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Rocker arm?

General engine tech -- Drag Racing to Circle Track

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rickb33x
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Rocker arm?

Post by rickb33x »

Planning to build a B-mod engine with a 7,000 rpm max rule, sing a 4412 holley. We must use either stamped steel rocker arms or stamped steel w/ roller tip. Have discussed rules with Mike Jones and he recommended a cam that will use 1.6 rocker ratio for increased breathing and a lift of around .584 intake lift.

What is the best rockers out there?
What can I do to them to limit breakage, etc?
Any type of coating etc aftermarket I can use to keep them cool?
rickb33x
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Re: Rocker arm?

Post by rickb33x »

Here are some of the rules.

* Maximum of 360 cubic inches with a 1% error. Compression of 10.0 or less 

* Stock-type stamped rocker arms or stamped steel, roller tip rockers allowed. 

* Screw-in rocker studs are allowed. 3/8-inch studs only with guide plates. No stud girdles of 
any kind, 

* Poly locks are okay. 

* Must have cast iron two-barrel intake. No acid dipping and no pressure porting. The depth of the 
plenum will be measured with a deep side of 3.950 inches maximum and short side of 2.030 inches. We expect to see an unmodified runner to the back of the divider, with ribs that stand up 0.150 inch. Caliper will be used to measure bores and depth. Unaltered marine cast iron two-barrel intake will be allowed with Vortec heads. The Rochester carb may only be used on the OEM two- barrel intake manifold. You can be disqualified or asked to race with a different manifold. The aluminum manifolds allowed are: GM Edelbrock# 2101,2701 or 2716 or Weiand# 7547 0r 7547-1 Ford. Edelbrock# 2121, 2171 or 2665 Chrysler. Edelbrock# 2176 Weiand# 7545. These manifolds may use a 1” adapter. 

* Flat tappet cam shafts only. No roller lifters. 

* Must have cast iron cylinder heads, original valve angle and location. Valve springs: 1.250-inch 
maximum diameter; .195-inch wire, steel retainers, five full coils. 

* Any distributor type ignition allowed. No crank trigger or magnetos allowed. No timing retard 
control allowed. Must use a rev limiter with a 7,000 RPM chip. Chip must be out of reach of driver. 

* Crank shaft, cam gear and balancer must weigh a minimum of 50 pounds. Must install a 1-inch 
pipe plug to inspect crank shaft or remove pan. 

* No titanium anywhere. 

* No tri-y headers. 

Holley 4412 or OEM two-barrel Rochester. Rochester carburetor may only be used on the factory two-barrel cast-iron manifold. When used on a Chevy manifold, Holley 4412 may not have an adapter any thicker than one-half inch with thin gaskets. Holley 4412 must retain all factory castings (no alterations of any kind; Fuel may be metered. Carburetor specs are as follows:

* Holley – Venturi: 1.376 maximum; Base plate bore: 1.690 maximum; Booster vertical dimension: 0.430 minimum; Booster legs will show all casting part lines; Booster leg width: 0.260 minimum; Booster outer dimension: 0.605 minimum; Booster inside dimension: 0.385 maximum; Thickness of throttle blade and shaft: 0.190 minimum; Holley choke horn must remain.
*
1. Fuel must be pump gas (includes E85). No additives or performance enhancers allowed. 

These mufflers must be run. Schoenfeld muffler valid part numbers: 112530, 112535, 113035 and 14272735-78.
Walter R. Malik
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Re: Rocker arm?

Post by Walter R. Malik »

rickb33x wrote: Thu Sep 24, 2020 10:15 am Planning to build a B-mod engine with a 7,000 rpm max rule, sing a 4412 holley. We must use either stamped steel rocker arms or stamped steel w/ roller tip. Have discussed rules with Mike Jones and he recommended a cam that will use 1.6 rocker ratio for increased breathing and a lift of around .584 intake lift.

What is the best rockers out there?
What can I do to them to limit breakage, etc?
Any type of coating etc aftermarket I can use to keep them cool?
I have used the "stamped steel" roller tip rocker arms from Elgin and have had no issues. Just be sure they get enough oil.

Use the Weiand #7547-1 Manifold.
Last edited by Walter R. Malik on Thu Sep 24, 2020 3:02 pm, edited 1 time in total.
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novafornow
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Re: Rocker arm?

