Adjusting valves on an inline 250 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67spanky · 08-12-2007, 10:00 PM

Can anyone help me or point me in the right direction on adjusting my valves in a rebuilt 1968 inline 250? I would appreciate it as this is the only thing holding me up right now on the restoration. I can't seem to find anything decent on the web. Thanks

68gmsee · 08-12-2007, 11:01 PM

Do a search on hydraulic valve adjustment or similar. The procedure is the same for v8 or 6 cyinder hydraulic lifters.

Are you looking to adjust them from scratch. In other words you just reassembled the engine and need to preadjust the lifters? If so, then you have to follow a specific procedure to preadjust the lifters.

Someone else may have the info in front of them. I found this procedure in the rebuild manual which I don't have at the moment. Basically, you are trying to adjust the lifters so that you can run the engine. It will not be smooth, but you can at least get it to that point.

The next procedure is to adjust the lifters individually. I do it with the engine running. Loosen or tighten until you barely hear the lifter clicking and keep tightening until you don't hear it anymore. Then tighten about 1/2 turn more. Wait until the engine smoothes out and do this with all of them.

69_hafton · 08-12-2007, 11:56 PM

It would be pretty hard to explain what all is involved, and I can't remember off the top of my head. You'd be better off to buy a Chilton's or Hayne's manual for other future technically involved repair reference.

67spanky · 08-17-2007, 01:28 PM

Well I figured I'd throw this out, maybe it will help someone. I adjusted everything cold before starting the engine (fresh rebuild) just as the old chiltons manual said to. Then I took an old distributor apart, put it in the hole and attached a drill to prime the engine and check the oil pressure before I started it. After the truck was warmed up I followed the old chiltons again and it said that after all freeplay was eliminated in the pushrods, go another full turn. Well I did that and lost compression on 3 cyls. Long story short I only went 1/4 to 1/2 turn on each rocker bolt and after timing it runs really smooth under load and will idle til it runs out of gas. Checked with an old chevy guy and he said he's had to back off on a set or 2 before and put 40,000 on the truck without a hitch. You never know.

08-12-2007, 10:00 PM	#1
67spanky Registered User Join Date: Nov 2006 Location: Lenox Dale, MA Posts: 13	Adjusting valves on an inline 250 Can anyone help me or point me in the right direction on adjusting my valves in a rebuilt 1968 inline 250? I would appreciate it as this is the only thing holding me up right now on the restoration. I can't seem to find anything decent on the web. Thanks

08-12-2007, 11:01 PM	#2
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Adjusting valves on an inline 250 Do a search on hydraulic valve adjustment or similar. The procedure is the same for v8 or 6 cyinder hydraulic lifters. Are you looking to adjust them from scratch. In other words you just reassembled the engine and need to preadjust the lifters? If so, then you have to follow a specific procedure to preadjust the lifters. Someone else may have the info in front of them. I found this procedure in the rebuild manual which I don't have at the moment. Basically, you are trying to adjust the lifters so that you can run the engine. It will not be smooth, but you can at least get it to that point. The next procedure is to adjust the lifters individually. I do it with the engine running. Loosen or tighten until you barely hear the lifter clicking and keep tightening until you don't hear it anymore. Then tighten about 1/2 turn more. Wait until the engine smoothes out and do this with all of them. Last edited by 68gmsee; 08-12-2007 at 11:03 PM. Reason: add wording

08-12-2007, 11:56 PM	#3
69_hafton Sleep-Deprived Join Date: Sep 2002 Location: Tulsa, Oklahoma Posts: 445	Re: Adjusting valves on an inline 250 It would be pretty hard to explain what all is involved, and I can't remember off the top of my head. You'd be better off to buy a Chilton's or Hayne's manual for other future technically involved repair reference. __________________ 1971 K/10 Long Fleetside 350/350 - 6" Lift 1969 C/10 SWB 292 - Sold It

08-17-2007, 01:28 PM	#4
67spanky Registered User Join Date: Nov 2006 Location: Lenox Dale, MA Posts: 13	Re: Adjusting valves on an inline 250 Well I figured I'd throw this out, maybe it will help someone. I adjusted everything cold before starting the engine (fresh rebuild) just as the old chiltons manual said to. Then I took an old distributor apart, put it in the hole and attached a drill to prime the engine and check the oil pressure before I started it. After the truck was warmed up I followed the old chiltons again and it said that after all freeplay was eliminated in the pushrods, go another full turn. Well I did that and lost compression on 3 cyls. Long story short I only went 1/4 to 1/2 turn on each rocker bolt and after timing it runs really smooth under load and will idle til it runs out of gas. Checked with an old chevy guy and he said he's had to back off on a set or 2 before and put 40,000 on the truck without a hitch. You never know.



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