Limited slip or full spool?

[furious70]

sorry the Offy intake is the bad one, Weiand is fine

Part 1 of Hot Rod's Mopar Intake Manifold Shootout

The OEM intake 68-70 for 383 is pretty good, if you had one I'd just use it. If you're buying one, might as well lighten up the engine a few pounds.

 

[SuperDave]

Okay, here's my 2 cents. If you're looking for low end, you want torque. I'm assuming you have an automatic transmission, I'd suggest you consider a looser torque converter, in the 2400-2800 range. That will multiply the torque to near double what the flywheel develops, allowing faster off-the- line performance. Any looser than that will cause excessive slip at highway speeds, unless you upgrade to a later model trans with a lock up converter. It is possible to have your 727 transmission rebuilt with lower 1st & 2nd gears to give you more low end grunt.

A750 carb sounds like overkill for a street car, the primaries are too big to provide decent part throttle response. Great for top end power, less so for low end grunt. For a 383 it's a tad too big, unless your goal is top end screaming on the dragstrips and highways. Same goes for a 3" exhaust. 2.5" duals is just fine for a street car, for low end response you want some back pressure on the pipes, and it won't sacrifice gas consumption or that nice musclecar idle we all love.

Speaking of idle, you never did mention what kind of camshaft you have/intend for this.

Back to the original post: LSD vs Spool. For a street car with limited track time, I vote LSD. Easier on the axles & tires, not to mention gas mileage. Manuvering around parking lots, corners and curves with a spool fighting you will require more power to push it thru the curves, requiring more throttle and gas.

You got 275s mounted under yours? Damn, I'm envious! What kind of rims and backspacing are you running? Post some pics please! That's a lot of traction, add a spool and see your gas mileage dip into the low single digit range as your 383 fights to push it around a corner. Seriously, limited slip please, before you buy some Arabian prince another Bentley or a fleet of Tesla's for some oil executive team. Your wallet and the ecosystem will thank you in the long run. Spend a little extra coin now and save it back in the long run.

 

[B-Rode]

Okay, here's my 2 cents. If you're looking for low end, you want torque. I'm assuming you have an automatic transmission, I'd suggest you consider a looser torque converter, in the 2400-2800 range. That will multiply the torque to near double what the flywheel develops, allowing faster off-the- line performance. Any looser than that will cause excessive slip at highway speeds, unless you upgrade to a later model trans with a lock up converter. It is possible to have your 727 transmission rebuilt with lower 1st & 2nd gears to give you more low end grunt.

A750 carb sounds like overkill for a street car, the primaries are too big to provide decent part throttle response. Great for top end power, less so for low end grunt. For a 383 it's a tad too big, unless your goal is top end screaming on the dragstrips and highways. Same goes for a 3" exhaust. 2.5" duals is just fine for a street car, for low end response you want some back pressure on the pipes, and it won't sacrifice gas consumption or that nice musclecar idle we all love.

Speaking of idle, you never did mention what kind of camshaft you have/intend for this.

Back to the original post: LSD vs Spool. For a street car with limited track time, I vote LSD. Easier on the axles & tires, not to mention gas mileage. Manuvering around parking lots, corners and curves with a spool fighting you will require more power to push it thru the curves, requiring more throttle and gas.

You got 275s mounted under yours? Damn, I'm envious! What kind of rims and backspacing are you running? Post some pics please! That's a lot of traction, add a spool and see your gas mileage dip into the low single digit range as your 383 fights to push it around a corner. Seriously, limited slip please, before you buy some Arabian prince another Bentley or a fleet of Tesla's for some oil executive team. Your wallet and the ecosystem will thank you in the long run. Spend a little extra coin now and save it back in the long run.

Great advice. The exhaust is actually going to be 2.5 for fitment purposes, just coming out of the headers is 3".
Rear wheels are American Racing Indy Mags 15x8 on 275/60 r15.
Camshaft is stock, whatever it is for a 70 383. Haven't looked into which cam I want yet.

