with stock pistons and .544 lift on valves, will this be ok with a head gasket of .015?

thanks!

 

Assuming stock block, yes.

 

thanks! now let me through this one out here, on stock block and pistons how much can i really push the lift?

 

more info would help, like which stock pistons, but it's all really pointless, you need to check to know for sure any thing else is just a guess.

 

stock l98 pistons, sorry im not trying to be ignorant, i just dont know better.

as long as the guess is all ok then thats ok with me.

 

you're a fool to not check it even if you "know" there isn't a problem

 

Is taking a guess to save yourself 15 minutes and 50 cents worth of plasticine worth it?

 

hey.. just a stock l98 bottom end.. not like its something special lol.

now the manley ss valves.. that would hurt but whatever.

but ill ask anyways. how do i check that? lol

 

i use a soft spring and a dial indicator

 

A cam's maximum lift is just about meaningless when it comes to piston-to-valve clearance. Remember that contact will happen during the OVERLAP period when the piston is near TDC and both valves are slightly open. At max lift the piston is more than half way down the bore.

A cam's duration, lobe separation angle and it's installed centerline angle have FAR more to do with whether you'll be too close or not. THAT'S why you have to check- there are far too many variables besides it's max lift.

 

well then do any of ya know of people being able to swap these xr276 cams into stock engines and work fine?

and any reason the clearance could be different between equal blocks?

 

Core shift, tolerance stacking in deck height, piston height, rod length, crankshaft stroke, and/or chamber size.

 

wouldnt some of those be given such as rod length and stroke when we talk equal engines, ie, l98's ? or even any stock350. ?

 

Lets say that a 350 has a nominal stroke of 3.48", nominal deck height of 9.025", and a nominal rod length of 5.7".

Maybe the cores shifted when the block was cast and the deck height is only 9.010". Maybe the guy who ground the crank was hungover and it's 3.49" instead of 3.48". Maybe the rods are actually 5.71" from center to center instead of 5.7". Maybe the wrist pins are .005" too low. Then you've just lost .040" of clearance.

This is one of the reasons engines are blueprinted, to make sure that every dimension in the block is known and correct.

 

ahh thanks... i appreciate the new knowledge. so is this a cheap tool i can purchase to check clearances?

 

You should be able to get a cheap dial indicator on a magnetic base with a set of checking springs like ede suggested all for about $25.

A lower tech way is to put a lump of plasticene on top of the piston under the head and then rock the crank back and forth a few degrees.

 

does the head have to be bolted down for this or what?

 

Two things to remember when checking.

The piston is chasing the exhaust valve and the intake valve is chasing the piston.

So, the clearance will be the closest when the piston is coming up on the overlap cycle and the piston is going down on the overlap cycle.

As Ed said, use a light sping on yhe valves so you can push them up and down to see what clearance you have in different positions of the piston. (while you are rotating the engine)

You will need a dial indicator for this.

 

Yes, the head has to be bolted down for this, using whatever head gasket you plan on using for final assembly.

Check clearance as Don suggested and make sure you do so from about 20* BEFORE TDC to 20* AFTER TDC during overlap.

For safety you want to see a minimum of at least .080" of clearance on the intake valve and .100" on the exhaust.

 

Two things to remember when checking.

The piston is chasing the exhaust valve and the intake valve is chasing the piston.

So, the clearance will be the closest when the piston is coming up on the overlap cycle and the piston is going down on the overlap cycle.

As Ed said, use a light sping on yhe valves so you can push them up and down to see what clearance you have in different positions of the piston. (while you are rotating the engine)

You will need a dial indicator for this.