under load

Posted: 1/22/07 1:39pm Message 1 of 17
C3454Vette
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Washougal, WA - USA
Joined: 1/12/2007
Posts: 12
Vette(s): 1973 coupe: Painted a root beer brown (soon to change). Running an all numbers matching 454ci and 4 speed. The engine has been punched 30 over, with Keith Black pistons, Cam, Edelbrock intake and 750 carb, with long tube ceramic coated headers.

Help!

I am having issues with my 73 running a 454 and 4 speed. I had the engine rebuilt with almost all new parts (mild performance) the heads, block and crank are stock, but everything else has been upgraded or replaced. The carb is a Edelbrock 1441 (750 cfm) on a Torker II intake and the compression is about 9.5 to 1. I am also running Hooker long tube headers (ceramic coated).

When it is just sitting, I do not get any cutting out when I accelerate. But when I drive it and put my foot into it, it pops and coughs. If I ease into it, I can make highway speeds.

I thought it was ignition problems, but I just purchased a HEI distributor from Mad Vette and the problem still happens. I tested the fuel pressure and it is fine and vacuum is steady at 13 pound.

I do have a issue of number 3 spark plug wire, it is to close to the header and it melts and then shorts out. I have the heat shield covers over the wires now.. but still gets hot.

Any help would great.

Thanks

Stacey

C3454Vette2007-01-22 15:29:13


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Cutting out under load

Posted: 1/22/07 5:08pm Message 2 of 17
Chips58
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Australia
Joined: 5/6/2004
Posts: 535
Vette(s): 71 Coupe Black on Black
Route your leads over the top rather than underneath.  It sounds like your plug leads are breaking down under load.  Your "getting hot" problem may be part of that.


Cutting out under load

Posted: 1/22/07 6:37pm Message 3 of 17
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hmel '74
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York, SC - USA
Joined: 9/4/2005
Posts: 534
Vette(s): 1974 mille miglia red with oxblood interior 355ci, 320hp
i had the same type of problem with my car.   my car was also switched over to HEI instead of the original coil/points.  
is your original coil wire (insulated with fabric) attached to your new HEI hot wire?  mine was and it was draining the 12 volts needed to properly run the HEI.  i taped that original coil wire off and ran a direct wire from an acces. tab on my fuse panel directly to the hot wire on the HEI.  that gave it 12 volts with no drain.
i've had no problems since.



Cutting out under load

Posted: 1/22/07 8:13pm Message 4 of 17
C3454Vette
Former Member
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Washougal, WA - USA
Joined: 1/12/2007
Posts: 12
Vette(s): 1973 coupe: Painted a root beer brown (soon to change). Running an all numbers matching 454ci and 4 speed. The engine has been punched 30 over, with Keith Black pistons, Cam, Edelbrock intake and 750 carb, with long tube ceramic coated headers.

I had ran a new wire when I had a Pertronix Ignitor module in it. I ran it directly to the fuse panel, to a tab labeled Ignition. I know the resister wire is a issue.

Thanks
 



Cutting out under load

Posted: 1/22/07 8:39pm Message 5 of 17
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Did you test the fuel pressure while driving it, or just sitting idle?
There are several things that come to mind for this problem.
1) Ignition
2) Fuel
3) Timing
The fact that you can "ease" into it, and it seems ok, kinda points to a fuel issue, to me. Could be a clogged filter, or the "sock" in the fuel tank is collapsed. Could also be a lean condition with the carb.
Have you pulled any of the plugs to see what they look like?
Many questions will follow...


Joel Adams
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Cutting out under load

Posted: 1/22/07 8:59pm Message 6 of 17
C3454Vette
Former Member
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Washougal, WA - USA
Joined: 1/12/2007
Posts: 12
Vette(s): 1973 coupe: Painted a root beer brown (soon to change). Running an all numbers matching 454ci and 4 speed. The engine has been punched 30 over, with Keith Black pistons, Cam, Edelbrock intake and 750 carb, with long tube ceramic coated headers.
Might be fuel....
 
1. Ignition, All new, wires, distributor and plugs gapped at 50.
2. Fuel, New Carb, new pump and new filter
3. Timed at 12
 
 
Is there a way to test if the "sock" is collapsing? I am running a stock fuel pump and have the return line still attached. When I tested the fuel pump, it was holding a 4 pounds. Not sure how to test it under load.
 
Plugs are a light tan/gray..



Cutting out under load

Posted: 1/22/07 9:30pm Message 7 of 17
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
4 pounds is a bit light, for a biggy-block. I'll almost guarantee it is dropping to almost nothing when you goose it down the road. You really should have around 6-8lbs.
You would need to "T" into the fuel line, after the pump, get get an accurate pressure reading while driving.

The only real way to check the sock is to remove it from the tank. You can, however, get a good flashlight (NOT a lighter, or electric drop-light), and look down into the tank from the filler. You can see the sock on the end of the pick-up tube. That is, unless there is too much poop in the tank, in which case, you've found the problem! If you can see rust, or any other kind of crap in the bottom of the tank, that stuff will clog the sock over time. You may need to drain the tank, or drive it 'till it's low on fuel to see the bottom of the tank. I can see the bottom on mine(the '74) when it is full, but I have a fairly new tank, that came with-out the funky rust option!

You might try to blow back thru the fuel line from the pump suction side, into the tank, and blow some of the poop off the sock, and see if it drives better for a while after that. If it does, then you've narrowed the possibilities.


Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Cutting out under load

Posted: 1/23/07 2:06pm Message 8 of 17
C3454Vette
Former Member
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Washougal, WA - USA
Joined: 1/12/2007
Posts: 12
Vette(s): 1973 coupe: Painted a root beer brown (soon to change). Running an all numbers matching 454ci and 4 speed. The engine has been punched 30 over, with Keith Black pistons, Cam, Edelbrock intake and 750 carb, with long tube ceramic coated headers.
Fuel... so it might not have enough flow...
 
I will try to blow it out and ee what that gets me and I will also get a in-line fuel pressure gage installed.
 
Thanks



Cutting out under load

Posted: 1/24/07 1:53pm Message 9 of 17
custom76
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Naples, FL - USA
Joined: 2/26/2005
Posts: 133
Vette(s): 1976 coupe with a custom body and a 396 big block with nitrous installed. Runs great!!
How old are your plug wires? I had the same problem and changed my wires and that did the trick. They were breaking down under a load.


Cutting out under load

Posted: 1/24/07 3:27pm Message 10 of 17
C3454Vette
Former Member
Send PM
Washougal, WA - USA
Joined: 1/12/2007
Posts: 12
Vette(s): 1973 coupe: Painted a root beer brown (soon to change). Running an all numbers matching 454ci and 4 speed. The engine has been punched 30 over, with Keith Black pistons, Cam, Edelbrock intake and 750 carb, with long tube ceramic coated headers.
The distributer and wires are new as of last week. I changed from a Pertronics Ignitor module in my stock disributor to the new HEI setup.
 
Thanks



in Forum: C3 Engines


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