Hello, I was wondering if some one could help. I have a 1971 Stage 1 that has been worked over. I didn't do the car and the former owner didn't know much about it either. This is what I know and can speculate at this time. It is a 455 stage 1 motor I am assuming it was balanced , blue printed at least .30 over and higher than stock compression, It has a very tall cam in it, maybe too tall , tons of lope when idling. roller rockers, Edelbrock B4B manifold, 850 holley DP comp. electric fuel pump, headers with big collectors, turbo mufflers, 3: 73 gears in a 12 bolt. TH400 with a valve body and a 12" TSI 2500-2800 torque converter. I am using radial TA's on the street but I want to buy some drag tires either slicks or drag radials. How tall should I go. I am more concerned abought the heigth than the width . Thanks Regards Dennis ps. I ran it at the BOP at Englishtown(time only) this summer. It only ran 13.9 at 100mph . It had a stock converter in it and I either melted the tires with a 1000 rpm power brake or bogged from a dead idle. My 60 foot times were terrible. I have since changed converters to the TSI . it was also the first time back at the track in 25 years.
Dennis, A 13.9 @ 100mph is actually pretty close in ET/MPH to a normal run. I had a really efficient 71 GS455 that ran mid 13's at about the same speed. Was that pass full - did you run it all the way through the traps??? Even if the ET is way off, due to spinning, I'd expect your MPH to be quite a bit higher. My mph was often it's best when I spun the most. Some people refer to spinning as "lengthening the track" as far as mph is concerned. It kills your ET, but your mph is in the ballpark. Not knowing the cam and headwork, and just doing some assumptions, I'd think you have at least a low 13 second ride, if not much better with tuning. You'd want to figure what you think the car's rpm's would be ideally at the end of the 1/4 mile along with it's top speed. Then use an online calculator to figure out what tire diameter you need to get you there. Using the calculator here and putting in a 3.73 gear with a 28" tall tire and 110 mph trap speed (similar to many cars running deep into the 12's), you'd be turning around 5100 rpm at the finish line. 26" tall tires bring it to around 5450 rpm. If you think you've got a car that can legitimately (with tuning, etc... ) run low 12's and 110'ish MPH, you may want to run a 26 or 27 inch tall slick at the track. The idea is to cross the finish line at the rpm that gives you the best ET, and have no spin off the line. That should be somewhere in the range of your peak hp number, or just beyond it.
good info Steve, Thanks for the calculator its a nice tool. I can't tell you what my Rpm was going through the traps,but my times were pretty consistant no matter how I got out of the hole that day. The cars sounds strong and fresh but the my times were really disapointing. Every pass I was picking up a tenth and 1 mph. I was probably getting more of a hang of it because I was cutting the light better. Like I said my 60' were pretty slow like 2.40 if I remember correctly. I would be disapointed if this car was not solidly into the 12's. I have a notion this car has too much cam for my combo; gears/converter/tires. I suspect this because all the previous owner knew about the car was it originally had 4:56 and a 9 or 10 inch converter. He put in the 3:73 and the stock converter. Do you think I made a mistake going for the 12: 2500-2800 converter instead of a 10" 3200. I think I am not making my horsepower in the right spot. I shouldn't jump to conclusions based on a drive to the track on a hot day and no tuning, but other then my lousy hole shots the car was not breaking up and it felt like it was pulling nice. I was actually shocked when I picked up my e.t slips. Thanks again ,Regards Dennis
It's really hard to tell. Regarding the convertor - is it going to be street driven? If so, you'll want to use the calculator to figure your cruise rpm with those gears and your street tires. If you're turning 2800 rpm at 60 mph, a 3200 stall convertor would slip quite a bit. My car isn't finished yet and has about 2800 rpm stall with the original 2.56 gears in it. On the freeway, it was turning 2600 rpm @ 60'ish mph on a slight incline. Down the other side, it was under 1800 rpm at the same speed. That was all converter slip. My mid 13 second GS455 ran 1.9 60 foot times. You're obviously soft out of the hole, but it's hard to tell how much is spin and how much is launch torque until you have no slippage. If he was running 4.56's, it likely was a 6000 rpm or so car. That's a lot of rpm's in a BBB. If that's the case, you could go with a smaller diameter slick as long as it hooks up. It could also be that the cam could just use being advanced 4 or 8 degrees to move the rpm range down too. If he was running those gears and converter, he could have it straight up or around 2 degrees advanced. Just by advancing the cam some more, you could move the tq and hp peaks into a more useable range for your current combo. But if you're going to go to that trouble, maybe you'd want to do a cam change that would work better with your gears and converter too??? Can you contact him and ask him what his ET's were? or maybe find someone at the track who knows the car.
Fast reply Steve thanks again. The guy I got the car from never raced it with the 4:56's and 9 inch. Thats how he bought it and knew no history of the car. He owned it 7 years and I own it 2 years now. The car is not beat and still looks and sounds fresh. I think it was a bit of an old school racer. He just used it as a cruiser and put very few miles on it. I think you may be onto something with the cam degrees. You may be right about the cam change although I love to way people jerk their heads when they hear the cam in the Buick on the street at cruise nights. Regards Dennis
If anybody knows the motor or racing history about this car please advise me. It was originaly purchased in the Jersey Shore area about 10 years ago and then spent about 7 years in Sussex County New Jersey. I would asume work was done in New Jersey and maybe raced at Atco, Englishtown or Island Dragways. It was probably retored and raced at least 10 years ago. It has a green interior and may have been lime green at one time before restoration.
