Thread: Strange rattle when under hard throttle

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I have a highly built 350 that rattles under hard throttle. I experience no power loss when the rattling is occurring. Recently the noise went away for a couple hundred miles followed by the distributor popping out (the clamp became loose). I think the problem may therefore be related to the oil pump / distributor connection. Has anyone seen or heard of this problem before? I have outstanding oil pressure with / without the noise.

sounds like spark knock ,what is timing set at and what is the total timing.

Originally Posted by hucks 50

sounds like spark knock ,what is timing set at and what is the total timing.

same here.

Yep, seems like your distributor was loose and able to turn, making the timing too far advanced at times. Chevys don't have the best distributor hold down clamps I have ever seen IMO. The fact it later popped out seems to back up that theory.

Don

Also known as "death rattle" and left uncorrected is certain to do significant damage to the tops of the pistons!!!!!

good point there Dave, I forgot to mention that. I think it could also be cause from cheap gas.

I have a 330HP 350 in my 29A and had the same issue. I checked the following items during my investigation of the problem.

1. correct spark plug wiring order
2. timing set at 10 degrees before TDC
3. correct spark plugs
4. cracks in flex-plate (auto trans)
5. quality of gasoline
6. correct damper and timing indicator (pointer)
7. distributor vacuum advance connected to a ported source

What I found was that my air-cleaner was shorting the plug wire on my HEI distributor. I purchased an offset air cleaner on ebay that was designed to clear the HEI distributor. I also retarded the timing 2 degrees. If you can get a copy the Jan 2003 Chevy High Performance there is a good write up on how to wip detonation issues.

Thanks everybody, I'll start with the timing because when it retarded itself over time the noise went away (I haven't gone full throttle on it much yet, still on break in)... I'll let you know how it goes.

-Chris

PS: Timing was set at 8 degrees BTDC

if you have a bigger cam ,you will want to check your total timing .

Hey, guys I agree with checking the timing but shouldn't we also be concerned with octang?