The rundown is this: Swapped my cam. (read about it here) Car ran fine until I took it Joplin for the HAMB drags where it developed a "tap tap tap" up top. Found a slightly loose lifter (not a lifter with a loose adjuster, but a lifter with a litte too much clearance) and fixed it. Noise seemed to go away briefly - or at least I convinced myself it did. noise comes back so I tweak lifters and recheck clearances. All good but noise is there loud as ever on initial startup. Pull all belts and restart to eliminate possability of pumps, fan or gen. making the noise. Still there. Fearing I would do permanent damage to my crank - filling my bearings with metal from the cam or lifters, I SWAPPED ENGINES. Installed onld intake and carbs. Good to go. New motor has the SAME "tap tap tap". Whatinhell? Plain as day. When I listen closer it sounds like it's coming from the same lifter or at least the same spot? So tonight I'm setting the paring lot at my work just listening to it and it hits me. SAME PCV setup. This is an off the shelf valve plumbed with copper line under the intake. Shake the valve and it rattles. Tilt it and the ball drops from side to side. So my question is... could it actually BE the PCV slamming shut (or open I guess) under va*** with each revolution? Ultimately I don't care so much about the motor in the car right now - it's a Ford with no high dollar internal speed parts. Good oil pressure and runs insanely cool so I'll drive it until it breaks. The hot motor is in a stand in the garage awaiting autopsy. That will be definitive but until then I'm just wondering what the possibility of the PCV making the noise is.
It seems to be a pretty solid TAP. Which makes me think I just put another motor with lifter problems in. Couldn't imagine why - there's some background on the replacement motor here and here. Sure would be nice if I found out it was just a wierd PCV though.
Does it change as the engine warms up? Change with RPMs? You still running a factory fuel pump that could have a ticking pushrod?
Kevin, I had the same tap, problem is I pulled the motor to rebuild a new one, so I cant help you. I originally thought it was rod bearings. What about gudeon pin? does it sound like piston slap. mine also was to do with rpm so obviously in the rotating m***. Have you gotten hold of your valve bar and just checked that the valves all seem to have the same sort of tension on them? have you checked your valve lash? just some thoughts that i had running thru my head.
K- there are two exhaust outlets on the intake manifold, centered in the 4 intake ports. see if those are leaking. mine did and it was a weird sound. good luck, TP
Dang it! I was gonna say I battled what I thought was a ticky lifter for a while just to find out it was an exhaust leak. The sound was so clean I just knew it was mechanical. As for the PCV valve. Is there any way for you to run it without for a few minutews so you can eliminate or confirm it? Really dug your car at the Drags.
Is your PVC hidden? Try removing it or just plugging the vacuum line to eliminate that possiblility Sorry rashy. i missed your response..
I don't see how it could. A burnt or bent valve will cause the vacuum gauge to fluctuate but even then it never fluctuates that much. A healthy engine should carry a steady vacuum signal only changing with the throttle position. If the valve was designed to be used in the vertical position and it's now horizontal then the pentle could be rattleing inside the housing. Most factory vertical PCV valves use gravity to close them. Horizontal factory valves use a spring to close them.
Make sure the PCV you have is for the correct cubic inch engine, there are differences. I used one from a 302, its on a 286 and it seems to be OK.
PCV's run on vacuum... Not being a ****, I have a theory. Are you using the same intake on both motors? Is it a multi-carb intake? There might not be enough vacuum for the PCV which might make it work a little 'clunkier' that it would at a higher pressure? Nuther idea... Anybody know what a PCV sounds like when it gets clogged? I had one on my 327 in my Shoebox for a while that was pretty noisy... Being on the outside of the motor though, it was a real high 'tick' sound but maybe if it was under the intake it might sound more like a bad lifter. I pulled it off and went to a breather...
First had a "thunk, thunk, thunk" in the engine, so we completely rebuilt it. Good thing cause it had really worn rod bearings, a**** other things. After the rebuild, we had a "tap, tap, tap". Oh, no, not again. Turned out the slight decking and new valves combined to put the spark plug a bit too close to the head of the valve. Flattened about five of the eight electrodes. Swapped the high-falutin BGK's for some good-ole Champion H-10's and we were good to go. I wonder if you are using too long o' plugs too?
Have you run either motor with a vacuum gage on it yet? I'd pull the pcv and plug it and see if that makes it stop. I usually try the easiest things first. Well, what seems easiest at the time
I’m digging up a super old thread but did you ever come to a conclusion on if it was the PCV rattling that was making the ticking noises? I am experiencing the exact same thing on a new built flathead I have done all of the same identical checks including new gaskets etc on the headers, pulled the intake checked the valves We are beginning to think it’s the pcv as well just wondering if you verified that in yours cheers
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