1970 Cuda 4 speed 60 ft problem

[wikd69]

Raf,

For your first burn-out, prior to your first run, I'd recommend you get your slicks nice and hot - make a lot of smoke. After that, burn them just enough to make a bit of smoke to get some heat in them.

I mentioned before to try and get some HD video of your ride launching, down low and off the rear quarter, so that we can see both rear tires as well as the rest of the body. That way we can see what the rear end is doing, what the wrinkle walls are like and see what sort of front end lift and weight transfer you get at launch.

That will answer a lot of questions and help you figure out what it's doing out of the hole.

[Hitchcock]

Let me start by saying that is one nice car!

But are you sure you dont want some big ass tires, and different suspension? Nothing wrong with cutting aup a good car, it makes them better! Here is a before and after of mine.

Also it was said to remove unnecessary front weight. Are you using an aluminum radiator? I removed over 60 pounds by going to a new front brake, and another 50 going to a rack and pinion steering. And went from a 42 pound hood to a 12 pound hood. THEN, I cut the front of the car up, to take out a lot more weight, had to modify a lot to get it done, but she should be light enough to help, because I have a girly engine for mine






And just for fun...

http://www.youtube.com/watch?v=TRpWUi48FMI

http://www.youtube.com/watch?v=91dmTS-U ... re=related

http://www.youtube.com/watch?v=QR7iB74p ... re=related


Here's a nice one...

[raffaplymouth]

Raf,

For your first burn-out, prior to your first run, I'd recommend you get your slicks nice and hot - make a lot of smoke. After that, burn them just enough to make a bit of smoke to get some heat in them.

I mentioned before to try and get some HD video of your ride launching, down low and off the rear quarter, so that we can see both rear tires as well as the rest of the body. That way we can see what the rear end is doing, what the wrinkle walls are like and see what sort of front end lift and weight transfer you get at launch.

That will answer a lot of questions and help you figure out what it's doing out of the hole.

thanks for your info !!ok i will let you know for a new video in the track the 1 september ... i dont have much time for a lot of work that i needed .. im very undecided if change the rear tires with a more soft compound ...

[raffaplymouth]

Let me start by saying that is one nice car!

But are you sure you dont want some big ass tires, and different suspension? Nothing wrong with cutting aup a good car, it makes them better! Here is a before and after of mine.

Also it was said to remove unnecessary front weight. Are you using an aluminum radiator? I removed over 60 pounds by going to a new front brake, and another 50 going to a rack and pinion steering. And went from a 42 pound hood to a 12 pound hood. THEN, I cut the front of the car up, to take out a lot more weight, had to modify a lot to get it done, but she should be light enough to help, because I have a girly engine for mine






And just for fun...

http://www.youtube.com/watch?v=TRpWUi48FMI

http://www.youtube.com/watch?v=91dmTS-U ... re=related

http://www.youtube.com/watch?v=QR7iB74p ... re=related


Here's a nice one...

woow , your vette is very cool !! how many seconds ?? i dont want modify the rear end ... i would use the car on the street some times .... i dont have alluminium radiator ... i have removed all bracket on the back of bumper , swaybar, battery on the rear ... i hope my 60 ft will be better ....

[raffaplymouth]

this is a good idea .. i can buy another header flange ant tube long 12" and drill for put another evac and lambda nipples , only for races ... you think will make power ??? or only much noise ??

It's my understanding that what you want is the right amount of back pressure for the best bottom end torque. Part of the benefit to tweaking back pressure is to help increase exhaust scavenge at the heads. You get back pressure from your street exhaust, but maybe too much and you most certainly get the weight penalty of all those tubes and mufflers.

Mine seems to run best with about 12" of extension - it just has more grunt and pulls better over the curve. An easy test for you would be to fab up some 18" extensions and make one run with full exhaust, one with the 18" extensions and one with just open tubes. Aside from the noise aspect, you'll be able to feel the difference. If the extensions are an improvement, you’ll need to determine how long they need to be.

