Checking Pushrod Length

[Vette#128]

So... I'm screwing together a 454 street motor and I am at the pushrod stage. Problem I have is, I have never checked pushrod length with hydralic lifters before.... Solids are a piece of cake. So, how do I deal with the .030 - .060 pre-load on the lifter, especially since they are new and dry. Do I use a solid and subtract, say, .045, or use a new hydralic that has the lash adjusted? Any help here appreciated...
Ed

[milkovich]

Re: Checking Pushrod Length

can't you set the pushrod in the cup, scribe it, then bottom it out and scribe it? That would at least let you know how much the plunger moves and you can do the math from there.

I don't know if the springs in the lifter are stronger than checking springs, if they are, checking springs could make the whole process easy.

[JeffMcKC]

Re: Checking Pushrod Length

use a solid and subtract is what I do I should also say I run most Hydraulic cams like a solid with only about .006 clearence they are quiet and dont need much adjusting to them I have hyd lifters on solid lifter cams this way also

[Vette#128]

Re: Checking Pushrod Length

Hello Jeff... Hope you have bent your car back from that wheelstand in Montgomery ;D I haven't actually put the heads on yet so I'm still making guesses, but since these are raised-port heads, I'm gonna need a longer pushrod. Since my original post, I found a magazine article that says put the cam on the base circle and adjust the pushrod out, including the preload on the lifter. Makes sense to me.... If anybody has a better idea let me know. I am familiar with Jeff's "scribe" method, which is supposed to be the most consistant way to adjust hydraulics, but I've always just taken out the slack, and given them another 1/2 turn. Close enough for government work and never had a problem with them.
Thanks,
Ed

[Eric68]

Re: Checking Pushrod Length

I always checked pushrod length with my actual hyd lifters I intended to use -- just pumped them up with oil before installing. If you get the lest contact patch possible it will be very close to what you will get under running conditions.

[Vette#128]

Re: Checking Pushrod Length

use a solid and subtract is what I do I should also say I run most Hydraulic cams like a solid with only about .006 clearence they are quiet and dont need much adjusting to them I have hyd lifters on solid lifter cams this way also

So that's what I did... Bolted on the heads (no gasket) used solid lifters & checking pushrods, blackened the valve spring tips with a Sharpie. Set rockers to 0 lash. Turned the engine over a couple of times, and pulled off the rocker to look at the witness mark the roller left on the valve stem. Took a couple of times, lengthening or shortening the check pushrods to get the mark I wanted to see (centered). Then added compressed head gasket thickness and .030 for lifter pre-load to the check rod total length and got my numbers. Ironically the exhaust worked out to 9.22 inches... and stock is 9.25. Intake needs .015 longer. I say ironically because these are raised exhaust port heads. I would have thought the exhaust pushrod would be the longer of the two. Wonders never cease.
Ed

[BlackoutSteve]

Re: Checking Pushrod Length

I always checked pushrod length with my actual hyd lifters I intended to use -- just pumped them up with oil before installing. If you get the lest contact patch possible it will be very close to what you will get under running conditions.

With checking springs, Eric?