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FE Power Forums => FE Technical Forum => Topic started by: Val406 on June 19, 2019, 09:13:26 PM

Title: Yesterday's minor damage.
Post by: Val406 on June 19, 2019, 09:13:26 PM

Went for a 50mi. drive yesterday and on the way back, a heavy rapping sound came on while I was turning left on a 6 lane road. I saw full oil pressure was was able to limp it onto the gravel shoulder 250ft. clear of the busy intersection. Had it flat-bedded home without issue (thanks Hagerty Plus). Here's what I found. Not gonna badmouth these old Doves... being 25yrs. old and on its 3rd motor. Rube Goldberg would surely approve.

Title: Re: Yesterday's minor damage.
Post by: Stangman on June 20, 2019, 05:26:49 AM

Had the same thing with a FPP bushed rocker. Had another and put it on and broke another on different cylinder a month later. Got a new set after that before my luck ran out. I guess the aluminum just has a lifespan and that’s that. Just make sure there’s no pieces floating around the cylinder head.

Title: Re: Yesterday's minor damage.
Post by: blykins on June 20, 2019, 06:12:14 AM

Make sure the pushrod cup isn't contacting the rocker arm body.

Title: Re: Yesterday's minor damage.
Post by: Thumperbird on June 20, 2019, 06:38:26 AM

You can see where that failure initiated in the lower left corner of the roller side, a slow ductile fatigue like thing, propagated across that side all the way to the little pedestal left on the top side then went into brittle failure.  Note that the rod side is a full brittle (high speed) fracture.  Amazing how long it held together before catastrophic failure.  Even a small ding along that edge started the process who knows when.  This is a main reason for deburring edges of machined parts, not just a cosmetic thing.
Load side bearing surface wear is also kind of neat to see as opposed to the top side.

Title: Re: Yesterday's minor damage.
Post by: BattlestarGalactic on June 20, 2019, 08:39:42 AM

I ain't sayin' a word.  Abe Lincoln sold me my Dove HD rocker assy on the wagon.   Along with my TW intake(that never leaked).... ;D

Title: Re: Yesterday's minor damage.
Post by: jwrmach1 on June 20, 2019, 08:59:45 AM

You may want to think about replacing all the rockers.  Aluminum unlike steel will get weaker and weaker as it is loaded and unloaded until failure.  Steel has an endurance limit where it reaches a certain strength and does not get weaker with repeated loading.  Many parts are designed so that the load is always less than the endurance limit strength so they do not fail.  You do not have that luxury with Aluminum.  The rest of the rockers will start to break too as a previous poster has mentioned.
JWR

Title: Re: Yesterday's minor damage.
Post by: TomP on June 20, 2019, 02:13:47 PM

It looks like it was wearing well and other than snapping in half they did a fine job.

Nice clear pictures, the FoMoCo oil cap is cool!