push rod length

[blykins]

He will need to measure more accurately...a span of .100" will move the pattern drastically.

[crenbbf]

Originally Posted by blykins

He will need to measure more accurately...a span of .100" will move the pattern drastically.

Thanks Brent

The engine is an FE

At 8.4" the rollers start at 1/3 across the valve stem and travel to 2/3 across before returning sounds OK?

If I set them up at 8.5 the rods sit just about smack in the middle of the manifold tunnels but either way I can take the difference out with the adjusters.

OR... am I missing something?

cheers

[blykins]

It's a lot trickier on a shaft mounted rocker system. Pushrod length does not change the pattern on the stem. That's changed by raising the shaft stands up or lowering them down.

Here's what you have to look out for:

The adjuster in the rocker arm needs to be choked up pretty close to the rocker body. Close enough so that it doesn't put a bending force on the adjuster, and so that you don't get a big arc of movement as the valve opens. It needs to be far enough away so that the cup of the pushrod doesn't rub on the rocker body and so that any oiling orifice in the rocker arm hits the adjuster and pushrod cup in the correct way so that the adjuster gets oil.

You didn't mention what rockers you have or if this is a hydraulic or solid cam. Those things will also dictate how you determine pushrod length.

You also didn't mention if you have a regular ball/ball pushrod length checker, or if you have a ball/cup checker. Trend usually wants a BOC (bottom of cup) measurement, and there are several ways to get that.

If you tell me what checker you have, what rockers you have, and what lifters you have, I can tell you exactly how to determine correct length.

[RICK LAKE]

crenbbf I have a roller and run 8.55" in a shebly block and heads,(aluminium). My motor also expands more that iron. If you have the checker kit with the lite springs and torqued the head to the block, with a 1020 felpro head gasket, this is the correct way. The only issue I have run into is the lifter with or without oil. I soaked mine over night and did the check. The closer to center the better of the valve. This reduces wear on the valve guides. I run high oil pressure in my motor and my lifters pump up at higher rpms. The normal adjustment is from 1/4 to 1 turn of the adjuster after contact with the valve close. I setup my valve train with .010"- .015" valve lash with hydro rollers. When hot there is no noise. They are Crane from 98 and still running fine. My motor doesn't have the large fall off of power in the 5,600 rpm to 6,200 rpms like other motors do. You can also cheap the hydros with adding shims inside the bodys to limit how much travel you want of the plunger in the housing. You are making a hydro lifter act like a solid one. This works great if you keep the travel to .050" to .060" total travel. You will still have a power drop but no as bad. The other note is to install C clips in the lifter to keep all the parts in the lifter housing. Those wire clips will come apart some times when running hard. Bottom line is if you are going to turn more than 6,500 rpms than go solids and get pressure oiling to the rollers and don't idle the motor if possible. Good luck Rick Ps don't worry about where the pushrod sits in the hole of the manifold. You will need to check each hole and maybe grind away a little material to have a good clearance from being of the cycle to the end of the valve lift cycle. There are 2 FE motor books out. Jay brown wrote one and the other has slipped my mind. Both give good info and setup of FE motors. I think it's Barry R. EMC master. Later.

[crenbbf]

Thanks guys

A quick round up

The engine is an FE fresh build with an Eagle 434 stroker with lunati 272 Voodoo hydraulic roller cam. The rockers are Procomp .If I run the 'rods up tight to the rocker maybe 1/16" clearance I'm at 8.5" on the dot.

When I turn over the engine the roller runs over the extent of the middle third of the valve stem.

my measuring tool was supplied with the kit and has to be said not to hot

There is no provision for shimming the pedistals with the kit.

Rick, the target top end would be no more then 5500-6000 rpm since the car will be street only.

cheers

[blykins]

Ok, worry about adjuster position first. Get the cup of the pushrod up as close as you can to the rocker without getting it close enough to bind when you turn the engine over through a full cycle.

Once you do that, since your pattern sounds to be somewhat decent (the width of the contact pattern is sometimes more important than where it is on the stem), then I would put the lifter in, adjust your length checker to where it's contacting the rocker arm adjuster, and just barely touching the lifter cup, without adding lifter preload. To make sure you're on the heel of the cam lobe, check the intake rocker when the exhaust valve is just starting to open. Check the exhaust rocker when the intake valve has opened fully and is just starting to close.

Put a ball bearing into the cup of the pushrod length checker, then measure from one end (ball end of the checker) to the end of the ball bearing. Then subtract the diameter of the ball bearing. That will give you a length of the pushrod, based on a bottom of cup measurement.

After that, add .050" for lifter preload, and that will be the length of pushrod that you will need.

Will also need to know the diameter of the ball on the rocker arm adjuster.