Think I can do a 13 with this combo?

[darktone]

Heavy 74 Roadrunner with 3.55 gears with auburn posi,727, super stock springs, 27" rear tires, 2400 stall converter.
The engine is a 30 over 360 and is at the machine shop right now. Settled on Speed Pro pistons and Total seal gapless rings and should be about 9.75-1 compression. Blocks been align bored,decked and parralleled, honed with deck plate. Windage tray,true roller timing chain, comp cams XE268 268/280 duration and 477/480 lift and degreed straight up, ported 360 heads with 2.02/1.60 valves, comp springs,retainers,push rods. Ported Edelbrock with TQ. Headers, mopar performance distributer and ignition box, viscous fan, carter 6PSI pump.
This is my first venture with a small block in a big car so I am not really sure what to expect performance wise. I am guessing I can brake into the 13's?

[dave571]

Perfectly matched (timing etc) and tuned, then maybe.

Seems a little low on cam to me. A nicely matched combo, but as you said, the car is heavy.

I've seen much more radical cars barely hit 13's.
In the same breath, I don't think it is out of reach. It will take a while. I'm thinking it will run high 14's initially. After tweaking etc, it will inch down, until it's closer. my .02

[darktone]

Thanks Dave for the input. I am hoping the attention to detail will pay off for me and I can get into the 13's. I have seen those cars with all the radical stuff not do so good too considering what they have all done. I am thinking about taking the wideband O2 off my other car to help get this one dialed in carb wise and the timing should be a piece of cake. I forgot to mention I have the comp cams pro magnum rockers- not sure if they really help the power at all but they can't hurt either.

[JLM440]

Darktone, don't know what your car weighs, but a friend of mine has a 77 charger (cordoba) its about 3700 lbs, he has a very mild 360 in it, 9.1 comp, stock heads, small cam (smaller then yours), 750 eddy, headers, 3000 stall, 391 gears, he runs 14.3s, ran a best of 14.12, so i think you could get into the high 13s with the right gear.

[darktone]

I am guessing my car will weigh in at about 3,600. With me the race weight would be 3,830 so that little small block does have a load to pull .

[BJSracing]

I would agree about the cam being a little small. I would and have used the comp cams 280H cam in that set up. In a 3100 lbs duster (w/o me in it) 3.23 gears no posi and a 235.60/15 tire leaving in second gear(manual valve body in a 904) the car would run a 13.94 @ 104 in the 1/4. I also only had a 450 cfm carb on it that had wore out throttle shafts. I think you can do it with the combo that you have. I would be worried about the auburn posi unit holding up. They do not like burn outs or slicks. Oh yeah and btw it was a stock /6 converter in the car.

[darktone]

Originally Posted by BJSracing

I would agree about the cam being a little small. I would and have used the comp cams 280H cam in that set up. In a 3100 lbs duster (w/o me in it) 3.23 gears no posi and a 235.60/15 tire leaving in second gear(manual valve body in a 904) the car would run a 13.94 @ 104 in the 1/4. I also only had a 450 cfm carb on it that had wore out throttle shafts. I think you can do it with the combo that you have. I would be worried about the auburn posi unit holding up. They do not like burn outs or slicks. Oh yeah and btw it was a stock /6 converter in the car.

Wow 104 and only a 13.94? What was your sixty foot time? I would think if you had traction a low 13 would be in order. I would have liked to have gone with a bigger cam but I don't want the lumpy idle in a stock looking summer driver.

[BJSracing]

The sixty foot time absolutely sucked. I had made 2 passes before that one leaving in first gear and the car got totally stupid on me. Remember street tires and no posi. I had some pucker effect going. The last pass I put on it I left from idle in second gear. It didn't want to move but that motor had a hell of a lot of top end. I had a Weiand single plane intake on it to help the top and kill some of the bottom end. I guess it didn't kill enough to leave with out posi or a mini spool. I also drove that car everyday in N.C. in the summer. Ran great.

[darktone]

Originally Posted by BJSracing

The sixty foot time absolutely sucked. I had made 2 passes before that one leaving in first gear and the car got totally stupid on me. Remember street tires and no posi. I had some pucker effect going. The last pass I put on it I left from idle in second gear. It didn't want to move but that motor had a hell of a lot of top end. I had a Weiand single plane intake on it to help the top and kill some of the bottom end. I guess it didn't kill enough to leave with out posi or a mini spool. I also drove that car everyday in N.C. in the summer. Ran great.

