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With a forged crank and decent aftermarket rods, a 496 revs just as fast as the 427, actually even faster when its in gear and moving the car rather than just being free revved in neutral.....reason is the more power you make, the faster the car accelerates and thusly the faster the engine gains rpm.

that old wives tail about 302 and 327 SBC, and 427 BBC being "quick revver's" stems from the fact that in the days when those were the new technology engines, comparing them to Y-block Fords, Flatheads, Chrysler PolyHead, Ford 390 FE's and other typical passenger car designs made the Chevy's seem like quick revvers. But in truth RPM gain depends entirely on how fast you can move the mass of the vehicle.
how it free-revs in neutral means about as much as how fast you can pedal your bike with the back tire off the ground :rolleyes::mwink::mwink:

As far as blowing the tires off on the road....you've got a brain connected to your foot....just use it. :D:D:D
When you've got real power you don't need to mash it clear to the floor just to get around somebody.

As far as that G-body goes....I hope you have more than a stock 7.5" 10-bolt in there, because real power will tear it up right quick if it hooks up at all....plain street tires usually won't hook well enough to break it, but stickier street/strip or autocross tires will.

Either the 427 or a 496 will be a several levels of magnitude improvement over the small BBC you have now, a real eye opener about cubic inches and how bore diameter impacts head flow for you.
 

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Yeah, the factory posi's are weak, the side and spider gear teeth are real fragile.
Care to share how you got 31 spline axles into a 7.5"?? No one makes them, or a posi or spool to fit them, and that size axle won't even fit through the carrier bearings on each end of the differential for that matter.

Biggest axles that will fit through the bearing are 28 spline, up from the factory original in your G-body of just 26 spline....but even then, with 28 spline axles the axles aren't the problem....you get this down into the high 12's at the strip and it's going to start peeling ring and pinion teeth off(pinion stem flexes due to small size and gear mesh goes all to crap and crunch :( ), and there ain't no heavy duty fix for that except an entire rear end swap to something that will handle the power....12-bolt, 8.5" 10-bolt, Ford 9", custom Dana 60.

There's a reason GM put the 8.5" in turbo Buick G-body's, looks like you're about to find out why with the new engine :pain:
 

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If you are talking about rotating assembly clearances, then the connecting rod nuts(if thru-bolt) or bolt head(capscrew type rod) may have clearance problems with the oil pan rail area of the block.....easy to fix, slight 1/16-1/8" groove ground to clear the rod in the oil pan rail, and the stroker oil pan with clearance flats stamped in the pan rail.
you will also have to put similar notches at the bottoms of the cylinder barrels, near the can tunnel, depending on which connecting rods are used.

You'll need to do a trial assembly, one cylinder at a time. to find all the locations to grind. SBC strokers have to go through the same process.

This pan image will give you a good idea what this is, block needs to look something like that at the oil pan rail.


Block images:
https://www.bing.com/images/search?...&selectedindex=13&ajaxhist=0&vt=0&eim=0,1,2,6



Hot Rod mag article that will help you a lot.
https://www.hotrod.com/articles/how-to-clearance-big-block-chevy-for-stroker-crank/
 

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SCAT is also Chinese sourced forgings and castings, but SCAT does finish machining here in the US whereas Eagle doesn't.

Most all you crankshaft companies entry level stuff is cast or forged in Asia..Callies CompStar, Molnar, Ohio Crankshaft, along with SCAT and Eagle.
The better companies just do the final machining here in the US, so they can control finish quality.

I like SCAT over Eagle....but Eagle has improved from their earlier problems with sizing and finish and don't appear to have the same problems and poorer reputation they once had.

Stay away from CAT though(Cal Auto Transpeed), very poor quality and finish on the cranks I've seen.
Current unknown on exactly how good the quality is happens to be SpeedMaster(ProComp)...some of it is Ok, some is poor, but it is steadily improving in most cases.
I don't personally know anyone who has used their cranks or pistons....but their connecting rods or decent. You can get the rods fairly cheap, but with questionable Chinese bolts in them...by the time you add replacement ARP bolts and pay for a roundness check on the bores after adding the better bolts you are getting close to SCAT or Eagle price territory.

For your plans, the SCAT or Eagle cast crank would work out fine. I recommend forged pistons to everyone who askes about a stroker, I just think it is good insurance as strokers are never driven by a grandma, they are driven fairly hard and forged pistons give you a wider tuning window along with room to grow down the road(nitrous, bigger cam, more rpm) as hot rod stuff often evolves as we change our minds on what we want or get greedy about power.

This is the best deal on stroker kits I've found as it includes harmonic damper and flexplate and has a special forged piston...you can find cheaper but they typically leave pieces out or use lower grade components or hypereutectic pistons to get that lower price point.
https://www.ebay.com/itm/BBC-CHEVY-...261648?hash=item569b27c290:g:nzUAAOSwo3pWgk44
 

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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.
 

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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.
 

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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:
 

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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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