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Broke a Rocker- 63


Zimm63
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Was having a great ride in my Riv this afternoon.  Went to the Dentist and had a new crown installed, finishing that job.  Decided to run a few errands on the way home.  Did about a 15 mile run at 70, stopped by my favorite parts store, and about 200 yards out of the parking lot, there arose a clatter under the hood.  No, I did not have my foot in it.  

 

The sound was exhaust like, clearly back through the carb, and spaced out enough to make me conclude it was a problem in the valve train of a single cylinder.  Had the car towed home, popped off the easier valve cover and found a broken rocker arm.  Wonderful diagnostics, I said to my self.  

 

Now, what's the likely issue here?  I've been around long enough to know that this might not be the problem, but a symptom of the real problem.  I quick twirl of the pushrod did not show it was bent.  Obviously, I need to see more.    Am I looking for a stuck valve or something else?  Or, is this something that just happens?

 

For reference, the heads were redone by Carmen Fasso several years, but not very many miles ago.  The rebuild included refurbished rocker arms and shafts.  

 

What say the experts? 

 

DSCN0190[1].JPG

Edited by Zimm63 (see edit history)
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Oh my. You have a '63 silver engine like mine and if I remember correctly, exhaust seat inserts - like mine. That is an exhaust valve but, I wouldn't think the Inserts the root cause.

Valve height?

I don't have an answer but will follow your troubleshooting on this.

I imagine the other side is OK. Replace the rocker and hope for the best?

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I neglected to mention that the car has an after market cam, installed by the previous owner between 18K and 20K miles ago.  Total miles on the motor is 80K.  

 

Specs on the cam are: Duration             268

                                      .05 Duration       212

                                      Cam lift               .293

                                      Net valve lift       .493

                                      Centerline           108 In   112 Ex

According to J&C Parts invoice the max lift is .500.

 

The heads were fully reconditioned approximately 3-5K miles ago, but that was also 2006 while I was in the middle of the world's slowest car fix up.  I had the heads done in response to it blowing smoke on start up, indicating bad guides or seals (which nailheads do not have from the factory).  It hasn't blown smoke since and given no indication of internal issues until now.  

 

I would think that the push rod would be the weak link if the valve somehow hit the piston, but thats not based on any real world experience with these engines.  

 

 

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Not sure how to tell if the rockers are original Buick or not.  I have a call into Carmen Fasso to see if he has any advice, since he did the rehab on them.  Not sure how active he is these days.  He was having some health problems when I talked to him a couple years ago.   

 

I took a look in the cylinder with a scope and found no indication that the valve had contacted the piston.  Thats good news I guess.

 

Hoping Tom Telesco will happen on this string and offer some thoughts.  

 

 

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Had a long talk with Carmen Fasso today and learned a bit about nailhead valve geometry.    He walked me through looking at things to see what the issue might be.  We found a small polished spot on the pushrod where it may have been rubbing on the head where it passes through.  We determined that the pushrods are aftermarket as they are thicker than the stock ones, which may account for the contact.  They were likely installed by the PO when the cam went in.  

 

According to Carmen, that contact may have added enough stress that the rocker may have eventually failed.   We also discussed how to relieve the opening using a chainsaw file and avoid having to pull the head.  I have a good idea how to inspect the rest of them to make sure there isn't another problem somewhere.  He had me tap on the valve stem with a plastic hammer to make sure it moved and snapped back, which it did.  Checked the pushrod and it is straight.  Valve height is equal to others that are closed, using a long straight edge.  Bunch of other stuff.  

 

So, at the moment Carmen is looking to see if he has a refurbished rocker to send me, along with gaskets for the intake and valley pan.  With any luck, I will have the parts next week and can spend some patient hours inspecting and correcting any issues.  

 

Interested in any other thoughts and experiences.  

 

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Zimm63,

 

    Looks to me by the brightness color of the other rockers that they are replacements.  The replacements have inferior castings compared to the originals.  They was a lot of problems with them in the past.  AND, you can't blame Carmen because at the time he didn't know about the quality of the replacements. The originals are a darker color. 

    And, just for your info a lobe lift of .293"  x 1.6 theredical rocker ratio would net a .469" valve lift NOT .493".  Which in reality has less than .440" net valve lift. IF actually measured at the valve would more than likely come up with an actual net lift of about .420".  So being a stock "Nail" can get about an actual  net .490" actual net valve lift in reality will be closer to .415" - .420" actual net valve lift.  So IF everything was done correctly as far as the rebuilding of the heads you have NOTHING to worry about concerning valve to piston clearances.

 Send me a PM with your address & I'll send you a good used replacement. All you'll have to do is change the tip which can be done with a hammer & punch.

 

Tom T.

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Forgot to mention.  IF the pushrod only has a slight wear/rub mark on it I wouldn't worry about it as long as it's NOT digging into the pushrod.  

For the most part the cam is basically a stock cam with 110 LSA with a little more lobe lift than the hottest original, .269" lobe lft, that had a .431" net valve lift which again is closer to .410" actual lift at the valve.

