Valve train gurus needed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72tutone · 11-02-2015, 07:23 PM

I'm rebuilding my .060 350 and am at the point of zero lashing my valves. This is on a hydraulic flat cam. If u look at the pic the witness mark appears to be outboard or the valve stem. Should I get some that are .050 shorter? I'm running 7.794 now
Thanks

GRX · 11-02-2015, 09:06 PM

My vote is yes. I would go with 8.050. This is where an adjustable pushrod length checker is useful. I have one from Crane Cams. Every full revolution of threads = .050" .

72tutone · 11-02-2015, 09:28 PM

Quote:

Originally Posted by GRX

My vote is yes. I would go with 8.050. This is where an adjustable pushrod length checker is useful. I have one from Crane Cams. Every full revolution of threads = .050" .

Wouldn't a longer pushrod move me more toward the exhaust side? I'm thinking ithe mark needs to move more toward the litter valley which means a shorter rod. Correct?

cableguy0 · 11-02-2015, 09:44 PM

Quote:

Originally Posted by 72tutone

Wouldn't a longer pushrod move me more toward the exhaust side? I'm thinking ithe mark needs to move more toward the litter valley which means a shorter rod. Correct?

Your correct. However as mentioned without a pushrod length checker this can become a very expensive guessing game.

72tutone · 11-02-2015, 09:54 PM

Quote:

Originally Posted by cableguy0

Your correct. However as mentioned without a pushrod length checker this can become a very expensive guessing game.

This is true. What about. Measuring the width of the mark with dial calipers and adding .050 up the valve stem? Or .100
Would this work?

picklito · 11-02-2015, 10:01 PM

Don't lose track of that set screw!

72tutone · 11-03-2015, 10:59 AM

Hmm, I just thought of something.
When doing this, I am zero lashing the valve but I'm also preloading the lifter 1/4 turn. I would assume when doing this, I would be adjusting the valves as I would the final time.
I just want to make sure that this is correct. I hear some people are just zero lashing the valves and "NOT" preloading the lifter when doing this.

Which way is correct?

cadillac_al · 11-03-2015, 08:57 PM

They should have at least a 1/4 turn to keep everything quiet.

cableguy0 · 11-03-2015, 09:10 PM

You should be using a solid lifter to check pushrod length. You will get weird readings with hydraulic lifters because the spring will collapse the lifter due to lack of oil pressure to pump up the lifter.

crazy longhorn · 11-04-2015, 12:59 AM

It sure looks like the pushrod is too long....Listen to what Cable has to say

I check mine differently (light checker springs), & use the hyd lifter. Tit for tat, no difference? You can also get the pushrod "checker"....drop that plastic , un moveable rocker on top @ tdc. Use the adjustable push rod,to show you the length. Maybe not exact , but pretty close, in most apps/ Just one last thought....do not guess on the length....longhorn

11-02-2015, 07:23 PM	#1
72tutone Registered User Join Date: May 2010 Location: St.Louis Posts: 646	Valve train gurus needed I'm rebuilding my .060 350 and am at the point of zero lashing my valves. This is on a hydraulic flat cam. If u look at the pic the witness mark appears to be outboard or the valve stem. Should I get some that are .050 shorter? I'm running 7.794 now Thanks Attached Images

11-02-2015, 09:06 PM	#2
GRX Registered User Join Date: Jul 2010 Location: MD Posts: 1,937	Re: Valve train gurus needed My vote is yes. I would go with 8.050. This is where an adjustable pushrod length checker is useful. I have one from Crane Cams. Every full revolution of threads = .050" . __________________ 1969 c-10 Step Side Long Bed. I-6 250cid = = 1969 Pontiac GTO hard top. 400, 4-speed.

11-02-2015, 10:01 PM	#6
picklito Registered User Join Date: Sep 2013 Location: Vacaville CA Posts: 490	Re: Valve train gurus needed Don't lose track of that set screw!

11-03-2015, 10:59 AM	#7
72tutone Registered User Join Date: May 2010 Location: St.Louis Posts: 646	Re: Valve train gurus needed Hmm, I just thought of something. When doing this, I am zero lashing the valve but I'm also preloading the lifter 1/4 turn. I would assume when doing this, I would be adjusting the valves as I would the final time. I just want to make sure that this is correct. I hear some people are just zero lashing the valves and "NOT" preloading the lifter when doing this. Which way is correct?

11-03-2015, 08:57 PM	#8
cadillac_al Registered User Join Date: Oct 2013 Location: Maine Posts: 2,400	Re: Valve train gurus needed They should have at least a 1/4 turn to keep everything quiet. __________________ 76 Chevy K20 76 GMC K15 77 Chevy C10 77 Chevy K10

11-03-2015, 09:10 PM	#9
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Valve train gurus needed You should be using a solid lifter to check pushrod length. You will get weird readings with hydraulic lifters because the spring will collapse the lifter due to lack of oil pressure to pump up the lifter. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

11-04-2015, 12:59 AM	#10
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Re: Valve train gurus needed It sure looks like the pushrod is too long....Listen to what Cable has to say I check mine differently (light checker springs), & use the hyd lifter. Tit for tat, no difference? You can also get the pushrod "checker"....drop that plastic , un moveable rocker on top @ tdc. Use the adjustable push rod,to show you the length. Maybe not exact , but pretty close, in most apps/ Just one last thought....do not guess on the length....longhorn __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....



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