[predator carb guru]

Oh, I forgot to mention, mine isn't a 454.....it's a big bigger than that.....

 

[lmsport]

Intake flow will dictate the power produced, if the head you have now is maxed out you won't make alot more power

 

[jjjaffo]

Don't get too wrapped up in HP numbers. An engine doesn't produce HP, it produces torque. HP is a mathematical calculation on how fast it can perform the work. More hp means the engine can do the work faster.....

That being said......there's no substitute for cubic inches. There will be some people that say they have smaller engines making more power, but they tend to be either turbo or supercharged, and all you're doing there is artificially making the engine "bigger" by forcing more air and fuel than it can take in on it's own. If you see a smaller engine with a lot of HP, check it carefully as it will tend to have a very high rpm peak for the hp and a very low number for torque, which will make it a slug to drive unless you rev the piss out of it.

As to what it would feel like to have more torque, here's how i'd put it: for example, if you had 300 ft lbs of torque and it pushes you into the seat, then at 500 it might crush you into it....and at 1000 you'll get blurry vision, have difficulty hanging onto the steering wheel, and might even have slight difficulty breathing.....but the other factor to put this into context is the HP factor. Have those torque values, but at low hp, you'll never notice them or they will be modest at best....but have those values with a combo that makes a substantial amount of HP in addition to that, then BAM!!! A big, over the road diesel these days can produce in excess of 2600 ftlbs of torque, but only make approx 650 hp. Yes, that's a huge amount, but how fast will the truck actually accelerate? Not real fast due to weight and other things. But put a 1000 hp, 800 ftlb engine into a car and what happens? INSTANT SPEEDING TICKET!!!

My dragster makes 1510 hp @ 7200 rpm. Torque is somewhere above 1300 ftlbs and that peak is below 5600 rpm. Not sure exactly what it is because when it was dyno'd the sweep started at 5600 rpm and the torque curve was already dropping at that point. So we had to guess. Car weighs 1935 lbs with my fat butt in it and a full tank of fuel. My 60' times are in the 1 second range....It's actually painful to launch the car because it hits so hard when the transbrake releases....and for the first 100 feet or so my vision is blurry and I feel like I'm being crushed...after that I'm still being pushed into the seat pretty hard, but it's not as violent as it is at the launch.....and this is all without the nitrous turned on....add the bottle and it gets worse....MUCH worse.....But damn it's fun!!!!

I can't even imagine that kind of power! I get the torque vs rpm thing. I've been in a 956 lbft diesel pick-up and I can beat him all day long- though that truck is really quick lol. Anyway, I use the latest dynosim 6 software to test engine combos before building them, and accurate head flow numbers are a must! The combo I was considering uses AFR 290 oval ports. Even AFR themselves recommended them. With the 112cc chamber I need only a small dome for 10.25 to one comp. This will promote good flame travel across the piston and a tight quench will keep detonation at bay. I'm sure I could go higher but I'm comfortable with these numbers. The cam would be a custom grind 268/274 solid flat tappet 230/236 @.050 with .555/.571 lift. All on a 106 LSA timed straight up. Yes it's a pretty tame cam and yes it's a flat tappet but I like it. With a dual plane, 850 carb and headers w/ mufflers I got 559 LBFT @ 4500 and 562 HP @ 6500. Seems optimistic yes, but a good head can really make a difference. Either way the actual numbers should be well north of the 500 mark and will be a substantial improvement over my little 408! I can look at numbers all day long but until it's tied to my butt dyno I just can't grasp the significance of those numbers.

 

[lmsport]

Get a hydraulic roller for any BBC, they have always been hard on cams and the roller makes that all a thing of the past.
I did a 496 for a street car with a similar cam but Brodix Racerite heads ported by some famous drag racer, made 590/560 with 10.5 compression and pump gas.

