NASCAR's quest to find the perfect technical combination to provide the best possible racing show at Speedweeks 2011 at Daytona International Speedway continued Thursday.

 NASCAR confirmed the carburetor restrictor plate that will be used for next week's three-day test session at Daytona will have 29/32nd-inch openings to restrict fuel and airflow into the intake manifold.

 A 30/32nd-inch plate was used at last month's Goodyear tire test at Daytona and speeds close to 200 mph were reached in the draft, when only 18 cars participated.

 More than 40 teams are expected to test next week, the final warmup for February's NASCAR season openers on the newly paved, 2.5-mile high-banked tri-oval.

 NASCAR confirmed Thursday that the rear spoiler dimensions will remain the same as previously used -- most recently in the October 2010 event at Talladega Superspeedway, Daytona's sister track -- 4.5 inches tall by 63 inches wide. The rear spoiler will be mounted at a 70-degree angle.

 At December's tire test, Jeff Burton cited speeds of "196-197 miles per hour" in the draft. But he felt no changes in the plate, which cuts horsepower and thereby reduces speed, were needed.

 NASCAR vice president for competition Robin Pemberton, who also was in the room, agreed with that assessment. No officially timed laps were made public at that test.

 Pemberton also said a plate change would be considered, saying then "we'll have to get back and talk to the teams and look at the speeds from the last two days of testing. I think we have some high-water marks at 197-and-a-half which, depending on where they pulled up in the draft, it may be a little quick, but it's hard to say."

 This week, teams were told of the reduction and Michael Waltrip Racing crew chief Pat Tryson, who'll be at next week's test with his driver, Martin Truex Jr., said he understood the rationale for the plate change as soon as it was announced to the teams.

"I think the decision was made to slow down the speeds because the speeds were too high at the first test," Tryson said. "It's a good move on the side of safety because no one wants to see a car go airborne at the potential speeds that could be generated with the plate they had last month. It will be better for the driver and better for the fans in the stands. Safety always comes first.

"By slowing down the cars, it will make the draft bigger and tighter. Before, with a little more power, the cars would spread out a little bit. I think now, we can expect to see the cars a lot closer together and more in one pack versus two, three or four."

Todd Bodine tested in December and said "in a 30-lap run there was no tire wear and no loss of grip." Tryson agreed with that assessment.

 "It's going to make for some great racing, for sure, because I expect to see more three-, maybe four-wide racing at Daytona, which is exactly what we saw at Talladega Superspeedway [when it was repaved]," Tryson said. "It's going to be a lot of fun for everyone to watch."