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After 25 yrs its out! |
Post Reply | Page <1 1314151617 19> |
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stickshifter
AMC Addicted Joined: Jan/17/2008 Location: Bed Rock Status: Offline Points: 573 |
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Based on nothing but your own results, I would be question your recommendations. Drag week includes racing. That racing is to be the fastest you can be. You push the engine hard while racing. You must be able to have a race engine that lives on the street too. You can not short change the requirements of the racing because you will also drive it on the street. Tony's biggest problem IMHO was not having enough time to sort out the entire combination followed by suspect components. Just my opinion, I could be wrong. Please carry on. |
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Kevin, my input isn't strictly based on personal experience alone. I do however reveal situations I have encountered though. As you've said either of us could be wrong, but if the car caint make it to the track the tour is hopeless.
I do understand that "true" race cars require their own approach. You seem to enjoy pointing that out at every opportunity too. I would think that those who have experienced the trials that a serious street/strip car presents may have some feel for what Tony is likely to encounter, and possibly how to avoid it.
SKeown
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stickshifter
AMC Addicted Joined: Jan/17/2008 Location: Bed Rock Status: Offline Points: 573 |
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I agree. But it is my opinion that having spring pressure too low for the cam for the racing in order to compensate for the valve train hardware is the wrong approach. If the current hardware can not survive the road trip with the proper spring pressure for racing, Tony really has just a few options: 1) Run a smaller cam that requires less spring pressure 2) Upgrade the hardware to survive the racing and the road trip 3) Change springs before and after each race event. 4) Don't really race it and keep it below 4000rpm with weaker springs |
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tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303 |
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Well I broke rockers, they were Harland sharps and it was due to the spring pressure, some incorrect angle on the adjusters, and a somewhat large camshaft for driving at 3-3500 rpm for hours upon hours. But its how it is, the road is what is killer, the racing not so much but it still needs to be able to run the number and that requires parts that match the rpm I need to make the power.
Theres not really much to upgrade to, everyone broke rockers be it T&D or jesel, they also broke springs and destroyed lifters. Its a trip of attrition. I have already thought that I may just give up some performance and run a smaller roller or even my old flat tappet to be able to survive. The flat tappet would be .672I 686E 268 275 on a 110 and may still give me the performance minus the headaches(maybe) If I had a car that was lighter I could run a milder engine and still run the number I need but I don't and have to live with it or cut the car which I most likely will not do. Ill just have to be a little slower, this engine in a 2800 lb car should run low 9s but in my car I just hope to eventually run 9.90. It may be a pipe dream to be able to do both with a car that really shouldn't but oh well. The winner of the small block class ran 9.90s all week, has a .860 camshaft with 130 lbs seat pressure and 600 open, but its been spintron tested to make a camshaft that will allow that, he still destroyed a lifter. |
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amx39068
Supporter of TheAMCForum Joined: Feb/21/2008 Location: Arizona Status: Offline Points: 11576 |
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Those track times and street driving are a pretty difficult set of variables to find compatibility without resorting back to spray.
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5818 |
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It's simply a matter of trying to effectively control a very agressive cam...350# on the seat is the norm for a cam like he is running...you have to have the parts to handle it..Aggressive profiles like Tony has with low spring pressure will in fact bounce the lifter..That decreases life of the lifter,cam and the valve job.... I have a s.b. chevy here right now with a .700 lift roller and the guy ran mid 200 on the seat(per man specs) and the cam is marked up on the back side of the lobe where the lifter slammed back down...Seen it many times.....
Carry on...
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5818 |
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Your example from brookshire is comparing a cam with .100 less lift than what Tony runs....compare apples to apples....
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Probably no one with the possible exception of Harvey crane has spent more time enguaged in spintron testing Than Harold Brookshire. Why not give him a call, provide the cam's specs and see what he says? The last time I discussed springs with him he was testing lobes with 1" lift.
The bottom line is Tony's first attempt at such an event wasn't a success. The main culprit was the valvetrain as for failure, yes indequate time to sort everything out was evident too. Maybe staineless rockers, less agressive lobes and a rediction in spring pressures are all called for to endure such a task? Personally the first thing I would explore is what's truely required in the spring department.
Before the past four decades of cam technology I turned over 8000 RPM with a 390" Chevy dragster running extreemly heavy Isky lifters, 5/16" pushrods, stock rockers and less than 550# springs. The one thing that helped was a rev kit which kept constant pressure on the lifters, that in conjunction with lighter springs may help? I do know that NASCAR resorts to all the ways possible to reduce the need for extreem valve spring pressures, ie titanium valves. A DNF in NASCAR don't cut it.
SKeown
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Jim you're the one not comparing apples to apples. Power tours aren't simply drag races. Its an endurance race with intermittent drag races, very similar to what my car is about. Making it home is a critical component, there's no trailer awaiting.
SKeown
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5818 |
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Tony already has the right answer...flat tappet...and Dan Curtis made a good point...spray
But telling people 250 at the seat with an almost .800 lift cam is fine is bad info..simple as that..wether you have to drive it home or not...Thats my opinion...
Merry Christmas..
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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