 

[jjjaffo]

This has probably been discussed thousands of times, but I have to ask: What power difference can be expected by going to a roller cam? According to David Vizard's teachings, up to about 270* a flat tappet has the same power as a roller. He also says that unless you buy the best of the best hydraulic roller lifters the heavy spring pressures can somewhat collapse them and reduce lift and duration which robs power. When going with a solid roller, depending on the lifter used, it's possible over time to hammer out the needle bearings in the wheel on the lifter. With that said I can't seem to find a cam with the numbers I want in a solid roller anyway. In the flat tappet arena there are many quite street friendly solids for my application. I don't mind the expensive oil and periodic adjustments. Plus when I smack the loud pedal I know it's all there right to redline. On that note does anyone know of a durable rocker? In the dirt track car my friend runs he ruined a set of comp gold rollers. The needle bearings just didn't hold up. I've been running roller tips in my 408 with a hydraulic cam but want a good reliable roller rocker for a solid cam. I know just enough about cams to get myself in trouble so people please enlighten and educate me with your knowledge. I am very eager to learn what others know.

 

[ericnova72]

Durable roller rockers, there are a few.

Crane Gold Race have long been highly respected for durability, as have Harland Sharpe's.
Scorpion is another good one, and are lifetime guaranteed. Scorpionis easy to deal with on returns also.
Howards Camshafts have a good one.
Lunati too.

Comp Cams gold is a relative newcomer....I know my cousin broke one in half, but it was on a big solid roller 588" BBC. He replaced the whole set with Comp
Cams Pro Magnum steel full rollers.

Actually, your friend that beat up a set of Comp Golds could well have a harmonic situation in his valvetrain and that is what pounded the rockers. Not enough spring, running in valve float, or too springy a pushrod will tear up needle bearings in a hurry, regardless of brand. So will poorly set-up valvetrain geometry.

Wrong pushrod stiffness, wrong pushrod length and thus wrong valvetrain geometry is a very commonly overlooked issue. Many guys don't even know to check it or how to set-it up correctly.

 

[lmsport]

Comp or Crower steel rockers Las and lifetime.
BBC are notorious for eating flat tappet cams, get a custom roller if you have to, hydraulic if you drive it alot.

 

[jjjaffo]

Thanks for the info on rockers. However I still have questions about the great cam debate. What's the difference between a flat tappet and a roller as far as power? Yes a roller cam usually has more lift and that's good for upper RPM power. Yes BBC have a habit of munching FT cams. And yes hydraulic cams are more trouble free vs a solid cam. The problem I have is the numbers. Strictly dealing with hydraulics, the big thing has always been the intensity of the cam meaning having more duration at 0.050" for a given advertised duration. Most rollers can't match a flat tappet in that area. But which one for a given duration will produce the best all around power? My problem is I've read a ton of books on the subject but have limited real world experience with these cams. I also haven't seen any cam dyno shoot outs between the two. But even then I don't want peak numbers, I want to see the whole curve. Does anyone know of tests like this I can read about? It all boils down to this: to me it's not worth the extra 5-600 dollars for a roller if the power gain isn't there. I'm here to learn, people, so please educate me on roller cams VS flat tappets of close to the same duration. Help me understand.

 

[jjjaffo]

Okay, so I dug a little deeper into the subject. turns out that roller cams have more area under the curve and greater ramp rates which equate to more lift for a given duration. On the dyno some tests between a hydraulic roller and a flat tappet of the same duration @ .050" have shown a roller starts to outperform a flat tappet above about 4500 RPMs. Below that there really is no measurable difference- at least on the videos I watched. It makes sense that the roller starts to outperform the flat tappet due to higher lift which equates to better breathing. One particular video I saw compared cams of 244* duration @ .050" And the difference was a whopping 6 LBFT of torque but a respectable 22 HP for the roller. This was in a 400 sbc and peak power was north of 6 grand which most street vehicles won't be spinning up to. Plus you'd need nasty gears and about a 3500 stall converter. Their words not mine. For those who want to know, the smaller the cam the less the gains appear to be. That being said, and to answer my own question, there appears to be no downside to running a roller other than cost. The benefits are many. Interestingly though, up to a point if you run a solid flat tappet of comparable duration {not the same duration #s due to how solids are measured} against a hydraulic roller the solid flat tappet can run with or even edge out the roller. Just so you know, solid rollers can be incredibly rough on the valve train and are not recommended for extended street use. Another thing to note, if you plan on running a hydraulic roller of decent duration, make sure you buy a quality set of lifters to go with it. The reason being is the heavy spring pressures and aggressive ramp rates can cause lesser quality lifters to bleed down reducing duration and potential lift. This reduces potential power. So, for anyone else who may have wondered about this stuff, for virtually trouble free operation of your engine a hydraulic roller cam is the way to go and that's why people who know engines recommend them. Don't get me wrong, flat tappets are still great performers if your wallet is light, but a fair amount of baggage comes with them.
On another note, I'm a bit disappointed in the knowledgeable people on this site. I got real good advise and information on my thread right up until I asked for a cam comparison. then, CRICKETS....
There has got to be people on this site more knowledgeable than I am on this subject. Seems counter productive to have to answer my own question, but I did learn information that I hope will help other people. If I missed the mark on anything please correct me. I look forward to any questions and comments.

