driveability problems with a built 460
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driveability problems with a built 460
Help! This is what I got...71 f100 with a 460 bored .30 over, .550 lift cam, weind stealth with 850 cfm holly, msd 6al and new coil,plugs,wires,cap and rotor. Magnetic trigger working normal(tested against new). I recently bought this beast three weeks ago and it ran very good and hard. I took it on the interstate for a 60 mile round trip cruise. after thirty miles i took the exit ramp to turn around and it was running like @#%$ ! It was all i could do to limp it home thats when ireplaced the plugs wires cap rotor and coil. I also checked the magnetic trigger and it was okay. Any suggestions with what direction to look at next? I fooled with the timing with no success. Could gas be the problem? I just put unleaded regular in it. With this set up would it make it miss, poor running at all rpms and backfire? It acts like its gotf three or four dead holes and I know better than that.....like I said when I first got it in ran great!!!thanks in advance
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
Probably- Run some premium through it and see if it improves. Also, check the fuel lines for kinks, restrictions and throw a new fuel filter on it.
Regular also will vapor lock long before higher grades will.
Regular also will vapor lock long before higher grades will.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
Guys build these engines for racing and wonder why it won't run on the street. You are not turning the rpms that the engine needs to clear it out. That engine is built to turn 5000-6000 rpms and you can't turn it at that rate on the hi-way.
Check the fuel flow to the carb. Cheep gas would cut the performance but I don't think to the extent that you have described, but I could be wrong.
John
Check the fuel flow to the carb. Cheep gas would cut the performance but I don't think to the extent that you have described, but I could be wrong.
John
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Well guys here is where we are at after the weekend.......I pulled all but a couple gallons out of the tank and put in two gallons of 110 leaded premium and also added a can of seafoam....it improved it some but it is still backfireing and running rough. The plugs are still "wet" with gas but not fouled. Im inclined to think that this holley 850 is trashed what with all the backfireing also I wonder if it isnt over carbed.......The wife is getting real irritated with me and my toys so I need to get this thing running right or "else" (and if you've been married as long as I "else" is not good)....
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Joined: Jan 2004
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From: syracuse, kansas
Will it idle?
If so pull the air cleaner and look into the carb with a mirror, both sides. At idle you should not see any fuel up top. If you do see fuel adjust float levels, if possible. If that does not help check fuel psi, look for 4-6 psi at all speeds.
The backfire issue sounds like ignition. Good luck...
The backfire issue sounds like ignition. Good luck...
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Logistics Pro
Joined: Jun 2003
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The backfire issue could be many things...lean condition, timing, etc.
I would check timing first.
If it's acting like it's got four dead cylinders and the dead cyls. are the 2 inside ones on one bank and the 2 outside ones on the other bank, you either have one side of the carb not delivering fuel or a vacuum leak on one of the affected side's runners.
The Weind stealth is a 180 degree intake manifold. The right side of the carb feeds the # 1, 4, 6 and 7 cylinders and the left side of the carb feeds 2, 3, 5 and 8.
The vac port on the #4 intake runner would affect 1, 4, 6 and 7 cyls. if a vac leak were present to something drafting vacuum from that port. (It would have to be a very noticeable leak, though).
Check and see which cyls. are not firing at idle. If it's the pattern listed above, at least you'll know you're headed in the right direction.
I would check timing first.
If it's acting like it's got four dead cylinders and the dead cyls. are the 2 inside ones on one bank and the 2 outside ones on the other bank, you either have one side of the carb not delivering fuel or a vacuum leak on one of the affected side's runners.
The Weind stealth is a 180 degree intake manifold. The right side of the carb feeds the # 1, 4, 6 and 7 cylinders and the left side of the carb feeds 2, 3, 5 and 8.
The vac port on the #4 intake runner would affect 1, 4, 6 and 7 cyls. if a vac leak were present to something drafting vacuum from that port. (It would have to be a very noticeable leak, though).
Check and see which cyls. are not firing at idle. If it's the pattern listed above, at least you'll know you're headed in the right direction.
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From: East Flat Rock NC
You may want to make sure the intake is tight, also did you make sure you
got your plug wires back in the right place.
P.S. also I thought I would take a stab at this, maybe when you stopped on the exit
maybe for gas?, some one played around and pulled the chip out of your
( MSD ) and put in a low rpm chip, the 6al has soft touch rev control, a msd
cutting the fire to some of the cylinders could be skipping and back firing, also
make sure the ground for the 6al is good!
got your plug wires back in the right place.
P.S. also I thought I would take a stab at this, maybe when you stopped on the exit
maybe for gas?, some one played around and pulled the chip out of your
( MSD ) and put in a low rpm chip, the 6al has soft touch rev control, a msd
cutting the fire to some of the cylinders could be skipping and back firing, also
make sure the ground for the 6al is good!
Last edited by Pro-Street/StateTK; May 8, 2006 at 03:24 PM.