Post by novafornow »

I have some experience with this. Yes coat the rockers. I also tack welded a piece of flat to the top of the rocker to send oil down to the ball. Use quality synthetic oil. Many years ago and memory fades. BUT, It will work.
PRH
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Re: Rocker arm?

Post by PRH »

Must have cast iron cylinder heads, original valve angle and location.
Aftermarket iron heads which meet that criteria are okay?

Valve size limitations?
Somewhat handy with a die grinder.
rickb33x
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Re: Rocker arm?

Post by rickb33x »

PRH wrote: Thu Sep 24, 2020 3:13 pm
Must have cast iron cylinder heads, original valve angle and location.

Any aftermarket cast iron head with stock valve angle, and no valve size limitation
rebelyell
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Re: Rocker arm?

Post by rebelyell »

OP rickb33x
? are you Certain ANY aftermarket iron head w/ orig angle-location ?

? any further guidance on specifically which aftermarket head casting / part numbers Are Legal ?

? any $ claim $ rules ?

? any constraints on valve stem size, valve head size, valve material, port volume. chamber volume, PORTING ?

? about how much $ are top 3 finishers spending on motors ?
rebelyell
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Re: Rocker arm?

Post by rebelyell »

Lap the rocker ball & seat together by spinning ball on a mandrel w/ valve grinding-lapping compounds.

Vast majority of friction is in ball-rocker fulcrum; not tip.
lotsa hype & monkey-see, monkey-do on roller tips; little to no evidence they help. But Can/do come apart; 'specially cheap stuff.
1980RS
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Re: Rocker arm?

Post by 1980RS »

This year I ran high 10's with stock rockers except for the intakes that were 1.6 ratio. I always feel less weight on the tip means more RPM. So far on 2 different SBC's both engines pull 6500 effortlessly. I did have a fill set of Crane roller rail rockers sitting on the shelf, did not think they were worth much over what I was using.
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Re: Rocker arm?

Post by rustbucket79 »

We've had good luck with the Crane Nitro Carb stamped rockers. I see no value in a roller tip, the fulcrum turns blue, never the tip.
rickb33x
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Re: Rocker arm?

Post by rickb33x »

My biggest concern is the 3/8" screw in stud rule in relation to the .584 lift on the intake. We are not allowed stud girdles.
Plan to focus on getting the geometry as dead on as possible, and wondering if stud stress is relative to pushrod length.
Walter R. Malik
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Re: Rocker arm?

Post by Walter R. Malik »

rickb33x wrote: Sat Sep 26, 2020 12:01 pm My biggest concern is the 3/8" screw in stud rule in relation to the .584 lift on the intake. We are not allowed stud girdles.
Plan to focus on getting the geometry as dead on as possible, and wondering if stud stress is relative to pushrod length.
Screw-in 3/8" studs will have no problem if the geometry is near correct and the fulcrum of the rocker is down near the bottom of the stud.
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rickb33x
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Re: Rocker arm?

Post by rickb33x »

Walter R. Malik wrote: Sat Sep 26, 2020 8:55 pm
rickb33x wrote: Sat Sep 26, 2020 12:01 pm My biggest concern is the 3/8" screw in stud rule in relation to the .584 lift on the intake. We are not allowed stud girdles.
Plan to focus on getting the geometry as dead on as possible, and wondering if stud stress is relative to pushrod length.
Screw-in 3/8" studs will have no problem if the geometry is near correct and the fulcrum of the rocker is down near the bottom of the stud.


Is having stock length valves critical? or should I look at longer stem valves?
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Re: Rocker arm?

Post by Krooser »

If porting is allowed that's where Is go... Vortex head's and the marine intake.

I've seen quite a few broken roller tips on rockers....just use long slot std. stuff.

Jones ground a cam for my son's Wissota b- mod... amazing pulling power down the straight.

Compression is your friend.....
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rickb33x
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Re: Rocker arm?

Post by rickb33x »

Sadly we are restricted to no more than 10.0:1 or below Krooser.
Porting is allowed. I'm considering the cast iron powermaxx 185cc head thru Summit. I gather with a bit of work they are pretty decent alternative to Vortec(used and most likely cracked), or expensive vortec bowtie small runner heads. Our track is a 3/8 mile and allows for carrying momentum through the turns with minimal braking. When it slicks up, I still want good pulling power to the flagstone.
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