 

[lmsport]

the roller versus ft debate is pretty short for me--rollers are more durable and can provide more power.
Rick at Isky told me many years ago that his flat tappets made basically the same power in the engines I was building (8k RPM oval, 350cid, 700hp) as the rollers. For street use, GM went roller for durability with modern oils and a little horsepower.

 

[2001Blazer4x4]

To me LMSport is obviously talking about a solid roller (at 8000 rpm), which is really the ultimate performance cam type.

Cams are much more than lift and duration. It's all about valve timing. You can choose a comparison cam to prove pretty much whatever you want to sell.

On the street, there is no disadvantage to a hydraulic roller in general - other than the high cost. But on the strip the hydraulic roller can be quite RPM limited due to the heavy valve train.

Flat tappet solid has more potential to make more horsepower than a hydraulic roller by being able to spin to a much higher RPM.

Flat tappet hydraulic brings up the rear in performance

 

[jjjaffo]

To me LMSport is obviously talking about a solid roller (at 8000 rpm), which is really the ultimate performance cam type.

Cams are much more than lift and duration. It's all about valve timing. You can choose a comparison cam to prove pretty much whatever you want to sell.

On the street, there is no disadvantage to a hydraulic roller in general - other than the high cost. But on the strip the hydraulic roller can be quite RPM limited due to the heavy valve train.

Flat tappet solid has more potential to make more horsepower than a hydraulic roller by being able to spin to a much higher RPM.

Flat tappet hydraulic brings up the rear in performance

Yes, that is pretty much what I found too. I have always liked solid flat tappet cams because what you see is what you get, all your lift and duration at lash. I find that even on the street if you are careful in your selection, and don't mind the noise, the torque and power of a solid flat tappet is way more fun than a hydraulic. And, with a good spring you can run up through the gears a littles higher than a hydraulic as the torque curve doesn't seem to drop off as fast resulting in a little more usable horse power.

 

[lmsport]

even grocery getter engines get hydraulic rollers now, it's about durability.
and don't worry about the RPM, hydraulic rollers will turn at least 7k comfortably. I am a fan of Howards HR lifters, zero issues with them. For solids/racing Isky is the only choice. Isky of PAC springs for everything.

 

[jjjaffo]

even grocery getter engines get hydraulic rollers now, it's about durability.
and don't worry about the RPM, hydraulic rollers will turn at least 7k comfortably. I am a fan of Howards HR lifters, zero issues with them. For solids/racing Isky is the only choice. Isky of PAC springs for everything.

Yes even grocery getters get them. And yes, you can wind them up pretty high. However, the heavy valve train and stiff springs can create bleed down issues in the upper RPMs resulting in less lift and duration. Not saying it will, but can. The average grocery getter has a pretty lazy cam in them designed to go hundreds of thousands of miles. As we all know performance cams tend to push the envelope of reliability and require high quality parts to make them live. This is especially true for flat tappet cams. Isky makes great camshafts and PAC springs are some of the best out there. I also have had good luck with Lunati and Comp cams. There's lovers and haters for all of them. For solid flat tappet cams on the street I tend to get custom cams from comp because they tend to have the milder profiles I'm looking for. I had another thread on this site where people questioned my choosing mild cams for the compression I run. Here's the deal: I like the highest cranking compression safely possible for pump gas. The higher that number, within reason, the more torque the engine produces. As has been said many times cams must be matched to the right compression ratio. My little 408 BBC runs factory closed chamber iron heads, 9.7 to 1 compression, 185 PSI cranking compression, terrible .070" quench and too much timing and it runs like an animal all day long on 91 octane pump gas. No detonation at all. This is with a 270 magnum hydraulic flat tappet timed 6* advanced. The only problem is the heads with the small 2.06 intake valves make the engine peak out at about 5 grand. Since the lift is only .510" I think I can up the peak a few hundred RPMs with a comparable solid flat tappet and gain about .035" lift after lash. It's just not worth the expense to put quality heads on this little guy because I have a 496 build in mind. Till the money becomes available to make that a reality I continue to tinker with my baby rat. And help others with their builds.

