thunderstruck507

iTrader: (18)

UPDATE: Dyno results in post 125

Long story short Kip proposed this experiment after hearing it had been done by another of his customers. The purpose being to more fully document the process, pros/cons, and closely monitor both performance and more importantly reliability of the setup.

For the test I am changing nothing on the car not related to the cam parts: cam, drop in solid lifters (use stock LS2 trays), pushrods, and install of Brian Tooley Racing trunions in my old rocker arms.

Method to be used:
Precision ground valve tips to get installed stem height within +/- .003" of each other on each head.
Off the shelf pushrods as close as possible to zero lash without being undersized.
Shims under the rocker pedestals to raise the rocker and relieve preload and set cold lash. Will then be checked hot. Targets are .000" cold and .010" hot due the aluminum block.

Parts being use: SBE LS2, hand ported 799 heads, typical bolt ons
Being replaced is a Cam Motion 230/238 .620"/.602" 113+3 hydraulic using GM ls7 lifters and my old Comp 7.4" .080" wall pushrods. 8* overlap. Car ran it's recent best of 7.25@94mph 1/8th and 11.46@116.5 mph 1/4. No complaints with that setup but it did peak close to 6,000rpm and at the track liked to be shifted low at ~6400rpm.

New cam is a 239/247 .636"/.620" 113+3. This cam will behave like a 234/242 hydraulic cam due to hot lash. Cam was specced to give me more top end and a wider power band. Cam Motion drop in solid lifters and pushrods will also be used.

Process documentation:

Measuring valve install height to prepare for grinding. This was a concern for me due to the heads having a recent valve job. Several seats were beat up and I was concerned about consistency of the valve seat cuts to correct sealing.

If the valve was too tall, we cut the tip. If the valve was too short in relation to the majority, we ground the backside of the valve to sink it deeper in the seat. This process took us around 2 hours, mostly due to measuring, removing, cutting, re-installing, measure again, repeat. A standard old school valve machine was used for the grinding. Any competent machine shop should be able to accomplish this if they will take the time.



New lifters and new ls2 trays


Comparison to ls7 lifter:



Note the difference in the oil passage. I installed my solids with this hole facing up. Kip said orientation shouldn't matter due to the band in the lifter body but it made me feel better.



Next up was trunion upgrade using Brian Tooley's kit. This was really easy to do with a Harbor Freight press I have in my garage.









Heavy duty snap ring pliers are a MUST. The retainers in the BTR kit are stout.





Next up I turned my attention to the rocker pedestals. My head guy had the idea to cut the rail into 4 sections for more precise shimming of sets but maintaining the self aligning geometry.




Next up was just putting things back together to measure for pushrods.



Measuring was difficult using the Comp Cams adjustable pushrod tool. The threads on the tool are lose and it often moved a bit just taking it in and out. I also wanted more precision than "counting turns".

I'm not a machinist by any means and I wanted a method easy to duplicate so I used a digital dial caliper to measure the gap created by the threads of the pushrod tool.

Once I found "zero lash" by adjusting the tool out until I could move the rocker arm body side to side but not up and down I taped the tool with a small piece of electrical tape and checked a few other rockers.

Going off Comp's claim that the tool is 6.8" long collapsed I added in my measured gap to determine required pushrod length. I came up with a range of approximately 7.267-7.270".

If my measurement is accurate enough a 7.275" pushrod set should get me right in the ballpark and from there I will shim to loosen to zero cold lash using the arbor shims pictured below. Shims Kip sent range from .001" to .020".



Once I receive pushrods I will document the process of shimming the rockers in full detail with pictures, process used, any surprise findings, and how long it takes me.

JakeFusion

iTrader: (7)

That Comp tool is a pain in the *** when you need precise measurement. What I did was I added tape to the threads. Made it harder to turn, but it knew it was right. And then I used my caliper to measure the tool itself.

The results should be quite interesting.

thunderstruck507

iTrader: (18)

I have a few machinist buddies but neither have a pair of calipers large enough to fit a 7.2-7.4" pushrod. I figured most other people also won't have access to such a tool so I improvised. The result of taping the threads and using more caution got my measurements down from a .020" discrepancy to .0055". Much more manageable and believable.

The end goal is to offer an alternative that people can use to buying the adjustable rocker arms and valve covers. So while some advanced skill, tools, and machining are obviously involved I wanted to try to keep things at a level others can duplicate.

kinglt-1

iTrader: (26)

Good stuff! Will be following this thread closely. I like the idea of keeping the stock rockers!!

