Long push rods effect ptv clearance??
#1
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I'm using the 7.45" push rods that wa in my cam only car to check clearance. I've converted 2 lifters to solid and I'm coming up with .076" on intake, .100"+ exhaust. New Hess are milled to 59cc so I'm assuming I'm going to have shorter rods. Question is, will using longer rods to check clearance effect anything?? I don't believe it will cause cam determines lift, bit just wanted to check.
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You don't need two checkers unless you want to do both valves at the same time, but you do need to use a "solid" lifter. If you were to check P2V and the lifter bled down, you could end up measuring more clearance than you really have, which could lead to bad things. I use an adjustable length checker and a stock lifter that I tack welded the plunger to make it a "solid" lifter.
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Just tighten down the two rockers on the low side of the cam for each one until you don't have any lash using a solid lifter. Even if the rods are too long you can still tell then how much PTV clearance using the clay method you'll have with a proper length one. Then use the checker to determine proper pushrod length properly tightening the rockers and add desired preload to the result.
#9
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1. You need solid lifters to check.
2. You need an adjustable pushrod to set you at Zero lash
then check...
If you use some odd length pushrod, your PTV clearence will not be accurate hence wasting your time and effort.
Too long = less perceived clearence
Too short = More perceived clearence
Just right = accurate
#11
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Head needs to be bolted down (not necessarily to full torque) and the gasket should be that same as the new one. I removed one layer of my GM gasket to get a 0.040" gasket to represent the Cometic I was going to install. Solid lifter requires a pushrod length that will get zero lash on the base circle of the cam. Too long or too short will result in a bad measurement for PTV.
#12
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59cc will require shorter pushrods.
Too long a pushrod can leave valves open upon lifter pump up thus creating PTV issue. Too long a pushrod equal too much preload.
Too long a pushrod can leave valves open upon lifter pump up thus creating PTV issue. Too long a pushrod equal too much preload.
#13
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Now, I got 2 more questions. Since I was using a much longer rod to check, and everything was still fine, can I go ahead and bolt heads down since the longer rod will result in less clearance?? If not, what wild be a good base to start checking with the checker rod?
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Guys, keep in mind for just measuring PtoV, with a solid lifter, the rocker just has to be set to zero lash....shorter or longer isn't critical for this measurement, just zero lash. If he goes past zero lash tightening them down, he will show less PtoV clearance, and if he tightens them and leaves some lash, he'll show more clearance than he'll actually have.
As long as it is done at zero lash, then all of the lobe lift gets to the rocker and multiplied to the valve(s), and clearance can be checked accurately.
As long as it is done at zero lash, then all of the lobe lift gets to the rocker and multiplied to the valve(s), and clearance can be checked accurately.
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No smacking was intended...just trying to clarify some misconceptions/advise floating around.
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