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 Bent Rod?!!
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rkellerjr
Many Feathers

USA
1242 Posts

Posted - 20 Apr 2017 :  3:20:11 PM  Show Profile  Reply with Quote
Well this was a surprise today. Was re-lashing my valve train and found this on intake #8. Glad we found it when we did, replaced it and all is well except for some carb adjustments we need to do.


Rich
1975 TA - http://www.youtube.com/watch?v=aR86YT69yeY

tjs44
Cochise

USA
373 Posts

Posted - 20 Apr 2017 :  4:47:23 PM  Show Profile  Reply with Quote
NOW you have to find out WHY!Tom
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RayK
Cochise

USA
925 Posts

Posted - 21 Apr 2017 :  05:08:52 AM  Show Profile  Reply with Quote
We always replace factory pushrods when we do a rebuild of any sort. Not sure if that is factory but for peace of mind go with thicker wall. After so many miles the original pushrods can be fatigued and should be replaced.

1969 Firebird 461, #62 iron heads, Comp roller, Performer RPM, Q-Jet Turbo 400 w/ Continental converter. GM 8.5" 10 bolt with 3:73 gears.11.50's@ 119+ MPH
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67drake
Sitting Duck

Azerbaijan
1495 Posts

Posted - 21 Apr 2017 :  08:18:36 AM  Show Profile  Reply with Quote
That's not bent,it's mangled. Did the engine run on "all 8" before checking the lash,or did this happen during the check?
Agree with Tom,I wouldn't even fire the engine till I knew what caused this.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 21 Apr 2017 08:56:40 AM
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Bill Boyle
Horse Feathers (Charter Member)

USA
4615 Posts

Posted - 25 Apr 2017 :  06:49:36 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Fatigue...metal fatigue combined with a lifter that was momentarily non-hydraulic. Rich, pull the intake and replace the lifter with a new one. Also, double check the springs and run a compression test on that cylinder once you have it all together.

I had a push rod bend while driving from NM to Florida. In my case, the pushrod broke the guide. I believe it was metal fatigue, having driven hundreds of mile that day along with high outside temperature and probably a maladjusted lash. I popped in a new push rod, set the lash and was off and running. Once I made it to my destination, everything was checked out as ok.

Bill

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Blued and Painted
Chief PONTIAC

USA
3331 Posts

Posted - 25 Apr 2017 :  10:48:21 AM  Show Profile  Reply with Quote
There is a possibility a cam lobe and lifter is going away.
Check that the new push rod spins on its own when engine is running. Other possibilities. Broken valve spring or valve sticking in guide.


Bull Nose Formula, 461, TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 25 Apr 2017 10:54:48 AM
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rkellerjr
Many Feathers

USA
1242 Posts

Posted - 25 Apr 2017 :  9:11:11 PM  Show Profile  Reply with Quote
Part of the bend was caused by pulling and jerking to get it out, it wasn't bent that bad in the motor We already replaced it and fired the motor and she purred like a kitten.

Rich
1975 TA - http://www.youtube.com/watch?v=aR86YT69yeY
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Phil
The Great White Buffalo

USA
7146 Posts

Posted - 25 Apr 2017 :  9:37:44 PM  Show Profile  Reply with Quote
Rich, do you remember ever having a backfire with this engine?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Blued and Painted
Chief PONTIAC

USA
3331 Posts

Posted - 26 Apr 2017 :  01:06:24 AM  Show Profile  Reply with Quote
It looks ok where it turns in the guide plate.

Guess you could spit one out running a five five test. That's 5K rpm's for 5 miles. Some consider the five five test a break-in procedure.



Bull Nose Formula, 461, TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 26 Apr 2017 01:07:39 AM
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rkellerjr
Many Feathers

USA
1242 Posts

Posted - 26 Apr 2017 :  09:21:19 AM  Show Profile  Reply with Quote
quote:
Originally posted by Phil

Rich, do you remember ever having a backfire with this engine?



Not of hand but, my tach doesn't work so it could have been an over rev at some point. Also, the lash on the valve train was loose. Too lose in some cases. Bought a new set of poly locks when we did this.

Rich
1975 TA - http://www.youtube.com/watch?v=aR86YT69yeY
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Sparafucile
Sitting Bull

158 Posts

Posted - 26 Apr 2017 :  8:36:22 PM  Show Profile  Reply with Quote
They call that a five-five test? I thought that was my daily commute.
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