Thoughts on street engine.

[darbgnik]

I'm nowhere near the engine expert as some members on here, but I honestly believe your limiting factor in your original post is the 727. Just not enough gears, and too much spread between. The newer muscle are hilarious to drive. My girlfriends new SRT8 Grand Cherokee is almost into 3rd gear by the time we're through an intersection, because it's an 8 speed. That 6.4 in there never revs out unless you hold it completely to the floor boards. Do I think you need an 8 speed to be quick and efficient? No. Six speeds? No. I think 5 is sufficient, and 6 speed plus autos, are mostly driven by fuel economy.

I think a 4 speed auto could get you close, as long as there is a big jump from 3rd to 4th. The key to a nice jump off the line is a low 1st gear, and keeping that jump requires the next two shifts to land the engine right back into it's powerband, so the ratios need to be reasonably closely spaced. Obviously, with a ridiculous 700hp monster motor all you need is 2 gears and a slippery torque converter.... but now we're not talking about cruisers anymore.

My 70 came with 4.10s behind the 727, which makes the stomp off the line reasonably entertaining, but anything over 50 mph painful, so not a cruiser. I have a 3.55 center section I'm going to throw in, in the spring to try how it feels, but I honestly feel what I'm looking for would be best solved with a 4 speed. Sadly, the easiest bolt in, no cutting, 4 speed auto is the GM 4L60 that SilverSport sells. If memory serves me correctly, they have a nice, low, first gear. And the lock up torque converter in OD is what nets you the most fuel economy.

Out old 727 trannys are stout, but efficient they are not.

[c00nhunterjoe]

You can buy low gearsets for the 727

[darbgnik]

You can buy low gearsets for the 727

This is true! But then wouldn't it miss the mark on the cruising/fuel economy part of his equation?

[Mike DC]

  
No, it's just the first two gears being lowered.  The top gear is still 1:1 so the steady cruising RPM isn't changed.

It mimics the ratios of the smaller 999/A500 T-flites from the 1980s-90s.




With the automatic overdrive options being so troubled with crossmember cutting, big prices, GM trannys, etc . . . I'm kind of surprised that lowering the 727's first two gears isn't a more popular mod.  Or you could combine an A518 overdrive + lowered first two gears, for a really wide spread.  

[BSB67]

I don't see how anyone can say a stock 383 is fun to drive.

Probably the least torque producing engine of this size ever, all else being equal.

[Mike DC]

  
The factory rating was 425 lbs of torque from 383 inches, at 3000-something RPM.  How is that a small figure for the size?  

[darbgnik]

 
No, it's just the first two gears being lowered.  The top gear is still 1:1 so the steady cruising RPM isn't changed.

It mimics the ratios of the smaller 999/A500 T-flites from the 1980s-90s.

Learn something new every day! Thanks.

With the automatic overdrive options being so troubled with crossmember cutting, big prices, GM trannys, etc . . . I'm kind of surprised that lowering the 727's first two gears isn't a more popular mod.  Or you could combine an A518 overdrive + lowered first two gears, for a really wide spread.  

But doesn't the 518 still require cutting in a gen 2? Then you'd need an adapter. And there would only be manual control of the lock up function right?

[BSB67]

 
The factory rating was...........

And I have some property.....I'd like to sell you.

[birdsandbees]

True dat..

That said. I shoe polished "13.80/2" most Sundays in 79/80/81 on my windshield and ran a fairly consistent 13.84/5 @ 100/102 MPH with my 'Bee.

Stock 383 magnum, 750 Holley, 4 gear, shit Tornado tires and 2.94 rear end gears. Just rev and launch as it could barely spin with that rear end and then just hold it to the floor and slam gears.. all the way to 3rd!   Went through a good number of rear joint retainer clips.

[BSB67]

Nice.  Those would probably be the best numbers I've seen posted by a stock 383 car.  In the late 70's me and my friends were in the high 14 to low 15 at about 89 to 92 mph.  I'm pretty sure Lew got his in the low 13's but was pretty far from stock by that point.

[birdsandbees]

The engine was rebuilt in 1978.. might have got a cam but I don't remember for sure. Other than that it's definitely stock. Somewhere I still have a time card. Thought it was in the glove box but it's not.. must be in my file folder for the car somewhere. Should dig it out and look for it.

Never mattered anyhow.. there was always two lads with Mom's Rambler station wagon... slant 6 / auto and I think they had about 28 seconds in the windshield. Never failed, they won the bracket money ever week! Wait 'till green. .mash it and go while the chaser sat at the lights for 14+ seconds waiting to launch..  Track in Luskville QC is about 200' ASL.

