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Rocker arm and pushrod breakage
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DRR Pro
posted
Borrowed a motor last year and ended up buying it. TRE 23* Pro Filer 436" deal...all brand new.

I put 25-30 runs on it and zero issues. It sat all winter and all this season until Sunday. First hit it breaks #3 intake rocker arm (breaks pushrod cup end off at the trunnion) and breaks the tip off #7 intake pushrod (rocker arm end).

Check it all over (lash, lifters, timing) and cant find anything wrong. Replaced broken parts. Next pass it brakes # 7 Intake rocker. then breaks #5...then breaks #2 rocker...then brakes # 7 pushrod again. Finally stuck it back in the box so I don't destroy the damn thing.

Springs all had 270 on the seat....valve lash checked multiple times. Nothing changed from last year....fresh oil and fuel and it starts breaking parts. All at idle. I made two runs on 8 cylinders in the middle of all the breakage.

Thoughts?


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Posts: 492 | Location: Lebanon, OH | Registered: March 18, 2008Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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Sounds like valvetrain is out of control. Maybe springs aren't right. Who's spring? I had issues with PAC, went to PSI and issues went away.


Mark Goulette
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Posts: 1462 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Pro
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quote:
Originally posted by Coloradoracer:
Sounds like valvetrain is out of control. Maybe springs aren't right. Who's spring? I had issues with PAC, went to PSI and issues went away.


This is where the problems start...I don't know anything. I don't have a cam spec...just lash numbers. Cant even tell you who's crank and rods. Nothing about this motor scream max effort or exotic so I would be extremely surprised if it killed springs after 25 runs. I'll tear the motor down this winter to check it all....just makes no sense that a brand new piece runs this good for 25 runs and then starts eating valve train.


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Posts: 492 | Location: Lebanon, OH | Registered: March 18, 2008Reply With QuoteReport This Post
DRR Sportsman
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Stud mount rockers,or shaft mount?
 
Posts: 479 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post
DRR Pro
Picture of jmarkaudio
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Retainer to guide clearance insufficient or distance to coil bind on the springs insufficient.




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Posts: 1047 | Location: Florida | Registered: November 16, 2007Reply With QuoteReport This Post
DRR Pro
Picture of Bruce Williams
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Like Mark stated.
Some sort of coil bind/valve train interference.


Bruce Lee Cool

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Posts: 2033 | Location: Chandler Arizona | Registered: August 11, 2005Reply With QuoteReport This Post
DRR Sportsman
Picture of Stephen Hughes
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It’s not going to break those pieces unless something is in a bind. like mentioned above, coil bind or some other interference issue.


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Posts: 336 | Location: Texas | Registered: September 12, 2005Reply With QuoteReport This Post



DRR Sportsman
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Www.pushrods.com talk with my buddy Al
 
Posts: 654 | Location: Here | Registered: November 15, 2012Reply With QuoteReport This Post
DRR Pro
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Could be an aggressive lobe profile that requires more spring pressure than you have now. I struggled with this with my engine till I finally upped the spring pressure above what everyone was recommending. You are better off on the high side with spring pressure than you are the low side.
 
Posts: 1557 | Location: PA | Registered: February 26, 2000Reply With QuoteReport This Post
DRR Top Comp
Picture of wideopen231
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agree there is binding issue. SOunds like springs either weaker or bad. One did not have to start with. If was build issue with clearnaces it would be from day one. On the other hand if springs have loss some pressure and clearance where close it could show up later.

Only other thing and this comes from running Hemi's with constant intake pushrod issues due to oiling system design. Are all oil supply passages clear? if same ones are breaking it could be issue.If its jumping around then probably not.




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Posts: 4130 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post
DRR Top Comp
Picture of wideopen231
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Rereading OP with it being same ones I am betting oiling or bad springs. I would pull check springs and if nothing pull pull lifter and look for trash in oiling holes.




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Posts: 4130 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post
DRR S/Pro
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Besides lash and seat pressure, what have you checked?

If you have coil bind, not sure they would live that many runs with no issues but that could also be related to how bad the bind is too.

Who's rockers?

270 pounds of seat pressure sounds OK for a SBC but it would be nice to have the cam card!

My guess based on the info given would be something binding up or junk rockers.

