67 BB rocker arm loose

[Kenneth A.]

I have a 67 427 car that sat in a car collection for several years. When i got it i changed the oil and fluids and drove it mostly around 10 mile area. Couple of weeks ago i took on a 10 mile on interstate When i got back i noticed it sounded like a lifter tick. I removed the valve
Cover and one rocker arm was cleary loose. I tightened reassembled and no more tick or knock. I know i need to get valves adjusted at this point but any ideas on why one rocker arm would work its way loose? Clearly i am not much of engine guy. Any thoughts are appreciated

[Mark E.]

Re: 67 BB rocker arm loose

- adjusted incorrectly by the last guy

- loose/worn threads on rocker stud or nut (these friction interference threads can wear with use)

- loose rocker stud

- badly worn cam lobe

[Joe R.]

Re: 67 BB rocker arm loose

Kenneth,

Take it to a qualified mechanic and don't listen to any advise! Your Chevrolet dealer should be able to adjust it properly and evaluate the cause of it being loose! Don't drive until it is adjusted properly! Could it be because it's a 1967 model???????

JR

[Keith B.]

Re: 67 BB rocker arm loose

Kenneth,

Take it to a qualified mechanic and don't listen to any advise! Your Chevrolet dealer should be able to adjust it properly and evaluate the cause of it being loose! Don't drive until it is adjusted properly! Could it be because it's a 1967 model???????

JR

are you being serious about taking it to a dealer? Finding a tech in there who would have a clue about adjusting rockers let alone on a very variable car/engine would be like finding a hens tooth. A GM dealer would be the last place I would take a classic car

[Mark E.]

Re: 67 BB rocker arm loose

are you being serious about taking it to a dealer? Finding a tech in there who would have a clue about adjusting rockers let alone on a very variable car/engine would be like finding a hens tooth. A GM dealer would be the last place I would take a classic car

Calm down. Joe Ray is just having an aneurysm.

[Duke W.]

Re: 67 BB rocker arm loose

Is it a 390 HP hydraulic lifer engine or a 435 HP SHP mechanical lifter engine? Approximately how much torque did it take to turn the nut?

Duke

[Joe R.]

Re: 67 BB rocker arm loose

are you being serious about taking it to a dealer? Finding a tech in there who would have a clue about adjusting rockers let alone on a very variable car/engine would be like finding a hens tooth. A GM dealer would be the last place I would take a classic car

Keith, The GM dealer here runs what is Called Gwatney Performance. They have one guy that builds motors all day up to 1250HP. Most dealers around here have at least one mechanic that can build a motor.
Look up Gwatney Performance as they hold records on a Corvette they race.

It doesn't take a Rocket Scientist to adjust a valve clearance. Check out the service manual and it will tell you how to adjust them. Also watching U-Tube videos will help on small tasks like adjusting valve clearance.

JR

[Keith B.]

Re: 67 BB rocker arm loose

Keith, The GM dealer here runs what is Called Gwatney Performance. They have one guy that builds motors all day up to 1250HP. Most dealers around here have at least one mechanic that can build a motor.
Look up Gwatney Performance as they hold records on a Corvette they race.

It doesn't take a Rocket Scientist to adjust a valve clearance. Check out the service manual and it will tell you how to adjust them. Also watching U-Tube videos will help on small tasks like adjusting valve clearance.

JR

I have done it. But your dealer sounds unique

[Kenneth A.]

Re: 67 BB rocker arm loose

Keith, The GM dealer here runs what is Called Gwatney Performance. They have one guy that builds motors all day up to 1250HP. Most dealers around here have at least one mechanic that can build a motor.
Look up Gwatney Performance as they hold records on a Corvette they race.

It doesn't take a Rocket Scientist to adjust a valve clearance. Check out the service manual and it will tell you how to adjust them. Also watching U-Tube videos will help on small tasks like adjusting valve clearance.

JR

Thanks i will take a crack at adjusting on my own. I have sourced a local restoration shop that knows what a carb looks like.

[Kenneth A.]

[Duke W.]

Re: 67 BB rocker arm loose

Are you saying it took no torque to move that nut up the thread? They are slightly out of round and must require some torque to turn up and down the entire thread. I've never seen a spec, but my recommendation is that they should be replaced is less than 10 lb-ft.

To properly adjust the lifter needs to be on the base circle of the cam lobe. This is assured by using the Hickley Williams valve adjustment paper method. Or you can use the method in the service manual to index at TDC #1 or #6 depending on what valve it is.

To adjust hydraulic lifters turn the nut CCW while wiggling the pushrod up and down. Once you feel clearance tighten it until it is just snug, then another 3/4 turn.

Duke

[Kenneth A.]

Re: 67 BB rocker arm loose

Thanks again for the information - turns out to be a bad cam shaft lobe - little money and little work will be back up and running. Not sure why a lobe would go bad after a complete rebuild less than 2,000 miles ago but I am the same age as the car and not everything runs as well as it used to

[Richard M.]

Re: 67 BB rocker arm loose

Ra-Roh, I can feel everyone shrugging their shoulders and cringing like I am right now.... Darn, a bad lobe?

Kenneth, When the engine was rebuilt, who did the break-in? Who Did the initial oil fill and what oil was used?

[Larry M.]

Re: 67 BB rocker arm loose

Ra-Roh, I can feel everyone shrugging their shoulders and cringing like I am right now.... Darn, a bad lobe?

Kenneth, When the engine was rebuilt, who did the break-in? Who Did the initial oil fill and what oil was used?

I agree...........I might also add, and what brand cam was installed?? .

Larry

[Kenneth A.]

Re: 67 BB rocker arm loose

Larry

Not sure yet - pulling Cam shaft is beyond my technical skills - local restoration shop is doing work but the also found two of the push rods were damaged. As far as the break in goes I do not have any details on that - when I got the car it sounded fine and ran fine to me. I immediately changed the oil to Brad Penn oil and drove it around residential streets and short runs to the store etc. After about 2 months I drove on the interstate at 65 - 70 mph 6 miles to next exit and turned around and brought it back - at the stop light on the off ramp I could hear the lifter noise. Drove it home about 2 miles and put in garage. Removed the valve cover and found one rocker arm that was loose and the rest is history. I suppose the damage was already done before my highway trip and I just pushed it over the top with the sustained rev on the engine - but I am not a mechanic