 

[jjjaffo]

On the bigger is better theory, I have another Idea/question: What about putting a super charger on either the 454 or the 496? Actually I'm leaning towards the 496. Predator Carb Guru got me thinking When he talked about being crushed into the seat. I have always loved the look of a roots style blower on top of a big block- even though they are not the most efficient. This is unchartered territory for me as I've never built a blown engine. I want to run this for extended periods of time on the street so the combination has to be dead reliable. I'm looking to keep the intake charge temperature at a reasonable level so as not to need a cooler or worry too much about evil detonation. What is a safe 91 octane street friendly compression ratio? Safe boost level? What size blower to feed this thing? I assume dual carbs, what size? Reasonable cam? Do I need a boost referenced ignition system? My car is a G-body so I need a good radiator that fits and would cool this thing. I know I'll need a seriously beefed up transmission to handle this thing. Torque convertor recommendation? Because it will be street driven I don't want to go any higher than a 3.42 gear. Will a custom 12-bolt hold up or is this Ford 9-inch territory? I already have 2" super comp headers w/ 3 1/2" collectors, will these be enough? Will 3" exhaust get the job done? Like I said it's mostly street so will spend little time in the upper RPM range. I need real advise on this because I'm totally out of my element here. P.S. how about a good head recommendation?

 

[Dfish1247]

What's your budget? Not just the cost of the motor, but having to build the car not to disintegrate around it(roll cage, trans, rear end,etc) The supporting cast is just as if not more expensive than the engine itself.

I asked about this myself and got talked out of it, way too much of a project that I wanted to tackle, including the money. Mainly the money as I'm not rich.

Have you ever ridden in a blown big block car? I have and it is a violent experience, you'd get used to it, but the first time was like getting hit in the back by a freight train, not very funny watching the gas gauge move just as fast as the speedometer if your the owner either.

Figure on using an 8-71, more volume with less rotor speed means less heat, less heat=less chance of detonation.

Call dyers blowers, I spent over an hour getting most of the deal explained to me, never tried to sell me a thing either. Other than someone who owns one, they can fill you in.

 

[ericnova72]

On the bigger is better theory, I have another Idea/question: What about putting a super charger on either the 454 or the 496? Actually I'm leaning towards the 496. Predator Carb Guru got me thinking When he talked about being crushed into the seat. I have always loved the look of a roots style blower on top of a big block- even though they are not the most efficient. This is unchartered territory for me as I've never built a blown engine. I want to run this for extended periods of time on the street so the combination has to be dead reliable. I'm looking to keep the intake charge temperature at a reasonable level so as not to need a cooler or worry too much about evil detonation. What is a safe 91 octane street friendly compression ratio? Safe boost level? What size blower to feed this thing? I assume dual carbs, what size? Reasonable cam? Do I need a boost referenced ignition system? My car is a G-body so I need a good radiator that fits and would cool this thing. I know I'll need a seriously beefed up transmission to handle this thing. Torque convertor recommendation? Because it will be street driven I don't want to go any higher than a 3.42 gear. Will a custom 12-bolt hold up or is this Ford 9-inch territory? I already have 2" super comp headers w/ 3 1/2" collectors, will these be enough? Will 3" exhaust get the job done? Like I said it's mostly street so will spend little time in the upper RPM range. I need real advise on this because I'm totally out of my element here. P.S. how about a good head recommendation?

