Projects Roller Rocker sweep

Installed Edelbrock E-street Aluminum heads on a SBF , Scorpion rockers, flat tappet cam, hydraulic lifters mild cam 4.80 lift. With length checker came up with 7.025 pushrod length. Run the motor and rechecked sweep mark its 1/3 on the intake side to 2/3 exhaust side. Is this OK or should I go with 7" pushrod?

 

I only see one picture and if that is the sweep, it is fine.

 

Thanks couple more pictures, I just checked one valve stem. Sweep is about .40

 

From what I'm seeing, the sweep is that shiny line in the middle? If so, then it looks fine to me. You have a low-lift cam, so the sweep line is pretty narrow - all good.

 

Thanks ,yes shiny part sweep line, gauged it about .40. From what I have read to be under .60

 

What does the rocker are looking like at half the valve lift?

 

You mean angle to the head? looks close to 90 degrees, roller looks close to center of valve stem as good as I can see. Picture at 1/2 lift

 

Could tell more from a picture looking straight at the rocker.

 

The best I can do

 

Set the lash and drive it for a while. Rest the lash and drive it until something breaks.

There are may possible explanations for this, and none are worth chasing.

***uming this is a stock Iron block, it could very well be a casting or machining variance. Given that that block already lived a good long life, and was still in good enough shape for you to continue to use it, then whatever it is, you ought not worry about it.

 

7" caught my eye as being longer than any I'm used to. You are probably OK even after hydraulics pump up. However
you may want to consider
How to Check Pushrod Length With Hydraulic Lifters - Engineer Fix

 

I would say from the sweep pattern you will be good.

 

Put the cam at 1/2 lift and see where the rocker sets. You are really close so you might not see much difference. At 1/2 lift, the roller should be dead center of the valve stem.

 

7" being there Edelbrock E-street aluminum heads not stock heads. Did check pushrod length with a length checker tool, thats how I arrived at he 7.025. Engine has been run some that's the sweep mark you see.

 

That's what the side picture is of rocker 1/2 lift and roller looks to be pretty much centered

 

The tutorial for correct mid-lift geometry.

To me it looks like you need to be longer PeggySue, I'd want to see what happens with a 7.050 ot 7.075" length. If pattern moves outboard a hair but gets narrower that is still better. Sweep is what wears parts out.

 

If you look at the first picture I posted of the valve stem sweep mark which I had run the engine for 3-4 minutes making a sweep mark the mark starts 1/3 on the intake side sweeping 2/3 past center toward exhaust side. going with a longer pushrod would move the sweep mark even more past center toward exhaust side. Using a gauge the sweep is .40 which I understand should be under .60

 

If you ran a shorter push rod (how much I don’t know) you could probably get it dead center. For a street engine it’s fine and looks side to side pretty centered. Personally I used 10* keepers so I can use lash caps…. but that’s just me.

 

I'm sorry but at .040 and it's location I'd quite worrying about it and run it unless you plan on keeping this motor above 6500 rpm all the time.

I doubt very many small blocks back in the day came that close from the factory and look how many hard miles and abuse were put on a lot of them....

 

I guess I don't understand your first comment about .40 and location - worrying-run it - keep about 6500 rpm, quite confussing

 

He's saying that the location and sweep are just fine, and to quit worrying.

The location and sweep are just fine, even at 0.060"

The comment about keeping it at 6500rpm, as one might with a dedicated race car, is related to what happens to valve springs and valvetrain at that speed.

Valvetrain velocity at that engine speed can result in valves opening farther than is intended and induced by cam/lifter movement. Valve springs can develop harmonic oscillation, vibration and twisting, which can result in all manner of damaging conditions.

The Laws of Physics being what they are (not negotiable), there is always some of this happening in every machine.

You do not have an engine set up, or intended to operate at a speed that would exacerbate these conditions. There is no need to worry.

 

Those slow motion videos of the valve springs at work are crazy. I remember Grumpy saying he ran the factory nylon cam gear to help keep vibration from traveling through out the engine.

 

Thanks I though that was the intent but the statement seemed to go back and forth. OK reread what he posted I miss read sorry

 

No worries!

 

He wasn’t the only one!