Reminds me of a guy I know at the track last year with a 440 Challenger- had a posi but spun them so bad he only ran mid 14's. His speed was only 91 MPH though- I bugged him because my little 4 banger had a higher speed in the 1/8 than he did in the 1/4.

[BJSracing]

1/8th mile time was 9.18 @ 84 mph. It really pulled hard the second half. If memory serves me correctly the 60 foot time was something like 2.20sec. Like I said it didn't want to get going cuz of all the gear it had to fight with me leaving in second. The light wasn't really that bad for that slow of a 60 ft. I had a .073 light. It would have gotten better but I never took it back to the track. But the new project is in the begining stages. Tear down. I hate this part the most cuz you know every time you take something else off of the car that is just that much more you are going to spend.

[darktone]

Originally Posted by BJSracing

1/8th mile time was 9.18 @ 84 mph. It really pulled hard the second half. If memory serves me correctly the 60 foot time was something like 2.20sec. Like I said it didn't want to get going cuz of all the gear it had to fight with me leaving in second. The light wasn't really that bad for that slow of a 60 ft. I had a .073 light. It would have gotten better but I never took it back to the track. But the new project is in the begining stages. Tear down. I hate this part the most cuz you know every time you take something else off of the car that is just that much more you are going to spend.

With a good launch you should be able to get in the 2.0 range or better I would think. That should be good for 3-4 tenths at the end. Your MPH will be slower with traction though. Also the reaction time does not count against your ET.

[BJSracing]

Yeah I know what your saying. I have been racing or around it since I was like 2 days old. But if I could get the car to react a little quicker that would help with the lights.

[Von]

[QUOTEYour MPH will be slower with traction though. . [/QUOTE]


Please explain this. HP is HP = MPH, traction or no traction.

Ive always heard this, but still do not see a basis for it.

[BJSracing]

Originally Posted by Von

[QUOTEYour MPH will be slower with traction though. .

Please explain this. HP is HP = MPH, traction or no traction.

Ive always heard this, but still do not see a basis for it.[/QUOTE]

Because when the car leaves the more traction it has it will pull the motor down hence causing it to work its way up from a lower rpm. It will have a better et. because the car moved quicker but it has more to pull to get the mph. if the car leaves and spins the rpm's stay higher in the power band and the motor will pull the car better. That is the same reason you hear people putting high stall converters in a car that they aren't going to drive on the street even though it has the same combo you have. Get the motor in the power band earlier so it will be quicker and faster.

[warlockpowerwagon]

darktone, If you get lucky with really good traction maybe high 13.90s. Why not advance the cam 2 or 3 degrees, and increase your gear ratio, or try a smaller tire. Bet you could do it then. Course, you may end up with 2.50 60 foots too. What size carb you going to use?

[darktone]

I'll probably use slicks or at least DOT slicks. The street tires are 26.8" tall and I would like to use a drag tire of about the same dimension I am leaving the gear ratio as is because this car will see interstate cruising in the summer on the way to mopar shows and different strips. As I am new to the small block Chrysler I was just following my brothers on advice on installing the cam straight up. Advancing should help the low speed but will it hurt me much at higher rpms? I am using the stock TQ and I believe they are all 800-85- CFM right?

[wildfish72]

dude upstep the cam to a 508 purple shaft ,victor jr intake and a procomp electronic distributor ,also a tight 11 inch converter ,750dp and a nx hitman kit, you will pass 13 all day long and sit real nice in the 12 low 12

[darktone]

Originally Posted by wildfish72

dude upstep the cam to a 508 purple shaft ,victor jr intake and a procomp electronic distributor ,also a tight 11 inch converter ,750dp and a nx hitman kit, you will pass 13 all day long and sit real nice in the 12 low 12

Dude, thanks for the advice but I am going after a stock looking car that run,sounds and looks like a stocker.

[wildfish72]

then you need to junk the small block and put a 440 in it if you want to run 13 sec

[darktone]

Originally Posted by wildfish72

then you need to junk the small block and put a 440 in it if you want to run 13 sec

A simple power to weight calculater shows that 350 horsepower at the flywheel will move a 4,100 car to a 13.9 ET. Now if I can get my race weight to say 3,900 pounds I can be well into the 13's. This is assuming I make 350 HP- which is the goal.

[warlockpowerwagon]

darktone, I was figuring that using that gear and tire size you would actually need that low-end power. If you cross the finish line at 100MPH (which would be too fast for high 13s), with 27 inch tires and 3.55 gears you'll be running around 4500 RPM. You will need that low-end grunt to pull you into the 13s. Actually, using slicks may put you there anyway.

