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.

 

Yes it definitely could.

 

This makes no sense then. If you don't know what size push rods you have to run, how do you know if your going to have clearance issues?? I could have swore t s p told me that it would-be fine..

 

You're supposed to use an adjustable pushrod length checker.

With a solid lifter, there's no room for the plunger to move so if your pushrods are .050" too long, they'll open the valve roughly .085" (.050" x 1.7 ratio) instead before the cam begins to open.

 

So technically your saying I need 2 checkers, one for each valve. TSP told me to use solid lifter when checking clearance so you got a true reading on clearance, even told Me how to make one of my old lifters solid for the process.

 

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.

 

So, I guess I just need to find what push rod length works with my wipe pattern and zero lash best then go with length for check-in clearance? I just thought that heads were bolted down before ever checking push rod length..

 

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.

 

Assuming you are working on an ls1....you are doing this all wrong.

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

 

Well, I'm about positive that my push rods will by shorter coming from a factory head to one thats milled to 59cc. My clearance is already doing good, with long push rod. I could probably go ahead and bolt head down bit I'll check anyways.

 

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.

 

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.

 

I understand that you all are saying, makes perfect sense.

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?

 

What is the cam you are installing?

Not sure I understand your second question.

 

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.

 

Cam is already installed, its a224/230 comp on 114

 

I love it when someone lays the smack down..

 

No smacking was intended...just trying to clarify some misconceptions/advise floating around.