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Discussion Starter · #41 ·
Frame will handle the NA 496 and not give a problem, but potential handling and traction benefits are there if you were to box it. Just takes about 20' of 1/8" x 4" to 6" ?? flat bar steel welded over the opening. It's been a while since I measured one, I don't remember for sure what width flat bar is needed, you'd have to give that a quick check if you wanted to do it. Makes it more solid like the a-body convertible and El Camino frames from the 60's and mid 70's that came boxed from the factory.
At the very least I would plan to replace all the stock rubber body-to-frame mount bushings with polyurethane performance versions....the old rubber is sure to be dry rotted and loose. This will stiffen things up a lot. With good stiff bushings, the body and frame together help stiffen each other….with dead rubber they can't help each other. Poly bushings and boxed would be the top dog way to go to avoid any need for a roll bar on the street to keep it stiff. more of a sleeper performance mindset, and the way I'd do it.

Yeah, stock rear axle and stock control arms in the rear will either break(the rear axle) or flex and cause wheel hop(the stock arms), so I would plan to replace all that. Springs are probably worn out too.

Roll bar or cage won't be necessary to keep it together, but on sticky tires the motor will make enough steam the car will be fast enough that strip rules will likely require one if you plan more than 1 track day.

you can plainly see the open channel section I this picture:
Never thought about the body to frame mounts. Yeah the rubber is totally junk. I also have factory motor mounts. Should I upgrade them and the tranny mount? Rear springs are weak and need to be replaced. Thinking Hotchkiss for the four link setup. Custom driveshaft needed to handle power? You say I might need a cage if I go to the track and hook up. I thought you only needed a cage if you broke into the 10s? I'm no expert on the subject of course but at almost 4000 pounds and a 3.42 gear I can't see it getting there. Am I way off base on that?
 

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Depends on how wild you drive is how the rear end and transmission will do.

My car still has the 8.2" 10 bolt in it, when I have the money, I'll get a 9", still has a factory th400 as well, same deal there. Have a 3000 stall converter though, so that's different.


Depends on how wild you make it, same with any engine, is how fast it'll go. You can either get power from rpms, forced induction, or cubic inches. Guess which is easiest to live with on the street.
 

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Never thought about the body to frame mounts. Yeah the rubber is totally junk. I also have factory motor mounts. Should I upgrade them and the tranny mount? Rear springs are weak and need to be replaced. Thinking Hotchkiss for the four link setup. Custom driveshaft needed to handle power? You say I might need a cage if I go to the track and hook up. I thought you only needed a cage if you broke into the 10s? I'm no expert on the subject of course but at almost 4000 pounds and a 3.42 gear I can't see it getting there. Am I way off base on that?
If the car retains 80% of the original flor pan, then from 11.49-9.90 just a 6 point roll bar is track legal, and that's the term I should have used instead of cage. Roll cage after 9.90 or if the car can exceed 135MPH 1/4 mile.
Stock driveshaft is just a piece of seamed muffler tube with yokes welded in, so they aren't real strong, just enough for the 200-ish HP of the stock motors that were in them.

Decent 496, 3.42 gear, and decent traction and getting faster than 11.50 shouldn't be that hard if you tune away at it, that was why I made the roll bar reference. I don't think it will make low 10's-9.90, but getting under 11.50 is a definite possibility.

You sure about that 4000 lbs weight?? Seems awful heavy, most of the G-body metric chassis '78-87 cars are relatively light...my step brothers '79 Monte Carlo is 3300lbs with aluminum wheels, a 383 SBC, Th-400, and a steel Sears roll around floor jack in the trunk! Nothing has been removed to lighten the car either, not an ounce. just the aluminum wheels and intake manifold.
Big Block is going to add a couple hundred lbs, but still shouldn't be anywhere near 4000 lbs.
 

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Discussion Starter · #44 ·
If the car retains 80% of the original flor pan, then from 11.49-9.90 just a 6 point roll bar is track legal, and that's the term I should have used instead of cage. Roll cage after 9.90 or if the car can exceed 135MPH 1/4 mile.
Stock driveshaft is just a piece of seamed muffler tube with yokes welded in, so they aren't real strong, just enough for the 200-ish HP of the stock motors that were in them.

Decent 496, 3.42 gear, and decent traction and getting faster than 11.50 shouldn't be that hard if you tune away at it, that was why I made the roll bar reference. I don't think it will make low 10's-9.90, but getting under 11.50 is a definite possibility.

You sure about that 4000 lbs weight?? Seems awful heavy, most of the G-body metric chassis '78-87 cars are relatively light...my step brothers '79 Monte Carlo is 3300lbs with aluminum wheels, a 383 SBC, Th-400, and a steel Sears roll around floor jack in the trunk! Nothing has been removed to lighten the car either, not an ounce. just the aluminum wheels and intake manifold.
Big Block is going to add a couple hundred lbs, but still shouldn't be anywhere near 4000 lbs.
I had the car weighed with me in it. All iron BBC except intake, turbo 400 trans, 1/2 tank of gas and my fat 330 pound butt in it. Came to just over 3900 pounds. Also steel wheels. Also, this car originally had a V-6 diesel in it. Not a typo, it was a V-6 diesel. Pretty rare I guess. Anyway I don't know if that makes a difference but it was a heavy little guy. Never even had to change front springs when the big block went in.
 
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