Hey all, I'm installing a head on my 1993 f350 7.5l. Id like to check the rocker arm to valve stem clearance. As part of this process, I need to compress the lifter using a special tool T70P-6513-A. My problem is, I cant find this tool for sale anywhere.

Im assuming theres another tool that works or some sort of workaround but i have not found any info on it. Anyone have any experience with this?

 

All you really need to do is use a pushrod length checker with the proper lifter preload, and confirm that your existing pushrods are correct.

If you wanted to do what you ask, you can still do it with a pushrod length checker and nothing fancier. Measure the distance that the lifter compresses, then measure the distance from the lifter to the rocker, then measure your pushrod. The math will get you the figure you want, but seems pointless to me unless you'd just like to know.

 

As long as the lifter compresses when the cam is on the base circle but doesn't compress so much as to lift the valve you're fine. Except at the extremes of performance (which I assure you a stockish 7.5 isn't) lifters don't really care whether they're at the top or bottom end of their range.

 

It sounds like what your saying is that I don't need the tool because the process in the book is mostly unnecessary.

I'm willing to accept this as the case but I'm still a little fuzzy on how I'm supposed to confirm fitment. If I were putting the from the factory head back on the motor, I wouldn't even worry about it. But because its a reman, this leaves the possibility for the head to have been decked which would likely change the distance from the tappet to the rocker.

89F2urd's response I think is saying that I could keep making an adjustable pushrod bigger while the hydraulic tappet is at the bottom of its stroke until the valve starts moving. The difference between my pushrod and the adjustable pushrod would be my rocker arm to valve stem clearance.

arse_sideward's response I think is saying that as long as the valves are actually closing when they should, there's no problem.

I'm having a hard time telling if the valve is moving when I tighten down the rocker. I think its not but its hard to tell. I do know that I cannot get a feeler gauge between the rocker and valve stem when the tappet is at the bottom of its stroke, even if I try to compress the tappet by hand. I'm not super familiar with hydraulic lifters so I'm not sure whether 1. hydraulic lifters are intended to keep the rocker in contact with the valve stem at all times and 2. whether the hydraulic lifters are very difficult to bottom out without some leverage which is why I can measure not rocker to stem clearance.

I just really don't want to tear this thing back apart anytime soon.

 

And that when closed the pushrod is not loose.

Hydraulic lifter have a huge range of adjustment. IIRC it's over .500 (the number .550 sticks in my mind for the lifters used in most domestic V8s but that may be wrong) . So unless you are trying to get the rocker tip to valve geometry dead nuts on (which isn't necessary with OEM stamped rockers) you really don't care abut minor variations in the pushrods. You just gotta get somewhere in that massive range. Which you will most certainly be with off the shelf parts that are correct for your applications.

 

I think we are talking about a few different things here.

The pushrod length tool allows you to install the head, set appropriate lifter preload via the pushrod tools length adjustment, then measure the pushrod to see if it's close enough to use. If not, order proper size as discovered by the pushrod length tool. If you're not familiar with this procedure, try searching it on youtube

 

I always check them when reassembling an engine. Mine have always either been sitting long enough to be bled down or new lifters. In some cases I have had to find different length push rods, I found them at different parts jobbers but this has been a while ago. I am thinking you can push down hard hard on the end of the rocker arm above the push rod to bleed them, a rubber handled carpenters hammer would be my tool of choice to try this.

I'm sure you have the procedure for which valves to check by turning the crankshaft to a certain position for certain valves. If the clearance is not right, most engines have a 1.6 ratio longer on the valve end so if the clearance is off, figure accordingly to probably hit the midway point of the clearance.

 

I'm back with some more information gathered with your comments in mind.

It appears to me as if the valve does in-fact move when I install the rocker arm while the associated tappet is bottomed out. As suggested, I used a rubber handled hammer to put my weight on the pushrod side of the rocker in an attempt to bottom it out. I still have 0 clearance between the rocker and valve stem. Assuming I am actually collapsing/bleeding the tappet when I use this method, I believe that I may need shorter pushrods.

I see that summit has some different lengths so I guess I'm now on to sorting out what length I need. Ill get myself an adjustable pushrod so that I can attempt to do more than guessing when I purchase a new length. However, there seems to be a discrepancy between the two methods outlined above. As far as I can tell, the two methods could be as follows.

1. Get an adjustable pushrod. Install on intake side and collapse the lifter. Keep adjusting the pushrod till I have the recommended clearance in the book (Between .100 and .150" if I remember right but ill confirm this of course). Then just measure the adjustable pushrod and get a pushrod near the measured length to install. Repeat for exhaust side.

