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10-13-2016, 08:49 AM
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#1 |
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Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Bent Pushrod
Coming back from a show this past Saturday my truck developed a dead skip. I was only a couple of miles from home so I limped it the rest of the way. I figured I had fouled a plug or a spark plug wire had come off. Neither of which happened, I put in new plugs and wires but still had the skip (engine miss). Drove it to my mechanics shop and after some basic troubleshooting he pulled the left valve cover off. The #5 intake valve push rod was bent at a 90 degree angle just under where it should have been under the rocker arm. My engine is a rebuilt 454 with less than a thousand miles. Its running all Comp Cams gear including the pushrods and rocker arms. According to my mechanic big blocks are known for breaking valve springs and bending push rods. I've never heard of this before. There was no other damage and once the push rod was replaced it ran great. Anyone else have this happen on a big block?
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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10-13-2016, 08:22 PM
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#2 |
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Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,732
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Re: Bent Pushrod
If I were to guess, either the rocker arm backed off or the flat tappet cam is going flat which is what Big Block Chevy's are also known for.
New rocker studs and nuts if it just backed off. If cam is going flat that's a pain. I bought a hydraulic roller setup for the 427 I'm building for my '69 short step because of the flat cam fear. If I had to do it twice it was going to be more $ than doing the HR once. Hope yours was just a rocker that backed off. Will be watching for an update.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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10-13-2016, 09:51 PM
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#3 |
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Who Changed This?
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,790
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Re: Bent Pushrod
Was the stud pulled, bad rocker ball or the nut backed off? If not, maybe it was just a defective push rod.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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10-14-2016, 08:00 AM
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#4 |
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Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Bent Pushrod
I'm hoping it was just a defective pushrod. The engine looked new inside. I'm driving it to another show this weekend, so fingers crossed it doesn't happen again.
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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10-14-2016, 08:44 AM
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#5 |
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Registered User
Join Date: Aug 2013
Location: Fort Worth, TX
Posts: 309
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Re: Bent Pushrod
That looks like it has been rubbing on something, not just bent. Does the wear/bend coincide with where it passes through the pushrod guide? Might have a guide issue. Might want to keep an eye on that new push rod.
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10-14-2016, 09:12 AM
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#6 |
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Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Bent Pushrod
I'm going to keep a close eye on it but there really isn't any wear per say. Just looks like it in the picture. It didn't happen for no reason, it was either a manufacturer defect in the pushrod or as you guys have said something else. Time will tell.
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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10-14-2016, 11:35 AM
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#7 |
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Registered User
Join Date: Nov 2014
Location: West Texas
Posts: 30
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Re: Bent Pushrod
BBC pushrods have a top and bottom, I always reccomend "hardened" pushrods, look for the hardened tip to be longer on the top. This helps in the wear area where it passes through the pushrod guide. Check to make sure you are using 3/8 giudes with 3/8 pushrods. BBC's can use 5/16, 3/8 or 7/16 pushrods WITH the correct size guides.
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10-14-2016, 11:45 AM
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#8 |
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Registered User
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
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Re: Bent Pushrod
make sure the rocker under the anti-gall ball isn't broken, I've seen that happen causing the rocker to tip at an angle causing the pushrod to break at the guide also...
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Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. |
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10-14-2016, 12:24 PM
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#9 |
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Senior Member
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,679
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Re: Bent Pushrod
Looking at the tip it was definitely rubbing on the guide plate. Something is out of alignment
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10-14-2016, 01:22 PM
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#10 |
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Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: Bent Pushrod
Valvetrain on big blocks are "consumables" like gas and oil...
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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10-14-2016, 03:54 PM
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#11 |
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Registered User
Join Date: Jul 2011
Location: strausstown pa
Posts: 3,394
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Re: Bent Pushrod
Looks like it was rubbing on the spring retainer in either the opened or closed postion but the p.rod was still spinning like it should be.
Hope all goes well only time will tell.
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81 camaro 355 4/spd 342 posi my first love  .67 swb step 454/4spd ott 373 posi 4/7 drop. 2000 s10 zr2 little blue truck that never gets stuck. '74 heald super bronc vt8. tecumseh powered moon rover. |
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