Unique Rattle

[AP2_RR]

Need some ideas to check...

OK, just swapped short blocks to High CR 89mm bored, 90.7 honda stroke. I have used this short block before for about 2 months. No issues, noises, nadda.

At first we had a large, loud rattle everywhere. Got louder with revs and resonated at 3500 RPMs then died reving (still loud). When driving it sound like it came from under the car. Sounded like cards in wheel spokes.

We swapped TCTs and modified the TCT piston (made it longer) and now there is no rattle at idle and nothing till you get to 4300 rpms then rattle just screams. Sounds more like jar of marbles now than cards in wheel spokes.

Odd thing it projects to the driver side of the car and sounds like it is coming from the under, on top of or around the intake manifold? If you stand on the passenger side of the engine bay, the sound is a fraction of what it is.

[repiv]

Time to probe all parts of the engine with a mechanic's stethoscope. Listen at all 16 locations of the valves, Idle Air Control solenoid, bottom end (bearings, wrist pins, piston slap, etc.). If it's as loud as you say, it shouldn't too hard to at least localize it to "front/rear/top/bottom/left/right". You say you've tinkered with the TCT, but that doesn't mean you've fixed it. Listen to it again with the stethoscope.

[zipwad]

Not sure if it is the same, but I have a rattle that sounds almost like a chain rattle. Mine is the timing chain tensioner. Had it replaced about 6 months ago and need it again.

[AP2_RR]

Well it was a new cam that I was testing. Put in the old cam and all gone. Must have been the intake cam as noise was projecting driver side. I will discuss with them and hopefully they will fix the problem.

Back to the drawing board.