Camaro is back to the action....finally!

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Tue Nov 10, 2015 4:56 pm

enigma57 wrote:Diego, there are many forces at work when you launch that hard. I do not have the answer regarding Cal-Trac setting, but have broken a main leaf once. Whatever you do, get your car on a lift and make a close inspection of all your rear suspension components, welds, etc. before you go out onto the track. You don't want to have this happen......

https://www.youtube.com/watch?v=V2tk8X8tZok

Best regards,

Harry
I'm sure the leaf springs are having a hard time actually. I'll change something before they decide to let go.

I checked a few suspension points at the track but I'll check everything meticulously again before next race for sure!

Thanks for reply!
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Tue Nov 10, 2015 5:05 pm

Old as Dirt wrote:Yes Diego, adjustable rear shocks with an increase in rebound stiffness.. will slow down the lift(separation)in the rear.. if that doesn't do the trick on the stiffest setting, you may have to go with a bit stiffer spring and a softer shock setting....

When you get in the ballpark with rear spring/shock combo's.. then work on the front..

You could also increase the rebound setting on the fronts to slow the front end rise before the suspension tops out(runs out of travel and jerks the tires off the ground vs. coming to the end of travel softly)

There is also a huge thread on Yellow Bullet that has some good info on CalTrac settings..
http://www.yellowbullet.com/forum/showt ... p?t=288916
Adjustable shocks would be awesome. Specially because they permit tuning on several track conditions. Too bad our coin is way undervalued now ,so import parts is terribly expensive . #-o

Maybe I could take away a lower short leaf and install another longer second leaf to increase spring rate and stiffness ?

Thanks alot fot he tips and link. I'll read it now!
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by Old as Dirt » Wed Nov 11, 2015 1:35 pm

Might want to look this over also.. good info.. I believe the Z28 5-leaf rear springs are somewhere around 125 lb./in. spring rate..
https://landrumspring.com/technical/lea ... formation/

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Wed Nov 11, 2015 6:23 pm

Old as Dirt wrote:Might want to look this over also.. good info.. I believe the Z28 5-leaf rear springs are somewhere around 125 lb./in. spring rate..
https://landrumspring.com/technical/lea ... formation/

Very good reading!

Tank you very much !
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Thu Nov 12, 2015 7:34 pm

Here is another HD video, same day with a different angle.

https://www.youtube.com/watch?v=WFguR4X ... e=youtu.be

Its funny to see the front wheels start and stop turning at launch...thats because the front brakes were dragging a little and need a little work. :D
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Tue Dec 15, 2015 4:54 pm

Finally got time for another update.......with videos!

Last 6th December, I raced the Z28 again to test some suspension and carb mods (I know , I know...never do two changes at the same time )

So far the suspension mods worked ok, I lowered the front end to improve stability at the end of the strip and changed the caltrac bars angle to the top hole for a more controled weight transfer. Car now launch like it should, front end rises smoothly and aligned side to side and lowers smoothly once. Too bad the track prep wasn't as good as the last race, so I didn't improve the sixty foot.

Engine didn't responded well to squirter changes. The first pass of the day the engine started to act like a it was with a stuck needle, and car didn't a good pass. Back to the pits I saw the distributor was rotated CCW like it was loose ,and it wasn't. Further inspection showed that both mechanical advance stop tabs broke and flew off the dizzy, rotating it and ---thanks God---retarding the timing. I'll post a specific topic as soon as I get the time to pull it off the engine to check.

Second pass, timing now is correct, engine kind of stumbles a bit before the wheelie but now the ET is ok...MPH is a bit lower than my best..but the day also was hotter than the last race a couple degrees...but I still want to lower ET :)

Third pass, car stumble a bit at launch, but now the ET and MPH were the best of the day: 1.59 60', 4.28@ 100m and 6.58 @ 108.25MPH.

Fourth pass, car launch better but MPH was a bit low,,I felt the rear end dancing a bit and figured the strip is now lost some grip.Ohh well.

Fifth pass changed the line, to hopeffully get more traction but no...ET was worse than before.

Sixth pass was fun! I staged the car, hamered it and felt it launch hard, but just the LH side goes up ? WTH, had to abort the pass... I tought one slick was turned in the rim or something, but no....the rear RH caltrac support broke right in the middle of the weld and the car launched like a G-body. Three wheel'n.. :D

Glad I was ahead of the competition and still got the first place Trophy. Lots of fun!

Next race will be in February 21th, and I'll make some plans to try to hit that 6.4xx ET...wish me luck!

