Bad 60 FT with 70 lb more of Megablock on my Cuda

Hi ... after my swap .. from 440 to 572 the car is very powerful .. but in the last race i see a worse of my 60 FT from 1.40 to 1.50 .. the new megablock weight is 70 lb more than the 440 block ... this weight on the nose can cause a bad 60 ft ?? i have caltracs setted with zero preload .. car weight is 3650 lb ...

Thanks

I'd say it's just not hooked up as well...

All those sort wheel based E body have terrible weight distribution, including my lightweight(2800 Lbs. with me in it) 1970 Grand Coupe Cuda tube chassis car.
By adding more weight to the front end and more power you will need to find more traction to make the car as fast as it was before or faster.
I would try adding 25 to 40 lbs. more weight as ballast at the rear bumper attached inside it so it has the most effect on the weight distribution.

Put Your car on scales and let's see what the weight distribution is now with the new motor. With weight/load numbers You can decide the 'how much?' and 'where?' questions if necessary. Also, is this a torsion bar frontend car or coilovers/Struts/...????

What shocks do you have?
Tires?
Air pressure?
Transbrake or footbrake?
Is this using the nitrous?
If so, do you have a progressive?

some info ..stock front suspension .. 90/10 shock , Rear monoleaf calvert , Rear shock qa1 double adj .. yes Nitrous with progressive controller 200 hp on launch and after 2 Sec 320 hp , caltracs at upper hole and ZERO preload

tire pressure 8.5 PSI

Set the CalTracs in the bottom hole (First).

Set the shocks on a pretty tight compression (Meaning hard to compress(1-10 set them at 8) rebound about in the middle (Second).

With you in the car and the bars set neutral put one or two flats of preload in the CalTrac bars (Three).

Set the tire pressure around 10 PSI (Four).

Report Back (Five).

I would agree with 4 corner weighing the car.
I have learned a lot from the guys here and one big thing i learned when on scales was- small adjustments to torsion bars moves weight around - A LOT.

You have added more weight on the front, this changes your torsion bar loading.
You might find your corner weights all whacky now and some slight adjustments on torsion bars brings balance back to the car- for instance, you may be way heavy on drivers front, passenger rear- a little torsion bar tuning levels out rear cross weights for you, also helps the front weights as well of course.
You will still be nose heavy but, better balance still helps.
Perhaps there are areas from front seats forward that you can lose some weigh- look at scales again.

Its pretty amazing what just a quarter turn one way or the other on torsion bars does to the entire car.

8.5 lbs in tire seems really low but i don't see what tire it is- I go for the highest pressure that doesn't spin much- if your tire is paddling up to much ( wadding up) and the tire isn't staying pretty round, thats hurting your 60 ft.

Just went with a guy to film his launches and car was porpoising ( bouncing the front) on launch, 95% was too low a tire pressure, rest was shock too loose on extension - fixed that and went from 1.60 to 1.50 60"s.
he is at 12 1/4 to 12.5 lbs now on a 13X 30 et- et street.
Guys here got me to testing and- they were right- highest pressure we can run before losing 60 ft time is working>
we are changing some springs and weight and if it hits the tire harder- we could end up at 12 3/4 to 13 lbs.

Lastly- we have found down here the big strokes don't like nearly as much timing as was generally thought.
moved from 36 degrees with 110 race fuel ( 13.1 compression) to 32 degrees and 60 ft dropped to 1.46 and picked up 1 mph.

every mopar bb stroker we have dyno'd liked timing around 32- 33 instead of the 36-38 people were running with their 440 motors.

Hope this is of some help- envy you that motor-grin.

Sounds like spin. Video the car from the side with an iPhone, iPad or GoPro and watch the car launch frame by frame. How about bringing the NO2 in progressively after the initial launch. I agree with the 34 max timing and retarding from there with the gas. 70lbs. is a bunch. The weight could help if you can get the car to transfer properly.

It may be nose heavy,but. The Cuda has a 108" wb compared to some B bodys that are as long as 119" wb. Even if it's nose heavy that weight is still closer to the rear axle than a B Body. 90/10 shocks are generally to loose causing the front to extend too quickly. This in turn unloads the rear. Get some good slow motion cell phone video directly from the side of the car at the start. My car has 113" wb and is 320lbs nose heavy. It'll carry the fronts 50-60ft every pass. 10.5x31, 13.5psi, 60ft 1.24-1.30 depending on set-up.
Doug

Very good Infos ..Thanks for your Help .. therefore is better at 10 psi ? my tires is 29.5 /11.50/ 15 drag MT .. yes Calvert bar was adjusted at 1/4 preload with my ass ..

with 572 i have 37 degree with naturally aspirated and best ET is 10.1@ 136 mph ... with 300 spray timing is -11 degree .. therefore is total timing 26 degree .. best ET is 9.3@151 mph 60 FT is 1.50 ... with 496 60 FT was 1.40-1.42 ...

no possible weight 4 corner in italy... Sorry.. i know only total weight 3650 LB

you think need only adjust f4ont bars .. or need different torsion bars ??

