Will I regret change to 3.55s from 2.76s

[TT5.9mag]

Now you've gone and hurt my feelings . In a good year I may do 3000. Believe me, if I was in Southern California, it would be on the road a lot more. Illinois weather can be pretty crummy. I basically will not drive it if there is a chance for rain as I don't want to feed the rust monster and it doesn't get left unattended in a parking lot. There are just too many stupid people around where I live. Took me 12 years to redo and I want it to stay nice as long as it can. I think my insurance actually limits me to 2500 miles, although they've never checked up on me. And no, 4.56 aren't happening.

Ok ok I hope you know I was joking. Kinda. I feel a little differently than you do because I’d never spend a bunch of money to redo a car and not drive it. I don’t see the point. And trust me when I tell you, there are WAY more idiotic drivers here than just about anywhere. But they aren’t going to keep me from enjoying my junk. My recommendation to you is this, and this time I’m very serious, put 3.91s in your car and then put an overdrive trans. It’s that whole “have cake and will eat it” type of deal.

 

[marksmopars]

Something which hasn’t been mentioned in this thread that does have an impact is the transmission. Is it an automatic or manual, if manual then 3 speed or 4? If it’s a 4 speed, is it a close ratio or wide ratio? The wide ratio transmission has a lower first gear and a bigger spread between the gears. The close ratio has a higher first gear and closer spacing on the gear ratios. Now it’s my understanding that most small block 4 speeds are close ratio and most big block units are wide ratio gearing, a big block will generally pull through a longer rpm range than a small block, which tends to make hp at higher rpm and through a smaller rpm range. All this needs to be factored in to understand what you can expect. No matter what it sound like your having fun!

 

[1973dust]

Ok ok I hope you know I was joking. Kinda. I feel a little differently than you do because I’d never spend a bunch of money to redo a car and not drive it. I don’t see the point. And trust me when I tell you, there are WAY more idiotic drivers here than just about anywhere. But they aren’t going to keep me from enjoying my junk. My recommendation to you is this, and this time I’m very serious, put 3.91s in your car and then put an overdrive trans. It’s that whole “have cake and will eat it” type of deal.

We're good. I just noticed that the stupid little smiley faces and stuff I thought I included in my response aren't there. I was attempting to make light of everyone being offended nowadays. Believe it or not, I get comments from people about how cool they think it is that I drive my car as much as I do. In this area, you really don't see classic cars on the road much at all. I just refuse to subject it to crummy weather. I've got more blood and sweat in it than money which probably makes me overprotective. It's really not even that nice but everything has been done by me. Yes, 3.91s and overdrive would be the ultimate but I don't think I'll ever justify spending that much money.

 

[Owen 340+6]

Aluminum headed 340, 3.91's and 4 speed 70 duster. It's great!

 

[66fs]

No real difference in feel between 3.23 or 3.55 gears. Most guys I knew, went for the 3.23 for better mpg and all around enjoyable driving. I always used to drive my cars long distance high speed. Nice not to have stop for gas before 300 miles. Long trips got the 2.76 pumpkin.

 

[Dana67Dart]

But that's barely a change

Yes I agree.

 

[junkyardhero]

The national average difference between premium and regular pump fuel is 30 cents. So @junkyardhero statement holds up. In “most” places a tank of premium vs a tank of regular will average about $6.00 not enough to worry about.

see! see! i am capable of level headed conversation and reasonable thought!

my feeling is, if it's costing more than about 1/4 tank to run premium or an additive then it's time to rethink strategy. but if you're putting on sub 5K miles a year and need premium, the cost per tank should be way down on the "concerns" list.

 

[273]

I find it funny when it comes to low speed torque at the crank, almost everyone goes on a rant about keeping every precious lbs-ft when it comes to cid, cam, cr, intake etc.. but when it comes to gearing their willing to toss a equivalent of a 100+ lbs-ft at crank

 

[junkyardhero]

3.23 is the compromise gear. it does well on the fwy, and it's still got some balls around town (especially when paired up with low trans gears).

but for your application? 3.55 would be my choice or heck, even 3.91's would be fine.

that cam starts singing around 3K and with the type of driving you're doing you'll never even get into the chorus with the freeway friendly sets and those tall tires.

big deal if you twist her tail a little bit. it's not like you're hanging it at 4K for hours on the freeway in the slow lane trying to keep up with traffic.

