390 will not run right

[Jarred Hodges]

After we put the new cam and lifters in the 390 it ran good. It was not a stump puller but ran smooth. A couple weeks ago I thought the timing might be off so I moved the distributor. When I went to crank it it backfired threw the carb and would never run right. I moved the timing back to where it was and it still would not run right. I figured blown power valve so I swapped another good carb on and it still won't run right. I put the original carb on the maverick and it ran great so I am stumped. if anyone has any ideas I would appreciate them

[fordman]

how does it not run right?

[Jarred Hodges]

it will barely crank, will not run right and will not rev up at all

[BobbyFord]

Have you put a timing light on it?

[Redcap]

Have you put a timing light on it?

My thought too. Sounds like the timing is off.

[fordman]

yes it does sounds liek timing to me.

[ToughOldFord]

Maybe bad points/condenser.

[Dragon]

important question what kind of carb and what went back on. If putting the old carb on fixed the problem then you don't need to do anything but make the timing right for now.

[ToughOldFord]

He put the old carb on a different vehicle to check it, as I read it anyway.

[tnbumper]

Is it running right at idle but not when you accelerate? The vacuum advance could be bad. Consider upgrading to a new distributor. I bought an HEI distributor for a 289, NIB on Ebay from a speed shop in Knoxville for less than $75 delivered. It's got GM cap,rotor, and coil and only requires 1 wire to a 12 volt source and has a tach wire port. tnbumper

[Dragon]

He put the old carb on a different vehicle to check it, as I read it anyway.

Then put the new carb on the Maverick and try it to eliminate any questions. If it does not work on the Maverick leave the truck alone and solve the carb issue.

Don't touch the timing, points or vacuum anything until the engine timing is set with a light.

[Jarred Hodges]

both carbs work fine on another vehicle.

[knightfire83]

It was not a stump puller but ran smooth.

Indicates to me that something was amiss after the cam swap. Aren't 390's considered torque monsters, they are at least to me.

Camshaft timing off?

Incorrect firing order?

Bent push rods?

Broken or weak valve springs?

[70_F100]

It's possible that the backfire blew out the PCV valve or one of the intake gaskets.

[Jarred Hodges]

It doesn't leak water so Idoubt if it is an intake gasket. Before we swapped cams it was weak too. This motor has never impressed me powerwise. I just want to get it back drivable so I can sell it