AND, as Loren has mentioned your not the 1st. or the last to have a problem with aftermarket rockers.

 

Tom T.

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Joe,

 

    I have someone in Texas looking at making them.  He is waiting to free up some time on his CNC machine & then he has to work up a $$$$ amount.  I'm sure BEFORE ANYTHING is done I'll have to come up with about 30G's.   We'll see how it goes.  Right now I'm a little optamisus.

 

Tom T.

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13 hours ago, 60FlatTop said:

Pretty easy to take a head off to be sure. You might find a chunk of piston rattling around in there. I would probably pull both heads and look real close at everything.

Looked in the cylinder with a scope.  No visible issues with the piston.  

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If someone was in there 3-5 thousand miles ago that's more reason to take it apart and double check their work. And the work was done by someone smarter they Buick. You might have a valve stem seized up due to lack of lubrication.

 

Always check the details. Even a little thing like not using a French lock on manifold bolts would make me suspicious.

 

I have pretty much given up on anyone other than me working on my car.

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  • 2 weeks later...

To close the loop on this one.  

 

Tom Telesco fixed me up with a set of real Buick rockers with about a week or so of turn around time.  Put it all back together over the weekend and it appears to be running well.  Need to put some more miles on it.  With any luck, thats the end of that.  

 

By the way- pay attention when you put the rocker cover back on so the gasket doesn't slip out of place.  It will leak a lot if it isn't right.  I tried to reuse the old gaskets as the ones I got at the local parts store were wrong.  The old ones weren't stuck to the rocker well enough.  Dug through my stuff and found a new pair that I had all along.  Did a better job sticking them to the covers so they didn't move this time.    Of course, it was the right side so I got to fool with the AC bracket and choke tubes etc. twice.  Great fun.  

 

All is well in the land of pleasant living.  At least for now.  

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On 10/19/2020 at 7:28 AM, Zimm63 said:

To close the loop on this one.  

 

Tom Telesco fixed me up with a set of real Buick rockers with about a week or so of turn around time.  Put it all back together over the weekend and it appears to be running well.  Need to put some more miles on it.  With any luck, thats the end of that.  

 

So, the rocker arms were aftermarket, all of them? That AC bracket, not ideal indeed.

Yes, hopefully that's the end of it. I was following your issue because it strikes awfully close to those exhaust seat inserts. In June, I scoped my 8 cylinders and found all exhaust seat inserts in-place. Around that time I stumbled upon someone locally with 1962 401 heads. I snapped them up for spares. He offered a pair of extra rocker assemblies after loading up as part of the sale. I declined, more junk that I'll never need!

After my analysis in June, I do not have a good feeling with the timing chain. It will need to be changed.

Thanks for the follow-up.

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12 hours ago, XframeFX said:

After my analysis in June, I do not have a good feeling with the timing chain. It will need to be changed.

 

An ounce of prevention is worth a pound of idioms. (Thinking about "If it ain't broke don't fix it.) Fix it.

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Yes they are Bill.  Problem is that the available new tips have a thickness that's about 3-4 times thicker than the originals which causes a problem with the preload on the lifters. In other words because of the extra thickness it makes the lifter cup sit much deeper in the lifter body.  This causes a problem when everything heats up from use, heat expansion  & has a risk of holding the valves open when hot.  I send the tips that are good, along with the rocker arms, so they can be reground.  It doesn't make any difference if the rocker is any good or not as I'm only concerned with the tips & the tips CAN'T be reground without the rocker.  I go through the hassle using original rockers because I don't have the ability to actually check the true ratio of the replacement rockers & I'm NOT going to ake a chance not having the radius correct.

The tips from Joe's rockers are too thick so I will send them off to be reground to the correct thickness installed in original used rockers. 

I usually send 4 sets, 64 rockers, to be reground at a time to get a small quantity discount plus save a little on back & forth shipping costs & have some in stock when/if needed.

 

Tom T.

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4 hours ago, telriv said:

Yes they are Bill.  Problem is that the available new tips have a thickness that's about 3-4 times thicker than the originals which causes a problem with the preload on the lifters. In other words because of the extra thickness it makes the lifter cup sit much deeper in the lifter body.  This causes a problem when everything heats up from use, heat expansion  & has a risk of holding the valves open when hot.  I send the tips that are good, along with the rocker arms, so they can be reground.  It doesn't make any difference if the rocker is any good or not as I'm only concerned with the tips & the tips CAN'T be reground without the rocker.  I go through the hassle using original rockers because I don't have the ability to actually check the true ratio of the replacement rockers & I'm NOT going to ake a chance not having the radius correct.

The tips from Joe's rockers are too thick so I will send them off to be reground to the correct thickness installed in original used rockers. 

I usually send 4 sets, 64 rockers, to be reground at a time to get a small quantity discount plus save a little on back & forth shipping costs & have some in stock when/if needed.

 

Tom T.

Is this the kind of job JB would do?

Turbinator

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