I have about .035 valve lash on most of my rockers no preload . Stock rockers the with a flat tapped hydraulic purple shaft cam . No idea which one,Engine already built when I purchased the car. The valves had a ticking noise oil pressure is 45 psi at idle. Checked rockers and notice they were loose. Could it have wrong lifters. I pulled a few bottom looks fine. Check pushrods they are correct length. Anyone every had the problem.

AMC lifters?

Obviously the pushrods are not the correct length for your combo.

Did someone put in an extra fat headgaskets to lower compression?..Since just about everyone lists the same part number for AMC or Mopar lifters I doubt that's it.

OE non adjustable rockers? you have that much lash at the rocker on base circle and the lifter cup is up against the retainer clip? Yes you would need longer pushrods to elim that .035 lash at the rocker & additionally to move the cup below the snap ring (for some preload) and iron adjustable rockers MAY be a solution. EDIT what length of pushrods do you have? MORE EDIT hyd-7.510". hyd with adj rockers-7.23". 273 solid lifter pushrods-7.340"

It could be the cam was ground on a smaller base circle.
Re-ground cams will have a smaller base.
Same with old aftermarket perf hyd cams, some were ground on a smaller base to get more lift. Often if a hyd cam had more than .510, instructions stated it must be used with adj rockers. New cams are now ground on cores that allow high lifts and still have a std base.

You really need to fix that before it causes problems you don't want like a lifter retaining ring coming out and then causing all kinds of other failures
The motor will make a noticeable amount of more power also getting the valve timing and valve opening corrected
You can have some .060 longer pushrods made that would correct that problem from Manton, Smith Bros or Trend

What Cab said, it cant be run like this (if we are reading this right: (Hyd lifters with no preload & .035" clearance at the rocker)

Long ago I tossed a hydro purple cam in a stock 360 and had that same problem, at that time the jinkie mopar adjustable pushrods was a good band aid, alot better options mentioned above to fix your problem.

Id guess the cams probably the 484 or 509, the smaller mopar cams seemed to fit better with oem parts.

Thanks for all the information I like it when all the options are in a positive manner and all are helpful. At this time the route that I going with is some old 273 adjustable rockers with the correct length hyd pushrods. I had heard about cams being made on smaller base circle but was not sure that the purple shafts were manufactured that way. This engine was built twenty four years ago and never run because when they started it up they didn't have much oil pressure. Then the owner suddenly passed away. SO it set in the garage for twenty four until I bought it. Found the oil gallery plug was missing and replaced it. (Don't ask how I knew to look for that ). Engine runs great other than Alot valve ticking.
Thanks again.

Enjoy it while it lasts. (We ain't like this all the time)

AMC lifters would use shorter pushrods , his are not long enough.

Was it doing this when you bought it ?

The pushrods are not the correct length if you have that much lash.

Pushrods measure 7.530 . you are right they are not the right length, but are correct for a stock 340. There is probably enough wear on the old factory rocker combined with a smaller base circle on the cam to get to that lash. Yes it has been this way from the first time I started the engine.

Sounds like it's not a STOCK 340 so that number goes out the window ... as you can see.

Get a checking pushrod , figure out the length needed , do a few on both banks , and by an ADJUSTABLE length pushrod from Smith Brothers and call it done .

Adjust each pushrod to get the amount of preload you want on every lifter.

What's wrong with going with a set of 273 adjustable rockers ?

Nothing, if you have a set .

Twenty years ago most parts houses and cam grinders stocked the early, pre 1967, and later hydraulic lifters. The early ones, both hydraulics and solid lifters have 1/4 ball cups in them. The 1967 and later Mopar hydraulic lifters use a 5/16 ball size so maybe your motor has mismatch components. They do not have the same height for the pushrod cups in relation to the cam lobes
Mopar, in all of it's infinite wisdom, introduced the LA 318 with hydraulic lifters and stamp steel non adjustable rocker arms in all cars made in the Los Angles plant in 1966, all the other 1966 Cars with 318 motors had the Poly 318 motors with solid lifters All Mopar V8 shared the same lifters back then, hydraulic or solids, same thing on the 1967 and later Mopar V8 lifters

I just so happen to have a set and just ordered 7.23 5/16 ball & cup pushrods from summit