Experiences With 3.27 & 3.54 Gears

Bob Bidonde

Bob Bidonde

Well-known member
I would like to hear from "A" drivers with experiences in this matter.

I have a Model "B" engine with a touring camshaft and a 6:1 hi-compression cylinder head. Each year my wife & I do a long distance tour into the New England Area using the interstate highways. My goal is to cruise at 55 MPH with a lower engine RPM than stock.

My concern is the engine's torque or in other words, am I sacrificing my "A's" ability to drive around town and keep up with traffic if I install 3,27 or 3.54 gears?

Here are the various RPMs at 55 MPH: 3.27:1 - 2013; 3.54:1 - 2200; 3.78:1 - 2354.
 
I would recommend, in my humble opinion, you investigate installing a Mitchel Overdrive. They come in various gear ratios. Perhaps one could work for you. I think you could achieve even lower rpms than the 327 or the 354 would provide at 55 mph.
 
I don't run either gear set but do have a Mitchell overdrive 27%. Only modifications are 5.5 Snyders head, B distributor and single stromberg 97 on a Burns intake. I'm in overdrive from 35 mph and up with no problem keeping up. I've actually thought about going with the 3.54 gear set with the overdrive. The car will run 55 and better but I'm more comfortable at 50.
 
I in stalled a 3.27 ring and pinion in our 35 Ford V8, thinking it would fly. Nope. It only pulled hard. Starting out in first gear was like starting out in second gear with a 3.78 to 1 rear end. And you are stuck there. It died on hills, and generally was a big disappiontment. I love my Mitchel on our Model A, because it's the best of both worlds...3.78 around town, and overdrive for out on the road.
 
Consider this, a lot of people really like the overdrive and you are probably shocked at the cost. However, unless you already have the ring and pinion and can install the gears yourself, you will be shocked at the cost of changing to the higher speed ratio and will not have the dual range capability.
 
I have a coupe with 3.54 gears and a 26% over Mitchell.To tell the truth I forget and leave it in overdrive most of the time.The only time I really notice it is when I am noodling around the camp roads around the lake.Those roads are like a pigs tail,up,down,right,left,the hills are steep,but short.My powers OK,but my speed is too much in first high.My only mod is a BF head,and a B dist cam.
 
My engine has a Weber down draft and a 5.5 Snyder's head and a Mitchel overdrive with 3.78 gears in the rear end. I can drive 60 to 70 on the highway with no problem. (I prefer to take the back roads at 50 mph.) The 1930 Fordor will go more than 70. My target is 65 but the speed drifts up and down with the hills. In overdrive the equivalent rear end ratio is 3.10 to 1.

By the way, make sure you have excellent steering and brakes if you are going to drive fast. (Or any speed for that matter.)
 
I run a 3.78 rear end in my outback touring car and a Mitchell 26% O/D. The effective ratio of that is close to 3:1 - a higher gearing than even the 2.27. There have been times when I have forgotten to take it out of O/d when I stop but I soon cotton on when I try to get moving again. That said, I have, once or twice stayed in O/D and lugged it up to second gear (remember, I'm towing a camper that weighs about a tonne).Your 6:1 head should give you the grunt at the bottom end but I don't know what cam shaft you have so I can't make a judgement on that. From what I understand, you build a decent motor capable of withstanding the revs for a prolonged period. Which ever way you go, there are benefits and drawbacks. It's your car, your decision but I think those who are saying "install an overdrive" will have the best of both worlds. A solo car with 3.54 gears and O/D and with a 6:1 head, IMO would give good high speed cruising and flexibility around town (effective ratio of about 2.8:1). High second is a very useful gear. All that said, what wheels and tyres are you running?
I am all ears too for what others have to say.
 
Bob-
I have a 3.27 in my '29 phaeton, with a really good B cam, larger intake valves, B carb and a 6:1 head. It's a pretty light car; only a roadster or a OCPU would be lighter. It does just fine with the 3.27; I do not think I would put it in a heavier car.

Having the extra O/D shift lever would be a bit of a pain, but having the O/D would be great. I especially would like to have 2nd-high in the mountains.

HTH.
 
