[Stan Weiss]

Dennis,
Thanks for sharing some more information.

Dennis posted this in the race section.

Originally Posted by SD455DJ

Don, Jonny, & Stan - We found that there was no quick way to check a cam's legality without taking extreme measures, time, and effort for a race where there is nothing at stake, except maybe bragging rights. Having fun and learning about your musclecar are the most important 'rules' of the race. We've had cars that didn't run really fast that had bigger "illegal" cams by the rules and cars that downright flew that had smaller than advertised factory spec cams, so we began to realize, as did the racers eventually learn, that the factory got it right in the first place which translated very well for our type of race with street tires. Now we do check compression ratio (1.5 max over advertised), displacement, convertors, and tire rubber (no 'treated' street tires or tread depth into the wear bars) on any new car that runs much quicker that we feel they should, such as a '74 Laguna low compression LS4 454 running low 13's at 105 mph, red flags go up, and we're going to look that car over. If we find 'issues' he is allowed to race still, but has to make corrections to the car if he brings it back next year because we will check it again.

Jonny, I built a '70 XV code 330 hp 400 4-bbl (small valve 10.0 compression) for my Tempest that made 380 hp/450 lbft torque through exhaust logs (2" outlets!) with a Summit 2801 cam. It has a very mild idle and made 20" at 1200 rpm, so running an 068 cam is not an issue. The et difference between the 067 and 068 cams in a good engine may be .2 seconds at the most. We are not going to get excited about that at the race...except if you were running low 12's , then well give your car the 'once-over'. If you had at least 10.0 static compression, I bet the 2802 cam would manage 18" vacuum at 1200 rpm.

Yes, you can run any cam that can meet the vacuum rule and race. As Mark Weymouth said in the quote Stan had in a previous reply, we found in dyno-ing several RAIV engines of identical parameters, with exception of the cam, that the factory 041 cam (and faithful clones) made the most power on the dyno and at the track. The factory engineers (Mac McKeller) knew what they were doing.

Dennis

This graph shows the HP curve for each.

Stan

[SD455DJ]

Originally Posted by Stan Weiss

Dennis,
Thanks for sharing some more information.

Dennis posted this in the race section.



This graph shows the HP curve for each.

Stan

Thanks Stan for sharing the graphs for the W72 and the XV 400's. It isn't unusual to get 425 hp/475 lbft from a 11.0 to 1 D-port 400 with an 068 cam in Pure Stock Race trim.

Dennis