[Dwight Southerland]

Although I am not a current SS competitor, I hope that the community will give me grace to weigh in on this issue.

First, there is nothing personal toward Eric Jones in my assessment of the problems and issues that have arisen in the decisions NHRA has made for replacement heads for the SBC.

There are so many issues that could be discussed due to the consequences of the acceptance of aftermarket heads for both Stock and Super Stock, but I want to address the specific problem of the angle plugs on the Edelbrock 60617 and 60947 heads and now the Jones Engineering head. The rule book specifically states “Grinding and polishing in combustion chamber permitted. Welding and/or applying epoxy in combustion chamber prohibited. Spark-plug hole must maintain the stock location, size, and angle as machined by the OEM; spark-plug adapters prohibited." Since none of the OEM cylinder heads that these heads are supposed to replace have angled spark plugs, then NHRA is violating its own rules and specifically giving favoritism to these parts. Many hours of testing by Chevrolet when the angle plug modification was developed for off-road use showed a significant power gain. Reputable and noted engine builders of the era when the angle plug heads were first released also verified that the modification increased power output over identical heads with straight spark plugs. The angled spark plugs is a modification that produces more power. However, no engine that Chevrolet produced for passenger car use from 1962 thru 1970 used cylinder heads that had angled spark plugs, which includes every engine in the Classification Guide and Technical Bulletins. And, Chevrolet never included in any of their parts books a service replacement for any of the engines of those years an angle plug cylinder head. In fact, Chevrolet has never listed an angle plug head as a service replacement for any first generation SBC of any year. The only two angle plug heads offered by Chevrolet, part numbers 336746 (casting 3991492) and 3965784 (casting 340292), were always listed as "off-road use". There is so much historical documentation that supports this fact that it almost is ridiculous to argue that there is a production precedent to allow an angle plug head on 1962-70 SBC engines. So, either NHRA’s rules don’t mean squat or the mentioned aftermarket heads should not be allowed as accepted replacements.

The argument “that ship has already sailed” is a lame excuse and does not mean the decision cannot be corrected. There are precedents where NHRA has corrected long standing use of parts by racers for the accuracy of the rule book.

If the rule for OEM spark plug placement can be ignored, what is necessary about any of the other rules concerning valve angle, valve placement in the combustion chamber or even port specs? The specs for those items are all based on OEM production just like the spark plug placement. But if one spec can be ignored, then why not all of them?

Several years ago, a noted big block Chevrolet racer developed an adapter that allowed the use of a small spark plug placed beneficially in the combustion chamber, but that was quickly shot down even though many racers were using them. Does that mean those adapters are now legal?

Could the Chrysler big block racers petition to have Edelbrock’s angle plug head accepted?

I could go on with many other examples that show that this one issue that comes from these decisions has consequences that can be avoided. It’s not like there are no replacement heads for these small block Chevrolets. Edelbrock already had two cylinder heads accepted that had straight plugs. Even Mr. Jones lists a straight plug head as one of his products.

Even to argue that these heads should have their own power rating is ludicrous in light of the violation of the rulebook. And that decision opens up another discussion about policy that we do not want to bring into this issue.

Please remove the angle plug heads from the accepted parts list for engines that were equipped OEM with straight plug heads.