Pushrods for AFR 195 and guide plates

[ChevyReb]

Here is 7-3/16 or 7.1875". I did not measure but the pattern seemed to be a little narrower but it was out toward the exhaust side a little. Also I figured out that I was not getting full lift on this set of lifters as the check spring was compressing. So I installed another set and it got full lift. So now the poly lock seems to travel more evenly from closed to open.

Valve closed

Valve mid lift

Pic at full lift did not take :-(

 

[warped]

Pat, what kind of lifters are you running and is your cam a std or small base circle. Mine is ground on a 1.050 small base and I have the retro fit morel 5372 tie bar lifters that are 2.49" from bottom of the wheel to the top of the pushrod cup.

I have a crower retrofit hydraulic roller. It uses the tie-bar lifters, the ones that came in the cam kit for the cam. I don't know the specs off the top of my head, I'd have to look them up. the cam is standard since I haven't stroked the engine and don't need a small base circle core.

 

[Todd80Z28]

Seems like the longer pushrod put the contact point off-center?

 

[ChevyReb]

Seems like the longer pushrod put the contact point off-center?

Yes it did but it did make a narrower pattern. I'm hoping to get some clarification on that too. Also need to find out if I need to add any length for the lifter preload or just use the measured PR length on the tool.

It does look to have plenty of clearance on the bottom of the rocker to the stud which is good. And since I replaced the one lifter set with another with the check springs the rocker is achieving full cam lift at the retainer and making full travel which now looks normal...at least to my untrained eye.

 

[ChevyReb]

I would really like to get the correct ones ordered today from Summit so I can have them tomorrow morning and get this thing buttoned up and in the car by Friday!

 

[79ZED]

From what I've read, go with the narrowest pattern you can get without the rocker going off the valve stem...
A narrow pattern is always more important than where the rocker tip mark is on the stem.
A narrow pattern will give you less scrubbing on the stem ( reducing guide wear) and also give you the most lift.

John

 

[Todd80Z28]

Trick Flow preaches half-lift centering. I have their Twisted Wedge heads that canted the intake valve, and they actually got Comp to make a special set of rockers for the intake with a 0.2" offset stud hole, so that the tip would be centered on the valve with the correct pushrod. They did this because the heads were eating intake guides, apparently. I've never had a problem, and I ran the "wrong" roller tip rocker for years (and most of the miles on the heads).

They say .080" sweep or less and centered at mid-lift.

 

[Damon]

Somewhere between 7.2 and 7.3 looks like it's going to be about right for you. You checked at zero lash, where in a running motor you're probably going to running them down about 1/2 turn past zero lash (effectively making the pushrod "shorter"). So, I wouldn't be afraid to go with the 7.3 sticks although the 7.2s will probably work just fine as well.

You're in the ballapark, so I don't think you would go far wrong with either choice.

 

[Todd80Z28]

Have you ever set up an engine with roller rockers that swept the tip back during lift? I was looking at this years ago when I installed the Pro Comps, and I would have needed a ridiculously long pushrod, and likely a longer rocker stud to get enough bite on the nut.

Look at this pic-

Even at mid-lift, a line drawn through the fulcrum and valve roller still isn't at a right angle to the valve stem. You have to cross that right angle to get the tip to pull back on continuing lift. From the pic, it looks like it would take more than another 0.1" on the pushrod to get you there.

Just curious, as I've seen this mentioned in a few articles out there, but typical small block setups don't appear to be conducive to getting to that point.

Thoughts? I haven't played with enough this closely really care.

Nice pics, BTW, ChevyReb. They're really good and clear at illustrating what's happening at the tip.

 

[ChevyReb]

Todd

Thanks for the complement on the quality of the pic's. I'm going to try and get a friend to video it going through the movement while I spin the motor.

Are you are saying the PR should be located toward the outside (exhast side of the valve tip and sweep back toward the lifter valley as the valve opens? The problem with going longer on the PR is that you run out of travel on the top slot of the rocker arm. Look at the following pic's to see what I got with a 7.250 stick.

Full lift - Notice how close the poly lock is to the PR side of the rocker slot?

It looks like the most even motion in the rocker in relation to the poly is at 7.150 length, and with preload considered looks to me like 7.1875 would be about the best but I don't see those so I guess 7.2 will work the best. I did not try 7.3 as it looked as though that would make the poly lock even further biased toward the PR side.

Mid Lift

Closed

Valve Closed

Valve mid lift

Valve max lift

same position close up