572 Launch

572 Launch

496 Launch

I would certainly try 1/4 pound of air in tires, see what she does- cant tell from pick where you are in relation to leaving on the light.

secondly- what front brakes do you have on the car?
If its the factory disc brake set up- you can easily lose some weight up front by going to aftermarket race brakes.

Not sure what your torsion bar options are for that car.
Yes, a little tuning on them can make a big difference, but you absolutely NEED scales.
Surely someone over there has a set of scales.

are you running a front anti-sway bar? If so, i would likely pull it off , save some weight, help front end respond better.

Do you have a picture of car just sitting still with 572 installed- a pit pic, from the side ?

37 degrees of timing for NA seems excessive to me- but hey, i'm not there.
Just wondering how yall came to that number and what fuel your using?

Much more air in those tires. M/T tire guy told me if they spin, put more air in them. He told me not to exceed 26 psi. You are not even close to where you should be with air pressure.

no sway bar ... front draglite wilwood ... alu radiator .. fiberglass bumper ...



free image upload

Beautiful car.
Stance doesn’t look bad at all.
Doesn’t sound like there remains big items for losing weight on the nose.
Hopefully some tire pressure tuning and chassis tuning can get you where you need to be.
Man I wish you could get your hands on some 4 corner scales.

Get the tires up to about 13 psi and try again. Keep adding air from there.

Next suggestion is some double adjustable front shocks.

Strongly suggest progressing the nitrous.

There should be many road course racers in Italy. They will have 4 corner scales. Make friends with one of them.

10lbs-12lbs of tire pressure will help the car not slam the tire in the ground.

The lower hole will help not hit the tire so hard (more push than bang) better lever.

Good luck and let us know how it goes

Many Thanks for this infos .ok for 11/12 PSI i can put lower hole on caltracs .. 1/4 Preloads ?

Megacuda New Look !

img upload

Very nice. I like

i Think .. when my car will wheeling like your Duster ... my 60 FT will be ok !

Don't forget that your back may end up hurting from the new hard leaving
I've had to learn that lesson more than once,
Make sure and push yourself back into the driver seat before hitting it real hard

New look is Super!!! The only thing I would add at this point is to only make 1 change at a time. Don't change air pressure, Caltrac setting and timing at the same time. You will never be able to determine what made better or worse times with too many changes.

Yes 12PSI, Lower hole on the CalTracs and 1-2 flats of preload, so yes 1/8 to 1/4 rotation of preload.

Great looking car!

Hi Guys ... Bad news ... Bad 60 FT around 1.50 wheel spin also with more preload Torsion bars... 11 psi of rear pressure .. 1/4 Caltracs preload this is the video

https://youtu.be/zpw1VFESjQM

Loosen the rear shock extension 1>2 clicks at a time so it stays on the tyre after the hit.

already tried .... no change with shock adjust ... i think front shock 90/10 doesnt work properly .. or torsion bars

Front looks too loose to me.

I can not see the 8s !!! ... incredible .. engine is too fast for the frame ... Tires is 29.5x11.50x15 .. tonight i will check the front shock calvert 90-10 if work properly

You need a double adjustable shock in the front, not that 90/10 thing.

You have no real way to control the front suspension.

opinion:Its not the hit thats the problem, its chassis control, she tries to hook hard at the hit it seems.
Do you have travel limiters up front?
Shock control in front looks to be toast/nada.
In my minds eye the reason shock adjustment on rebound isn't making any difference is due really poor front suspension control and, perhaps too much bottle too soon but, wont know that until front end is tightened up.
If you just have90/10 front shocks- are they adjustable at all- can you go to 70/30 and at least lengthen up the bump stops?
I would tighten up rebound on rear shocks as far as they would go and try to tighten up the front.
Man i wish you could find a set of scales.

It also appears you "might" still need a little more air pressure.
We have found here that tires actually need a bit more pressure than we used to think.

I would try 6 flats of negative preload. big motors hit the cal tracks so hard they quickly rebound and lose traction maybe 12 flats negative.

How old are the rear tires and how many runs on hem?

If you have Calvert's 90/10 front shocks, take them off and sell them and buy a decent DA shock. The Calvert 90/10s are WAYYY too loose. Any 90/10 is wrong for your car anyway.

yes i have 90/10 Calvert..... why not work on my car ?????

