Valve chatter

I've been sorting out various issues with my engine and now I've discovered that when the engine is under load the valves sounds like it's a diesel. The engine was recently rebuilt including a new oil pump. I put in an aftermarket oil pressure gauge and its very steady at 40 psig. The valves chatter only when I'm going up hill, which I do a lot here in Pittsburgh! So what's causing the noise? The oil level is correct too.

first are you sure its valves? could be detonation under load.

Yeah...sounds like detonation to me as well. Try backing off on the ignition timing and run premium gas and see if that helps.

I had the head and the block milled and then with the headgasket the CR is calculated to be 9.2 to 1. I run 93 octane in it at all times to be safe. Currently the there is a "rattle" during any kind of acceleration but its not the "marbles in a coffee can" sound that is typically spark knock. Also the timing is 10* BTDC. The "rattle" is there during any acceleration but goes away at WOT. This "valve chatter" started this past week and is only there when going up larger hills and regardless if the engine speed is constant or I'm trying to accelerate up the hill. Could it be camshaft/lifter related?

If you have a C4 trans, the flexplate moves toward the starter on acceration & causes the flexplate bolts to hit the starter nose if there is no relief machined on the starter nose??
Pull the starter or drop the inspection plate to check for interference.

WSA111,

The "rattle" I hear sounds like its coming from that part of the engine. It doesn't sound like its from the engine itself, but off to the side, almost like the heater core area. And I'll bet hard earned money you are right!! I'll take a look.

And if the nose of the starter needs to be clearance, it there a dimension I should try for? I'm assuming I can use an angle grinder to make the necessary "adjustment" ;-)

tanx,
Mugsy 8)

Mugsy, also check for a cracked flexplate.
The proper way is with a Bridgeport machine, but a hand held tool will work.

I just replaced the torque converter a couple weeks ago. I didn't closely inspect the flex plate but I didn't notice any cracks on the flex plate when I tightened the bolts down on the T/C. And this "rattle' has been there ever since the Rebuild...

That's some pretty neat work on that ebay adapter.

Oops! Wrong thread! :duh:

well I pulled the starter tonight and inspected it. No signs of hitting anywhere on the starter or on the flex plate bolts. So the search continues.....