The trick I used on mine was to start with 18" extensions and use a heavy crayon to mark the extension all the way down its length. Then, make a run. The point at which the crayon stops burning is where you cut it. There may be better ways to get the right length (on a dyno, for instance) but the crayon trick is supposedly the best way to figure it out on the track. Mine doesn't perform as well with straight open headers, and, the induced harmonics makes all the screws in the interior back out and drop on the floor

Also: You're running 2" primaries, 3 1/2" collectors and 3 1/2" tubes. I have close to the same, with 2 1/8" primaries and 3 1/2" collectors. With mine however, I neck my extensions down to 3" out the back. That ensures I get good back pressure and doing the crayon thing lets me figure out the right extension length to level it out. If you can afford it, you might want to try both 3" and 3 1/2" extensions. Again, as I understand it, the idea is to get the right scavenge effect at the exhaust ports - the amount of back pressure needed to help that along will be purely dependent on your intake air flow, intake/exhaust runner size, cam profile and compression ratio. You're running enough displacement to maybe need the bigger tube size all the way back, but it might be worth trying the slightly smaller tube size just to check.

Note that I'm running a lot smaller motor (434 ci / .030 over 427) but I'm also running a bunch of boost out of the blower, so that changes the mix, when looking at overall tube size and flow, etc. With your much larger displacement you would think you'd need much larger tubes in back but (in my opinion) you're using relatively small primary tubes (2") for your displacement. Add to that the fact that (according to your first post) you're pushing a healthy shot of nitrous into the motor. That increases cylinder pressures and delivers a corresponding increase in exhaust flow and volume. I'd prefer you had bigger primaries (2 1/8" to 2 1/4") but again, that’s a personal opinion (they may be just perfect as is ). I think tho, the 2” primary size makes tuning your exhaust even more important. Getting the right level of back pressure to balance primary tube flow and the resulting scavenge effect at your exhaust ports will help a lot overall.

I'm also running a TH400 with a brake. I launch at 4000 and shift at 7400 so I have a nice long power band to play with and only 3 gears to worry about. You don't have the benefit of the transbrake and all that raw grunt at launch (I launch with full boost out of the hole )

This aspect of tuning is as much voodoo as science so you'll just need to play with it a little. Like I said tho, same day, same track, same tune - I made one pass with my street exhaust and the next with my extensions. 2 tenths difference at the stripe and a big diff with my 60’s.

If / when you get to the right length of the extensions let us know the weight difference between the extensions and the full exhaust. I'll bet you're looking at least 35 pounds difference, weight wise.

However, like everything else in this business, your mileage will vary I tend to build all this stuff in my head while I’m puzzling out what I want to put together and it all seems to make sense to me . If you asked any number of the guys on the forum here you might get a completely different view of things.

It'll be interesting to find out what you find in playing with this part of your build.

Hello , i working now on the exhaust .. i have removing and i will build two header reducer from 3.5 to 3" with only 15" longer tubing with only Evac connectors , no mufflers ..
this morning i have installed rear wedge from leaf spring to axle for put the pinion angle at 6 degree .. for you is ok ?? before was zero degree ..

[raffaplymouth]

Raf,

For your first burn-out, prior to your first run, I'd recommend you get your slicks nice and hot - make a lot of smoke. After that, burn them just enough to make a bit of smoke to get some heat in them.

I mentioned before to try and get some HD video of your ride launching, down low and off the rear quarter, so that we can see both rear tires as well as the rest of the body. That way we can see what the rear end is doing, what the wrinkle walls are like and see what sort of front end lift and weight transfer you get at launch.

That will answer a lot of questions and help you figure out what it's doing out of the hole.

hi , i will put some video of burnout and launch at the end of week ... i hope the 60 ft will be better ..this morning i have removed the exhaust system ... my last 60 ft was very bad 1.90 sec .. i don't know about , how do you do 1,30 to 1,40 60 ft ... or the Italian track is a shit or my car is shit....

[raffaplymouth]

need cut only the right side , look like too long



Uploaded with ImageShack.us

[wikd69]

That looks great !

Did you have a chance to get a weight on the original exhaust setup, to see what your weight savings was ? It'd be interesting to see the difference.