 

[1973dust]

3.23 is the compromise gear. it does well on the fwy, and it's still got some balls around town (especially when paired up with low trans gears).

but for your application? 3.55 would be my choice or heck, even 3.91's would be fine.

that cam starts singing around 3K and with the type of driving you're doing you'll never even get into the chorus with the freeway friendly sets and those tall tires.

big deal if you twist her tail a little bit. it's not like you're hanging it at 4K for hours on the freeway in the slow lane trying to keep up with traffic.

I've been really paying attention to the tach this week and you are correct. Even under what I consider pretty decent acceleration, I almost never even hit 2500 rpm. I drug the rear out after work today so I can start hacking. I never realized how much I've been holding it back with the 2.76s until reading all of these responses. I'm pretty excited now to see what I've apparently been missing.

 

[Dave999]

i have heard it said that 3.73:1 is the ideal set up for a weekend warrior street strip set up...
with the right tyre height gives best of both, a good all rounder

this is potentially just internet BS.... or GM Chevy chatter......but you can't un read it once its been said a few times....

i have set but never fitted cos the 3.45:1 do the job for me...

obviously when i saw that 3.73:1 gear set, the magic number triggered my wallet and i purchased it... rare as hens dentures, for my axle...only used in Morgan Aero 8.... probably still be on the shelf when i'm collecting my pension but you never know...one day when i get an appetite for the smell of gear oil again...

Dave

 

[273]

I've been really paying attention to the tach this week and you are correct. Even under what I consider pretty decent acceleration, I almost never even hit 2500 rpm. I drug the rear out after work today so I can start hacking. I never realized how much I've been holding it back with the 2.76s until reading all of these responses. I'm pretty excited now to see what I've apparently been missing.

Hp percentage of torque is less than half at 2500 rpms and under and by 1313 rpm is a quarter. So if making around 300 lbs-ft your only seeing 150 hp or less definitely not getting into the power.

 

[413]

i have heard it said that 3.73:1 is the ideal set up for a weekend warrior street strip set up...
with the right tyre height gives best of both, a good all rounder

this is potentially just internet BS.... or GM Chevy chatter......but you can't un read it once its been said a few times....

Depends on so many things.
car weight 2500 or 4100 pound?
what is the trans ratios?
Overdrive?
Tunnelram or dual plane intake.
Power band of the engine? A 426 hemi needs more gear than that to drag race.
Drive to the track 10 minutes or 75 minutes?

I drove to track with 3.91 and it would have work with 3.73 gears, it needed 4.10

 

[volaredon]

see! see! i am capable of level headed conversation and reasonable thought!

my feeling is, if it's costing more than about 1/4 tank to run premium or an additive then it's time to rethink strategy. but if you're putting on sub 5K miles a year and need premium, the cost per tank should be way down on the "concerns" list.

A big "if".
Here the least difference I see is $.60 per gallon, $.90 is more common and I've seen as much as $1.10 PER GALLON difference between grades. If we were still $.30 like you have, I wouldn't worry about it near as much.
If premium means "ethanol free" it does make more sense. But there is absolutely no such fuel here as "ethanol free". Nowhere.
And no, gas mileage isn't the ultimate be all end all or else I'd be driving a little **** box that would fit in the bed of my current truck...
I've never owned a FWD anything, and don't plan to.
I've only ever owned 1, 4 banger and it was in a Wrangler. And it was no better in that department than the other wrangler I had at the same time which had the inline 6. Just like my 318 Dakota's have tended to be better on fuel than my 3.9 powered ones.
I will never "not" have a truck of some sort.
I do like the best mileage I can get "for what they are" but how I drive and where I drive doesn't bode well for that to happen, so I do what I can.
I have 2 Durango s.... Which weren't known for being very good there either .. but having $0 monthly payments is nice.

