Do you know the length of the stock pushrod ?

 

Why do you ask? If machine work or gaskets have been done the stock ones may work but will not be optimal for performance.

 

I bought all new parts for the motor and never thought to compare them to the old parts. started putting the motor together and went to put the lifters in and found that they were to small, then i replaced them with the right ones and never thought to check the pushrods. now to me it seems like the valves are staying open a little and the motor not running right. so now i am thinking that the pushrods are to long.

 

For this to actually happen the pushrods would be excessively long. The hydraulic lifters have a good amount "play". If you did not save the old pushrods then I would suggest you verify that the valves fully closing. You could loosen a rocker when valves are supposed to be closed and see how much tension is on the spring or if valve stem moves. Dont guess and just swap parts on a hunch. This can get expensive.

 

When I assembled my 67 400 I ended up using 9.5 inch pushrods. With these I shimmed the rocker bridges I think .090 and it gave me the lifter preload I wanted. Just enough to keep rockers quiet. You should be in the ballpark using similar pushrod length.

 

It doesnt matter what you are working on, the correct way to obtain pushrod length is to measure and be sure!