I just went from 3:78 to 3:54, and I love it. I have a tudor, with a pretty strong engine. I do miss the hill climbing ability, but I can still pull most of the steep ones in 3rd. It will do below 25 in third on the flat with no problem. I drove it at 55 before, and now 55 is much quieter and easier on the engine.
 
The Mitchell 26% with a 3.78 gear ratio has a 2.91 ratio in high range… 7.5 to 1 Winfield, late B high lift cam and a single Holley 94 with a header and FSI will pull the car no problem in high range but like everyone I split second gear.. I cruise effortlessly at 58, the Mitchell gear splitter is amazing..is it worth 2k plus? I’d say yes.
 

Attachments

  • 3AE5FCB9-7E5E-4C1D-8DD8-EF2FDF286FCC.jpg
    3AE5FCB9-7E5E-4C1D-8DD8-EF2FDF286FCC.jpg
    47.6 KB · Views: 29
I think your car is a little heavy for a 3.27. I think the 3.54 is the way to go.
I put a 3.54 in my car with an almost stock engine and it would do 55mph better
but was a little sluggish.
I rebuilt the engine and used a touring cam a 6.5 comp head and a Model B carburetor
with a bored out Model A manifold to suit.
I have another Model A with a touring engine, 7-1 head 3.78 gears and an overdrive
that is a real sweet car. I really like the cruising rpm and being able to overdrive
2nd gear going up the windy twist roads around here with out holding up traffic.
You just have to honestly ask yourself how your going to drive it.
Remember it's only money.....
 
Chuck Sea/Tac said:
I just went from 3:78 to 3:54, and I love it. I have a tudor, with a pretty strong engine. I do miss the hill climbing ability, but I can still pull most of the steep ones in 3rd. It will do below 25 in third on the flat with no problem. I drove it at 55 before, and now 55 is much quieter and easier on the engine.
Click to expand...

Hill climbing would be important in New England and other hilly areas, so other than stock gears is a compromise. One more vote for a Mitchell OD from me. (Plus a 6:1 1head.)
 
3.54 vs 3.78 on a 30” tires
I’d think you’ll loose too much with the 3.27
 

Attachments

  • 35AE642B-4971-4E47-80F7-319A46A4A423.jpg
    35AE642B-4971-4E47-80F7-319A46A4A423.jpg
    16 KB · Views: 61
  • 9C1A93EE-BA80-4F79-AA5F-144BFEF4AFB0.jpg
    9C1A93EE-BA80-4F79-AA5F-144BFEF4AFB0.jpg
    15.4 KB · Views: 40
Thanks for all of your responses. Normally I would opt for the Mitchell OD, but I have family financial responsibilities that make the Mitchell unaffordable. So my choice is to change the differential gear ratio. I have been touring the New England Area for many years driving my 45B Coupe and more recently, driving my 190A Victoria. Both have 3.78:1 differentials, and Model "B" engines. I am going to put 3.54 gears in my Victoria first which has a 6:1 compression head and a touring cam.
 
I put a Mitchell 26% OD in over the winter, 31 Tudor 3.78 gears. 2nd to 2nd od, 2nd od to 3rd, 3rd to 3rd od is so much fun. The sweet spot is 53 mph, 53-57 mph is in one of the harmonic variation areas, I mostly drive 53 but if needed 60 mph, at 60 mph it’s tolerable for wind and engine noise. If you put 3.27 gears in I feel your A’s not going to be happy slipping the clutch in low gear pulling away from stops or on hills. In city driving it’s going to live mostly in 2nd reving away and then jumping to 3rd, the gap between 2nd 3rd is going to be more aggravated.
If it’s a money thing go with 3.54 only, may I suggest taking the money you will spend for new gears and all other parts you’ll spend from the price of an OD, i feel you’ll be much happier!
 
I ran a 3.27 in my speedster for awhile, with a V8 trans, but didn't like the effort it took to leave a stop sign. It may be OK with the A trans? If you travel 55, I would use the 3.54 rear. An OD is the best way, but more expensive. I have a 4.11 and a Colombia rear, 26% OD, in my pickup, and love it. Too high ratio is not good either, it lugs the engine and thr gas mileage goes down.
 
You must log in or register to reply here.
Back
Top