Super Lark ShakeDown

[Karl]

Now those are some nice skins.. .i need to spring for a set...

[Sonny]

Uh oh! There went any cruzin' on down to the local car show! Or, any nasty little surprises for the street crowd... Just kiddin', Tom, those meats are lookin' real fine.

[R5 Lark]

Finished up the experimental rocker arm modification today. This is the first version. Took a full day to sort it out. Had a nice gain. Used the Packard 289 as the test bed. Learned more on what not to do than what to do. Will work on a better version tomorrow. Current design is offering around .043" lift gain over stock .360" net lift. If I make one a week then in 16 weeks I will have a set. Enjoy!

http://www.youtube.com/watch?v=_TU_H8Ridbs

[63larkr1]

Tom,
I think Nelson Bove sell the modified rocker already if that helps.
Richard

[R5 Lark]

Thanks, this is just my efforts to see if it can be done and be reliable. Would be a better quality product if I had machine shop tools here. Here is version 2. Got a max of .425" after lash on standard lobe. I need to install an R cam and see where she might go. (tom c).

http://www.youtube.com/watch?v=9-JdijhMbdE

[Jeff Rice]

Malcom Berry showed me some he made up several years ago.....
Maybe he and Phil Harris have them already done up...
Jeff

Tom,
I think Nelson Bove sell the modified rocker already if that helps.
Richard

[R5 Lark]

Race this evening after a storm closed down Thusday's scheduled event. Tested the new tires and runner port cleanup work I made with Z-Spar filler on the R-3 intake to solve the large port to small port mismatch. Intake set new ET and MPH records. So I was really happy a weeks work of port filling had not fallen on its face.

Run 1: 2.158 6.057 9.316 @ 74.98 14.57 @ 92.99 Head wind run against 8 mph. Tires slipped on the line.

Run 2: 2.080 5.926 9.177@ 74.97 14.461 @ 92.47 Set the tires down from 20/20 to 14/14. Good burn out on new tires. Intake reponding just nicely. Instant starts, no fuss on take off, good transition, good idle, good vacuumn, and thankfully, no leaks.

Run 3: 2.057 5.908 9.239 @ 73.62 14.595 @ 91.63 Good start but had a sputter on the second gear pull close to 5000. Checked the timing, ok, wires ok, added gas incase it gulped air on launch. In the stage lane I had a thought about the choke pate, that maybe the spacer didn't like that choke plate, so quickly popped the hood and took out the plate and bar.

Run 4: 2.004 5.824 9.062 @ 75.16 14.331 @ 92.90 Zero slip and pulled the rpm band perfect. Dialed a 14.50 but broke out. This run was made on 87 octane fuel because I had no mixture 93 left and tank was low. Cranking compression is 126 on number 1 so apparently its ok. Winds down to about 4.5. As for the air temperature readings in the filter box, lowest I saw was 101 degrees and that is beyond the 1/8 point. And the air is still 110 plus on the line. So the engine heat is adding a good 10 to 15 degrees to the incoming air which is only a few inches away from outside the hood. Pit air was around 88. Looks like I need one of those super tall velocity stackers.

A new Hemi in my lane was running 14.20's. A supercharged Hemi on 9 lbs was running 13.05's. The Lark was the only Studebaker in the field. (tom c)

[R5 Lark]

I didn't race this weekend. Instead worked out a third version rocker arm mod that is looking good on dry test mock up. Hit .455" max lift after lash. Seems ok but may be too close on standard springs. Don't have coil bind yet but it is close. If this lift will hold up on a running engine then it will hit the sweet spot for my heads. They start to sink some good air from .450 up. This mod would be easy with a Bridgeport. Tuff going here with a hand drill. This one hit pretty much dead on. Got lucky. Now can I repeat on the other 15 is the question. (tom c)

http://www.youtube.com/watch?v=aVCX-w7NnW4

[R5 Lark]

Finished up 8 high lift rockers and got them installed and running Thursday. Got to the track Thursday afternoon but only managed one run before the skies opened up. Had to load up in a severe thunderstorm with lightening and winds. Got out safely but soaking wet. The one test run was ok but nothing outstanding. And I didn't like the response reving in the pull. And was hearing a funny "tinning sound"

Run 1: 2.117 6.121 9.471 @ 73.29 14.847 @ 91.67

Friday, I removed the valve covers and rechecked the lash. Decided it was to tight. Pulled the rocker assembly and inspected all the intake pushrods. Several had very minor contact smear that was occuring when the valves seated. And it appeared the end ball was not centering accurately on the adjustor cup. So pulled the intake, lifter cover, and carefully added a small notch in the pushrod hole opening at the top of the head. Reassembled everything and got a much better pushrod to adjustor cup seating action. Made a quick .025/.026 cold lash setting and got it running in time to load up by 4:30. Had to mix up some 87/93 fuel but managed to make the first run by almost 7:00 p.m.

