Bigger Pushrods & Guideplates Legal in Stock now

[Dave Noll]

In case anybody missed it, NHRA posted this in "2008 Rules revisions" yesterday.

Stock Cars

Section 9A

Engine: 1

Page 136 (05/08)

Camshaft/Lifters: Delete last sentences of paragraph and replace with “Larger diameter pushrods permitted. Pushrod guide plates permitted. Cylinder head may be clearenced for larger diameter pushrods.”


Dave

[Jeff Lee]

So who out there want's to take the ball and run with it in getting NHRA to accept roller rockers in Stock?

[SSDiv6]

Originally Posted by Dave Noll

In case anybody missed it, NHRA posted this in "2008 Rules revisions" yesterday.

Stock Cars

Section 9A

Engine: 1

Page 136 (05/08)

Camshaft/Lifters: Delete last sentences of paragraph and replace with “Larger diameter pushrods permitted. Pushrod guide plates permitted. Cylinder head may be clearenced for larger diameter pushrods.”


Dave

Does the rule means that cars such as the Ford small blocks, Oldsmobile and Buick engines can runs guide plates? The interesting part of this rule is that for many years, many cars have been running larger pushrods. Prior to this rule change, there has never been a published specific pushrod diameter available.

[larry dowty]

ssdiv6 will you pm me please i just finished my stocker heads.

[SSDiv6]

Originally Posted by larry dowty

ssdiv6 will you pm me please i just finished my stocker heads.

PM sent.

[Alan Warman]

I am a "newby" to stock eliminator racing, but when I was building my motor, it would have been a lot easier and cheaper if I had been able to use roller rockers. It wasn't all that expensive for me to buy rocker arms, and adjustable push rods for my Olds, but I know the big block Chevrolet guys spend a small fortune on yours. Though I'm sure all the purists here have a point as well when they say that using roller rockers is getting away from stock racing.

[LNorton]

I know a lot of you guys get killed by the stock rocker rule. We have it pretty easy as the 3800 has roller rockers from the factory.

[Jeff Lee]

"Killer" yet legal valve-train for Stock:

1) Steel billet camshaft
Options: large cam journals (babbit or roller bearings) , change in firing order.
Cost: upwards of $1500 parts / labor (includes boring cam tunnel).

2) non-OEM lifters
Choices: Schubeck carbon composite heel or body, OEM style altered plunger conversions (available through various sources), tool-steel lifter bodies.
Options: various coatings to reduce wear.
Cost: upwards of $850.00

3) "Any size" pushrods
Choices: Manton as primary source, single or dual taper 7/16" to 3/8", .120" to .168" wall construction. Larger sizes available.
Cost: approximately $30 per pushrod or $480.00 per set.

4) rocker arms
Choice: BBC using 9/16" stud mount and 8.1L BBC rocker arms, various other treated / coated assemblies also available.
Cost: approximately $750.00

5) valve springs & retainers
Choice: Beehive or traditional to deliver 400-450#'s open pressure. Available from various suppliers. Retainers: tool steel
Cost: approximately $450.00

6) Guide plates
Choice: OEM to aftermarket.
Cost: ? $150 ?

Any Sportsman reps want to comment on why a roller rocker rule would "ruin" the sport?
Next to guide plates, your $289.00 Crane "Gold" rockers are the cheapest parts here yet the only parts that lead to engine longevity.

[Alan Roehrich]

You're a little high, on several of your prices.

You left out 8620 bar stock rocker shafts found in more than a few of the shaft rocker engines.

You ignore the fact that roller rockers, especially on engines with shaft rockers, will allow ANOTHER escalation in tappet velocity, increasing both performance AND strain on other parts, especially for engines with larger diameter lifters.

Where does it end? $1K Jesel or T&D systems? Any tappet diameter? Roller lifters? No lift rule?

[Jeff Lee]

If I'm off on total pricing, it can't be more than 10%.

If you fix the "wobbly" end of the spectrum (the stud mounted rocker arm; as found on GM / AMC / FORD), I really don't see that it will increase strain to a point of breakage anywhere else on the engine. If the goal is limiting the performance or adhering to "Stocker Purity", i.e., valve-train limitations, then everything mentioned in my list should be banned outright and all components should resort to OEM parts and specifications only.

But I've always been lost on the concept of allowing full-bore race modifications and parts as listed below, but keeping one breakage prone part which can (and does) lead to complete engine failure.

I guess the wording of a rule would read something like "mounted in same configuration as OEM"

Where does it all go? I've often thought Stock will (regarding engine) eventually be limited to restrictions on factory valve lift, factory carb, intake, valve sizes, piston configuration, bore and stroke. If I missed something, I 'll assume you get my meaning.