It's pretty easy to take a spring off and measure where coil bind occurs and compare that to the actual lift measure on the motor!

If you have shaft rockers and coil bind is ok, make sure you check the pushrod clearance to the head (intake ports especially)through out the lift range,,, if they are hitting/rubbing you will see a shinny smooth spot where this is occurring causing a side load on the pushrod and rocker cup!
 
Posts: 2123 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR Top Comp
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Twenty five to thirty trouble free trips down the track, what changed?

I dunno, what was the pressure on the seat a year ago?

I run 300 on the seat. 750 plus hp 23 3.875 x 4.185 427 sbc. T & D, Smith Bros PR
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Pro
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quote:
Originally posted by Mike Rietow:
Twenty five to thirty trouble free trips down the track, what changed?

I dunno, what was the pressure on the seat a year ago?

I run 300 on the seat. 750 plus hp 23 3.875 x 4.185 427 sbc. T & D, Smith Bros PR



That is just about enough time for spring pressure issues to rear their ugly head.

Mine started out with wear issues on the cam lobe nobody could figure out, then manifested into broken lifters, rockers and springs.

Another 100 lbs pressure over the nose fixed my issues.
 
Posts: 1557 | Location: PA | Registered: February 26, 2000Reply With QuoteReport This Post



DRR Pro
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I don’t know what the pressure was last season. This started out as a borrowed motor for one race. Motor ran so good that I bought it. Problem is, TRE doesn’t give a build sheet or cam card...so the guy I bought it from has no info (TRE built it for someone else and stuck them with it...my guy bailed them out).its an all new piece. Had dyno pull only when I got it. It’s very frustrating not knowing what you have.

These are Engine Pro .083 pushrods (Smith Bro’s) and Comp Cams Ultra HD steel rockers with a girdle. I had full intentions of putting T&Ds on it after I bought it, but this is the first time out this year so that tells you where the priority was (kids sports and a kitchen remodel).

Yes...25 runs last season with zero issues and zero changes. Car ran 4.67 on a converter built for my 399” motor. I sprayed it one run and it went 4.31 shifting at the hit and blowing through my NOS converter...so it’s a good piece. Just not happy after 25 runs...lol


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Posts: 492 | Location: Lebanon, OH | Registered: March 18, 2008Reply With QuoteReport This Post
DRR Pro
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Interesting twist...T&D list this head as needing a .375 offset rocker. Hmmmmm could be 99% of the issue right there.


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245" Harry Clack
399 inches of Horse Power Sales Power
1.031, 2.978, 4.640 at 147.47
 
Posts: 492 | Location: Lebanon, OH | Registered: March 18, 2008Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by OhiomafiaWireGuy:
Interesting twist...T&D list this head as needing a .375 offset rocker. Hmmmmm could be 99% of the issue right there.


If you don't have offset rockers on it now, I don't see how you could even get the pushrods to line up! Unless they put the wrong guide plates on that head,,, The offset rockers are only on the intakes,,,, to move the pushrod away from the intake port! SO you would have a left hand and right hand offset rockers.
 
Posts: 2123 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR Pro
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quote:
Originally posted by TOP38:
quote:
Originally posted by OhiomafiaWireGuy:
Interesting twist...T&D list this head as needing a .375 offset rocker. Hmmmmm could be 99% of the issue right there.


If you don't have offset rockers on it now, I don't see how you could even get the pushrods to line up! Unless they put the wrong guide plates on that head,,, The offset rockers are only on the intakes,,,, to move the pushrod away from the intake port! SO you would have a left hand and right hand offset rockers.


Yea, they used the split guide plates. We looked at the valve train hard last night and its clearly side loading the intake rockers. And based on the .850 lift cam....clearly not enough spring.

I've always spec'd my own engines...hate not knowing what I have and especially hate trying to figure out the mind set on decisions of others.

Cam is coming out and getting profiled, new springs, and T&Ds on the way.


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245" Harry Clack
399 inches of Horse Power Sales Power
1.031, 2.978, 4.640 at 147.47
 
Posts: 492 | Location: Lebanon, OH | Registered: March 18, 2008Reply With QuoteReport This Post
DRR Elite
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Yeowza! Think you found it.
Offset lifters too or not?


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Posts: 6318 | Location: Illinois | Registered: July 08, 2004Reply With QuoteReport This Post
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