I have been fighting this problem for quite awhile! Can't figure it out I have this tick that sounds like an exhaust leak but much more distinct. I rebuilt the engine witch started life as a '71 360, put a 390 crank+rods and h395 pistons bored 40 over comp xtreme energy cam and lifters had it balanced and installed new cam, main and rod bearings Rebuilt heads d2te-aa (rebuilt to stock no mods) melling high vol oil pump. It runs great starts good idles good but it has what seems like a slight burned exhaust valve when cold (judging by one cyl on the left bank sucking through the exhaust) only when its cold! Did a compression check that looked good so that seems to rule out the burned valve idea so now I am thinking MAYBE it could be due to excessive oil pressure over pressuring the lifter and holding a valve open when cold since oil pressure would drop as the engine warms and the noise goes away? My oil pressure gauge is high when cold then at running temp runs in the upper end of normal! Only other thought is possibly a broken inner valve spring? Any help would be greatly appreciated

 

It is possible you have a lifter that isn`t operating correctly. Seeing as how they are all new, and the fact that high oil pressure should affect all the lifters, or at least more than one (and closest to the oil feed), perhaps the adjustment is off.

I suspect there isn`t any adjustment, next to changing pushrod length, but you could make sure all the lifters collapse down the same amount by pushing on them (corresponding cyl on compression stroke).

I do detest weird noises, and they sure are hard to diagnose over the net, even with video, but if you can post a video it may help. The noise could be something else entirely, like a bad exhaust gasket for example, loose when cold, tight when hot.

One thing I`ve been slowly learning to use is a mechanic`s stethoscope. Basically the same as a medical one, but it has a metal rod on the end vs a diaphragm. They are very cheap....I got mine on sale for less than $5.

One nice trick is to listen to each cylinder and see if they all sound the same, and if one doesn`t, you`ve narrowed it down a bit. I put the probe in that little depression behind each exhaust (top) flange on the head. Hold the probe firmly as if it bounces, you`ll really think something is wrong.

You may be able to make one by just using a long piece of steel rod. even a shorter piece with some rubber hose over the end, and long enough to reach your ear should work....don`t shove the hose in your ear....hold the open end pointing up, and next to your ear.

Does the noise increase in freq when the engine is revved? Does it go away or get worse when the engine is revved?

sidenote....I was hearing a strange noise on mine....turned out to be the exhaust making noises as it warmed up....just the metal expanding....similiar to the contraction pings when it cools after shutting down. It's diffiuclt sometimes to establish whether a noise is coming from the engine, or out the exhaust. The stethoscope can help with this.

 

One question - how do you know one cylinder is sucking from the exhaust port?

 

I have dual exhaust and the pipe that comes from the drivers side I can feel a slight suction at idle and a audible poping type noise. It seems when I put my hand in front of the tail pipe I get a steady "puff" of exhaust from each cyl. on the passanger side but not from the drivers side there is one odd cyl. almost feels like its wanting to pull my hand instead of push! Hopefully that makes sense.

 

That could be a cylinder misfiring for various reasons. Intake gasket leak, plug fouled, bad plug wire, bad cap, bad distributor upper bushing (only with points), etc.

With a wild enough cam, the exhaust valve opens before the bottom-dead-center (BDC) and it actually sucks air back in if the cylinder didn't fire properly.

 

I have a petronix system so no points. New spark plugs twice so probably not that. I did put new bosch wires on but I have not looked into that as a possibility, in fact never crossed my mind. Same with the distributer and cap they are both new so didn't look into that. I have never had a simple misfire ack so strange. The plug wires though good idea!! Could have weak spark possibly on a cyl causing a miss and with the cam popping out the exhaust! I'll check into that.

 

Your problem goes away when the engine gets hot. When I had a weak spark, the misfires started after the engine got hot. That was traced to using the wrong coil with my Pertronix Ignitor.

Spark plug wires. Try the midnight test. Open the hood at night and look for arcing, etc. Also as you say it is the left bank, make sure the wires for #7 and #8 are seperated as far as possible apart.

Krewat does make a good point. It's usually a good idea to start with checking the ignition when having engine troubles like yours.

 

When I ordered the petronix I also ordered the correct coil so that should also be ok. Something I haven't mentioned yet is I can hear the tick decellerating too when I accelerate it almost sounds like an exhaust leak then I let off the gas and can still hear it while decellerating. I can't imagine that would be a spark issue? but I've tried so many other things trying to fix it I'm not about to rule it out. Like I said earlier it's alot louder cold. I can feel a slight miss but its no dead cyl just one not firing 100% Hopefully if I keep throwing symtoms out there it will narrow it down. I really appreciate your help thanks again.

 

Sounds like a sticky lifter, when the motor gets warn the oil thins and is easier to lube the lifter.

 

Whats the best way to test the lifters??? I was also wondering if there was a way to compress them without removing 'em? I read somewhere a good way to figure pushrod length is measure the rocker to valve clearance at tdc with the lifters compressed. Is that true?

 

Yes, that is basically correct. Ford specifies that a lifter full of oil takes 5 to 50 seconds to collapse 1/16" when a 50 lb load is applied. Now there's a wide range of acceptability.

For valve lash, I would find a spot half way between fully up and fully compressed and make sure that is close to where it is when adjusted. How to do that, I'm not sure, but a bit of experimentation might reveal where you need to be.

I'm sorry I can't help more, but I went to solid lifters just to avoid such a problem.