Big block Chevy valve lift

[noah_t]

This is my first engine build so I’m sure I am missing something. I am building a 496 with the clay smiths “old school” hydraulic roller cam. Valve lift is .600 intake / .569 exhaust with 1.7 rockers. I’m using comp cams ultra pro magnum 1.7 rockers. I used Jim miller’s method on getting pushrod length. When I measure the travel of the spring retainer it doesn’t travel .600 on the intake and .569 on the exhaust. It’s more like .480 intake and .428 exhaust. I have checking springs installed. Am I thinking of this wrong or is there something else I can check?

 

[Bextreme04]

This is my first engine build so I’m sure I am missing something. I am building a 496 with the clay smiths “old school” hydraulic roller cam. Valve lift is .600 intake / .569 exhaust with 1.7 rockers. I’m using comp cams ultra pro magnum 1.7 rockers. I used Jim miller’s method on getting pushrod length. When I measure the travel of the spring retainer it doesn’t travel .600 on the intake and .569 on the exhaust. It’s more like .480 intake and .428 exhaust. I have checking springs installed. Am I thinking of this wrong or is there something else I can check?

That's a hell of a cam for a truck... you mud bogging this thing? I bet it's gonna sound like an absolute beast... please post some pics and videos when you get it going.

I don't really have anything for your problem.. maybe the lifters are collapsed? Have you primed it yet? Did you degree in the cam? Did the lobe size measure right when degreeing it?

 

[DoubleDingo]

I am going to say it's the lifters not being pumped up, so the spring is compressing.

 

[Bextreme04]

I am going to say it's the lifters not being pumped up, so the spring is compressing.

I was thinking that at first, but he said he has check springs installed... which shouldn't compress much of anything

 

[Craig Nedrow]

are you using a dial indicator on the valve stem? What method are you using to determine lift, and where are you measuring it at? I measure on V-blocks first on a bench, if in the car, I measure off the lifter. Pushrod length is right when your contact pattern on the valve stem is in the middle of the valve. I use an adjustable pushrod (for your application for 496) and use dykum blue, or prussian blue, preferably the latter. Turn the engine over until the lifter has reached full travel up, then returns to the seat. It your pattern is in the middle, you're done. However if it is toward the intake side, pushrod is long, and, conversely of it is toward the exhaust, is is short. Buy a adj push rod, and check this. If you get this wrong, your valve train will suffer and life span will go down as well as stressing the valve train. You are using quality parts, don't ruin them.