BBC rocker arm hitting valve spring retainer - Team Camaro Tech
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post #1 of 15 (permalink) Old Apr 24th, 15, 07:42 PM Thread Starter
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BBC rocker arm hitting valve spring retainer

Setting up my 427 BBC and noticed today after adjusting a couple of the valves that the rocker arm is abutting the valve spring retainer on both intake and exhaust. After the 1/4 turn valve adjustment the little roller wheel on the rocker can be spun by my finger so the rollers are not pushing directly on the valve stem. They are stock length pushrods in there so I'm guessing I'll have to get longer pushrods? The heads are 66-67 oval ports so machining must have caused this to happen.
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67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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post #2 of 15 (permalink) Old Apr 24th, 15, 08:12 PM
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Re: BBC rocker arm hitting valve spring retainer

Check the rocker geometry. You may need different push rods.
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post #3 of 15 (permalink) Old Apr 24th, 15, 08:45 PM
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Re: BBC rocker arm hitting valve spring retainer

It's hard to say without seeing the sweep pattern on the valve tip, but the pushrod looks really short. How far down the stud is the adjuster nut?
The valve spring diameter, valve stem length or installed spring height must have changed a fair amount when the heads were re done.
Unless you are doing a stock rebuild you can pretty much plan on needing to at minimum check pushrods length/geometry.

Sean

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post #4 of 15 (permalink) Old Apr 24th, 15, 09:41 PM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

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Originally Posted by 68rs406 View Post
It's hard to say without seeing the sweep pattern on the valve tip, but the pushrod looks really short. How far down the stud is the adjuster nut?
The valve spring diameter, valve stem length or installed spring height must have changed a fair amount when the heads were re done.
Unless you are doing a stock rebuild you can pretty much plan on needing to at minimum check pushrods length/geometry.
The adjuster nut and fulcrum look to be about 2/3rds of the way down the stud. Machine shop that did the heads says those are oversize valves in there, but wondering if that would have made a difference in the spring diameter. I'll get some adjustable pushrod length checkers and see.

67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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post #5 of 15 (permalink) Old Apr 24th, 15, 10:10 PM
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Re: BBC rocker arm hitting valve spring retainer

The stud should only be a bit above the nut, maybe a 1/4" or slightly more? I bet they used a .100" longer valve or something of that nature, I'm willing to bet it needs longer pushrods. Tough to tell in a picture but it just doesn't look right.
Get a checker for sure, that should clear things up.

Good luck with it!

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #6 of 15 (permalink) Old Apr 25th, 15, 07:18 AM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

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Originally Posted by 68rs406 View Post
The stud should only be a bit above the nut, maybe a 1/4" or slightly more? I bet they used a .100" longer valve or something of that nature, I'm willing to bet it needs longer pushrods. Tough to tell in a picture but it just doesn't look right.
Get a checker for sure, that should clear things up.

Good luck with it!
Just took a measurement of the nut on stud and it's about 3/8" or a tad bit more down. If I adjust the nut up in turn it should give clearance from rocker arm to retainer when pressing "up" on the rocker arm. Makes sense about the valve being .100" longer as they're already the oversize ones diametrically. I'll stop by the machine shop early next week and query them on that. I'll see if I can dig up some pushrods length checkers. I'm guessing that that due to the valves being .100" longer I might end up getting pushrods .100" or a little more over stock length.

67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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post #7 of 15 (permalink) Old Apr 25th, 15, 08:36 PM
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Re: BBC rocker arm hitting valve spring retainer

Check this video out Gordon :

https://www.youtube.com/watch?v=o5is...ature=youtu.be

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post #8 of 15 (permalink) Old Apr 25th, 15, 11:25 PM
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Re: BBC rocker arm hitting valve spring retainer

What are the od of your valve springs? The Comp Ultra-Gold have the highest rocker-to-valve spring clearance up to 1.650 od. I am sure I had to get the Crane Gold Race Roller rockers for my 454 BBC. I have a Crower mechanical roller cam 01485. Lift is .641/.636 and duration is 256/266.
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post #9 of 15 (permalink) Old Apr 26th, 15, 08:35 AM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

Thanks for the video, Anne, will be studying that part for the next couple of days. Doug, I'll check the OD of the springs along with querying the machine shop on that. I've a couple of buddies who put together expensive BBCs only to have them bust up in the first few hundred miles, I think I know why.....

