I'm trying to determine if my pushrods are the proper length. What's the proper procedure for checking lifter preload (stock non-adjustable rocker arms). The lifters are bled down.

Also, do I need to check all or just one?

Thanks!

You should check them all but you don't have to , at least one on each side. the lifter needs to be on the base circle of the cam, using an adjustable length push rod is the easiest way to do check them.

There is a large margin of tolerance. Unless you have milled a whole bunch off the heads or decked the block you should have no problems. Unless you replace the rockers and push rods with adjustable rockers and push rods to match you have no choice but to bolt it together and run in. Just the way has been done since the introduction of hydraulic lifters.

The most accurate means of checking preload is to use an adjustable pushrod, as John said, and set it to zero preload. Then compare that length to your regular pushrods' length which should be longer. The difference between the two would give you the actual preload of your current set up.

If you don't like the current set up, you can order a set of custom length pushrods made to your specs from Smith, or others, or you can put shims under the rocker arm shafts if you need to reduce the preload amount abit.

A cruder, but, no cost method, of checking pushrod preload is to loosen the rocker shafts with the lifter on the base side of the cam lobe that you are going to check, and then gradually (and evenly) tighten the shaft hold down bolts until you feel a little resistance to turning the pushrod with your fingers.

That would the zero preload point. Lay a straight edge across the lifter bosses and with a very fine marker, make a mark on the pushrod.

Then tighten the shaft all the way down and make a second mark on the pushrod. Be careful to maintain the position of the straight edge so your second mark is truly relevant to the first mark.

Release the tension on the shaft, pull the push rod out and measure the distance between the two marks to get the approximate preload. This will be close enuf for government work.

Then you either shim the rockers or order a new set of pushrods made to your desired length.

It is always good to check more than one location on both sides of the engine to find a good average that reflects the depth of the valve seats, etc...particularly if you are trying to be exact on a high output engine....

In most cases, it is not that sensitive an issue as mentioned above.

I recently decided to check the preload on my 440 as the intake fit so badly that I suspected that either the heads or block had been decked excessively. Average was about 0.120" which is probably way too much in anyone's book.

Thanks guys! I'll check it out and let you know what I come up with.

Hydraulic lifters were made available to be relatively maintenance free with a lot of forgiveness built in. With a big block it is very simple to take off the intake and visually see what you have.

there's a stackup of tolerances on block deck height/head dimentions. I'd measure the other bank then buy or make an adj pushrod measure twice & get the correct length you need. Measure geometry & Hughes' engines & others has some procedures for length/wipe pattern checks.

Are you sure that you had the lifters on the base circle of the cam. If this is a stock engine in a street driven application and the plunger aren't bottoming out in the lifter drive it.

http://www.compcams.com/Products/CC-%27Pushrods%27-5.aspx

Get one of these. It is easy to use, and VERY obvious what the proper length is to order. I got Chebby type pushrods to length from auto parts store, only about 40$ until I get new cam and rockers.

Dig in the auto parts store book for the proper length, ball-ball end if they are stock...found proper length for my Indy heads.....had to order but they were there in 1 day.