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Okay, in my 351C 2V aussie head build I want to run roller rockers. First, I am not very familiar with doing heads...

someone said to set them up for screw in studs. Is this any different than pedestal mount?

Also if I use crane roller rockers I understand that I will need a pushrod guide plate kit. Why is this, does this just lie in the specific company product or is this for any roller rocker setup, and why is this?

If using roller rockers do I need to get specific pushrods for them or will stock rods work?

Thanks
 

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I would mill the heads for screw-in studs ... around $125.00.

You will need guide plates for any roller set-up you choose ... no difference.

When I buy valvetrain parts for a new build I buy all parts from one manufacturer ... They will then be able to insure you choose "compatible" parts and if something isn't right ... you have a much better chance of "holding thier feet to the fire" over it


My Two Cents
 

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Let me try to help
Pedestal rockers have a little stand on the bottom of the rocker, so you just bolt them down. This keeps in from twisting side to side so you don't need guideplates. Also, you set the lash with different length pushrods since they are non adjustable.

Stud mount can either have push-in or screw in studs in the heads. The lash is set by tightening the nut on top to lower the rocker. You need guideplates because the rocker can twist side to side.

The stock length pushrods would work, but when you run guideplates you need hardened pushrods because the rub on the guideplates.

Hope that helps
 

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MonsterMach hits two important points. Use screw-in studs; they won't pull out of the press-fit with the higher pressure springs needed for performance cams, and good screw-ins will be made of better metal that will flex less. This helps maintain valve train integrity at high rpms. Worth it.

Unless you're a very experienced builder, do stick with one manufacturer for valve train parts for compatibility...and clear responsibility in case something fits poorly or goes awry.

When choosing pushrods, proper rocker arm (valve train) geometry demands selection of the correct, usually custom, length push rods. This is a major factor in both performance and reliability, and is often overlooked.

What you want is for the contact point on the rocker arm (roller or contact patch) to be exactly centered on the valve stem when the cam is exactly at 50% of maximum lift. This minimizes sideways deflection of the valve stem by the rocker arm working laterally against the substantial valve spring pressure.

Properly set up, this optimization of the valve train geometry will allow you to rev higher (if desired), or alternately to attain your desired maximum rpm with less spring pressure. Reducing unnecessary, excessive valve spring pressure reduces internal drag, reduces valve train wear rate, and increases longevity/reliability.

The centering of the rocker contact point on the valve stem also avoids rapid valve guide wear...a surefire way to avoid premature oil consumption and valve seat wear. EVERYTHING works better and longer with proper valve train geometry.

You can buy an "adjustable pushrod" tool for a few dollars that will let you find the perfect pushrod length to optimize your valve train geometry. Don't be too surprised (especially if you've had a high performance valve job), if you need different length pushrods for the intake and exhaust valves. Measure both.

Remember, almost everything you do in a custom build-up knocks rocker arm geometry out of whack. Milling the block deck, milling the heads, different rockers, new valves, different cam base circle, setting the exhaust valve proud in the chamber, etc. etc., all changes the push rod length needed. You must measure.

With everything properly set up, if you paint some machinist's dye onto the valve stem tip and rotate the engine a few turns by hand, you should see a "wear" pattern on the valve stem tip that is dead center and only about .060"-.070" wide. If it isn't, keep looking; something's out of whack.

Any major cam/valvetrain maker can make your pushrods in the exact length you need.

Many years ago, I used to build racing motorcycle engines. An engine that would float the valves at 12,000 rpm with less than optimum valve train geometry would rev cleanly to 13,500 rpm with corrected geometry and no other changes. That's how much difference it makes.

Steve Amos
 
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