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post #10 of 15 (permalink) Old Apr 26th, 15, 07:37 PM
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Re: BBC rocker arm hitting valve spring retainer

When I first saw the post I thought it might be interference from large OD springs and stock type rocker, but I'm 99% sure thats not the case here. The rocker is near flat across the retainer and the rocker looks clear at the retainer edge, or close to it.

I would almost bet its going to be pushrods length. Once the pushrod geometry is close then check for interference, but it looks like its going to be ok.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #11 of 15 (permalink) Old Apr 26th, 15, 07:50 PM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

Thanks, Sean, for the input. I'm betting that, as you said in your first post, that the valves are .100" longer. I'll be stopping by the machine shop tomorrow and query them on that.

I got a pair of adjustable length checkers today and made them just about .100" longer than the stock pushrods and there is enough clearance between the rocker arm and retainer to the tune of 10 thou so it's looking good. I searched out pushrods and see that there's listings for +.100 so I'll get the Jegs set as the price is more reasonable at $109 than the Comp Cams set at $159. The stock length rods from Comp Cams are only $40 by comparison. I'm sure Jegs would sell a good quality street set as I'm not gonna take my motor above 6200 rpm.

I eyeballed the rocker roller's sweep on the valve stem today and it looks like it starts at 40% of the way across and when the valve is fully on the lobe the sweep ends at 70% of the way across so I'm assuming that's good.

67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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post #12 of 15 (permalink) Old Apr 26th, 15, 08:53 PM
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Re: BBC rocker arm hitting valve spring retainer

Gordon, Check out this video on checking Push-Rod Geometry. This is the most correct way I have ever seen. If your push rods are too short you will be able to tell now. https://www.youtube.com/watch?v=o5is9BsH5OU
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post #13 of 15 (permalink) Old Apr 26th, 15, 09:31 PM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

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Originally Posted by Cdminter55 View Post
Gordon, Check out this video on checking Push-Rod Geometry. This is the most correct way I have ever seen. If your push rods are too short you will be able to tell now. https://www.youtube.com/watch?v=o5is9BsH5OU
Thanks, Doug, for sending this on. It's actually the same video Anne sent in her post above but a different link, so thanks to the both of you. The gist of it is having the centers of the rocker's rollers be on a level plane with that of the valve spring retainer. I'll take a good look at mine tomorrow and see if I can match that as my rockers are just roller tipped and fulcrum based on the stud side.....will see if I can grab a similar center line to be on a level plane with the retainer. Love those full roller rockers!

67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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post #14 of 15 (permalink) Old Apr 27th, 15, 03:00 AM
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Re: BBC rocker arm hitting valve spring retainer

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Originally Posted by gordr View Post
Love those full roller rockers!
I love those wide factory valve covers, so that's one reason I stuck with the factory long-slot rockers (good up to .600" lift). They don't interfere with the valve covers like roller rockers do.

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post #15 of 15 (permalink) Old Apr 27th, 15, 05:32 PM Thread Starter
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Re: BBC rocker arm hitting valve spring retainer

I stopped by the machine shop this morning and asked them if the valves were .100" longer than stock. They indicated it wasn't the case but that machining over the years especially in the valve seat area might have recessed the seats bringing the valve higher up into the head. Machine shop said to put lash caps .80 thick on the valve stems and that should take care of it. I looked them up and they seem to be a simple install, just hoping that one would never fall off!

67 Plain Jane being assembled with 427, 4 spd Muncie, 12 bolt rear with Mosers, 4 wheel discs
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