454 or 496 blown on pump gas.
-7.5-8.0:1 compression ratio, 6-8 psi boost. Will need forged steel crank and better than stock connecting rods, forged pistons flat top or dish depending on head combustion chamber size. Crank will need to have twin crank keyways for blower drive hub or harmonic balancer drive reliability.
-8-71 blower, a water/methanol supplement injection to help cool the mixture during boost, and a boost retard ignition, the injection and retard could allow the use of boost up to 10-11 psi on the street, twin 850 cfm carbs or 950's
-Aftermarket 12-bolt, Dana 60, or 9" will all work(but avoid a stock housing 12-bolt).
-TH-400, 4L80E, or aftermarket PowerGlide for the trans,(700R4/4L60-65-70 or TH-350 won't have a chance). Stall converter doesn't need to have real high stall but does need to be built to handle the amount of power put out, a $200-300 "2800 stall" is not going to live long, figure $800+ for the converter, 9.5 to 11.0" blower spec converter.
-DART/Brodix/AFR/ProFiler for heads, talk to both them and the blower company to find out the best spec for the use and power you want.
-Supercharger...Blower Drive Service, Mert LittleField Blowers are a couple that come to mind. but there are others out there. Not Weiand/Edelbrock/Holley
-2" headers and 3" exhaust would work, 2-1/4" headers 3.5" exhaust would be better.
-Don't forget a stout driveshaft, along with it really ought to have the frame boxed(it is open channel from just behind front tire to just before rear tire, a weak section that should be boxed shut. Probably should have a cage, minimum would be at least a rear half 4 point roll bar but that won't be legal without a door bar on the driver side if you even intend to go to the track.
- if staying with stock suspension in the rear, will need to be all aftermarket arms, and have all the frame mounting points reinforced.
-Radiator shouldn't be a big issue, these cars have a large core support area for radiator mounting. A good big aluminum core should do it.

Between engine parts, blower, and the parts for drivetrain, trans, fuel system, ignition and all the little bits you probably looking at $30,000.
motor parts is 8k in a stock block(another 3K aftermarket block), trans 2K, converter 1k, rear axle and suspension parts 3k, blower, carbs, water-meth, ignition 7-8k...and then you've got all the little things like roll bar, frame mods, wheels, tires, driveshaft, exhaust, radiator, waterpump and pulleys to fit with the blower drive in the way, fuel pump/lines/filters/regulators, tank sump or cell

Big power costs money...then beefing everything else up to that power standard costs as much or more....otherwise it just sits in the garage busted all the time if you try to take shortcuts.

 

[Dfish1247]

454 or 496 blown on pump gas.
-7.5-8.0:1 compression ratio, 6-8 psi boost. Will need forged steel crank and better than stock connecting rods, forged pistons flat top or dish depending on head combustion chamber size. Crank will need to have twin crank keyways for blower drive hub or harmonic balancer drive reliability.
-8-71 blower, a water/methanol supplement injection to help cool the mixture during boost, and a boost retard ignition, the injection and retard could allow the use of boost up to 10-11 psi on the street, twin 850 cfm carbs or 950's
-Aftermarket 12-bolt, Dana 60, or 9" will all work(but avoid a stock housing 12-bolt).
-TH-400, 4L80E, or aftermarket PowerGlide for the trans,(700R4/4L60-65-70 or TH-350 won't have a chance). Stall converter doesn't need to have real high stall but does need to be built to handle the amount of power put out, a $200-300 "2800 stall" is not going to live long, figure $800+ for the converter, 9.5 to 11.0" blower spec converter.
-DART/Brodix/AFR/ProFiler for heads, talk to both them and the blower company to find out the best spec for the use and power you want. -Supercharger...Blower Drive Service, Mert LittleField Blowers are a couple that come to mind. but there are others out there. Not Weiand/Edelbrock/Holley
-2" headers and 3" exhaust would work, 2-1/4" headers 3.5" exhaust would be better.
-Don't forget a stout driveshaft, along with it really ought to have the frame boxed(it is open channel from just behind front tire to just before rear tire, a weak section that should be boxed shut. Probably should have a cage, minimum would be at least a rear half 4 point roll bar but that won't be legal without a door bar on the driver side if you even intend to go to the track.
- if staying with stock suspension in the rear, will need to be all aftermarket arms, and have all the frame mounting points reinforced.
-Radiator shouldn't be a big issue, these cars have a large core support area for radiator mounting. A good big aluminum core should do it.