2. get an adjustable pushrod. Install it on the intake side. The video I saw was with new lifters so I'm assuming this would be with a collapsed lifter. Keep making adjustable pushrod bigger till the play in the rocker is taken up. Purchase a pushrod that is about .070 longer than the measurement of the adjustable pushrod for the purpose of preload.

My problem is that these two methods would result in a final number differing by around 1/8th inch. Am I interpreting these two methods wrong?

 

Upon further research, method number 2 seems to assume that there is a spring in the hydraulic lifter that returns plunger to its upward position even when no fluid is present in the lifter. I'm not quite sure whether I've actually observed this on the lifters in my Ford 7.5. Regardless, if this spring was present, the intention is that your preloading the tappet to put the plunger between its two limits instead of adjusting to the very top of the plungers travel. This clarifies the discrepancy between the two method for me. Essentially method one is ensuring your between the two limits on the plunger by measuring clearance from your bottomed out position on the tappet plunger and method two is ensuring your between your two limits by moving in from your max upward position on the plunger.

 

If the lifter is bled down, I believe it should press down very easily such as when you insert a feelers gauge between the valve and rocker arm.

Now back to measuring the clearance. The position of the camshaft has to be where it is on the flat spot where it is not trying to open the valve to check the respective valve you are checking the clearance on. I don't think my Haynes manual gives any specifics to set the engine in a certain spot to check certain valves for the 460 like it does on the smaller engines. However if you get a certain cylinder in the firing position, you should be able to check the clearance on both valves on that cylinder.

How do you do this. If you turn the engine over with the front crankshaft bolt clockwise watch as the intake valve on cylinder one opens and then just as it closes and just as it closes keep turning the crankshaft in a clockwise direction until the timing marks line up to top dead center, this should be roughly a half turn after the intake valve closes. Check the clearance on cylinder one there.

Now make a mark on the crankshaft pulley half a turn from Top Dead Center. Then make a mark in between those 2 marks to quarter it. Now turn the engine a quarter turn clockwise and check the next 2 valves in the firing order. Keep doing this for 2 crankshaft turns to check all 8 cylinders. Firing order 1-5-4-2-6-3-7-8.

 

At this point in thinking the next step is to ensure that the lifters are actually bleeding down. Sounds like if its bled, I should be able move the plunger relatively easy and see it return. Ill look for that next.

 

For others like me that know enough to dig into a project like this but not enough to know what they are doing, I realized that my lifters were not bleeding down. I was applying pressure to the pushrod side of the rocker and then trying to measure the clearance between the rocker and valve stem without confirming that the lifter plunger was actually compressing. I just assumed that it was doing what I intended. Once I got the lifter to bleed, the clearance was within spec. (The spec according to the book for a 1993 7.5 was .100"-.150" ideally and .075"-.175" acceptable)

This is obvious to most of you but for those of you that its not, there's a plunger in the hydraulic lifter that moves independent of the lifter it self. Once you manage to bleed the hydraulic lifter, you should be able to tilt the rocker to the pushrod side by hand and see the plunger compress and then return to its upward position due to an internal spring. The amount of plunger travel in a bled lifter is plainly observable if you have the intake manifold off. You will initially see that the internal plunger is against snap ring at the top of its travel and then when you apply pressure you will see the plunger move away from the snap ring while the lifter itself stays stationary. If the plunger does not move away from this snap ring at all when you apply force to the pushrod side of the lifter, then your lifter is not bled. I found it very difficult to bleed the lifter. I imagine that the tool mentioned in the beginning of this thread would have made it a lot easier. How I eventually got the lifter to bleed is by bumping the starter with an auxiliary switch several times with 10 second or so brakes between bumps. (don't do it with the key unless you disable the fuel pump and coil pack and such or you will make a mess). I'm assuming that the reason bumping the starter worked is because the valve would compress and put pressure against the plunger but since I was not continuously running the starter, oil was not being forced into the lifters. Or maybe I just got lucky. If someone else has an equivalent tool or method to bleed the lifters then go ahead and post it for others.

Below is a drawing of a hydraulic tappet that helped me understand how it works.




Additionally, the following video at around 9:40 shows how the plunger will move when its bled. In the video, they are using new lifter which is why they are bled initially. Its worth mentioning that this video shows an adjustable rocker valvetrain so the adjustment is not applicable to the fixed valvetrain type but the plunger movement shown at 9:40 is useful to see how you know when your lifter is actually bled.