I guessing you should be able to feel the difference in the bottom end, at launch as you run through the gears.

[raffaplymouth]

That looks great !

Did you have a chance to get a weight on the original exhaust setup, to see what your weight savings was ? It'd be interesting to see the difference.

I guessing you should be able to feel the difference in the bottom end, at launch as you run through the gears.

Wik , exhaust weight is around 40 lb ... tomorrow i will removing the heater !! anyone know help for caltracs preload ?? now have zero preload

[raffaplymouth]

guys anyone know better rpm for launch ?? i did around 4000... is too ??

[raffaplymouth]

http://www.youtube.com/watch?v=bVLFThZ0 ... ature=plcp

[sc68z28]

Raffa, looks and sounds GREAT! Sorry I'm late to this discussion, but everything so far is all good advise.
I'm no expert, but I've been where your at. 7 years ago I took my street Camaro to the track, it ran 2.+ 60' , 12.+ second ET @ 131 MPH, with similar power to yours and weighing in at 3710 lbs. It was a sad day and flat out scary spinning the tires most of the way.

I'm not going to try and tell you what to do, but since both our cars have many things in common some of what I did should translate to your car.

Your "M5" 29 x 10.5 slicks with 11 to 12psi should work fine, and will work best on a 10" to 12" wide wheel.

Mine is also a 5 speed/clutch car and BTW, CONGRATS to YOU for drag racing a stick shift. You may not realize it is vary rare to find a 3 pedal car (excluding Pro and SS) at a drag strip here running less than 11 sec.

Like you, I started with muti leafs and Slide-a-links (same as CalTracs) had a street clutch and about 800 HP.
After my first outing, like you I went home and started changing things, the guys here were a big help on what to do. I moved the batt, removed the sway bar, removed frt bumper, removed exhaust.... same stuff you are doing. Added 90-10 adjustable F shocks, a roll cage and went back to the track. Went 10.70 @ 135 with a 26 X 10 M/T "M5" slicks on a 10" wheel, NOTE... at a good track!

Your track/air strip will be a chalenge, I still had problems if the track was not well prepared.
The next thing I did was a larger tire (11" x 28) this helped some, but at poorly prept tracks it would still over power the tires... Here is a vid from then http://www.youtube.com/watch?v=Uk_pWioiI3s
That vid is a pretty good example of a burnout, I was using 3rd gear then.

At this point I started breaking things, (60's @ 1.50s). If the tires hooked hard (dead hook) or sometimes wheel hop, I'd break the rear gear (2 times) and or bent both leaf springs and Slide-a-link bars.

With bent leaf springs I changed to a Ladder bar suspension and double adjustable coil over shocks, big weight reduction, was near 100 lbs lighter.Also went with lighter F drag race brakes saved 45 lbs. Now my car was around 3450 lbs, still had a street type hard hitting clutch, so I was stuck running bottom 10 second passes @ 138 to 140 mph.
Note...the ladder bars are lighter, but you can go just as fast with CalTracks with his split monos. Not just any mono, get them from Calvert Racing!

It was at this time when I got my adjustable clutch, 30 lbs lighter, and 3+ tenths quicker.
To understand an adjustable clutch read this thread http://www.chevelles.com/forums/showthread.php?t=232952
There are pics of my clutch on page 3 and on pg 4 you will see pics of some of my broken parts.

Shortly after the adj clutch I went with a clutchless shifted 5 speed, picked up another .15 et.

I have made a few other changes since the above including mini tubs and 12 X 29 slicks on 12" wheels.
My car now weighs 3350 and will run bottom 9's at just under 150 on a safe tune all day any day. It still has full interior, a back seat, carpet, ect and I drive it a little on the street.

9.10 vid http://www.youtube.com/watch?v=9tK2vx1o0fw

Best 60' VID in my sig.

Hope this helps.
...Bill.