Between engine parts, blower, and the parts for drivetrain, trans, fuel system, ignition and all the little bits you probably looking at $30,000.
motor parts is 8k in a stock block(another 3K aftermarket block), trans 2K, converter 1k, rear axle and suspension parts 3k, blower, carbs, water-meth, ignition 7-8k...and then you've got all the little things like roll bar, frame mods, wheels, tires, driveshaft, exhaust, radiator, waterpump and pulleys to fit wit the blower dive in the way, fuel pump/lines/filters/regulators, tank sump or cell

Big power costs money...then beefing everything else up to that power standard costs as much or more....otherwise it just sits in the garage busted all the time if you try to take shortcuts.

See what I mean? Couldn't help it, too good not to give credit where it's due.

 

[jjjaffo]

454 or 496 blown on pump gas.
-7.5-8.0:1 compression ratio, 6-8 psi boost. Will need forged steel crank and better than stock connecting rods, forged pistons flat top or dish depending on head combustion chamber size. Crank will need to have twin crank keyways for blower drive hub or harmonic balancer drive reliability.
-8-71 blower, a water/methanol supplement injection to help cool the mixture during boost, and a boost retard ignition, the injection and retard could allow the use of boost up to 10-11 psi on the street, twin 850 cfm carbs or 950's
-Aftermarket 12-bolt, Dana 60, or 9" will all work(but avoid a stock housing 12-bolt).
-TH-400, 4L80E, or aftermarket PowerGlide for the trans,(700R4/4L60-65-70 or TH-350 won't have a chance). Stall converter doesn't need to have real high stall but does need to be built to handle the amount of power put out, a $200-300 "2800 stall" is not going to live long, figure $800+ for the converter, 9.5 to 11.0" blower spec converter.
-DART/Brodix/AFR/ProFiler for heads, talk to both them and the blower company to find out the best spec for the use and power you want.
-Supercharger...Blower Drive Service, Mert LittleField Blowers are a couple that come to mind. but there are others out there. Not Weiand/Edelbrock/Holley
-2" headers and 3" exhaust would work, 2-1/4" headers 3.5" exhaust would be better.
-Don't forget a stout driveshaft, along with it really ought to have the frame boxed(it is open channel from just behind front tire to just before rear tire, a weak section that should be boxed shut. Probably should have a cage, minimum would be at least a rear half 4 point roll bar but that won't be legal without a door bar on the driver side if you even intend to go to the track.
- if staying with stock suspension in the rear, will need to be all aftermarket arms, and have all the frame mounting points reinforced.
-Radiator shouldn't be a big issue, these cars have a large core support area for radiator mounting. A good big aluminum core should do it.

Between engine parts, blower, and the parts for drivetrain, trans, fuel system, ignition and all the little bits you probably looking at $30,000.
motor parts is 8k in a stock block(another 3K aftermarket block), trans 2K, converter 1k, rear axle and suspension parts 3k, blower, carbs, water-meth, ignition 7-8k...and then you've got all the little things like roll bar, frame mods, wheels, tires, driveshaft, exhaust, radiator, waterpump and pulleys to fit with the blower drive in the way, fuel pump/lines/filters/regulators, tank sump or cell

Big power costs money...then beefing everything else up to that power standard costs as much or more....otherwise it just sits in the garage busted all the time if you try to take shortcuts.

Boy did you put everything into perspective in a quick hurry, LOL! So with that being said, what are the odds of the car staying together with a naturally aspirated 496? I know the rear end has to be replaced; that's just a given. But do I need a cage or box the frame? If I get a good tire on it and get it to hook up decent will I damage the frame by tweaking it all out of shape? I guess I need a reality check from the experts. I love the idea of hero power, but not at the expense of my safety! Money is not free flowing but there is usually a few hundred available at the end of every month and the car is safely tucked away in a shop. Time is on my side as I'm in no hurry. Actually right now I have more money than time due to working 60+ hours a week, LOL! So yeah, let's be more realistic about this build and figure it with a N/A 496 of around 500-530 horse power. I would imagine torque would be close to 550 lbft. Of course all dependent on how I build the engine. So, for a safe and pleasurable drive what key things do I need to pay attention to on the car itself? My only real experience with a heavy power to weight ratio was when I was 17 and I took the bone stock 2-bbl 351w out of my 77 LTD and put it in my 80 Pinto. An incredible undertaking and it wasn't as powerful as I'd hoped, but still damaged the frame and when you floored it you could watch the air cleaner shift almost two inches under the homemade scoop. I'd like to be several degrees safer than that!

 

[ericnova72]

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: