Need help with valve adjustments ????
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Need help with valve adjustments ????
I'd appreciate any suggestions, advice etc on my problem. I'm completing a top engine overhaul (new cam, lifters, heads etc) on my '77 L-48. When I get the valves adjusted on #1 (as an example) the locking nuts on rocker arm studs are barely half way thru the nuts.
I soaked the lifters in oil for over a week. The new stud bolts are same size/length as old ones, I'm using the old push rods and rocker arms, the spring heigth is same as the old ones that I removed.
Appears the lifters are certainly expanded but I should have to scew these nuts onto studs much more than I do now.. BTW, these are hydraulic lifters. Sure could use some help.. Thanks
Terry
I soaked the lifters in oil for over a week. The new stud bolts are same size/length as old ones, I'm using the old push rods and rocker arms, the spring heigth is same as the old ones that I removed.
Appears the lifters are certainly expanded but I should have to scew these nuts onto studs much more than I do now.. BTW, these are hydraulic lifters. Sure could use some help.. Thanks
Terry
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From: Boca Raton Florida
Lifters will not expand that much. It sounds like the cam is holding the valve open due to the #1 piston not being at TDC. Roll the motor over and line up the mark on the harmonic ballancer with the tab on the timing cover and readjust.
I didn't think about the pivot washer, goes in round side down
I didn't think about the pivot washer, goes in round side down
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Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
Take a look at one - lifters don't "expand"; they have a limited travel that's determined by the clip that holds in the cup. The purpose of pre-soaking is solely to ensure the lifter is full of oil on startup...and this is not required as long as you pre-oil. I still do it briefly just to be sure it's wet all through.
You're not giving any detail about how you're trying to adjust the valves - tell us what you have specifically and the approach you're using, and then we can help you get it right.
I agree with Duke that if the nut is that high, it's worth looking at the pivot ball ("washer")
Pushrod length and geometry is critical - but it's rare that it would be such a significant issue that you couldn't adjust the valves. It just manifests as incorrect positioning of the rocker tip on the valve stem.
You're not giving any detail about how you're trying to adjust the valves - tell us what you have specifically and the approach you're using, and then we can help you get it right.
I agree with Duke that if the nut is that high, it's worth looking at the pivot ball ("washer")
Pushrod length and geometry is critical - but it's rare that it would be such a significant issue that you couldn't adjust the valves. It just manifests as incorrect positioning of the rocker tip on the valve stem.
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I was told by my longtime friend who has built racing engines for +35 years, that the combo I'm building will work. He rebuilt my '68 Z-28 heads with new guides, springs etc and did no milling. Gary has a full service hi-performance racing engine shop complete with Dyno-room.
Droshki, I was told my old push rods are good to go. If not, then what length should they be??? I did suspect the push rods are too long, but was assured by Gary thats not the case. He is human and could be wrong.
Pivot washers are in correct position.
I'm trying to adjust the valves on the 'back side' of the cam lobes or at their lowest point. My book says "#1 TDC and tigthen nut while spinning push rod between fingers, when it gets to where you can finger turn, give the nut one more complete (360*) turn.."
Many thanks for you suggestions and advice... Gary is not available (on a 12 year cruise
) or somewhere....
Tks,
Terry
Droshki, I was told my old push rods are good to go. If not, then what length should they be??? I did suspect the push rods are too long, but was assured by Gary thats not the case. He is human and could be wrong.
Pivot washers are in correct position.
I'm trying to adjust the valves on the 'back side' of the cam lobes or at their lowest point. My book says "#1 TDC and tigthen nut while spinning push rod between fingers, when it gets to where you can finger turn, give the nut one more complete (360*) turn.."
Many thanks for you suggestions and advice... Gary is not available (on a 12 year cruise
) or somewhere....Tks,
Terry
Le Mans Master
Joined: Mar 2001
Posts: 6,640
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From: Ann Arbor Michigan
Which heads are you using? Also, don't use the "spin the push rod" method as it is not accurate. Instead, move the PR up anddown until there is no more travel then turn the nut 1/2 turn more.
Gary
Gary
Drifting
Joined: Aug 2005
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From: League City TX
Based on what you have said the only possible explanation that I can think of is that
you are not on the #1 compression stroke, but TDC of the #1 exhaust stroke.
Spin the engine over one revolution and see if it will adjust properly.
you are not on the #1 compression stroke, but TDC of the #1 exhaust stroke.
Spin the engine over one revolution and see if it will adjust properly.
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Le Mans Master
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From: Seattle WA
St. Jude Donor '14
Pushrod length is measured, not "assured". There are a number of approaches, but the best tool is the CompCams High-Tech checking pushrod and some light springs - see the CompCams website.
Are you setting the engine to TDC #1 and then trying to adjust ALL the valves? Not possible.
I use and recommend the companion cylinder method, although the one in your service manual will work as well. The key to finding zero lash is to twist the pushrod while tightening the nut until you *just* find the first hint of drag on the pushrod.
No. 1 cylinder at TDC compression
Adjust exhaust valve: 1, 3, 4, 8
Adjust intake valve: 1, 2, 5, 7
No. 6 cylinder at TDC compression
Adjust exhaust valve: 2, 5, 6, 7
Adjust intake valve: 3, 4, 6, 8
As an aside, I can't imagine those heads are flat and have a good surface after all this time - I generally always make an .003 cut...but I obviously haven't seen the heads, so...
Are you setting the engine to TDC #1 and then trying to adjust ALL the valves? Not possible.
I use and recommend the companion cylinder method, although the one in your service manual will work as well. The key to finding zero lash is to twist the pushrod while tightening the nut until you *just* find the first hint of drag on the pushrod.
No. 1 cylinder at TDC compression
Adjust exhaust valve: 1, 3, 4, 8
Adjust intake valve: 1, 2, 5, 7
No. 6 cylinder at TDC compression
Adjust exhaust valve: 2, 5, 6, 7
Adjust intake valve: 3, 4, 6, 8
As an aside, I can't imagine those heads are flat and have a good surface after all this time - I generally always make an .003 cut...but I obviously haven't seen the heads, so...
Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
I was told by my longtime friend who has built racing engines for +35 years, that the combo I'm building will work. He rebuilt my '68 Z-28 heads with new guides, springs etc and did no milling. Gary has a full service hi-performance racing engine shop complete with Dyno-room.
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Reggie, thanks for your informative response. My "buddy" is out of the country on vacation. OK??? I can't ask him so thats why I saked here.
Moving forward (with Reggie left at the station), I'm 99.1% sure I've found the problem. I took my Swiss made Mics etc and did some serious measurements on the old heads vs. whats now bolted on.
I (Dummie me) didn't measure the 'boss' height of the old heads vs, the new ones where the stud bolts screw in. I have .338 thousands (3/8") higher boss on the new ones vs. the originals. Everything else I measured was good.
So, I can buy shorter push rods or longer stud bolts.
Many thanks for your responses and to Reggie.. GFY.....
Terry
Moving forward (with Reggie left at the station), I'm 99.1% sure I've found the problem. I took my Swiss made Mics etc and did some serious measurements on the old heads vs. whats now bolted on.
I (Dummie me) didn't measure the 'boss' height of the old heads vs, the new ones where the stud bolts screw in. I have .338 thousands (3/8") higher boss on the new ones vs. the originals. Everything else I measured was good.
So, I can buy shorter push rods or longer stud bolts.
Many thanks for your responses and to Reggie.. GFY.....
Terry