I was talking to a fellow dragracer at our club Christmas dinner a couple of weeks ago & he said I should be flashing the converter rather than foot braking on the start, what is your opinion?

My present combo is bog stock 383 Barracuda, 1700kg with less than factory compression (8.2:1) at present, auto, 3.91 gears & brand new Hoosier 275x50x15 quicktimes.

For consistancy I always run with an empty boot & a full tank

We only race on crap surfaces (roads & airports) & don't get many 60' & 1/8 times but I still want to go faster.

My best 60' to date is a 2.172 (9.311@75.31 & 14.466@94.78)

My best 1/8 to date is a 9.014 (with no 60' or MPH recorded)

These times were footbraking the car to 1700 RPM then steadily pushing the gas to the floor.

The car will stall to 2600 RPM on the brakes every time tested.

I have tried starting at an idle & flashing the converter a couple of times but went up in smoke (although this was with my old Hoosiers)

Any tips or hints on launching would be greatly appreciated, Cheers

1st what's an "empty boot" and full tank? I'd go w/ 1/2.

You have to do what works best for you. If you flash it and it boils the tires then what good is it. I usually take mine up to 1400 or so then mash it when the last yellow lights. I have tried the "flash" method but with my slow cars I've never seen much if any gain.

Somebody that looks a lot like me, in his younger days, used to street race a 66 Hemi Charger. To impress the kids I could flash the converter and do a funny car burn out. To actually leave hard the car had to be foot braked to 2000 RPM to get maximum traction with the street tires. My race car doesn't care, it will leave hard either way.

Quote:

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1st what's an "empty boot"

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That would be an empty trunk

I agree, find what works best for your car. I had someone tell me the same thing once and it made no difference in my ET.

Not saying that this will work for you BUT if I leave
at low rpm 1800 or so and hit the gas it will blow
the tires off but if I go up onto the converter it
will plant the tires.... in your case its all trial
and error for the best launch

Cheers guys, sorry about my poor "English"

There are a few good points here, I'll get out & do more "testing"

As for Loot in the boot or junk in the trunk, any more than 2 hands full is too much

( . )( . ) on the other hand are not limited in size

My cars have always seemed to repeat the best when I was up against the converter.

I tried flashing it a few times and it didn't work good but that probably depends on the converter and chassis setup.

When you are on the converter The suspension is loaded, which makes everything more consistant. If you flash the coverter you lose time with the suspension reacting.

Is it spinning the tire? If so, add some loot to the boot...and an off idle leave that loads the suspension would be more consistent...

Nice car! And nice view at the track!

Dave

Wow!!

But I don't see ANY sheep!

Dave

It sounds like you are doing the right thing with your launch proceedure. I would start working with rear tire pressure and loosen up the front of the car to get more weight transfer.
Also try different length of burn outs. I run MT ET street radials and if I make them to hot it seems to hurt my 60 ft time.
I'm not real familar with the tires you are running but I am pretty sure my 325x50x15 MT Drag Radials would hook a high 12 second or slower car almost solid.
I am still working on my set up be I've gone 1.68
60 ft times with these tires on a poorly preped track. My son videoed my runs and you can hear the tires sqealing most of the way through first gear but they didn't go up in smoke.
I'm running leaf springs and stock big block torsion bars.
I like your cuda. But I'm not a big sheep fan!

I like to come up on the converter some. My 63 seems to launch it's best bringing it up to about 2200. And the car reacts faster this way. Nice Cuda and cool pics. Ron

With only being able to run on roads and at airports and not a dedicated track is making it a lot harder to dead hook the car. I would look at taking some hit out of it at the line, change the cam or move it. Go for more of a big end charge like the fast class racers do.
Ever try Q time pros they seem to work well when I ran them on the street, real soft compound.

The 6 cylinder bars would give you more reaction then the 318 bars but the car wouldn't handle as good on the street. Also you could either trim or remove the factory bump stops. I think some on here have tricks on loosening up the stock bushings but I don't remember what they are. Many recommend using worn bushings since they aren't as tight as new stock. The more front end travel the better.

I'm running 275x50x15 Hoosier Quicktimes on 10" rims, would the sidewalls work better on a narrower rim?
Hoosier say 8"-10" & 9" is best.

Any suggestions?

The tire might work better on a narrower rim. I never heard of a 275x50? only a 275x60. But I think the improvement you might see in a narrower rim would be the tread surface. With a wider rim the tire will tend to cup in the center quicker and ride on the sides of the tread.If you go to a narrower rim you should be able to run lower air pressure with better tire surface contact to the road. But the only way to find out for sure would be to test on 8 inch rims.

I`ve been beating/tweeking my car for years and my new combo which is a 470 bb stroker w/an 8" vert likes a 3000 rpm leave for the best 60ft/et. If you climb too far up in the r`s at the line you will start seperating the suspension and yes it is planting the tire somewhat but it`s also limiting the useable travel so whatever. I run 6-cyl bars but my car is lighter than yours and they work good for me on the street as some say they won`t. Too many variables......loosen the ft. as much as possible,play w/tire pressures launch etc. and the et`s will come.

