Pushrods and clayed pistons...

[mrjody]

So measuring for new pushrods..
Trickflow sends 6.750 pushrods when you order their kit(which I did not) I do have Trickflow Tqisted wedge heads on a stock block 302. Measuring for the pushrods I came up with 6.750 with a frozen lifter. Basically making it like a solid.
If I have this right or wrong, if anyone know.,let me know

I put the lifter down in the hole, well both lifters, intake an exhaust.
Brought the opposite lifter/pushrod I was measuring on to the top. Put the adjustable pushrod in there and hand tightened the polly lock to.achieve zero lash. Marked the top of the valve stem with a sharpie.. finally got it to where it looks pretty centered to me.

So the question is.... do I add anything or.subtract anything for the hydraulic lifter pluger?

Now piston to valve clearence...

From what Ive read.. .120 on the exhaust is what you want to be and .80 on the intake..
Here is mine.. what do you think?

 

[CDW6212R]

That looks like the right process. I think the pushrod should be aimed at the measured size with the expected lash, so a good .035" down in the lifter. I've never read it detailed that far(set the lash), but at zero lash that pushrod will be just slightly short. I'd add about .035", they come in various lengths depending on brands etc.

The PTV clearance is based on fully assembled, so what thickness of head gasket did you use? Gently bolting down the heads on new gaskets without crushing them, will have that gap more than the final spec. It's a very minor distance, I would either do that and aim for a hair more clearance, say .010 or .020", or bolt down an old gasket that is about the right thickness.

 

[mrjody]

The head gasket should be about .033-.035 compressed. It was .039 when I checked it with the micrometer. Part number 1011-2 felpro

So I should add . 030 to the length of the pushrod?

 

[CDW6212R]

Very good, that measured .004-.006" gasket difference is useful and you can trust your micrometer checks with the clay. The cam has a ton to do with PTV clearance so the clay check is a final test.

The pushrod length is based on the three check points, the tip of the pushrod, valve, and rocker pivot. The valve tip is fixed, but the rocker pivot goes up or down based on the pushrod. That's what the valve tip wear pattern confirms, the proper pushrod length. If you trust your measurements, the lifter filled or fixed length, then the lash needed for hydraulic is around .035", and yes the pushrod will need to be about that much longer than the rigid measurement. That should be very close, and the rocker adjustment can fine tune that.

 

[mrjody]

Very good, that measured .004-.006" gasket difference is useful and you can trust your micrometer checks with the clay. The cam has a ton to do with PTV clearance so the clay check is a final test.

The pushrod length is based on the three check points, the tip of the pushrod, valve, and rocker pivot. The valve tip is fixed, but the rocker pivot goes up or down based on the pushrod. That's what the valve tip wear pattern confirms, the proper pushrod length. If you trust your measurements, the lifter filled or fixed length, then the lash needed for hydraulic is around .035", and yes the pushrod will need to be about that much longer than the rigid measurement. That should be very close, and the rocker adjustment can fine tune that.

Thanks! Appreciate the info.. so I just checked again..and again..ANNND again.. im going to order 6.800.. From what you say and others.. the .035 "squish" from the lifter.. I believe they come in .050 increments?

 

[CDW6212R]

I haven't bought any in almost 20 years, but I gather some brands can be special ordered. That 6.8" sounds very close to what you are measuring to need.

 

[mrjody]

I haven't bought any in almost 20 years, but I gather some brands can be special ordered. That 6.8" sounds very close to what you are measuring to need.

Yeah man, I think I'll go with the 6800. Seems to be the best scenario based off measurments and things I've read..
Appreciate your input.

 

[CDW6212R]

Keep leading the way. That is all new to many, and refreshing for some old guys like me who have forgotten most of it.

 

[410Fortune]

That is all new to many, and refreshing for some old guys like me who have forgotten most of it.

Exactly!

 

[mrjody]

Thing is, I never really new to forget..lmao. im just learning this stuff. .
But a little update..
You measure with a solid lifter of the same type you are going to be using.. or, a fully pumped lifter.. just made sure the plunger does not move ANY.
Bring the opposite lifter up in the bore that you are going to be measuring, Intake up, measure the exaust..vice versa...
Color the top of the valve stem with a sharpie, put rhe rocker arm on along with the Adjustable Pushrod.. set to zero lash, spin the engine over 3.times.. take the polly lock off and rocker and.look at the center of the valve..you want the witness mark left from the roller rocker bearing to be in center as you can get it. Keep adjusting the pushrod +/- to get the right length.. this is what you want in the picture. Then take a measurement with the micrometer or a tape measure.. and order that measurment. They only come.in .050 lengths..so round up or down whichever you are closest too.. .6.557..get a 6.550 ///// or 6.580.. get a 6.600

 

[Blackhawkxx]

along with the Adjustable Pushrod

If you use a Comp Cams adjustable pushrod there is no need to measure. You know the closed length and each turn of the top of the push rod is .050 so you just count how many turns you do.

 

[mrjody]

If you use a Comp Cams adjustable pushrod there is no need to measure. You know the closed length and each turn of the top of the push rod is .050 so you just count how many turns you do.

Yeah my pushrod tool does have the numbers.. but the micrometer is dead accurate

 

[Blackhawkxx]

Yeah my pushrod tool does have the numbers.. but the micrometer is dead accurate

That is true, I was talking to those who don't have a mic that big, I don't.

 

[Gary Crist]

Get an 8 inch plastic mike at Amazon for $14