Engine Build Question

[Izzy]

I am trying to wrap up the build on the 5.0 and I'm stuck at one spot and I just can't make heads or tails of what I am supposed to do.

The engine is a roller rocker 5.0 from a 98 explorer. It has NON-adjustable rockers (stock), I'm using the stock lifters, and stock push rods. The machine shop told me to check the length of the rods by tightening down the rockers all the way, put the cylinder (start with 1) on the conpression strock and verify that the lifter has room to travel and the rocker is not loose. Sounds simple but I don't get it.

How do I know when the piston is at compression?

 

[Skiddy]

when you turn the motor over by hand put your finger over the spark plug hole and when you get pressure coming out you are on the compression stroke

 

[Apogee]

Compression occurs between intake and exhaust, so you can also just watch the valves. All you're trying to do is make sure that the lifter is on the base circle of the camshaft such that the pushrod isn't preloaded against the lifter or rocker arm.

 

[Broncobowsher]

Start with cylinder #1, I'll get to the others latter.
If the timing cover is off, line up the timing marks as directed with the instruction in the timing chain kit or service manual. That will be TDC #! compression stroke.

Now if you have the timing chain on the engine, not a problem. Rotate the engine and look at the valves for #1 cylinder. You will get the exhaust valve open, then close. then the intake will open then close. After the intake closes neither will move and you are coming up on the compression stroke. Watch the timing pointer and Line up the timing marks to TDC. That will eithre be on the compression TDC.

Now for the next cylinder, follow the firing order. That should be #3 for that engine I believe. Rotate the crank 90° and you will be ready for #3. Rotate another 90°, do the next cylinder in the firing order. Which way to go? normal rotation. Forgot that? use a socket on the big bolt that holds the damper on the end of the crank and TIGHTEN. That is standard rotation. Just stop every 90° and do the next in the firing order. The intake valve should be the last to open before you do the check and the exhaust the one to open after you check.

Another option:
Find a valve that is completely open. The other for the same cylinder will be closed. But it is a lot easier to miss one doing it this way. But you don't need to follow the firing order. remember that both valves are never fully open together. But there is some overlap between exhaust and intake strokes where there is a little overlap. But as long as you get the valve fully open, the other one is fully closed.

 

[DirtDonk]

I'll go out on a limb here too, with unusual-for-me advice. If you're running the engine, literally as it came from the factory, I'm gonna' say you don't need to check the pushrod length. The factory rarely (if ever?) makes a pushrod length mistake, and if it's been running well for all those previous miles, I'm guessing you're good to go.

Now if you mean that, even though stock, all those components are new to the engine, then yeah, I guess it's still a good idea to check. You could start by comparing the new to the old, to see where you stand.

I'm not quite getting their methodology though. What you're looking for is the tip of the rocker arm to be roughly in the center of the tip of the valve stem, so that as it rocks back and forth, it stays in the center area of the tip. This reduces side loading of the valve stem and wear of the stem and tip.

Hopefully though, If I'm missing something, someone will chime in (edit: as they already did) with additions/corrections and give you the skinny on the methods of doing any testing.

Paul

 

[G's Baja Bronco]

X2 with Ddonk, if it is all stock, just re-assemble it, did they mill the heads down a lot to raise compression??

The Lifters are hydraulic, they should make up for a few thousands milling.

Just my 2 cents

 

[Izzy]

Broncobowsher, At the risk of sounding really stupid, which is the intake valve and which is the exhaust valve? I did watch these the other day when turning the crank and I never saw them move, maybe I didn't turn it enough though.

Dirtdonk, I am using the same rockers, lifters and pushrods that came out of the engine so you are right, I shouldn't have to worry about it at all and the machine shop did say the same but they just noted that its good to check.

 

[needabronco]

If it were my mill, I'd just bolt it together! Unless you've changed heads, cam, rockers.... Then check but for a stock rebuild it'll be close enough.

 

[DirtDonk]

Yeah, I figured they were being smart when they said that, because it's true. It really never does hurt to double-check on the important things!

With the heads off, the intakes on modern automotive engines are always the larger valve. With the heads on and things bolted up, line of sight does the trick. The exhaust valves are the closest to the exhaust ports, and vice-versa.
I know there is a simple "the front is always this one, and the next one is always this valve" lesson, but I can't remember which one is which right now. So look for the port runners on the intake, and the exhaust openings in the head.

Paul

 

[DirtDonk]

...I did watch these the other day when turning the crank and I never saw them move, maybe I didn't turn it enough though.

Nope, you only have to turn it a slight amount to get at least one of the cam lobes lifting a lifter, but the issue is lifters that are un-pumped, or "oil-less" so that all you're working against is their inner spring. Which is usually not strong enough to push down on a much stronger valve spring.
That's why the machine shop said to turn the rockers all the way down. Unfortunately, on a non-adjustable type like this, that's not enough. You'd have to turn the rocker nuts down far enough to literally bottom the pushrod out in the lifter. This is not really good practice, in case you go to far and something binds up. Luckily that would take a lot, and you're only turning it over by hand, so usually nothing is harmed.

In your case though, to see any movement you'd have to release the rockers, then watch the pushrods go up and down. Which doesn't tell you anything about their length being right or wrong, only that the rockers are rising and falling.
So, short of pumping up all your lifters by hand, or running the engine to do the same thing in seconds (which defeats the whole purpose of testing "before" running), you might as well just put it together as-is, make sure everything is assembled correctly of course, and then see how it runs.

Sound like a plan? Add anything I missed in all the excitement.

Paul

 

[Izzy]

Thanks for the tips and advice guys. I just don't want to blow this thing up after everything I have done and spent.

 

[G's Baja Bronco]

Same fears here, I re ringed the engine and build the AOD with 4RW70 internals, Hope all works the first time

 

[broncnaz]

Basically they are just telling you to check to make sure there is still enough clearance left in the lifter once the rocker arm is bolted down. What you do is collaspe that lifter by leverage on the rocker arm. (not sure how you do this on a pedastal type as ford used to sell a tool for the stud type rockers) and measure how much clearnace is between the rocker arm and valve stem. with older hydraulic lifters I know you should have something like .100-.180. Not sure what roller lifters need but usually .100 is the least clearance you want in any valve train part.
Like the others siad its probably fine unless they milled the heack out of the heads or decked the block. But I would check it just to be certain.

 

[Broncobowsher]

You can tell what valve does what by looking at the ports. The intake runner will line up with a valve, the exhaust a different valve. Should be pretty obvious when you look at it.

 

[oleguy74]

driver side is E I E I E I E I
pass side is I E I E I E I E