29.5 11.50 15 MT with around 15 pass

now on the rear... qa1 double adjust all closed -6 compression -6 return

very good info ...i Will let you know.. if I can find the balance ...which benefits with 70/30 instead 90/ 10 ??

They are too loose. Lets the front rise too fast unloading the rear.
I tried the Calvert 90/10s on my car a long time ago and it refused to hook w/ them...that was running mid 9s on motor. Put stiffer shocks back on and it went back to working good. Slowing that rate of front separation does a lot.

The Viking double adjustable shocks I have now are much better.

Bars need to be in the bottom hole, PERIOD!

It hits the tire hard then unloads

You need push not bang

How old are they and do they sit outside in the sun light when not in use?

Cab is getting at something here, and I agree. The sidewalls are most likely killed from the combination of power/ weight, and running such low air pressure.
Put me in with the guys that suggest front shocks also.

No sun ... 1 year age

Finally

Little bit less shot in 1 step 150 hp wide time from 1 step to 2 step before 2 sec.. now 3 sec ?

caltracs at bottom hole

new front shock Viking or AFCO

Torsion bars ??? is possible have drag racing torsion bars ?? mine is original from the car

What engine was in your car originally? Don't get the drag race torsion bars...they'll make it worse. Like a loose shock, a loose torsion bar is not what you want.

The Cal-Tracs in the bottom hole will soften the hit. I still think you need more air pressure. My car responded well to adding air pressure from 12 up to 14-15 psi.

Add weight to the trunk. If 70# on front hurt then add 100# to rear.

I agree with an8sec70cuda here: Front shocks and front suspension is too loose/too fast in both planes.
Car tries to carry the front and certainly has the power, she seems to grip at the hit but- the front "bounces up, then drops down".
When coming down, it comes down too fast and, to far, when the car pivots forward on the front- rear is unloaded.
Granted it started to slip/spin at apex of front coming up.
Think of a piston at the top of the stroke- for a microsecond- it stops.
Same with the front end travel, it stops moving up and immediately starts down and that movement changes weight transfer.
We are working on one here with the same issues.
adjustable bump stops or travel limiters can help some but you really, really need adjustible shocks and- a set of dang scales.
If i could i would ship you a set to set up with.
Why?

lets say you car is on scales and this is what they say:

Lf- 946 RF- 796
LR-756 RR-848

car is left front, right rear heavy- really not good.
A QUARTER TO HALF TURN ON A TORSION BAR will pretty well level out the weight bias on the car.
the point is- it only takes a tiny bit of torsion bar misadjustment to have car unhappy.

Hope this helps.

FWIW I've been a 1.33 60 ft. with Rancho 90-10 fronts and 5-ways out back but every car is different up to a point........

I might add: Those were real weights on a race only car here at the shop and we balanced the car with Torsion bars as we realized they were indeed part if not most of the problem- turns out they were indeed the real issue .
We made sure everything on the rear was square, lined up to the front and on scales ( leveled) we found one side of the front was a little higher than the other, i think it was about 1/4 to 3/8 of an inch.
Car with driver in it isnt going to be dead square but we got it to :

LF 921 RF- 832= 89 LBS difference and with 185 lbs driver in car.
LR 786 RR- 806= 2LB difference and with driver in car.

Car now pulls straight, pulls both front wheels almost the same, but the really interesting part is the tire patch measures the same after a launch, it didn't prior to balancing the car .
shooting before and after videos- prior we had more tire paddle on one side than the other at 12.5- 13 lbs.
After they are visually the same and was able to raise pressure to 13.25- 13.5.

You might try launching the car and measuring your contact marks and see if they are close to the same.

I'm not as bright as the other guys here but these things have helped us>
If you cannot get scales, i would really try to measure well to see if torsion bars are loading the front the same- car at exactly the same height on both sides.

fwiw.

Your car is a lot lighter w/ a lot less power.

I guess it's good to be light and slow BUT consistent...........

Consistent...once a year?

Ouch!!!!!!! It’s not even Fall yet

Funny.........At the track my car repeats nicely but it's taken years to get it there and the op's nose heave deal makes tuning a bit more difficult for sure but doable...........And again, I beat my car harder on the street and more often than most racers on here race theirs and who insist "But you only RACE once a year bs"...........

Hi Chip .. my original car is 1970 Cuda 318 4 speed .. i think this is originbal bars ... never tried caltracs in the lower bottom hole .... i tried pressure with 9 psi 1.52 60 ft with 11 psi 1.60 60 ft .. never tried at 14-15 psi

will try ! i can also move the front hanger .. i have two hole

on rear bumper is possible ? i cam put some weight on the bumper and some on the trunk... but i have add weight ....

Looks to me like the car was trying to work, just move the bars to the bottom hole no need to change where the spring is located in the car.

Set the rear shock real stiff.

Good Luck!