lsthirdgen

i need to check ptv clearance on my 4.8 before i have my heads milled so i can be sure i dont have issues. i plan on taking .040 off of them and using an .041 head gasket if i can. my question is how do i measure for what pushrods to get before i have the heads milled? can i just snug the head down with a few bolts without a gasket to measure? thanks

bww3588

iTrader: (49)

That will work. You can either wait and measure for pushrods after all the work is done and heads are on, or you can do it the same time your measuring ptv. Just snug it down with a few bolts without the gaskets and check ptv, add in your gaskets thickness and subtract your mill on the heads. Same for pushrod length.

lsthirdgen

I need the correct length pushrods to properly check ptv don't I? I am assuming the stock length pushrods will be to long by the time I mill the heads and put in the thinner gasket. Thanks for the help I've built motors before but I've never checked ptv or pushrod length before

chevybayboy

iTrader: (6)

Get a comp pr checker from tsp or ebay

lsthirdgen

That's the plan I just wanted to make sure I get everything set up right to get the right measurement

vettenuts

iTrader: (4)

Use the old gasket, don't bolt the head directly to the block. The pistons will hit when you do PTV or if they are up when the head is bolted down.

Old Geezer

iTrader: (3)

What "nuts" said^^^
Also, you don't need the pr's to check PTV. Use lite wt springs, a dial indicator, a degree wheel. Check at 10* increments BTDC and TDC...
As mentioned, check the pr length after all's done being machined and assembled.

lsthirdgen

ok i think im still missing something here. how can you check ptv clearance without pushrods? also i dont have a degree wheel or dial indicator so i was just going to use the clay on the piston method and measure that way. sorry for all the questions. is there a thread explainig how to check ptv somewhere on here? i searched with no luck. thanks

vettenuts

iTrader: (4)

If you use check springs, you need to be at zero lash so use the adjustable pushrod to check with a solid lifter. I prefer the dial indicator method to check over the clay method.

AGearHead4Life

iTrader: (5)

didnt somebody on here have a trick to make a regualr lifter solid? I need to do my ptv soon.

01ssreda4

iTrader: (96)

With a checker spring you shouldn't need a solid pushrod. And plus 1 for old gasket. However factor in whether you are going back with the same gaskets during rebuild. Not all HG are the same thickness.

lsthirdgen

The only reason I wasn't going to use any gasket is because I plan to mill .040 off the heads and use a .041 gasket basically putting me right back to the same height

AGearHead4Life

iTrader: (5)

Yea but I believe you'll have to use a gasket since the piston usually comes out the hole a lil. that'd make it hit the head without a gasket.

badazz81z28

iTrader: (6)

I made some checker lifters that I will give up for $20 shipped

lsthirdgen

I'll double check that but I don't think a 4.8 piston comes out of the hole. Thanks for the heads up though

luigiandme

iTrader: (2)

So you're shaving off 0.040 and ~0.012 thinner on the head gasket? Total of ~0.052"

I'd double check manifold to head mating surface, making sure the intake manifold isnt trying to fold on top of the engine.

01ssreda4

iTrader: (96)

My heads are milled about 40-50 and I had no alignment issues.

badassracing

iTrader: (13)

I'm not sure why you would need a pushrod length checker or a solid lifter to check ptv clearance.

bww3588

iTrader: (49)

To keep the lifter from compressing giving you a false reading. You shim the lifter up solid and use the adjustable pushrod to account for lifter preload.

badassracing

iTrader: (13)

makes sense