[BSB67]

Did it still have the small factory AVS carb on the factory cast iron intake and exhaust manifolds.  Not too many folks were rebuilding motors and putting all the original factory parts back on.

There is a thread on Moparts on how fast were factory 440s.  The few that are responding with what sounds like true stock 440 experiences seem to generally be in the 14 sec, mid 90s mph. This would not include the 6 bbl.  Mine went 14.6 at 94 mph.

[birdsandbees]

Was running either a 650 or 750 holley.. can't remember (the old one is in a bin in the shop) and I did have Hedman headers at the time, short stacked at the rear end. Stock dual plane intake. Gotta find that time slip... and hope my memory is on paper and not in my head!! 

[Dino]

But doesn't the 518 still require cutting in a gen 2? Then you'd need an adapter. And there would only be manual control of the lock up function right?

You will need to put a dimple or two into the trans tunnel and you'll need to fabricate a rear crossmember. You'll also need to cut off the stock bellhousing and get another one. You can have automatic lock up function as well. Only $85, top of the page: https://transmissioncenter.net/shop/patc-727-to-518-46rh-conversion-kit-click-here-for-727-to-46rh-swap-wiring-diagram/

I'd have done this already but I'd rather spend the effort into installing a T-56. Way different budgets though. 

[PRH]

Off topic a bit...... But.....

About 7 years ago or so I got to drive a very stock, 21,000 mile 69 RR with a 383, 4 speed, 3.23's.
It was kind of a mutt.
I had gone through the heads and installed hardened ex seats for unleaded fuel, and went through the carb.
The shop that was working on the car went through all the suspension, new tires, brakes, etc.

It was really a pretty nice car to drive...... Just not much of a power house.

[Bad B-rad]

Yes I think the 727 transmission makes it a bit harder to compete with cars with more gears,I would needa lot more HP to make up for the gear advantage. I am starting to look into the 518. As I think this may be the cheapest automatic OD transmission for the B-body,with out cutting stuff up.
Someone on this forum has a 518 in his 2nd gen and said he loves it, he gave me a ton of advice on making one fit and work in B-body, and it just required,as said above just some dimples in the tunnel some grinding on the trans itself and new lower crossmember and driveshaft.
I did a 46RE in E-body and a camero/firebird transmission mount bolted to the 46re and made making lower trans mount much simpler. I think I have the "prototype/first one" I made kicking around the shop. After I made the mount and made sure everything fit and worked as it should I re-made the mount using tubing and made it a little more professional looking vs the first one that looked a little more "redneck".

I think the GM based auto overdrive transmission kit costs about $5500-$6500. I hear it is very nice kit,I do not have that kind of money to slap down on one right now.

[c00nhunterjoe]

Yes I think the 727 transmission makes it a bit harder to compete with cars with more gears,I would needa lot more HP to make up for the gear advantage. I am starting to look into the 518. As I think this may be the cheapest automatic OD transmission for the B-body,with out cutting stuff up.
Someone on this forum has a 518 in his 2nd gen and said he loves it, he gave me a ton of advice on making one fit and work in B-body, and it just required,as said above just some dimples in the tunnel some grinding on the trans itself and new lower crossmember and driveshaft.
I did a 46RE in E-body and a camero/firebird transmission mount bolted to the 46re and made making lower trans mount much simpler. I think I have the "prototype/first one" I made kicking around the shop. After I made the mount and made sure everything fit and worked as it should I re-made the mount using tubing and made it a little more professional looking vs the first one that looked a little more "redneck".

I think the GM based auto overdrive transmission kit costs about $5500-$6500. I hear it is very nice kit,I do not have that kind of money to slap down on one right now.

Putting a 518 in the car will not make it faster because of 4th gear. 4th is overdrive, you wont be going down the track in overdrive.

