[Hesslerk]

I recently did a CAM swap/head/intake swap on my 72, 307 V8. I did everything to the T. New cam is mild, 0.44 lift, new lifters, 305 re-machined heads and valves. I measured the new pushrod lengths and set the valve lash appropriately.

When I cold start the car, sounds great but after it warms up, especially after driving it for a bit, when I come back down to idle I get an audible tick. If I let it sit for a little bit idling the sound seems to quiet down. I bought a stethoscope and poked around while idling. Passenger side no problem. Drivers side, the sound is most noticeable at the No. 7 cylinder with the scope on the exhaust manifold. If I move it up to the intake manifold it's less noticeable. The tick sound sharp like metal on metal and not dull as I would expect an exhaust leak might. Since it's more pronounced on the exhaust manifold, am I looking at valve slap on that valve as opposed to a lifter tick or other issue? How bad is it to drive it?

 

[Midmo Joe]

A valvetrain noise will vary directly with the engine rpm. A piston/bearing noise will vary with “load”, in otherwords by lightly revving the engine the noise should sound different. Generally the noise will increase as the engine is lightly accelerated.

 

[Hesslerk]

I did unplug the No. 7 wire while it was running with no change in sound. If I listen closely the ticking does speed up with higher rpm but gets drowned out by the engine noise. Sounds like something in the valve train then. Since it's more pronounced when I put the scope on the exhaust, is it the exhaust valve slapping on the seat? I can try to reset the lash on the valve to see if that helps. What else can I do to fix it? It's a new spring, valve, keepers and machined seat. Should it not make the same noise when cold?

 

[lwlevens]

Pull the valve cover fire it up and look if the rocker is out of adjustment. If everything looks to be ok then I would pull the intake and head, could be a collapsed lifter.

 

[Jared65ss]

Willing to bet it’s a lifter bleeding down...especially if it’s all quiet while cold. The extra viscosity when the oil is thick and cold is taking up the slack. Had the same issue on my 283. Does it have roller rockers?

 

[bracketchev70]

Like is being said, its at the rocker where the noise is. The valve is only going to close as fast as the cam allows it. So its not going to be any different than the other cylinders. Your issue is between the lifter and the valve tip.

 

[Hesslerk]

It's hydraulic lifters, brand new along with the cam. Will take a look with the cover off and readjust the #7 E/I lash and report back.

 

[g2072]

I know a lot of people use poly locks when running roller rockers and I guess I must be jinxed but I cannot run poly locks without them backing off. I've literally been building engines almost forty years and I still cannot keep them from backing off. I put a stud girdle on everything I build. Just throwing it out there. Don't know what rockers/adjusting nuts you are using.

 

[Hesslerk]

Stock rockers/nuts

 

[Jared65ss]

One thing that can work really good for diagnosing something like this, especially if you have stock rockers - is to cut a slot into an old set of valve covers. Cut the slot about an inch or so wide right across the top of the rockers and fire up the motor. If you cut it into the right spot on the valve cover hardly any oil flies out while the motor is running. It’s a great way to adjust valves while the car is running. Adjust to see if there’s a change in the tick.

 

[Hesslerk]

Still haven't got around to adjusting the valve again, however, my idle oil pressure after warm up is only 14 psi in drive, 24psi idling in park. Highway speeds is ~30psi. Cold start, 40psi. Wondering if my oil pump is just getting old and not forcing enough oil into the No. 7 lifter.

 

[Hesslerk]

Backed the No. 7 cylinder valve lash out 1/4 of a turn. I originally set it 1/2 past zero lash. The tick improved, only noticeable when it's fully warmed up and when I sit at idle for about a minute it goes away. I'm going to back it out another 1/8 of a turn and hope it takes care of the problem.

 

[lwlevens]

Thanks, keep us posted.

 

[Hesslerk]

Backed the No. 7 valves off another 1/8 of a turn for a total of 1/8 of a turn preload on the lifters. I took for a ride, it's been a little cold here so didn't get the oil heated as high as it will in the summer but I didn't hear the tick anymore so that's good news.