First run had a fllutter sputter a little beyond the 330 point. I looked down at the shifter and it was in D so pulled it back to 2nd. Engine went into a stutter flutter so moved it back to D. Something was not happy at about 4700. But it pulled ok in low and tried to recover in high.

Run 1: 2.033 5.895 9.287 @ 69.59 12.325 14.847 @ 89.83

Drove straight back around for a second run. Plenty of heat in the motor now and valves sounded a lot quiter. Too quiet I thought. Air reading at carb was 110 on the line.

Run 2: 2.029 5.878 9.221 @ 73.23 12.102 14.518 @ 93.46 New mph record for the cup piston 289. Only issue was the trans shifter was going beyond the 2nd notch and ending up in D. I saw it in D, so left it alone and the governor shifted it about 4800. But it pulled to 5400 fine on the low.

Run 3: 2.052 5.884 9.161 @ 74.30 12.017 14.426 @ 93.68 Slightly better mph so that was good. Had a couple of hops on the tires though on take off for some reason. They were at 15/15 so may be to tight. It shifted from second to high on the D position. So a governor shift again. Nice pull though to the finish line. I set a 14.60 dial and broke out. Didn't think it would dip that low. Mustang also broke out but by less. On load up I back the idle down real low and the valves sounded quiet. So I am thinking it might need more lash. Thinking perhaps .030 on the intake cold. Perhaps the ratio change is altering the opeing and closing ramp points on the cam. Don't know but should be noiser than it sounds. When it comes to making modifications I am learning a lot about what not to do. But learning what to do is still foggy.

To all those who are at the Salt Flats this weekend. Good luck and may the Good Lord Above watch over everyone is our prayer.

[PackardV8]

Hi, Tom,

Thanks for the updates. A new record MPH is always proof it worked. Thoughts for you:

1. Don't open the lash. You'd be wasting that much of the lift you worked so hard to gain. The cam ramps haven't changed.

2. What has changed is the load your valve springs see, especially closing more quickly from a higher lift. My guess is you'll need more spring pressure to get the most from the higher ratio rocker arms.

3. If you wanted to experiment, open the valve lash .005" and then close .005" from your baseline of .025". I'm betting with better valve springs, it will run faster .005" tighter.
jack vines

[R5 Lark]

Ok, that makes sense. These springs were new once back in 63 and obviously are marginal even with a factory 1.5:1. I am going to see if a Beehive Spring set might be available that want require spring pocket cutting and can match up to the rather tall spring install height of these valves. Hate the thought of having to pull the heads though for the upgrade. Richard reported he had tried 1.7:1 rockers and the motor didn't want to rev above 5400. One other point. Ted informed me that his tests show R cams have a .400" after lash lift based on lifter measurements. I have yet to measure that here at the valve itself. I have checked three R cams and they all check around .375" after lash lift. So either the cams have lobe wear (very possible) or the rockers are less than 1.5:1. Also very possible.

Can we get a second opinion on this. An actual dial indicator measurement at the valve itself.

[PackardV8]

I am going to see if a Beehive Spring set might be available that want require spring pocket cutting and can match up to the rather tall spring install height of these valves.

I haven't found any beehive springs tall enough to work with Stude valves.

If I were going to seriously race a Stude V8, the infamous Chevy valve conversion would be the first modification. Best valves, best springs, dirt cheap prices.

jack vines

[63larkr1]

Yes Tom I could not rev above 5400 with the 1.7 rockers, got there fast though. I got the roller rockers for my new 344 engine but I don't need them and may sell them to finance the completion of the new drag car. I need lot’s of stuff!
I will try to get a part # for you on the beehive springs. I think a spacer may be available to make them work and not do any cutting. My R1 cam will not even get the .375 yours gets!
Richard

[63larkr1]

Tom,
I'll post this here so if anyone else needs the # they can get it here.
The part # is Comp Cams 26918-16 for the springs. That is 125lbs at 1.800 installed hight. You would need a .200" spacer.
Richard

[PackardV8]

The springs are a CompCams catalog item. Where and how much and the P/N for the .200" spacer which fits the springs, the pocket in the Stude head and the Stude valve guide?

jack vines