66coronet440

whats better for a 318 poly? 3.23, or a 3.55 gears?



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1966 Coronet 440 318 poly

Archer

66 -

You'll never notice the difference (assuming you get the right speedo gear, of course).

Archer

66coronet440

But will i notice a difference from my original 2.73?

blue 68 gts

3.23's would be alot better for all around driving... though if its going to be a DAILY DRIVER i'd even say maybe go to 2.7's...

66coronet440

Its going to be mostly casual drive, definitely not my daily anymore, im getting it painted in the spring time when its out of storage, but will there be a acclereration difference and top speed?

rr69half6bbl

If you want a little get up go and your not gonna be driving to the west coast and back. id put the 3.55`s in the car, its heavy, the 318`s probly a 2 bbl. right? so little low end power. If your gonna build up the poly later or upgrade to a 360, Id put the 3.23`s in. but if your just gonna leave it alone do the 55`s.

66coronet440

yea im leaving the block, im just doing headers and 4bbl carb upgrade, so which is better for what im doing

rr69half6bbl

Do the 3.55`s. itll help the heades n carb change, dont get crazy on the cfm ither for the carb, the stock 2 bbl cam wont be able to handle alot of extra fuel air, itll just wash out the cylinders. id put a 525 cfm holley on it. thast more then enough, Id go with a single plain intake also. itll give you more off line grunt. stay away from all the go fast **** too. like the lokar stainless throttle return, or a 2 in spacer for the carb to intake.spend the money in the right places and make it look clean and faster. Ive seen t many guys spend money on that bullshit and then take it off because it doesnt really make the car run faster after all, and took money from doing a cam change or a more gainfull upgrade. Just my experience.

78D200

What do you have for a transmission in the car?

66coronet440

Thanks for your help, yea im sort of limited with what to do because the motor runs so strong and smooth, i dont wanna open a new can of worms by opening the block up. I just want all little better throttle response and a little more get up and go, and not kill the imagine of an original mopar.

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1966 Coronet 440 318 poly

66coronet440

Im actually not sure because i've heard way too many opinions and i dont know who is right, the car is now in storage for winter and i cant see it. All i know is, its a 3 speed on the tree, i've been told its got 8 3/4 rear end. But some people say the 318 poly should have a "904" but others say its gotta be "727" because its a 66 poly, so im not quite sure.

heres some quotes i saw

"1966 318 = Poly motor , a/k/a "A" Motor . These had the A-727-A trans behind them . IF it's a same-year 273 , then it'll have the A-904-LA behind it ."

and

"Actually if it's a 318 it's most likely a 904. Pretty much the same as a 727, just smaller."

I would Appreciate if anyone truely knows the right one, i'd appreciate it please and thank you
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1966 Coronet 440 318 poly

Silverick

Look at this chart, then crawl under and look at your transmission pan.

http://www.teufert.net/trans/trannyid.pdf

66coronet440

I dont have the car at the moment, its locked away for winter...
but thanks for the tranny id

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1966 Coronet 440 318 poly

78D200

Usually "3 on the tree" refers to a manual transmission. How many pedals do you have? If you have two pedals, then you have an automatic (either a 727 or 904). If you have three pedals, then you have a manual transmission (I'm not sure what manual transmission(s) cam in these vehicles).

If you have an automatic, I would go with a 3.55-3.73 gear ratio. If you have a manual then I would go with a 3.23 ratio. The reason for this is due to normal automatic transmission slippage. I noticed this with some of the Dakota trucks that I have drove.

A friend of mine had an automatic Dakota with the same rear axle gear ratio as my manual. His truck felt "sluggish" compared to mine. I helped him out with installing a numberically higher gear ratio (from 3.55 to 3.92) and it felt more like my truck did.

62Furious

I have to disagree with rr69 on the intake, if you plan to use it as a casual driver I would use a dual plain intake not an open, dual plain low end tork, open plenum top end high rpm horse power

78D200

X2

66coronet440

No no, its an auto 3speed, im just not sure of the transmission (904/ or 727) and i dont have access to the car. And the higher the gear ratio the more top end or more accerlation gain do i get?

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1966 Coronet 440 318 poly

66coronet440

Will my cam be able to handle the 4 bbl carb, or should i just go grab a regular 2bbl?

condor74

Your cam can handle a 4bbl carb. Stay with a small carb though no bigger than 625. An edelbrock 600 would work nicely. I would stay with the 3.23s This is not a hot rod. It already drives and runs smoothly. All the 3.55s will do will increase the acceleration ever so slightly and increase the RPM going down the freeway. I would either go with 3.23 or 2.72s and just motor on down the freeway at around 1500 rpm. The car will still have power it just wont do that great in a drag race...Drag racing doesnt sound like the point of this car anyway. Personally I think I would stay with the 2 bbl carberator and only upgrade the carb when I upgraded the motor but that is just me.