[wikd69]

Raffa, looks and sounds GREAT! Sorry I'm late to this discussion, but everything so far is all good advise.
I'm no expert, but I've been where your at. 7 years ago I took my street Camaro to the track, it ran 2.+ 60' , 12.+ second ET @ 131 MPH, with similar power to yours and weighing in at 3710 lbs. It was a sad day and flat out scary spinning the tires most of the way.

I'm not going to try and tell you what to do, but since both our cars have many things in common some of what I did should translate to your car.

Your "M5" 29 x 10.5 slicks with 11 to 12psi should work fine, and will work best on a 10" to 12" wide wheel.

Mine is also a 5 speed/clutch car and BTW, CONGRATS to YOU for drag racing a stick shift. You may not realize it is vary rare to find a 3 pedal car (excluding Pro and SS) at a drag strip here running less than 11 sec.

Like you, I started with muti leafs and Slide-a-links (same as CalTracs) had a street clutch and about 800 HP.
After my first outing, like you I went home and started changing things, the guys here were a big help on what to do. I moved the batt, removed the sway bar, removed frt bumper, removed exhaust.... same stuff you are doing. Added 90-10 adjustable F shocks, a roll cage and went back to the track. Went 10.70 @ 135 with a 26 X 10 M/T "M5" slicks on a 10" wheel, NOTE... at a good track!

Your track/air strip will be a chalenge, I still had problems if the track was not well prepared.
The next thing I did was a larger tire (11" x 28) this helped some, but at poorly prept tracks it would still over power the tires... Here is a vid from then http://www.youtube.com/watch?v=Uk_pWioiI3s
That vid is a pretty good example of a burnout, I was using 3rd gear then.

At this point I started breaking things, (60's @ 1.50s). If the tires hooked hard (dead hook) or sometimes wheel hop, I'd break the rear gear (2 times) and or bent both leaf springs and Slide-a-link bars.

With bent leaf springs I changed to a Ladder bar suspension and double adjustable coil over shocks, big weight reduction, was near 100 lbs lighter.Also went with lighter F drag race brakes saved 45 lbs. Now my car was around 3450 lbs, still had a street type hard hitting clutch, so I was stuck running bottom 10 second passes @ 138 to 140 mph.
Note...the ladder bars are lighter, but you can go just as fast with CalTracks with his split monos. Not just any mono, get them from Calvert Racing!

It was at this time when I got my adjustable clutch, 30 lbs lighter, and 3+ tenths quicker.
To understand an adjustable clutch read this thread http://www.chevelles.com/forums/showthread.php?t=232952
There are pics of my clutch on page 3 and on pg 4 you will see pics of some of my broken parts.

Shortly after the adj clutch I went with a clutchless shifted 5 speed, picked up another .15 et.

I have made a few other changes since the above including mini tubs and 12 X 29 slicks on 12" wheels.
My car now weighs 3350 and will run bottom 9's at just under 150 on a safe tune all day any day. It still has full interior, a back seat, carpet, ect and I drive it a little on the street.

9.10 vid http://www.youtube.com/watch?v=9tK2vx1o0fw

Best 60' VID in my sig.

Hope this helps.
...Bill.

Yeppers, Mr. Bill has one fast ride

I just wish mine weighed in at 3350 lbs...

[raffaplymouth]

Raffa, looks and sounds GREAT! Sorry I'm late to this discussion, but everything so far is all good advise.
I'm no expert, but I've been where your at. 7 years ago I took my street Camaro to the track, it ran 2.+ 60' , 12.+ second ET @ 131 MPH, with similar power to yours and weighing in at 3710 lbs. It was a sad day and flat out scary spinning the tires most of the way.

I'm not going to try and tell you what to do, but since both our cars have many things in common some of what I did should translate to your car.

Your "M5" 29 x 10.5 slicks with 11 to 12psi should work fine, and will work best on a 10" to 12" wide wheel.

Mine is also a 5 speed/clutch car and BTW, CONGRATS to YOU for drag racing a stick shift. You may not realize it is vary rare to find a 3 pedal car (excluding Pro and SS) at a drag strip here running less than 11 sec.