 

[david hill]

A spool is strictly for the strip, not a 2 1/4 ton full size car. With that much weight and a 383 a 750 AFB and 3.23 gears a much better package. A Higher stall convertor will give you even poorer. results. Not enough eng. to warrant convertor change. Off throttle response in traffic w/ a convertor, big carb and 3:55 gearing is not a good combo. I do think a sure grip would be a great move. Just drive around a car show on grass venue w/o one.

 

[MoparapoM]

IMHO, the Headers are a waste of money and reliability also. With that tame engine and the RPMs you will Max out at, the Manifolds with Duals are a much better investment.

Bruce

 

[B-Rode]

A spool is strictly for the strip, not a 2 1/4 ton full size car. With that much weight and a 383 a 750 AFB and 3.23 gears a much better package. A Higher stall convertor will give you even poorer. results. Not enough eng. to warrant convertor change. Off throttle response in traffic w/ a convertor, big carb and 3:55 gearing is not a good combo. I do think a sure grip would be a great move. Just drive around a car show on grass venue w/o one.

3.23 sure grip is probably what I'll go with. Seems like a great balance

 

[67valiant 100]

I would suggest the higher stall 340/383hp torque converter. That is one thing I want do this year to my car (383-2bbl originally with a 4bbl swap, mopar performance 484 purple camshaft, hp manifolds w/ dual exhaust & a 3.23 gear set that replaced the original 2.76s)

 

[78Brougham]

Nice looking car

I'd leave it alone... Drive, Enjoy, Repeat.

 

[B-Rode]

I would suggest the higher stall 340/383hp torque converter. That is one thing I want do this year to my car (383-2bbl originally with a 4bbl swap, mopar performance 484 purple camshaft, hp manifolds w/ dual exhaust & a 3.23 gear set that replaced the original 2.76s)

How do you like the car overall with the 4bbl, 3.23 and duals? Better all around the powerband?

 

[67valiant 100]

How do you like the car overall with the 4bbl, 3.23 and duals? Better all around the powerband?

These were upgrades done over the last 20 years. The gear swap was definitely the biggest improvement, gone is the feeling of always lugging the car around. It drives & cruises nicely in the mountains of the northeast.

 

[furious70]

Best money some members could spend would be a motor trend online sub to watch engine masters where they test many of these age old questions

 

[B-Rode]

These were upgrades done over the last 20 years. The gear swap was definitely the biggest improvement, gone is the feeling of always lugging the car around. It drives & cruises nicely in the mountains of the northeast.

How's the highway rpms with 3.23? Do you have a louder exhaust?

 

[furious70]

With stock converter and 28" tires I ran 3000rpm @70mph give or take 1-2mph back in the day. Wasn't too bad with normal exhaust, with the flowmaster 10 series I ran for a time, it was loud!

 

[FURYGT]

Why go with 3" headers to only choke the exhaust flow down into 2.5" pipes? That makes no sense to me.

To me the biggest pros and cons on headers vs HP exhaust manifolds is getting and keeping headers sealed and not having any exhaust leaks.

There is a lot of good advice here. I would go with an Eddy carb vs. a Holley. You don't need a 750 IMHO but in the future if any further upgrades are made then the 750 may be beneficial.

As far as I know the 383-2V cam in 1970 is the same cam used in the 350 HP T code 440. The heads are the same on all big blocks in 1970.

If your 383-2V is healthy and tuned properly I don't know why it won't spin the tires even with a 2.76 rear gear. A little power brake and it should do it.

I think with a good electronic ignition, HP exhaust manifolds, dual exhaust, the right mufflers, the right 4 bbl intake (even a stock one) and carb along with a 3.23 or 3.55 rear gear will make you very happy with the cars performance. Just my 2 cents.

 

[marty koirtyohann]

70 Sport Fury 383

I'll be getting 3.55s put in but can't decide whether lsd or full spool will work better for me.
A friend said my 275 rear tires are "too big" for lsd to help with traction and that a full spool is the only way to go. Spool is much cheaper as well as very strong, and I may be willing to sacrifice some low speed driveability for performance. Lsd however, would be my choice IF it is effective enough with the tires, gears and power the car will be making.
The car will be getting headers w/3 inch dual exhaust, as well as Holley 750 street demon carb w/weiand dual plane intake. Those should wake the car up quite a bit, but is lsd worth the extra $$?

