440 mystery
 

Hi,

I recently purchaced an RV with a M500 chassis. it has an RB 440 in it. Problem is that cylinders 3,5,2,8 don't fire. I've changed the distributer cap, rotor, spark plugs and wires. When I milk the wires off of the dist. cap the dead cylinders are getting a good spark. The cylinders have compression and the plugs are wet with fuel. Can't figure it. Any help would be greatly appreciated.

Thanks,

Kurt

Hi Kurt welcome to the forum.

Have you taken off the valve covers yet? Perhaps there are no rocker arms, or pushrods.

If he has got plugs wet with fuel, then the valves are opening. The exhaust could be stuck closed but I would imagine that would cause some damage to the motor then.

What are the compression numbers for all the cylinders? Since you have spark at the dizzy cap, see if the spark is traveling down the wires to the plugs. If not then that is the (first) problem. If you have spark down the wires, then change out all the plugs for a set of champion plugs and set them to the right gap. How strong is the spark? Also, how well grounded is the motor to the battery?

I had a problem with my AMC 360 not firing properly andit turned out to be because the engine was not grounded wel enough for the spark toget back to the battery. I ran a ground wire from one cylinder head to the next in the back of the motor and from one cylinder head to the negative on the battery. That fixed my firing problem.

have you ever had it running since you bought it or did you buy it not running and has any one had the distributer out, maybe the chain has jumped a tooth or two but i would try what 78 says first and make sure when you have cylinder # one up i would check that you are on tdc and the rotor is pointing on # one on the cap :) then let us no so we can re group and find another cure for you ok if none of that works