My BBC progress

General engine tech -- Drag Racing to Circle Track

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6.50camaro
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Re: My BBC progress

Post by 6.50camaro »

As stated earlier by I think rustbucket adjustable limiters on the front will help start with around 3" to 3.5" of upward body movement before they make contact . Dan
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Re: My BBC progress

Post by 6.50camaro »

F-BIRD'88 wrote: Mon Jun 10, 2019 3:47 pm Basicly moving the instant center forward puts leverage in to lift the front of the car.
Moving the instant center back puts leverage in to cause rear axle- body separation (rear lift) as opposed to rear squat, on launch.
Moving the rear point of the lower bar down increases the mechanical leverage "the hit" like as adding more gear...
He's already got enough hit , in fact to much if he was spinning I would agree with you but in this case I feel I need to disagree Dan
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Re: My BBC progress

Post by prairiehotrodder »

ok i think i understand that moving the ic forward lifts farther forward but loses the leverage or hard hit as you say. Won't lifting farther forward be a good thing ? Because the farther forward you lift, the harder it is to lift ?

I'm emailing a couple suspension shops to see what they say. TRZ told me my lowers need to go up at the back because they are set at a drag radial setting and not a slick setting. I personally don't know what the difference is. The only advice everybody agrees on is get rid of the 90/10's on the front.
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Re: My BBC progress

Post by F-BIRD'88 »

Can you post the link to the recent video(s) ?
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Re: My BBC progress

Post by prairiehotrodder »

i have the video on facebook but i don't know how to get it here.
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Re: My BBC progress

Post by prairiehotrodder »

https://www.youtube.com/watch?v=HeVnCXfj9z0

ok here it is. It was made by my 12 year old son on a cheap chinese gopro.

Brian

sorry there is no sound.
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6.50camaro
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Re: My BBC progress

Post by 6.50camaro »

I don't know about that statement from trz because radails want a slower smoother bar setting .because of stiffer sidewalls sticks can take a harder hit because the sidewalls have more flex and there for forgiveness instead of breaking loose. That looks like a wheelstand you would not want to be having to often.
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Re: My BBC progress

Post by F-BIRD'88 »

Ha ha ha ,too much.. Looks like my buds car.
Probabily would have been fine if you did not lift.

Get the wheelie bars. IMHO it is your next best move.
Good vid... Cool car..
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Re: My BBC progress

Post by GRTfast »

prairiehotrodder wrote: Mon Jun 10, 2019 4:33 pm https://www.youtube.com/watch?v=HeVnCXfj9z0

ok here it is. It was made by my 12 year old son on a cheap chinese gopro.

Brian

sorry there is no sound.
Whoa that was a big one!
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Re: My BBC progress

Post by prairiehotrodder »

will lowering the chip in the 2 - step even do anything to the launch ? I mean the convertor is still gonna flash to the same rpm right ? I made 2 changes today. I raised the back of the lower control arms so now they are just about parallel to the floor. They are pointing up at the front 2*. Then i ordered a new pair of QA1 single adjustable front shocks. i'm on the fence with the wheelie bar idea. They aren't cheap but i could likely build them myself. I hope my modifications cure the wheelie problem but the wheelie bars would give me peace of mind.
i talked to a really helpful guy at S&W race cars and he also suggested the 2 mods i did. He also said it would be good to lower the front of the lower control arm.
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Re: My BBC progress

Post by Old School »

The wheelstand was not a violent jerk in on the bumper in the first 20 feet. It was a slow smooth wheelstand that just kept getting higher due to increased power. There is a fine line between keeping the wheels down and getting the car to hook. The car was working good on the prepped track, did not work nearly as well the night before on a marginal track.

You can try the changes you have done and see how it works. It may be fine and work great, it might not hook, that is what test and tunes are for.

Myself I would rather the car hook and ride it about 2 feet in the air for as long as it wanted if I knew the wheelie bars would catch me. The wheel bar must not disrupt the traction by allowing the rear tires to unload. That is why you need the very long ones that extend past the rear bumper of the car.

The 10.5 guys, who are not allowed wheelie bars, pull timing with a grid but that will slow you down. Tightening the front shocks will help if you can still hook.
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Re: My BBC progress

Post by econo racer »

If you have a fiberglass front bumper I would put the factory one back on. What kind of converter? It needs to settle down just a little when landing. But NICE =D>
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Re: My BBC progress

Post by Orr89rocz »

prairiehotrodder wrote: Mon Jun 10, 2019 8:55 pm will lowering the chip in the 2 - step even do anything to the launch ? I mean the convertor is still gonna flash to the same rpm right ? I made 2 changes today. I raised the back of the lower control arms so now they are just about parallel to the floor. They are pointing up at the front 2*. Then i ordered a new pair of QA1 single adjustable front shocks. i'm on the fence with the wheelie bar idea. They aren't cheap but i could likely build them myself. I hope my modifications cure the wheelie problem but the wheelie bars would give me peace of mind.
i talked to a really helpful guy at S&W race cars and he also suggested the 2 mods i did. He also said it would be good to lower the front of the lower control arm.
You are on the right track. Tighten rebound up front to slow front travel and it will stay down.
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Re: My BBC progress

Post by prairiehotrodder »

I'm trying to get my act together to make it to the track this weekend. New QA1 single adjustable shocks are on the car. The old 90/10 calvert shocks had nearly no resistance on extension and these new shocks have lots of adjustment. I raised the back of the lower control arm which i don't really have alot of confidence in knowing what that will do. TRZ and S & W race cars told me that was the right thing to do. Not sure if that will just take away traction or actually try to keep the front of the car down. I also wanted to note that on my big wheelie pass i had just filled my fuel tank to the top and i put much lighter front tires on the car a few weeks before. So those things may have been contributing to the wheelie. Also i had been data logging my runs and the AFR trended richer so i had changed my HSAB from 35 to 36 on that run. With 2 carbs thats 8 jets. Maybe the power was up a little. The friday night before, i had went 9.39 at 141 and 9.40 at 142 through the exhaust. On saturday the exhaust was off the car.
I found a used set of wheelie bars that are about 51" long, not sure if i will have them in time to get them on the car. I'm trying to keep track of everything i do so that i can actually learn what helps and what doesn't.
Brian
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Re: My BBC progress

Post by prairiehotrodder »

I made it to the track this saturday and made a little progress. Best pass was a 9.37 at 142.5 mph. No more wheelies but traction was also not great. Hard to know if my above mentioned modifications took away the traction but i do know the track was being difficult. The engine is working really good and runs awesome on the cheap 100LL Av gas with 12.9 CR. At 3400 pounds the math says 780 hp at a 142 mph and 820 hp at 9.37 ET. My 1/8 mile is 5.95 ET. The car is quite consistent once the track warms up and it starts to hook.
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