Not a daily, mixed driving.

Any info helps, thanks!

put a oem mopar "posse" if it its a 8 3/4 unit go to the diff doctor Drivetrain :: Mopar 8 3/4" he builds new ones

 

[NewportRbod]

70 Sport Fury 383

I'll be getting 3.55s put in but can't decide whether lsd or full spool will work better for me.
A friend said my 275 rear tires are "too big" for lsd to help with traction and that a full spool is the only way to go. Spool is much cheaper as well as very strong, and I may be willing to sacrifice some low speed driveability for performance. Lsd however, would be my choice IF it is effective enough with the tires, gears and power the car will be making.
The car will be getting headers w/3 inch dual exhaust, as well as Holley 750 street demon carb w/weiand dual plane intake. Those should wake the car up quite a bit, but is lsd worth the extra $$?

Not a daily, mixed driving.

Any info helps, thanks!

Spool on the street even with limited use is bad news. Yes it can be done, just like a hotel room lobotomy, but it isn't a good idea. Where the idea that 275's are too wide for a limited slip differential is blowing my mind. The only real thing that comes to mind: HE DRIVES A CHEVY or even worse A IMPORT.

 

[Big_John]

Yes it can be done, just like a hotel room lobotomy, but it isn't a good idea.

I'm going to use that quote for a lot of things, not necessarily car related.

 

[NewportRbod]

I wasn't going to comment, but here goes...

If that is truly what you want, you need to step back a little. You've been getting some bad advice about how to set up for low end.

First, let's talk about the rear... Yes, a sure-grip rear is the way to go, but it really won't give you any more low end power. All it does is make both tires spin rather that one. The spool is just plain stupid and you need to stop listening to whoever suggested that for the street. The locker is an "off road" type piece for a Jeep or truck. Look up the downsides of using one for more info. I think the 3.23 ratio is a good choice.

You have a (relatively) heavy car and building low end power is where you want to be. 3" exhaust isn't going to take you there. I'm not a fan of headers (yes, I've run them) and I really think for a C body, built for low end performance, that the high performance exhaust manifolds is the better choice. TTI makes a nice fitting 2 1/2" exhaust that will work better with your combination.

You are probably OK with the choice of intakes, but I might think about going smaller with the carb and looking at the Edelbrock AVS or AFB carbs rather than the Holley. Again, low end performance and drivability.

The "upgrades" you speak of aren't going to get you where you want to go... You have to look at the car as a whole rather than little pieces. You start adding headers, big exhaust, big carbs... They all sound good until you realize that you've now got a car that still needs a different cam, looser converter, more gear etc. to take advantage of your mods and have it run better than where you started.

If it were me, I'd just do a dual exhaust using the existing manifolds, find a stock 4bbl intake and an Edelbrock AFB, maybe recurve the distributor. From there, the 3.23 gears would be good. You would end up with a nice running car with better performance than what you have now.

I agree with most of these, it may be kind of hard to find a good guy to recurve a distributor these days. The carb if you drop to 650 cfm will liven up throttle response. The 750 is a good choice but the kickdown on the 650 gives a better response in my experience. It is hard not to end going down a rabbit hole. Increase power then overtax systems down the line. Go faster new brakes...new torque convertor new transmission cooler. On and on it goes.

 

[furious70]

One reason for 2.5" tailpipes at least is the 3" is a pita to install and keep it from hitting things.
I get the theory of the smaller carb but my 383's have always liked a 750

 

[HWYCRZR]

I agree with most of these, it may be kind of hard to find a good guy to recurve a distributor these days. The carb if you drop to 650 cfm will liven up throttle response. The 750 is a good choice but the kickdown on the 650 gives a better response in my experience. It is hard not to end going down a rabbit hole. Increase power then overtax systems down the line. Go faster new brakes...new torque convertor new transmission cooler. On and on it goes.

@halifaxhops can recurve a distributor.