The Dodge Challenger Message Board

I need some help. I have 1970 Challenger with a 440 6-pack automatic. When I drive in 2nd and 3rd gear I get what sounds like lifters tapping. It only seem to happen when the engine is running 2000-3000 rpm crusing not under load under load it seem to go away. Only does it when I'm driving and not in park. I have replaced the lifters, push rods, rocker arms and shafts with new ones. I have also used the non adjustable and the adjustable rockers arms with new shafts. I still have the tapping. Does anyone have any ideas?
I have used 10-30w oil to sae 30w. Still have the sound.

That oil is way too thin for an engine built to original spec. You need something around 40w or maybe a 20w/50w if the bearings are original otherwise you will get low oil pressure and that will cause your problem.

The oil pressure is OK. The needle on in the dash is about 90%. I didn't know if it was working properly so I tested with a pressure type gauge and it would read 60-80 depending on the rpm's driving. I know it's not the original engine but I don't know how old it is. The car has 42K mile on it. I runs great and drives great. I will try heavier oil. Thanks

If it was happening under load I would say check the header gasket is not leaking.

The only other thing that springs to mind is that it is not the tappets but detonation you can hear due to the too much timing or the carb going lean. But that would be worse under load as well.

Might as well try backing your timing off a bit and disconnect and plug the vacuum line to the distributor. If the problem goes away you need to adjust the timing curve of your distributor.

If it is neither of them it can only be a worn cam or thin oil.

Looks like you are right on track again. I removed the vacuum line from the distributor and plug it and the noise is gone. Stopped and put the line back on and the sound is back. So what is the next step? Do I just leave it off? The ignition has been converted to electronic been I got the car.

Sounds like you need to modify the timing curve of your distributor.

Read the stuff under 'timing and distributor modifications' in the electrical section.
My old electronic distributor does not have an adjustable vacuum advance but the newer ones do.

Better fuel or octane booster might be a quick fix in the short term.

Thanks again Dave.
I re-worked the springs and weights and spot welded the plate and did away with the vacuum advance. Works great now.