MrMopowered

I had a blast this weekend at the track, with only one problem: I can't seem to get out of the 15 second range. I orignally thought it was a traction problem after studying my last time slips, but I actually ran slower after switching to my m/t's from street tires. I think it could be one of two things; or a combination. 1.) Tired motor- my car has 37,000 original miles on it, and the motor is stone stock. 2.) Carbs not tuned right- I can't help but think this is part of it.

Specs on my car, as raced:
1970 Challenger
440 six pack: all stock
727 TF, 2500 stall & shift kit
Dana 4:10 rear
M/T E.T. street tires, 26x10.5, set to 14 psi
Weight: 3836 with driver

Best timeslip on Friday night:
R/T: .114
60': 2.472
330: 6.733
1/8: 10.178
mph: 71.32
1000: 13.149
1/4: 15.659
mph: 89.69

Racing/launch technique used: Good burnout, hard out of the burnout box. Stage immediately. Footbrake to 1000 rpms. Leave on the last yellow. "Roll-on" the throttle progressively to not cause wheelspin.

FYI- this was foot-to-the-floor. They mickeys hooked good. Little wheelspin from the start- they were catching so hard in second it almost gave me whiplash. I know I shouldn't expect much from an unrestored car, but seriously- I should be in the 14's- the low 14's. Any advice will be appreciated.

hypermite

DUDE ! Did you even read my post from last week? There is something WRONG with your car! Your exhaust system might be plugged, those end carbs might not be opening, the engine is grossly out of tune, or a little of all three, and you could be DAMAGING that super valuable numbers matching engine,by racing it the way it's running, If it's too lean, you're melting the pistons. If it's rich, you're washing the oil off the rings & scoring the cylinder walls. I hope I'm not coming off as a total jerk, It's not my intent, but man, you need to take a serious look at that thing! Pull the spark plugs out, look at 'em, and see whats happening inside that engine.

MrMopowered

Thanks for the advice. On a sidenote, I don't think it's extremely out of tune either way. The guy who builds motors for my dad's shop rebuilt and tuned the carbs about 2 months ago. We pulled the plugs then and they looked alright. No fouling or deposits (spark knock). I took it by his shop on Friday so he could check it out. Don't get me wrong- the motor is hearty. I posted to find out if it wasn't just me thinking it should run a bit better. Just to be safe, my dad and I are gonna check out the tuning again, pull & inspect the plugs, and run a compression test. That will be later this week or this weekend- i'll post the findings.

MrMopowered

Thanks Steve. I was waiting for someone to give me the equation to figure that out. One of the things eventually i'd like to do is make a run on the local dyno. I'd like to see what it really makes- just for fun.

stickshifted

+1 on this one. hopefully theres nothing wrong with your engine other than turning issues. your car should be much faster than that.

stickshifted

yes we know these cars arent rocket ships despite the fact that when your riding in one its a freaking BLAST!

however i will say this. that car should be MUCH faster than the 15's he is running. i base my information on this:

my buddy has a '68 chevelle. hes a big guy so we're guessing the car weighs about 3700 give or take, with him in it. he's got a nice 327 in it right now, but back when he had his GM goodwrench 350 engine he took it to the track and his FASTEST time was 14.7. usually he would run 14.9's and low 15's.

his car had a nearly stock gm 350 crate motor, with a cam, intake, holley 600carb, headers, muncie m20, 3.36 gears, and i believe 27 or 28 inch tall tires. The motor probably made like 270 hp and 350 ft-lbs. and his rear end was an open differential so he has shitty 60 foot times - i believe his top speed in the quarter was like 94 mph, but i might be wrong. he probably woulda been faster with slicks and a posi.

now, if his car can run a 14.7 with a run-of-the-mill nearly stock GM 350 engine, in a medium weight car like a chevelle, then your CHALLENGER with a big block 440 6 pack should FOR SURE run much faster than that chevelle.

you say your car weighs like 3800 lbs? 440 6 packs produced 390 hp and 490 ft-lbs of torque right? or something close to that?

ok so your motor is old, is purely stock, and has some miles on it so there will be some gunk here and there on the intake and exhaust runners, and the rings probably dont hold as much compression as the engine would when it was new, BUT it should still make at least like 350 hp right now. that should be MORE than enough hp to push your car down the track doing low 14's.

i would do a complete compression test, power balance test, and leackdown test on all the cylinders, and check the plugs again, do a vacuum test, and check for vacuum leaks, and maybe pull the valve covers and look for bent pushrods. I know the 360 in my truck wasnt running right after i over-revved it once and it turned out to be a bent pushrod for the cylinder #8 intake valve. (lol i got lucky that was all that was wrong - i calculated it that i must nearly spun it to 7000 rpm!)