Like you, I started with muti leafs and Slide-a-links (same as CalTracs) had a street clutch and about 800 HP.
After my first outing, like you I went home and started changing things, the guys here were a big help on what to do. I moved the batt, removed the sway bar, removed frt bumper, removed exhaust.... same stuff you are doing. Added 90-10 adjustable F shocks, a roll cage and went back to the track. Went 10.70 @ 135 with a 26 X 10 M/T "M5" slicks on a 10" wheel, NOTE... at a good track!

Your track/air strip will be a chalenge, I still had problems if the track was not well prepared.
The next thing I did was a larger tire (11" x 28) this helped some, but at poorly prept tracks it would still over power the tires... Here is a vid from then http://www.youtube.com/watch?v=Uk_pWioiI3s
That vid is a pretty good example of a burnout, I was using 3rd gear then.

At this point I started breaking things, (60's @ 1.50s). If the tires hooked hard (dead hook) or sometimes wheel hop, I'd break the rear gear (2 times) and or bent both leaf springs and Slide-a-link bars.

With bent leaf springs I changed to a Ladder bar suspension and double adjustable coil over shocks, big weight reduction, was near 100 lbs lighter.Also went with lighter F drag race brakes saved 45 lbs. Now my car was around 3450 lbs, still had a street type hard hitting clutch, so I was stuck running bottom 10 second passes @ 138 to 140 mph.
Note...the ladder bars are lighter, but you can go just as fast with CalTracks with his split monos. Not just any mono, get them from Calvert Racing!

It was at this time when I got my adjustable clutch, 30 lbs lighter, and 3+ tenths quicker.
To understand an adjustable clutch read this thread http://www.chevelles.com/forums/showthread.php?t=232952
There are pics of my clutch on page 3 and on pg 4 you will see pics of some of my broken parts.

Shortly after the adj clutch I went with a clutchless shifted 5 speed, picked up another .15 et.

I have made a few other changes since the above including mini tubs and 12 X 29 slicks on 12" wheels.
My car now weighs 3350 and will run bottom 9's at just under 150 on a safe tune all day any day. It still has full interior, a back seat, carpet, ect and I drive it a little on the street.

9.10 vid http://www.youtube.com/watch?v=9tK2vx1o0fw

Best 60' VID in my sig.

Hope this helps.
...Bill.

Bill thank for your help ,Your Camaro look like awesome 9 sec for strettable car !!! look like your car had the same problems with my cuda !! I've seen all your changes and I'm glad you able to do high 10 with 26-10 tires!!!! at the moment I do not have the ability to spend for jerico and slipping clutch , also for ladded bars need a lot of work , at the end of this week i have the race in a good prepped track , i dont know if the wheater is good , i hope .. if you have see all thread my last race , my best time was 11.49@138 mph 1.98 sec 60ft ... launch RPM around 4500 ... this car spinning tires from zero to 100 mph, my cuda have around 1000 hp with nitrous , car spinning in firts , second and third !!!only in 4th hook good ....all this before making this changes and the track was not good prepped

now ( Thank to you all ) for this help

1) front travel from 4 to 5 "

2) front shock calvert 90-10, rear shock at 4 click to soft is ok ???

3) sway bar removed

4) all bumper bracket removed

5) battery on the trunk

6) exhaust removed ( only headers and 15" extension) with EVAC

7) connecting frame

8) pinion angle to 2 degree nose up at 2 degree nose down)

9) caltracs at zero preload ( i dont understand if is better at zero or 1/2 preload i dont see change )

10) tires screw installed with tube , Tire pressure 11 psi

11) car weight from 3650 to 3490

with all this work, as it will be my 60 ft??

for you rpm launch is ok at 4500 or is too ???

sorrt but i dont have monoleaf ... calvert told me caltracs work also with multileaf but i will change in mono this winter ...

[raffaplymouth]

bad news... i tried traction, it seems worse than before, too much wheelspin ... I do not know more what to do. does not seem to raise the nose ...im sick... It is not possible that after all this still does not connect...and incredible wheel wheel hop !!! .this is the video

http://www.youtube.com/watch?v=nnrxw26v ... ature=plcp