[Troy]

How much money do you want to spend? Pick an engine build first then decide how many RPMs you want to turn and that will pretty much decide your rear gear and transmission. A 727 is perfectly fine for a "street car". I drive 60/40 on the highway in my old cars. My current 70 Challenger has a 440 Six Pack, 4-speed, 3.23 rear gears, and 28" tall rear tires. The secondaries open at about 3,100 RPM (~72 mph) at which fuel mileage goes to hell. I had 3.91s installed a while back which made stoplight to stoplight runs a whole pile of fun but limited me to 61 mph on the highway. If I had an OD trans that would have worked well - but it wasn't worth the money or effort in my opinion. My previous 69 Charger had a 440 and 727 with 2.76 rear gears. For a highway car it was awesome - around town too. Acceleration was down but it didn't have any trouble spinning tires. I also have a 2015 Scat Pack Charger with the 6.4 and 8-speed trans. It's pretty awesome everywhere - but retrofitting that to one of my old cars would cost more than I paid for the car and the computer controls would make the wiring somewhat daunting (if it even fit!). There's rarely a "perfect" solution: build for stoplight drags and highway driving and mileage will suffer and vice versa. But honestly, the stock(ish) setup is fairly hard to beat with regards to simplicity and cost. Swinging the performance envelope one way or the other requires compromise.

I agree, all those extra gears aren't helping the drag times... depending on the engine!!! A decent 440 will have gobs of torque from somewhere near 1,800 RPM to about 5,500 RPM. Gearing isn't critical. Throw in a high winding small block that has a usable RPM range of 4,500-6,500 and you're gonna need gears! My 70 Mach 1 has a close ratio gearbox for pretty much exactly that reason.

Troy

[Bad B-rad]

No but putting in a 518 lets you run deeper gears(numerically higher) Like stated above 3.91 and he was limited to 61mph  on the highway to cruise.
I had 46RE in an E-body and  I had 4.10 or 4.11 gears and in OD it was turning the same rpm as if I had like 3.00 in the rear. So if you can run an OD trans you can run deeper gears and still cruise the highway at a nice rpm,less noise, less heat, less engine wear, less fuel burnt.
So the 518 wont make you faster but knowing that you can run 4.30 rear end gear and when your transmission shifts in to OD its turning 2300rpm same as maybe 3.07 rear gears that will make you faster,or more specifically you acceleration faster. 

[Kern Dog]

When I had the Gear Vendors in my Charger, I ran a 3.91 gear. In Overdrive, that 3.91 was reduced to 3.05. After I sold the Gear Vendors, I went back to a 3.55. Dropping down to anything close to a 3.05 for economy ( Ha ha ha ha ha ha ha ) makes the car sluggish at low speeds.

[Bad B-rad]

Troy as you said about your Scat Pack Charger being awesome everywhere, I agree and imagine that type of performance in a 69 Charger(straight line acceleration not braking and cornering)That would be amazing correct?
How much power is the Scat Pack Charger putting out? I got stuck with a 2016 Charger R/T I could have gotten an SRT two years older, but my wife HAD TO HAVE the dam R/T that we got.
I also do not have the funds to marry the two car together in one super car.
I would be after a very similar 60/40 highway driving with my car. If I was building a 440 or maybe the 383 stroker then I maybe able to run 2.76, or 2.92 so highway rpm is nice, if the engine make enough power to be respectable.

[Bad B-rad]

Just my opinion, with any 66-74 Mopar car I have had with 727 transmission and 14 or 15 inch tire 3.55 or 3.23 is MY preferred gears if I intend to do lots of highway driving.
3.91 if I only plan on doing short highway trips.
That's just me. I know guys that run 4.10 and don't mind it. but I never enjoyed even the 3.91s on the highway. The speed limit here is 65mph, everybody is actually going 75+ and I never liked running my car at 75 I forget what I was turning for rpm but it just wasn't for me. Everyone is different, and can run what ever they want. I loved the power the 3.91 had but love that the 3.23 made the highway a nicer drive.
I think the new Chargers run like 2.87 or something. But have 8 gears(auto) to make up the difference.

[birdsandbees]

Why I love my 2.94's... the Provincial Police in the late 70's / early 80's not so much !!     

[Bad B-rad]

Why I love my 2.94's... the Provincial Police in the late 70's / early 80's not so much !!     

That is great!!!!!!!!

1968 Dodge Coronet 2.76,s speedo pinned at 120mph let off throttle 8 seconds before it came down off being pinned.Stupid things you do when you are young.I think I had 4 mis-matched semi bald tires to boot.
That was my first Mopar, the car that started it for me.

[Kern Dog]

The Wife and I ordered our 2015 Challenger R/T with the Super Track Pack. The car is the base model R/T with 372 HP and the 8 speed A/T. The Super Track Pack comes with a 3.09 ratio diff. That seems weak but the 8 speed auto 1st gear is 4.7 to 1. What This means the car still pops out of the hole harder than a 727 car with 4.10 gears!