Adjusting valve lash on BBC - Team Camaro Tech
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post #1 of 11 (permalink) Old May 12th, 15, 03:54 PM Thread Starter
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Bob
 
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Adjusting valve lash on BBC

Ive searched the forums and there are a ton of posts on adjusting valve lash (preload), and everyone seems to have their own method. In my case I have a BBC, 496, hydraulic roller rockers. Pretty sure I need around .060 preload.

Ive read everything from doing them individually turning the crank by hand each time, to setting to #1 tdc and doing half, then #6 to tdc and doing the other half. Just want to be sure I do it right so if anyone has suggestions on how to do it correctly (not necessarily quickest way, I want to do it right!) then Im all ears. And by the same token, if anyone is in the Waterbury CT area that can give pointers, beer and food is on me!!!!
Thanks all!

68 RS/SS 496 T56 6 Speed Tuxedo black w/ white bumblebee. Strange Dana 60, Spicer 3.73 Helical Gears
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post #2 of 11 (permalink) Old May 12th, 15, 05:03 PM
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Mark
 
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Re: Adjusting valve lash on BBC

Don't worry about the .060 preload. That's got to do with the number of threads you have on the stud vs the size of the nut and how much the lifter gets pushed. A waste of time IMO.

I set mine the way the GM service manual does.

Hydraulic flat tappet and roller - 3/4 down from 0 lash.

TDC#1 set
EX - 1-3-4-8
IN - 1-2-5-7

Rotate to TDC #6
EX - 2-5-6-7
IN - 3-4-6-8

To get to 0 lash for each valve, loosen the rocker nut and move the push rod up and down until all the slack is gone, then turn the push rod until you feel a little drag, this is now your 0 lash. Turn the nut down to your desired amount. Some guys like 1/4 to 1/2 turn. I go 3/4. What I do because of some obstructions in the way of my racket, I put a dot at the 12:00 position on the nut then make my turn down. Simple, 1/2 turn the dot would be at 6:00 position. When you rotate the engine to TDC on #6, wait for 10 min for the lifters to bleed down before setting the next 8 valves.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #3 of 11 (permalink) Old May 12th, 15, 06:05 PM Thread Starter
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Bob
 
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Re: Adjusting valve lash on BBC

Thank you Mark for the info. This is pretty much what I was thinking of doing. Just for clarification, I will do it cold, right? with the lifters not pumped up. The car hasnt been run in about 2 weeks so its a good time to do it I would suspect.
I could never find whether to do it hot or cold, lifters pumped or bled etc... in fact I found a place that says to do it with the engine running and still giving it 1/2-3/4 turn!

68 RS/SS 496 T56 6 Speed Tuxedo black w/ white bumblebee. Strange Dana 60, Spicer 3.73 Helical Gears
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post #4 of 11 (permalink) Old May 13th, 15, 05:54 PM
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Mark
 
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Re: Adjusting valve lash on BBC

Yes, cold, cause if you do it after going for a drive the lifters will be pumped up and you don't want to set them when they are pumped. BTW I meant ratchet above not racket.
You can do it running after you go for a drive, but I can't cause I have lock nuts. If you have the factory nuts then go for a drive then come back and set them running. Make sure you have an old valve cover with holes cut with a hole saw to stick your socket through otherwise you will have a messy oily engine and exhaust. When you set them running, back off the nut slowly until it starts to chatter, then turn down in 1/4 turns only then wait 15 sec before making your next 1/4 turn if your using a 1/2-3/4 turn(s) final resting point.

Setting them while the engine is running is more exact when you have stock rocker arm nuts.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #5 of 11 (permalink) Old May 13th, 15, 06:24 PM Thread Starter
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Bob
 
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Re: Adjusting valve lash on BBC

Thanks again Mark. Ill give it a go this weekend, and report back. Im definitely doing the cold/not running method!

68 RS/SS 496 T56 6 Speed Tuxedo black w/ white bumblebee. Strange Dana 60, Spicer 3.73 Helical Gears
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post #6 of 11 (permalink) Old May 16th, 15, 09:18 PM Thread Starter
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Bob
 
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Re: Adjusting valve lash on BBC

Made the adjustment today, was pretty painless. I went to zero lash then closer to 5/8 turn vs 3/4 turn. Engine fired up nd sounded good. Actually sounded better than before. Before I had a bit of an occasional mechanical noise once in a while at idle. They were all fairly loose. With #1 TDC, the ones that were to be adjusted were all very very sloppy. I could actually wiggle the rocker arms, and the pushrods had a ton of movement. Now they are all nice and tight. I didnt go for ride with it but I dont foresee any issues.
Thanks for the tips guys.

68 RS/SS 496 T56 6 Speed Tuxedo black w/ white bumblebee. Strange Dana 60, Spicer 3.73 Helical Gears
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post #7 of 11 (permalink) Old May 17th, 15, 07:00 PM
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Re: Adjusting valve lash on BBC

Glad to hear it all worked out.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #8 of 11 (permalink) Old May 17th, 15, 07:58 PM
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Re: Adjusting valve lash on BBC

Pretty good method described above. For future searchers it is important with what was given above that you take into account the specs for your particular lifter. Some lifters will be bottomed out with 3/4 of a turn. That is why you see the different specs from the service manual.

I'm a fan of #1 on TDC compression stroke, adjust both #1 valves, rotate crank 90degrees, do number 8, and so on through the firing order. Two turns of the crank and you are done.

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post #9 of 11 (permalink) Old May 17th, 15, 09:02 PM
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Re: Adjusting valve lash on BBC

I like the EOIC method. Exhaust open Intake closed. The tools I use are 5/8 box wrench, feeler gauge set, and a 3/8 ratchet and alien head socket. I use a remote starter switch to turn the engine over. I start on #1 cylinder at TDC I turn the engine over until the exhaust valve starts to open and the intake valve is closed. I have an aluminum head engine and my adjustments are .026 for the intake and .028 for the exhaust. On a cold engine I use a .020 feeler gauge for the intake and a .022 feeler gauge for the exhaust. Once the intake valve is adjusted and the polylock tighten with the set screw locked I turn the engine over until the intake is closing then adjust the exhaust valve to .022, tighten the polylock and set screw. Move on to #3 cylinder following the same procedure EOIC until every cylinder is done.
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post #10 of 11 (permalink) Old May 18th, 15, 09:11 AM
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Mark
 
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Re: Adjusting valve lash on BBC

Quote:
Originally Posted by Cdminter55 View Post
I like the EOIC method. Exhaust open Intake closed. The tools I use are 5/8 box wrench, feeler gauge set, and a 3/8 ratchet and alien head socket. I use a remote starter switch to turn the engine over. I start on #1 cylinder at TDC I turn the engine over until the exhaust valve starts to open and the intake valve is closed. I have an aluminum head engine and my adjustments are .026 for the intake and .028 for the exhaust. On a cold engine I use a .020 feeler gauge for the intake and a .022 feeler gauge for the exhaust. Once the intake valve is adjusted and the polylock tighten with the set screw locked I turn the engine over until the intake is closing then adjust the exhaust valve to .022, tighten the polylock and set screw. Move on to #3 cylinder following the same procedure EOIC until every cylinder is done.
He does not have solid lifters. I've read about the EOIC method and wonder why the GM manuals didn't use it.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #11 of 11 (permalink) Old May 20th, 15, 09:00 PM
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Re: Adjusting valve lash on BBC

Quote:
Originally Posted by COPO View Post
He does not have solid lifters. I've read about the EOIC method and wonder why the GM manuals didn't use it.
Probably because it is so slow.

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