66coronet440

But will the 3.23 improve any acceleration/ top speed over my original 2.73?


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1966 Coronet 440 318 poly

condor74

there will be a marginal improvement on acceleration with the 3.23 and a little more on the 3.55s To feel real differences go with a 3.9 to 4.1 or higher number gear. The 2.72 will give you a higher top speed, lower revs at highway cruising speeds and less wear and tear on the drivetrain. In a stock cruiser I like the 2.72 or 3.23.

They still accel ok. I had a dodge Dart with a 340 and 3.23s that I ran 13.8 in the quarter mile with on street tires.

66coronet440

Did the 3.23's come sure grip or do i have to buy a separate unit? Will a 4.1 gear work on a poly well? I think those only came on the hemi's which obviously have more power than a 318 poly.


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1966 Coronet 440 318 poly

Silverick

Yes, the 3.23's can come as a Sure Grip and yes, a 4.10 will work in an 8 3/4 and on a poly but, when you get into the lower gear ratios like a 3.91 or a 4.10, your poly, at 55 mph, is going to be spinning a lot more than it is now because it will take 4.1 revolutions of the motor to turn the tires one time and with the 2.73 that you have it only takes 2.73 revolutions of the motor to turn the wheels one time.
For what you want, the 4.10's are not a good match. Stick with a 2.73 or a 3.23 and you can thank us all later!

66coronet440

Thanks for all the advice and experiance everyone! This is my first classic mopar and am glad this forum exsists! Thanks again
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1966 Coronet 440 318 poly

78D200

A lot of how and where you will be driving the car will play a factor in which gear ratio you go with. Other factors include transimission ratios, tire size, driving style, and if you will be taking it to the drag strip at all.

The 727 ratios are 1st - 2.45, 2nd - 1.45, 3rd - 1.00
The 904 ratios are 1st - 2.74, 2nd - 1.54, 3rd - 1.00

You need to first determine the how you plan on using this car. If it is just the occasional cruiser (weekend driver) and you don't plan on being on the highway that much (more city driving and back roads were you would be at 40-50 MPH), I'd go with a set of 3.55 or 3.73. If you are planning on using the car to travel on the highway quite a bit then I would go with a set of 3.23 or leave the set that you have in there and swap the carrier out for a sure grip unit.

Numercially higher gears mean better acceleration but decreased top speed.

Factoring in a 26" tall tire these are the RPMs that I calculated.
2.73 gears will put you at about 1940PRMs at 55MPH.
3.23 gears will put you at just under 2300RPMs at 55MPH.
3.55 gears will put you at just over 2500RPMs at 55MPH.

These are pretty normal values even now-a-days IMO. You have to remember that you do not have OD. Maybe that is something else to look into if you want a better acceleration while still keeping a decent top end speed with lower RPMs on the highway.

rr69half6bbl

I was looking at his projected setup for the car , If he goes w/ a 4bbl ,headers, and 3.55`s, then the car will have enough umph off the line, and midrange acceleration, but as heavy as the car is and givin its a 318. hes gonna run outa juice about 4600 r`s, so an open plenum intake will give him a little extra over 4800. so it wont flatten out at higher speeds. Itll give him a higher power band into the 5400 r range, and the motor can handle that. just my thoughts.

66coronet440

Actually im glad you brought it up im not sure what tranny i have, but hoping someone here might know. Its 1966 dodge coronet 440 2 door hard top with 318ci 2bbl 3 speed auto with a 8 3/4 rear end.
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1966 Coronet 440 318 poly
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66coronet440

My Tire size is 225/60/R16 and they are alot taller than the stock ones, they were like pizza cutters. hahaha. But the speedo is still somehow accurate. I dont beat on the car but when i wanna feel some power i give her a little. No drag strip and stuff strictly fun pleasurable cruise.


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1966 Coronet 440 318 poly

condor74

I would not sell the numarically low gear ratios short. For what you want they will do fine. I used to have 2.72s in my 68 satellite with a 318 and to be honest it ran quite well. I raced it against a few other cars and beet them easily. It was probably a high 15 second car and the only mods to the engine were carter afb 4 barrel carburator with dual exhaust that exited under the car in front of the rear axle. stock style muffles. The other nice thing is on the highway it got like 22 miles to the gallon which was great for a college kid.