The small block thermoquads were 800cfm.

(My $.02)

[darktone]

Thanks for the good idea's warlock. Slicks sure make it easier to be consistant and the DOT ones will get me in some street car brackets too.

[Clair]

My mild 340 makes about 300hp at the crank, 260hp at the wheels, with 8:1 CR, Crane HMV272 (454/480, 216/228), ported 976 heads with 2.02's, Weiand Stealth intake, TTI headers, and box-stock 9810 TQ.

The XE268 seems to be a bit hotter than the Crane HMV272, and the extra compression and displacement will really help getting out of the hole. I bet you'll have 350hp at the crank if it's tuned right. 13.9XX is what I'm shooting for, too, and at 3600# with me in the car, I might JUST make it.

Clair

[451Mopar]

Well I think your engine may make 350 HP, and the drive train looks fairly well matched for a street car, but I don't think you will see 13's.

First weight your car, I bet it is at least 3800 pounds without driver.
Second, the power to weight calculator assumes optimal converter, traction, and gearing for the 1/4 mile, which you don't have.

I would guess the car will run 15's, maybe high 14's with good wether and traction?

If your main goal is to have a nice daily driver, I would keep the combination you have because it will be easy to live with on the street. Then you could add about 100HP shot of Nitrous to run 13's at the track.

On the other hand if you just plan to race the car, go with better heads, bigger cam, more gear and higher stall converter.

Either way, if you can reduce the cars weight it would help, the later B-Body cars are pretty heavy cars. They usually have the heavy underlayment under the carpet, and alot of undercoating, not to mention the wrap around bumpers.

[darktone]

I sure hope I do better than a 15! No nitrous for this car- my other car has two bottles and it's a hassle I don't want to deal with on this one. If I want to go quick I'll take the other car but if I just want to have a fun liesurely day at the strip I'll just hop in this heavy A$$ roadrunner . I'll be sure to post what it runs in the spring and I am sure hoping for 13's the first time out.

[wildfish72]

you ever thought about putting magnum heads on their , i here they flow verry well right out of the box ,i would say that could really git you ever closer to that 350hp mark .

[darktone]

Originally Posted by wildfish72

you ever thought about putting magnum heads on their , i here they flow verry well right out of the box ,i would say that could really git you ever closer to that 350hp mark .

I really want to stay with the factory heads- anyway's they are almost done now. Hopefully I will have some dyno numbers in Febuary.

[451Mopar]

Just for HP/ET Comparison,

Here is the weight and performance on my '71 Charger:
Race weight (car and driver) is usually between 4100-4150 lbs depending on how much gas is in the tank.
Dynoed (un-corrected/true) Rear Wheel HP was 360@6,100 on a Dyno Jet 248C Chassis Dyno. Torque was about the same 360@4,000 rpm.
Normal ET is in the 12.50's @ 108-110 MPH.
Tires are 27x10.5" MT ET Radials.
8-3/4" axle with 3.91:1 sure-grip.
Mostly stock 727 trans with a shift kit.
Converter is a 10" Dynamic, I think about 3,500 stall?
I usually launch the car between 1200-1500 RPM, any higher and I usually will spin the tires.

The car is really setup for the street, It has the Heavy 0.990" torsen bars, front/rear sway bars, so it dosen't transfer weight for better traction.
Also, all belt driven accessories (water pump, Fan, Alt, Power Steering) are on the car, and the car also does not have a fresh air intake (no scoop or ram air setup.)

If I was going to race the car more, besides reducing the cars weight, I would fix the stuff above, going with a hood scoop, smaller torsen bars, and electric water pump and fan.

[darktone]

Well figuring a 17% HP loss in the driveline that would put you in the neiborhood of about 420HP at the crank. Your suspension must be set up pretty good to run a 12.5 with a 4,100 pound car and 369 WHP. Punching these numbers into one of the 1/4 mile calculators shows a 13.1. On the other hand if you punch in your weight and ET it says you need to make 415 WHP to run a 12.5. I know these things are just estimates but I don't think I have seen one be that far off on that side of things?

[BJSracing]

Sorry but with the set up that you are limiting yourself to I don't think that you will come close to those kinda #'s that you are talking about. You are basically building a just above stock motor. I had a set of ported head with alot bigger cam that you are using and couldn't hardly do what you are talking about. I figured mine to end up at about 360 rwhp. You will need to step up the cam most importantly to even start to come close to the kinda #'s that you want or are thinking.