These are the videos:

https://www.youtube.com/watch?v=xM-hzRML3PY

https://www.youtube.com/watch?v=fEstGe7xZsU

This one show a slow motion burnout:

https://www.youtube.com/watch?v=vXUb0HNIoiQ

Thanks !
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by Wolfplace » Tue Dec 15, 2015 10:09 pm

Excellent, Looks like you are having way too much fun :D

Happy Holidays to you & the family Diego
Mike
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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Wed Dec 16, 2015 4:10 pm

Wolfplace wrote:Excellent, Looks like you are having way too much fun :D

Happy Holidays to you & the family Diego

You bet!

Thank you for the words Mike, Have a happy Hollidays too! :D
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by F-BIRD'88 » Wed Dec 16, 2015 4:36 pm

Too bad our coin is way undervalued now ,so import parts is terribly expensive

I feel your pain..... The Canadian dollar is going the way of the Paso again. $.73/US. Its tied to the tanking price of OIL.

Adds a premium on the race parts wish list. With Free Trade/NAFTA I don't know why some of this automotive parts production has not migrated to the "C side", with the dollar difference now.

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Wed Dec 16, 2015 4:43 pm

F-BIRD'88 wrote:Too bad our coin is way undervalued now ,so import parts is terribly expensive

I feel your pain..... The Canadian dollar is going the way of the Paso again. $.73/US. Its tied to the tanking price of OIL.

Adds a premium on the race parts wish list. With Free Trade/NAFTA I don't know why some of this automotive parts production has not migrated to the "C side", with the dollar difference now.
Your dollar would be Heaven here.... Our corrupt politicians screwed everything and made our coin worth 3.88 times less than the USD. I won't be telling you about the gas prices...you'd think I'm kidding. #-o Real shame.
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by Tuner » Sat Dec 19, 2015 4:34 pm

Further inspection showed that both mechanical advance stop tabs broke and flew off the dizzy, rotating it
??.. what kind of dizzy is this?

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Sat Dec 19, 2015 4:39 pm

Tuner wrote:
Further inspection showed that both mechanical advance stop tabs broke and flew off the dizzy, rotating it
??.. what kind of dizzy is this?
Brand new Mallory S/S 32 maybe 1200 miles old when it failed. I still hadn't time to pull it from the engine to inspect it closelly.

Looks like the advance tabs broke right at the bend IDK why. I'll post a topic about that soon on engine tech section.
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by Tuner » Sat Dec 19, 2015 4:50 pm

High volume/high pressure oil pumps cause harsh torsional oscillation of the distributor shaft so the weights jackhammer against the stops.

In this case with the Mallory it is the stop tabs bouncing on the ends of the adjustable slots. (If it is the type of Mallory distributor with the two torx head screws you loosen to adjust slot length to set advance range limit.)

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Sat Dec 19, 2015 4:57 pm

Tuner wrote:High volume/high pressure oil pumps cause harsh torsional oscillation of the distributor shaft so the weights jackhammer against the stops.

In this case with the Mallory it is the stop tabs bouncing on the ends of the adjustable slots. (If it is the type of Mallory distributor with the two torx head screws you loosen to adjust slot length to set advance range limit.)
Yes,it's the two torx bolt type distributor.

Your explanation makes perfect sense.

PM sent.
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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Re: Camaro is back to the action....finally!

Post by BrazilianZ28Camaro » Tue Feb 23, 2016 9:40 am

Hello again Gents, another update from the last race to you.

Last weekend I raced the Z28 and after lots of work, fighting to make the car hook on a poorly prepped strip #-o , fighting a carb hesitation at staring line and a fuel pressure problem (probably the pump bypass wasn't holding fuel pressure all the way through the pass) I managed to lower my best et to 1.45 sixty foot , 4.16 330 foot and 6.45s @ 108.25 mph on a hot 90°F day !!

Overhere, never before a true street strip car like mine ran these times! So yes, I'm very happy with the new results. I believe I can fine tune the suspension and carbs better, and maybe run a 6.3s in the eight mile. That might be the first high nines, all motor, pump gas street-strip car in Brazil!!

This is a video a buddy did at the grandstands:

https://www.youtube.com/watch?v=um7ikXF ... ture=share

Thanks all for the help! :D
'71 Z28 Pro-Street Camaro
Pump gas -T-ram - All motor SBC 427"
3308 lbs- leaf spring/Caltrac Car
29x10.5 Hoosiers
New best 1/8 mile ET
1.45 60' / 4.12 330' / 6.38@109mph :D

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