LSCHLEM

I was driving home and stopped at the Supermarket. When I came out and started the Car It made a banging noise. At first I thought that something was under the car but not so. I drove it Home about a 1/4 Mile
and noticed the banging noise was was more with rpm's but the car did not appear to lose power or misfire. In the garage it seemed like the noise was under the FAST MANIFOLD. I removed the Spark Plugs on
the drivers side and when I cranked it the noise went away. I then compression checked all the cylinders and they were around 180 PSI each. I put the plugs in one by one and the clunk came back when I installed the plug in CYL #3. I removed the plug and the clunk went away. Hooked up the Compression Gage and the clunk came back. BTW I was using a hand held switch to turn over the Engine without appliy
ing SPARK OR FUEL .I AM REALLY BAFFLED ??.. ANY IDEAS WILL BE APPRECIATED. Thanks LSCHLEM

Red06Vette

Does the sound appear to be coming from the cylinder head area or deeper inside of engine? How regular is the banging when running? I think I would pull a valve cover and check for broken springs or rocker arm first. At that time, if all looks good with the valve springs and rockers, crane it over and watch to see if they move the same as the other cylinders.

LSCHLEM

The banging is consistent and appears to come from the deep center of the FAST INTAKE. ALL indications appear to be possibly a blown head gasket. with no load
meaning when the cylinder is has the spark plug out there is no rocker/ spring,valvetrain noise whatsoever. A head gasket will be quiet under no compression and could leak water, or compressed air when the plug is in. I hope I can determine what it is before tearing it apart. Thanks for your reply

LSCHLEM

Found the problem. YELLA TERRA ROCKER FAILURE. The EXHAUST ROCKER FAILED AS THE PUSH ROD PUNCHED THRU THE TOP OF THE ROCKER., EXPLAINS ALL THE NOISE.

TucoTom

What would cause a quality Yella Terra Rocker to fail....Adjustment, Push Rod length????

Red06Vette

An easy repair and Yella Terra might just send you a new one free, they seem like stand up guys. Exhaust valve side is why compression was good, friend of mine had an LS6 Chevelle that had intake rocker failure, it showed no compression in that cylinder, valve cover off and rocker arm turned sideways, easy repair.

irok

Not sure what caused the Yella Terra rocker to fail but several posts over the years on this forum where they have failed

Red06Vette

Where did it break, fulcrum pushrod end or valve end?

KW Baraka

Wrong rocker for the spring pressure and cam.....

Yella Terra has several rockers for any given head/cam combination (Ultra-lite, Ultra-lite Pro, Pro-Street, and Platinam Race). More 'race' oriented applications require a more race oriented rocker.

Use their 'Ultra Lite' rocker for a 'race' application (Pro-Street or Platinum Race) and the rocker WILL eventually break.

KW

HC Mechanic

i think there’s only one vendor on the forum who pushes those things..

My condolences about your luck man, I was actually going to guess a lifter.
Hope you get her back up and running soon Brother

HC Mechanic

Well known fact, and unfortunately some still think they are good based on some shady vendors who’s primary goal is making as much margin as possible.

Any solid, honest LS engine builder will tell you the stock rockers are very good, especially with the Comp Cams trunnion upgrade. But if cost isn’t much of a factor and your goal necessitate changing them, spend some coin on T&D or Jesel; both are world class brands

My personal favorite:
https://www.jesel.com/pro-steel-series-shaft-rockers

LSCHLEM

Problems were fixed. I installed comp gold rockers 1:.73: 1. I also installed the holley tall valve covers. It runs better than ever and looks really neat
thanks, for all your help.

HC Mechanic

Glad to hear that brother, comp makes great products!!