Resolved Weird sound coming from a freshly rebuilt 5.0L

karhoot

Member
Apr 23, 2026
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Back again with another post! Engine build has been completed. Ended up refreshing then installing a XE274HR cam, AFR heads alongside an Edelbrock Performer RPM intake. Went with Holley Terminator X standalone. Plugs (NGK BK5RE) are currently gapped at 0.045" & ignition has been upgraded with MSD 8456/8227 (TFI & coil respectively). Took the car out for a rest drive last week, kept dying above 3k (BEFORE MSD spark components installed). Car idled perfectly fine & no noises were heard.

After installing the above named MSD components, this WEIRD noise is being heard. I've already confirmed positioning of the TFI (removed all plugs, set #1 to TDC on comp stroke, then set rotor pointing toward #1 plug wire on cap)

Tried original distributor/coil, nothing.
Removed & checked plugs (see below, 1st pic is bank 1, 2nd is bank 2, each bank is in order : 1234, 5678)
I did confirm firing order following 1-3-7-2-6-5-4-8

Rerouted all of my spark plugs wires in accordance with TSB figuring it was crossfire & nothing
Below I've attached a video of the sound



Kind of lost at the moment. Have any of you ever heard this noise before?
 

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Well..... this may be the quickest diagnosis yet. Pulled valve covers and boom, found this. Going to start from scratch & reset all of my geometry because CLEARLY someone left something loose! Lol. Marking this resolved.
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