 

[RustyRatRod]

If this is an 8 3/4, just whoop up another chunk with a 3.55 in it. That way you can easily swap it back if you want to.

 

[Dana67Dart]

Something that has always amused me is when gas stations advertise "save $0.10 per gallon" and people get excited. 20 gallon tank is $2.00

1 tank per week that's $104.00 per year

If that's enough to cause you to go a few miles out of your way to buy the gas you might have a problem!

 

[junkyardhero]

A big "if".
Here the least difference I see is $.60 per gallon, $.90 is more common and I've seen as much as $1.10 PER GALLON difference between grades. If we were still $.30 like you have, I wouldn't worry about it near as much.
If premium means "ethanol free" it does make more sense. But there is absolutely no such fuel here as "ethanol free". Nowhere.
And no, gas mileage isn't the ultimate be all end all or else I'd be driving a little **** box that would fit in the bed of my current truck...
I've never owned a FWD anything, and don't plan to.
I've only ever owned 1, 4 banger and it was in a Wrangler. And it was no better in that department than the other wrangler I had at the same time which had the inline 6. Just like my 318 Dakota's have tended to be better on fuel than my 3.9 powered ones.
I will never "not" have a truck of some sort.
I do like the best mileage I can get "for what they are" but how I drive and where I drive doesn't bode well for that to happen, so I do what I can.
I have 2 Durango s.... Which weren't known for being very good there either .. but having $0 monthly payments is nice.

everybody has their level of comfort of what they're willing compromise on to get what they want.

 

[junkyardhero]

Something that has always amused me is when gas stations advertise "save $0.10 per gallon" and people get excited. 20 gallon tank is $2.00

1 tank per week that's $104.00 per year

If that's enough to cause you to go a few miles out of your way to buy the gas you might have a problem!

yeah, i'm in that boat of a tank (or more) a week and if it's not a $0.50 swing then it's not worth the hassle/time. sure that's some loot at the end of the year but dealing with the ding-dongs at the cheap station wears on my psyche and that's gotta be worth something.

 

[Ottmundr]

No, you won't regret it.
I had a 7.25 pegleg 2.76 if I remember right and I switched to a Dana 60 with Eaton Trutrac and 4.10.
This is what it did to my little 318. If you say I'm lying, you drive fords.

 

[mopardude318]

I had 323s once. Wasn’t enough. Then I went 355’s. Still mediocre. 410’s were magic. Put in a solid roller and you’ll be even happier.

 

[71GSSDemon]

I have 2.94, 3.23, and 3.91. Soon also a 2
76. If heading up to Mopars in thr Park, in go the 3.23. Rest of summer usually 3.91. Or in a whim change it back. 2.94 in the Charger, may go to 2.76. Next year, down to 2.50 and up to 28" tire AND use the 4sp OD......

 

[Dave999]

you guys pay what? $3.50 a gallon i'm paying £5.50 yeah thats $7.12 today

and i live in a country with access to brent crude oil possibly the easiest to refine into something useful like petrol..... similar stuff to what you guys import from canada....! goldilocks zone in the north with some real good oils.. i wonder what is under greenland...?

this is what tariffs do, be warned, 80% of what i pay for my fuel goes to the government.
and once they have upped that tax, the next mob don't change it back...

mind at least the price is stable
when i lived in Australia i was horrified by the fact that the gas stations have a free hand to whack the prices up every weekend

you had to buy your fuel on a Tuesday to avoid the price gouging that went on....

even higher for a holiday weekend fuel and barbeque gas...

and at the time there was no standard for ethanol content, russian roulette when it came to how it would run. (they have fixed that in the last 20 years)

i used to comment that Caltex was Texaco chevrons brand of fuel for 3rd world countries (just as a gentle pisstake/joke) That never went down well... ever...... and obviously in my wise old age i feel terribly guilty about my hurtful attempt at humour

Dave

 

[Dave999]

Depends on so many things.
car weight 2500 or 4100 pound?
what is the trans ratios?
Overdrive?
Tunnelram or dual plane intake.
Power band of the engine? A 426 hemi needs more gear than that to drag race.
Drive to the track 10 minutes or 75 minutes?