MrMopowered

I too have discovered the spectacle known as the F.A.S.T series. Those cars are something else. Looks stock, but runs 11 seconds, even faster on bias-ply tires! A magazine did a feature on some of these cars- very trick stuff indeed. Believe it or not, the stock e.t.s for my car are 13.8 or 13.9, depending on which magazine tested it. How in the hell they got it to do that back then, with stock tires, i'll never know. Though i've heard of companies giving magazines cars with a hell of supertune. Also like you said, Don Garlits was driving. Check out my newest post- I'd really like to get everyones opinion on it

stickshifted

let me just say, that im not trying to **** you or anyone off, so i apologize in advance if i end up sounding like a dick.

ok, i dont see how im comparing apples to oranges, unless of course by the fact that im comparing a small block chevelle to a big block challenger, where both cars weigh nearly the same.

his crate 350 might have been using the modern hp ratings, but it still came in as a BONE stock 350. this means cast crank, moderatly crappyly heads with a kinda rough exhaust runner, ( i know, i felt around it with my finger) and it had 7.8:1 COMPRESSION!

those motors make about 240 hp stock, and with his cam, holley 600 carb, holley z28 intake, and headers he probably was making like 270 hp - maybe more, idk. but STILL, basically a stock motor, and his car ran a 14.7 quarter mile.

and with your math formula it shows that he's making 230 hp, its probably a little more, since he probably has a crappy 60-foot time cuz he's probably losing hella traction, and due power lost through the drivetrain, TC, and the wide gear drops of a 3 spd automatic vs a 4spd manual. and that formula is only good for calculating the RWHP, and not the BHP of an engine. and most muscle car engines were all underrated by some extent, so i dont consider 390 hp to be off, even though the rating system was changed. and yes, his car SHOULD be running at least a mid 14.

now all numbers aside, lets compare the 2 motors in these vehicles of similar weights. 3700lb chevelle with a 350, and 3800 lb challenger with a 440.

the 440 has all the natural advantages over the small block. the larger diaplacement already makes it able to churn WAY more hp and torque than the small block ever will, also the heads have much larger, and better designed intake/exhaust runners, larger valves - 2.08/1.74 vs the 1.94/1.50 valves of the sbc, and the intake of the 440, and the 3 carbs flow WAY more cfm's than the 350 will. plus i think the 440 should have like 10.5:1 compression vs the crappy 7.8:1 compression.

physics doesnt lie, and neither does chemistry, you take that much more gas and air, and compress it that much harder, that engine is gonna make more power.

and to top it all off, the challenger has 4.10 GEARS! when he hits it those tires should be grab pretty quickly after they get done spinning, and with that gear reduction, he should be in the powerband the whole time he's running down the track.

so with that said, it makes no sense in my mind that his car should go slower than a chevelle that weighs 100 pounds less, with a nearly stock 350 engine with highway 3.36 gears.

hypermite

For some reason I feel compelled to throw some Mango's into this Apples & Oranges comparison, about 10 years ago I had a 70 coronet, that a friend & I rebuilt a 1968 non HP 440 for. .030 over, sealed power replacement pistons, reproduction 375 horse camshaft, heads from a 75 440,(lowered my compression, how much, I don't know) An ancient wieand dual plane intake, with a 700 Holley on top, And Mopar electronic ign. with a 3.91 sure grip & crappy radial street tires the car went 13.7 @ 104 mph. The car had crazy amounts of torque & was so docile a grandmother could (and DID!)drive it. Granted it was rebuilt, but MrMopowered has a lighter car, more gear, better intake,more compression, & better tires than I had ! Later on I added headers, a more modern intake, and some Hoosier street tires & was turning 13.1 @ 108 mph.

stickshifted

hmmm. well regardless, i think we can agree his engine has some issues. we can only hope its simply tuning, but he might have messed something up running it like that.

and if the best time he can hope for is a mere 14.5, then he should be running at least 14.7's then he in no way should be running a 15.659. his reaction time cant be that bad

wonder how much better he'd do with a A-833 instead of that 727.....

stickshifted

yeah you're right. i was talking to my buddy with the chevelle the other day and he pointed out to me since the motor is stock, kinda old, and the fact that it has all the restrictive factory air cleaner, intake, and exhaust manifolds which i sorta forgot about, that he really cant expect to do any better than 14.5 maximum. however yeah he should be doing a little better than a 15.5


ehh i dont think id ever want the responsibility of having a rare muscle car and having to keep it nice, dent-free, and 100% stock.

i guess thats why my dream car is a 1968 dodge charger rolling chassis. hopefully at least 80% rust free...