4 Dead cylinders
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4 Dead cylinders
I have a 1966 F100 That has 4 dead cylinders. They are 2,3,5, & 8. They all have compression that is good, and they have spark, and seem to have fuel. I am stumpted. Any help is appreciated.
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From: Central Oregon
Have you pulled the plugs to see if they are fouled? If you have compression, fuel and spark it should be running. You may not be gitting good fuel flow from the carb. If notting is working pull the valve covers to make sure all valves are working good, no bent push rods or loose rocker arms.
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Originally Posted by bertha66
Have you pulled the plugs to see if they are fouled? If you have compression, fuel and spark it should be running. You may not be gitting good fuel flow from the carb. If notting is working pull the valve covers to make sure all valves are working good, no bent push rods or loose rocker arms.
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Lead Driver
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From: Central Oregon
When you pulled the plugs did you put them back in the same holes? It is running, but missing? Have you looked inside the dist. cap?
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Half of your carb is not getting fuel. Or there is a vacuum leak affecting one half of the carb. On dual plane intake manifolds, one half of the carb fuels two cyls on each bank, one at the front and rear of one bank, the other on two inside cyls. Look at your intake runners for 2, 3, 5, and 8 and see which side of the carb is common to them and go from there.
Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
I would say, Your sure doing a lot of hard dirty work first before the ez stuff too check! First 1.Stock Plugs are cheap if you go to all the trouble of remove them replace with New ones. There only good for 12,00-15,00 miles. (1)Note! never clean a plug with a wire brush it can help or make them short out! And because a plug is new don't mean it's any good!..A little light spark tester Don't mean the wire is any Good! Check your wires with an ohm meter is a Ture Test. Your Cyl. aren't Dead there not working as hard as the others.
You didn't say how much compression you have in those cyl other than good.
Good could mean it blows your finger off the plug hole when cranked over..We don't know so tell us. We have to guess that you mean it's over a 100 psi And anything less they don't work as hard as a cyl. with above 100 psi ..Hope this helps you in someway
. my 2cents
orich
You didn't say how much compression you have in those cyl other than good.
Good could mean it blows your finger off the plug hole when cranked over..We don't know so tell us. We have to guess that you mean it's over a 100 psi And anything less they don't work as hard as a cyl. with above 100 psi ..Hope this helps you in someway
. my 2centsorich
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From: Fairbanks
Just because you pull the wire off and do not see a drop in rpm does not mean you have a dead cylinder. It may mean you have 4 that are not working as hard as the others. You could have the rpm up to high the carb could be adjusted wrong. You might have low compression in those cylinders or even weak spark in them. your firing order could be off also.
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This sight is great!!
Thanks to all of you who have written to me. I've switched plug wires from plugs that are on bad cylinders to good ones and no change. I put the plug from good cylinders into the bad ones and no change. the compression on the cylinders are 95lbs to 100lbs, no big fluxuations. The carb is spitting gas into both sides of the intake.
I had a neighbor who is great in auto mechanics and he said it has to be electrical since it is everyother cylinder in the fireing order.
I'm in the process of putting it back together and see what happens.
Thanks for all your suggestions and I'll let you know what happens next.
Thanks to all of you who have written to me. I've switched plug wires from plugs that are on bad cylinders to good ones and no change. I put the plug from good cylinders into the bad ones and no change. the compression on the cylinders are 95lbs to 100lbs, no big fluxuations. The carb is spitting gas into both sides of the intake.
I had a neighbor who is great in auto mechanics and he said it has to be electrical since it is everyother cylinder in the fireing order.
I'm in the process of putting it back together and see what happens.
Thanks for all your suggestions and I'll let you know what happens next.
