Just finished putting my engine back in my 68 coupe after pulling it to replace the rear main seal.

when we first started it up, there was this weird knocking sound as if the fan was hitting something, and the sound increased frequency as rpms increased.

so i checked tranny fluid...pretty low...filled it up and knocking went away. now im afraid i filled it up TOO much cause its well above the full line on the dipstick. and whats more the engine feels like its driving on 7 cylinders except it doesnt have the loss of power.

you know that feeling when you leave one plug wire off by accident and you can really feel the pistons moving, feels kinda like that.

you think the overfilled tranny fluid could be causing this? when i free rev the engine it sounds very nice so thats why i think it has to be tranny related.

any advice is appreciated

-Jon

 

Can't comment on the knocking cause I didn't hear it. You should have been able to differentiate it front to rear of engine. Too much fluid will cause foaming and eventual overheating in an AT. Drain some out by pulling the TC plug for a few seconds.

 

i guess i should revise my description of the sound

it kinda feels like im driving on 7 cylinders...i can really feel the compression of the engine when accelerating.

any ideas?

 

using a pair of insulated pliers, i proceeded to pull one wire off at a time from the dizzy, listen for an idle drop and then put it back and do all 8 like that. cylinder's 4 and 7 produced no idle drop, so i guess its safe to assume they are not firing, which would explain my lack of power and heavy pulsing vibration when accelerating.

now the question is why the hell are they not firing...dizzy is brand new, spark plugs are relatively new, and wires are new. ugh

 

bad spark plug wires, swap the wires to a different cylinder see if you get spark

 

bad spark plug wires, swap the wires to a different cylinder see if you get spark

 

well i swapped #7 and #8 wires and same story, still no firing in #7, so i can rule out bad wires.

can rule out bad plug too cause i put a different one in and no change.

im pretty much out of ideas now lol

 

Try checking the inside of the dist cap. Make sure the the rotor contacts are present and clean. Do they have any carbon buildup on the contact points. Does the dist points cam have all edges and in good shape. With cap off and ignition on crank the engine and watch to see it the points are working at all 8 cam edges.

 

did you mess with the valves when you had it out?you should check compression

 

All is well now. Turns out 2 of the spark plugs were bad. Replaced all 8 and runs perfect again. Funny how its always the things you don't even consider, the simple things, that usually cause the problems.

And good call on the compression test. Found one cylinder with a small leak which in turn was causing only 120 while the others were hitting around 140ish. Im willing to bet i burnt the valve during those months i was running around with that f-ed up edelbrock carb leaning everything out.