I have a 302 I bought that allegedly has a Comp 268H in it. I heard the video of the engine running and I had it running but it was idling high. I was having some throttle cable issues and a vacuum leak at the carb base. I was hearing something metallic while the engine was running. I got a vacuum gauge and hooked it up and the needle was bouncing around everywhere. There were a couple things that I kinda found that were it. One said ignition not working on a cylinder(s), the other one mentioned valve(seal, sticking). I did a compression test and #4 was at 0. I then took the valve cover off and the rocker on #4 exhaust just fell out. I put it back on and tightened it down. It seemed to be more than a full turn (hard to tell with it being all the way in the back) to reach torque. I then just did #3 to double check and they turned just a little before reaching torque. I rechecked #4 compression and it was 0. I checked #3 and it was now 0. I checked #2 compression, retorqued rockers and it still had compression. My question is can pedestal rockers be torqued too tight to where the valve sticks open? What would happen when the exhaust rocker comes off? Would it just go out the intake or is there a hole burned in the piston? Could it be that now that #4 has compression again it maybe made a gasket bad and now #3 & #4 have no compression?

 

A whole lot of what, if, and how come, if it was mine I'd pull it down and see what was done and if it could be saved.

 

What cam do you have? hydraulic flat tappet?

Check the oil on your dipstick for metal I bet the cam went flat if its a flat tappet due to improper break in. that would would resul tin 0 compression as the valves would not be functional.

 

The rocker backed its way off, and was just laying in the valve cover, I put it back on and the the valves still open and close on #4. I went and put a spark plug in on #4(as there was one in there while I was doing the compression test on #3) and #3 got compression back. I put a sparkplug in #3 and rechecked #4 and its still at 0psi.

 

sounds like its time to pull the engine and tear it down and see whats going on. there is no reason for a rocker arm to just come loose and fall off unless it was not tightened and if that's the case what else in the motor wasn't tightened.

 

Many times when a aftermarket cam is installed, the valve train has to be converted to be adjustable. The stock valve train as it came from Ford was not adjustable. Sounds like they left the bolts loose to "adjust it" and then of course they will not stay there and they work themselves loose. If the valves were too tight, and you go and tighten them all down, then some of the valves can be hanging open, and the engine will run rough or not at all.

What you need to do is turn the engine around to TDC #1. I don't know how much you know about engines, but you will need to look at the valves on #1 cylinder as you turn the engine, they need to be shut when the mark comes around. You have a 50-50 chance when the mark comes around to TDC for the valves to be shut, or they are on the exhaust cycle.

Once you get #1 at TDC, you need to loosen the rockers till you have play on the pushrod. As you are wiggling the pushrod up and down, slowly turn the rocker bolt down and stop just as the play is gone. Then stare at your ratchet, and count how many turns it takes to lock the bolt down. 1/2 turn to 3/4 turn is golden. 1 turn is probably still ok, 1 1/4 turn is borderline too tight. 1/4 turn may work, less than that and it will be too loose and make lots of ticking noise.

If your rockers are too tight when they are locked down, some people get shim stock, take the whole bolt and rocker out, and make a little shim to put under the pedestal and then try it again. This is sort of a backyard way of doing it, but sometimes you can get it to work. You need all the rocker bolts to be 1/2-1 turn from zero lash to when they are torqued down. This is a very common problem on Fords with aftermarket camshafts.

 

When I retorqued #4, I thought it turned past 1 turn... from the swings that I could get it, it did seem to add up more than 1 turn so I was thinking that it was maybe left a bit loose to get the proper spec. #3 is "fine" now. It seems that its a for sure head gasket since when I put the sparkplug back in #4 it gained compression in #3. I just didn't think that a head gasket would make the cylinders 0psi.

 

Here is a shim kit you can buy. https://www.summitracing.com/parts/f...b302/make/ford

Here is a adjustment conversion kit you can buy. You need to check your bolt size, they have a couple different stud sizes they sell. This is the 7/16 kit.

https://www.summitracing.com/parts/c...5-16/make/ford

 

Whoa! Step back from the ledge! Don't pull the cylinder heads yet. It's not very likely you've got rocker arm AND head gasket problems at the same time. When troubleshooting, don't try to steer your efforts to a preordained conclusion. That's not standard protocol, unless you're a climate change researcher.

Instead, do a cylinder leakdown check. That's where you put a piston at TDC on the compression stroke (both valves closed). You inject a metered amount of compressed air using a special tool (not expensive at all) through the spark plug hole. The tester's gauge then indicates how much air is leaking out due to a compression leak. In extreme cases, you can even hear where the air is escaping.

If you've really got a leaky head gasket, this test will quickly confirm it. No engine teardown required if it passes.

 

Forgot to add: If concerned about a potential problem with the cam, use a dial indicator to measure how much each pushrod lifts up. The only access required is to pull the valve covers, and it sounds like you've already done that.

Let my personal motto be your guiding mantra before digging too deeply:

"As little as possible, for as long as it takes"

 

But with #3 gaining compression by putting the #4 spark plug back in, wouldn't that indicate a blown gasket between the two cylinders?

 

Not really cause if a gasket is blown between two cylinders you would have more than 0 psi compression you would have low compression of almost equal value between the two. Reading 0 psi on one cylinder indicates that the valves are not opening allowing the cylinder to be able to bring in air to compress it.

When you do a compression test you have all the plugs out anyways and you install the compression gauge in each cylinder hold the throttle wide open with the ignition system disabled and fuel system as well if fuel injection. Then you crank for 3 pulses and that is the pressure you note.

 

It could also be the #3 valves suddenly behaved themselves (for reasons still unknown) coincidentally at the same time you reinstalled #4 spark plug.

Remember you've already identified one MAJOR problem: The rocker arms being out of adjustment. Just that alone could cause all sorts of grief. It's very likely this isn't letting the valves close fully, causing a major compression leak. Or maybe it's limiting the travel so the valves barely open. Either scenario will cause low/no compression. Don't go convincing yourself of other problems just yet. From Troubleshooting 101, usually taught on the first day before lunch: Fix the known problems first. Then proceed from there.

One important tidbit with a cranking compression test: Never condemn an engine based solely on this simple test. There are just too many variables that can make a good engine look bad. If it passes, that's great and the problem is elsewhere. But if the cranking compression test fails, ALWAYS follow up with a leakdown test to be sure.
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Update: Since I don't have a leakdown tester, I did what I could with what I have for right now. I went out and #3 is working on its own. It was only building about 30psi last night. Before I did the test I redid the rockers and it is back up to 120psi with no sparkplug in #4. I got the camera out and I can see the valves open on #4. I cant really confirm close since it wont bend that way.I might go back and try to inspect the whole cylinder and piston but from what I saw it looked good.

 

So I thought a little bit and while it wouldn't show loss, I took the valve out of my compression tester. I turned it over and I do feel puffs of air through the hose. Then I hooked up my compressor and set it at 20psi. There is a definite leak from the exhaust. I even loosened the rocker to make sure the valve wasn't pressed down.