Every car and track are different so you have to experiment to find the best methods to use on your car, sorry that I can't give you the exact methods to make your car hook every time Don't forget that as the track gets more runs on it during the day that it may (probally) will change later in the day so what work in the morning may not be the best procedures to use in the race later in the day BTW, I had a 1970 Barracuda that I used to race in NHRA A/S, it had a hemi in it The weight distribution was very similar but worse than yours 2160 lbs on the front and 1290 lbs on the rear with no driver and half a tank of fuel 4 speed on nine inch tires As far as tire width and rims you might want to get a extra set of rims and drag race only slicks to use at the track only I have several sets of M/T ET Streets and ET Street Radails on ten inch and twelve inch rims. My car is a "street car" that I built to race the high dollar street racers in Los Angles before I moved to Oregon ( I never got to do that ) so I wanted it to look like a not so serious race car, hence the "street tires" The point I want to make is it will run the same ET and 60 ft. times leaving at 1200 rpm or at 2300 RPM, this is the first car(out of 12 or so automatic cars) that I have raced that is this way Most of the others like a higher stall,2300+RPM, especially the dedicated race cars with 8 or 9 inch converters. My current car has a custom built 10 inch converter, it has gone as fast as 10:43 at 128.9 MPH with that converter in the 1/4 and 6.86 in the 1/8, best 60 ft was 1.43 so far. The motor is a 518 C.I. pump gas (10.29 to 1 comp. ratio)low deck stroker in a 3450 lbs.1971 Duster with me in it with the 315x60x15 ET Street Radials on ten inch rims on the ladder bar rear suspension with coil overs. IHTHs , don't forget to test, test, and test some more.(write every change and the results down after every run, don't wait until the end of the day or the next day Please keep us posted with your results

Cheers Guys, & Happy New Year, you are getting me very inspired to spend my holidays "Testing"

DodgeCharger
“The tire might work better on a narrower rim. I never heard of a 275x50? only a 275x60.”

I'll keep my eyes open for some narrower rims.
I went with the 275x50 as they have a 1" wider tread than the 275x60 & to keep the gearing lower.

Thumperdart
“If you climb too far up in the r`s at the line you will start seperating the suspension and yes it is planting the tire somewhat but it`s also limiting the useable travel so whatever.”

OK, good call & I have a plan to check it, if use a remote tacho & a yard stick at each wheelarch I could video the rise relating to the revs on the converter in my garage, idle to 2600.

“Too many variables......loosen the ft. as much as possible,play w/tire pressures launch etc. and the et`s will come.”

I'll see what I can do with loosening the front, shorter bumpstops, research bushes etc. Would I be better to go to a pivot style joint on the track rods rather than the factory rubbers, as the rubbers do seem to limit movement a bit.

Cab_Burge
“don't forget to test, test, and test some more.(write every change and the results down after every run, don't wait until the end of the day or the next day Please keep us posted with your results”

Yes, this is great advice & I do follow it. I would like to test more (who wouldn't) but I do take notes straight after every run & have pads of notes & excel spreadsheets that I refer back to all the time.

Some of you may thing I'm getting a bit carried away for such a slow car but I want to keep it factory stock looking but go as quick as I can. I am beating quite a few faster cars already on the 1/8 due to the fact I'm getting quite a bit of my power down rather that have more power & go up in smoke. I am collecting parts for a much stronger (stock looking) 383 so more power is the next goal.

whether you flash it or leave on the converter depends on the suspension and weight transfer of the car. If it doesn't transfer weight quickly it will most likely want to be flashed to get the extra momentum of hammering against the stall of the converter. How much hammering it will want will take testing. On a light chassis car like Mr P said it usually doesn't like to be hammered against the stall. Mine is most consistent and smooth if I leave off the converter or 100 rpm's below.

My car has always seemed to leave its best around 2000-2200.

I tested the wheel arch height v RPM on the converter, sorry the heights are in mm but that was easier for my good lady to measure.



RPM LF RF LR RR
Off 613 617 613 617
800 615 614 618 617
1000 615 614 618 618
1200 615 614 618 618
1400 620 610 620 615
1600 620 610 622 615
1800 622 606 625 612
2000 625 606 627 612
2200 626 603 629 610

BG and FRED --- DONT GET ANY IDEAS

Some of you may thing I'm getting a bit carried away for such a slow car but I want to keep it factory stock looking but go as quick as I can. I am beating quite a few faster cars already on the 1/8 due to the fact I'm getting quite a bit of my power down rather that have more power & go up in smoke. I am collecting parts for a much stronger (stock looking) 383 so more power is the next goal.

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When you get ready to build that new more powerfull stock looking 383 you should ask for ideas from this board. The number one priority for your build would be to stroke the motor.The more cubic inches the beter. I seen a T/A Challenger at our local track a few years back that looked completely stock right down to the stock Polyglas tires. The car ran high 11'. I later found out the owner was a FAST racer. These are the guys that can help you out. They run faster on stock tires that many run on slicks.

When you get ready to build that new more powerfull stock looking 383 you should ask for ideas from this board. The number one priority for your build would be to stroke the motor.The more cubic inches the beter. I seen a T/A Challenger at our local track a few years back that looked completely stock right down to the stock Polyglas tires. The car ran high 11'. I later found out the owner was a FAST racer. These are the guys that can help you out. They run faster on stock tires that many run on slicks.

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Yea, you are on the same page as me, I want to build my car like a FAST car (without polyglass tyres) while keeping it streetable & having fun beating a few Fords & Chevs with "built" engines.

Caveat...I am no expert racer...

It looks like you are getting a fair amount of torque roll in the body when bringing up the RPM. If you can keep the back more even, you should get better traction. I don't think the 70 cuda had a rear roll bar option, but the later ones (72-74?) did. I'm curious if anyone else thinks that addition of a rear roll bar would help.

Dave

And that was my point about bringing the r`s up too much and seperating the suspension. That`s where a trans break comes in handy.......no suspension seperation and hits the tire harder although a t-brake is probably out of the question in your case. I foot brake my car but next time around I may go w/ a t-brake.