Darth_V8r

iTrader: (4)

@Thunderstruck - great thread! The pic showing the rollers side by side was surprising. The oil port on the solid - I assume that is dedicated axle oiling? I'm sure you'll see peak power close to 6500 when you're done.

Few questions for you - On the rocker pedestals, if you need different sized shims for the two different valves, how do you think that will go? Are you thinking a couple of .001" will not make a big difference?

What if you need .001 on the intake and .006 on the exhaust? Do you think the slight side-loading could be an issue, or are you thinking it's within the tolerance of being flat anyway?

What if the base circles between intake and exhaust are different - or was that taken into account on cam design?

Ditto. I did the same

thunderstruck507

iTrader: (18)

While we tried to get all the valve stems close across the whole head, we paid more attention to pairs. Most are within .001" of it's neighbor. The most variance between neighboring valves is .0025". I have shims all the way down to .001" and I will experiment with what happens when neighboring valves are shimmed slightly different. The pedestal itself should also have some flexibility to it being poorly cast aluminum rather than billet.


Kip made sure the cam is ground with identical base circles for intake/exhaust. While doing my pushrod measuring I found that zeroing lash on the #1 intake valve and moving the adjusted tool to the #1 exhaust resulting in zero lash as well.

This makes me optimistic that the process will go smoother than I originally feared.


My biggest concern at this point is that if the pushrod length and shimming upsets the rocker tip to valve wipe pattern it will take some thought as to how to correct that.

Overall though I'm having fun when I'm not losing sleep because my mind won't stop running numbers. Now that I'm coming up on the final turn I can't stop thinking about that homestretch and hearing it light off the first time so positive energy is abound.

JakeFusion

iTrader: (7)

The axle-oiling is a nice feature. The Johnson high-dollar hydraulic roller lifters have them. As well as some of the Morels. So getting it in the drop-in solid is nice.

It's a Cam Motion branded lifter?

thunderstruck507

iTrader: (18)

The yellow box pictured with the lifters/trays is the box the lifters arrived in. It has a sticker on the end stating they are drop in solids and initials of who they were packed by and the date.

I wouldn't be surprised if they are manufactured by Morel but I'm sure Kip could tell you for certain. I honestly didn't ask a lot of questions in regards to the products themselves as I know he only deals in quality stuff he deems worthy. I believe he runs the same lifter set in his personal 2010 Corvette.

CGCBandit

sub'd, I had a feeling someone was going to try this sooner or later.

LJMSJohn

If shimming a pair of rockers differently unsquares the rocker tip to the valve... you will have to shim above the stands...

Thats the approach I am planning to take... unmodified rocker stands with no shims underneath.... each rocker independantly shimmed.

thunderstruck507

iTrader: (18)

What kind of shim would you use since the rocker sits in a contoured shape?

LJMSJohn

I'll be using shim in a can... but it wont be going between the trunion and the stand...

Darth_V8r

iTrader: (4)

Ummmm, so it's not going between the trunnion and the stand, and it's not going between the stand and the head?

1989GTA

"The yellow box pictured with the lifters/trays is the box the lifters arrived in. It has a sticker on the end stating they are drop in solids and initials of who they were packed by and the date."

They are Morel. I have the exact same lifters and they came in the exact same package from Cam Motion.

S10xGN

iTrader: (11)

Interesting approach! Just to let others know, all this is completely dependent on many different factors. Heads milled, gasket thickness, base circle, etc. So whatever thunderstruck comes up with for pushrods and shims on his combo will most likely NOT work on a different engine. As you can see, he has done very thorough measuring to get where he is now...

brobinson216

iTrader: (11)

Moly applied to the treads works well too.

Tony @ Mamo Motorsports

Just order this....with everything else you have making things much more challenging you will thank me for the time it saves you by getting the pushrods closer to perfect. Its $49.....no big deal

(Then you can loan it to your buddies when they need it!)

http://www.harborfreight.com/12-inch...per-47261.html

Good luck

-Tony

joecar

There are individual steel rocker stands (they fit the stock rockers, with or without trunnion upgrade)...

( I think they came with the heavy duty GM rockers (with the heavy duty trunnions/bearings) I got a while back )

I think these steel rocker stands are sturdier ( less flexible ) than the aluminum ones, and being individual they allow separate shimming...

( I have not figured out their part number or how to obtain then separately )

joecar

BTW: good work with the scientific experiment

gagliano7

You could also get this caliper for $30 http://www.harborfreight.com/8-inch-...per-47260.html