cam break-in PROBLEMS

Murray · 02-27-2001, 12:48 PM

I put an '80 351W into my 68 mustang. I first installed an Edelbrock Performer cam, timing chain and gears and Performer intake.This morning was the 30 min. initial start-up to break in the cam. I turned it over first to build up some oil pressure, then started it on high idle. She purred like a kitten. About 5 minutes into the run there was some random clunking and the engine started running a little rougher. There was a few more occasional clunks and after a couple of louder ones I shut it down at the 15min. mark. I followed the installation instrucions to a tee. Did I knock a lobe off? Any suggestions what to check now? Murray

Fostang · 02-27-2001, 03:06 PM

Kinda sounds like what mine did when I went to break it in. Had to tear it down again and found it was a stuck lifter.

NO SLO PK · 03-02-2001, 11:39 PM

I'd say pull the valve covers and make sure the valvetrain is tight, e.g., no loose rocker arms. Also, pull the dipstick and look for fine metal sediment in the oil.

I once lost a cam during break in, and it really stunk...it destroyed a few bearings and the little 289 had to come out.

Russ

------------------
'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

Murray · 03-04-2001, 11:43 AM

Problem solved. I pulled the valve covers and found a rocker arm bolt very loose,rocker cocked to the side and push rod wedged. I rechecked all the bolt torques and found one other under torqued. I was sure I did them all twice. I decided to redo all the bolts with loctite. Luckily no damage was done. Murray

leestanger · 03-19-2001, 12:22 PM

Remember which rocker was off line. In the future if (hopefully never) you have any problems that could relate to a bad/worn valve guide, side loading of that valve could make its guide go sooner than the others.

Rev · 03-19-2001, 07:00 PM

Whew, glad that's all it was. Some time ago, when I installed roller tip rockers on my '66, I also installed poly-locks to insure a permanent adjustment. I had been admonished not to torque down the stud nuts too tight against the allen head lock screws as one can twist off the studs on those stepped rocker studs. Anyway, while testing out these new roller tip rockers, what comes up beside me at 60 mmph on a suburban freeway but a damned Camaro reving and jumping forward. After dropping to 2 nd and putting a few lengths on him, my car just cratered running on about six cylinders. Same thing had happened to me that happened to you. Two push rods were not even connected to the rocker arms. Was an easy fix. Now I adjust everything, lock the poly-lock allen screws, and then put 20-25 lb/ft ont he stud nuts to insure a firm adjustment. No problems since and they stay in adjustment. Scared the pee out of me when that happened though. Glad yours wasn';t any worse.

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

j's69stang · 03-19-2001, 08:35 PM

i had a rocker arm snap in half on me one day i was just driving easy and all the sudden i hear the loud tappen noise. so i get out and its coming through the carb. i was like oh Lord what now. i drive it all the way home and take the valve covers off and i find a rocker arm snapped in half on me. scared me to death but thank goodness it was easy and cheap to fix

02-27-2001, 12:48 PM	#1
Murray Registered Member Join Date: Feb 2001 Location: Brandon, Manitoba, Canada Posts: 11	cam break-in PROBLEMS I put an '80 351W into my 68 mustang. I first installed an Edelbrock Performer cam, timing chain and gears and Performer intake.This morning was the 30 min. initial start-up to break in the cam. I turned it over first to build up some oil pressure, then started it on high idle. She purred like a kitten. About 5 minutes into the run there was some random clunking and the engine started running a little rougher. There was a few more occasional clunks and after a couple of louder ones I shut it down at the 15min. mark. I followed the installation instrucions to a tee. Did I knock a lobe off? Any suggestions what to check now? Murray

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02-27-2001, 03:06 PM	#2
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Kinda sounds like what mine did when I went to break it in. Had to tear it down again and found it was a stuck lifter.

03-02-2001, 11:39 PM	#3
NO SLO PK Registered Member Join Date: Mar 1999 Location: Arcadia, CA, USA Posts: 731	I'd say pull the valve covers and make sure the valvetrain is tight, e.g., no loose rocker arms. Also, pull the dipstick and look for fine metal sediment in the oil. I once lost a cam during break in, and it really stunk...it destroyed a few bearings and the little 289 had to come out. Russ ------------------ '91 LX Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

03-04-2001, 11:43 AM	#4
Murray Registered Member Join Date: Feb 2001 Location: Brandon, Manitoba, Canada Posts: 11	Problem solved. I pulled the valve covers and found a rocker arm bolt very loose,rocker cocked to the side and push rod wedged. I rechecked all the bolt torques and found one other under torqued. I was sure I did them all twice. I decided to redo all the bolts with loctite. Luckily no damage was done. Murray

03-19-2001, 12:22 PM	#5
leestanger Registered Member Join Date: Oct 2000 Location: Stone Mountain, GA, USA Posts: 7	Remember which rocker was off line. In the future if (hopefully never) you have any problems that could relate to a bad/worn valve guide, side loading of that valve could make its guide go sooner than the others.

03-19-2001, 07:00 PM	#6
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Whew, glad that's all it was. Some time ago, when I installed roller tip rockers on my '66, I also installed poly-locks to insure a permanent adjustment. I had been admonished not to torque down the stud nuts too tight against the allen head lock screws as one can twist off the studs on those stepped rocker studs. Anyway, while testing out these new roller tip rockers, what comes up beside me at 60 mmph on a suburban freeway but a damned Camaro reving and jumping forward. After dropping to 2 nd and putting a few lengths on him, my car just cratered running on about six cylinders. Same thing had happened to me that happened to you. Two push rods were not even connected to the rocker arms. Was an easy fix. Now I adjust everything, lock the poly-lock allen screws, and then put 20-25 lb/ft ont he stud nuts to insure a firm adjustment. No problems since and they stay in adjustment. Scared the pee out of me when that happened though. Glad yours wasn';t any worse. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.

03-19-2001, 08:35 PM	#7
j's69stang Registered Member Join Date: Apr 2000 Posts: 102	i had a rocker arm snap in half on me one day i was just driving easy and all the sudden i hear the loud tappen noise. so i get out and its coming through the carb. i was like oh Lord what now. i drive it all the way home and take the valve covers off and i find a rocker arm snapped in half on me. scared me to death but thank goodness it was easy and cheap to fix