I drove to track with 3.91 and it would have work with 3.73 gears, it needed 4.10
View attachment 1716377383

some context to compare weight and torque

2981 LBs curb weight

4 speed choice

close 2.46 - 1.78 - 1.27 - 1 (usually used with 3.5:1 diff)

or
wide 3.23 - 2 - 1.43 - 1 (usually used with 2.92:1 diff

so i use the closest modern ring and pinion 3.45:1 (Holden commodore V8/Camaro IROC Z 1982-92) and the wide box at the mo. although i have both boxes.....

235 70 r 14 hercules street tyres (not the best but what can you get for 14 inch wheels)

265 I6 3 weber dcoe 45, extractors, side pipe, 1.72:1 ratio rockers and the thin stem 2.02 inlet valves out of an edelbrock 440 head 12:1 static CR Dynamic CR 7.6 so it runs good on premium...

gott about 300 ftlb or torque and 250-300 BHP i haven't had it on the dyno in years but can do a 13.8 on street tyres with a set of slapper bars out back and an incompetent idiot in a fishing hat driving. Then drive it the 2 hours back home with tools tent and empty beer cans rattling around

got a mate with a standard 340 barracuda says his car feels sluggish, heavy and constrained compared to mine, no get up an go.... A833 equipped before he bust the UJ snapped off the tail shaft housing and oiled the start line.... side stepped the clutch.

got a mate with a stroker 360 in a barracuda, leaves the line with his rear bumper on the floor and competes in supers stock, my car is standing still compared to his, mine is a "grocery getter" in comparison

thiers sound like v8s mine sounds like a disaster in a trombone testing facility

dave

 

[Cuprum-74]

IMO general purpose gears are from 2.94 to 3.55. With 3.21/3.23's being the 'compromise' gears as others have stated.
I currently have 3.21 gears, and I've done quite a few 500+ miles trips with it. Mostly doing 70mph while pegging at 3100 RPM's. Rear wheels are at 25.7 in diameter (275/40R17 tires).
Keeping between 65-70 mph I can usually get about 16 mpg (I've even got over 17 before). 11-12 around town.
The exhaust drone isn't that bad, since I have straight through style mufflers (Magnaflows) with a crossover pipe. (I had chambered style like Flowmasters before, gave me headaches after about 3-4 hours of driving)
I also have an A999 transmission that surely helps with the off-the-line punch. Honestly, sometimes I do wish I had 2.76 or 2.94 gears when doing the long trips.
BUT, funny thing is I'll be installing an 8.75 rear with 3.55 gears soon and a Gearvendors Overdrive. So with 3.55's plus a 0.78 OD, I'll have my 2.76 gears! (2.77 to be exact).

I had cars with 4.11 gears which sure was fun, but whenever I did any freeway driving 60mph and above it got old pretty quick.

@1973dust Not sure if you knew or not, but the A999 is basically a beefed up version of your A904 commonly found in Dodge Diplomats & Plymouth Gran Fury's plus others in the 1980's and also with different 1st & 2nd gears.
A904: 1st=2.45, 2nd=1.45 & 3rd=1.00
A999: 1st=2.74, 2nd=1.54 & 3rd=1.00

 

[273]

IMO general purpose gears are from 2.94 to 3.55. With 3.21/3.23's being the 'compromise' gears as others have stated.

There's is no general compromise gear or at least there shouldn't be.
Generally the slower and higher your engine revs the deeper the gears needed aka a 7000 rpm 170 /6 vs faster especially with lower peak power rpm aka 4500 rpm 543 (which around a 3.23 probably be it's ideal 1/4 mile gear, zero compromise). Generally 3.23 are gonna be closer to ideal for larger engines, less of a compromise and be further from ideal on smaller one's but yes you can put them behind anything but the compromise ain't the same. To me, is the main reason to build larger displacements if your unwilling to run deeper than 3.23/3.55.