| Peder D | -- 05-13-2012 @ 1:40 PM |
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Hey Guys! My car has the 3:54 rear. Would I notice any considerable change in rpms if I installed a 3:25? Thanks! Peder
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| TomO | -- 05-14-2012 @ 6:57 AM |
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Peder, I would not recommend a 3:25 ratio. Your engine would be working too hard to move the car. Your overall gas mileage may go down with the higher ratio. A 3:54 is the best all around ratio for your car, unless you are in a mountainous area. I suggest that you look for a Columbia rear end or an overdrive. Tom
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| carcrazy | -- 05-14-2012 @ 9:19 AM |
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If you did install a 3.25 ratio rear axle your engine speed would be 91.8% of the speed with the 3.54.
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| shogun1940 | -- 05-24-2012 @ 5:04 PM |
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for every inch of tire diameter ,it changes ratio one tenth,,3.54 would be 3.44 wth a bigger tire. Maybe you could borrow some tires and rims to try it out
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| Peder D | -- 05-25-2012 @ 12:13 PM |
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Should hasten to say that I bought and had mounted P205/75 R15 radials back in 2004. Was the only tire available at the time...so this increases the engine rpm since this tire is smaller than the original 650x15? What is the difference in numbers? Thanks again, Peder
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| carcrazy | -- 05-25-2012 @ 1:16 PM |
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Your original 6.50x15 tires have an aspect ratio of 90% so their overall diameter is 26.7 inches. Your new P205/75R15 tires have an aspect ratio of 75%. Converting the metric 205mm into inches yields 205/25.4=8.07 inches. Your new tires have an overall diameter of 27.1 inches. Your original tires turn 755 revolutions per mile while your new radial tires turn only 744 revolutions per mile. Therefore your new tires offer a very slight overdrive of 1.5% slower engine speed for a given vehicle speed.
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| TomO | -- 05-26-2012 @ 7:41 AM |
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Hi Peder, The original standard size for your Mercury was 6.70x15 and the optional tire was 7.10x15. The closest radial tire diameter to the original 6.70x15 is the 225/75 R15. You can check out tire diameters at http://www.cokertire.com/ without having to do the math. Your radials are now 8 years old and are near the end of their safe use life. If you can find some 7.10x 15 tires in your country, you could use them, otherwise I would go with the 225/75 R15 radials. Tom
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| Peder D | -- 10-28-2012 @ 11:14 AM |
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Hi again! The suggestion was to look for a Columbia or an overdrive...I see Mitch*ll Manufacturing is advertising in V8-Times a model 1000 overdrive...any experience with this unit...a good buy? Thanks....Peder
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| supereal | -- 10-28-2012 @ 8:25 PM |
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Have an overdrive in my '47. It isn't a Mitch*ll, but operates the same. I chose a 33 percent reduction with my 3-78 rear gears. If i did it again, I'd go for a 30 percent, as it lugs down below 40 mph in OD. With a 3-54 gearing, I wouldn't go for anything more than 25 percent. Overdrive is great for highway cruising, but a bit pricey if you don't need it.
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| Peder D | -- 10-30-2012 @ 12:27 PM |
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Thanks for the input. Mitch*ll saying a 26% reduction with the unit they offer. Interesting you mention lugging. My car does that even with the 3:54 at lower speeds. Mechanic says "it's an old car". Thinking carb. or ignition? Don't like this situation and hoping still there is a solution to lugging. Everything under the hood upgraded. Any suggestions? Thanks again..Peder
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| TomO | -- 10-31-2012 @ 7:44 AM |
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Lugging at lower speeds can due to idle speed adjustment. The engine should idle at 450-500 rpm and have at least 18 inches of vacuum. Some of the things that can affect the idle speed are: carburetor leaking gas or vacuum, timing of when the points open, point dwell, vacuum leak or poor compression. Check your spark plugs for a nice tan color with no deposits as in the normal photo in the chart. http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm Check for vacuum leaks around the intake manifold and distributor housing vacuum connectio. Tom
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| Peder D | -- 11-10-2012 @ 3:01 PM |
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Hi again! Have you had any success in dealing with lugging? What have you tried? Have a brand new engine and everything that goes with that...don't know what else to do? I do have a rubber hose in the line from the fuel pump, thinking about changing to a whole copper line...maybe help somewhat? Have checked and tighted down all nuts and screws...all else is good...what else...thanks...Peder
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| supereal | -- 11-10-2012 @ 8:50 PM |
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The 3-54 is a "flat land " ratio. The better all around gearing is 3-78. That is why Ford supplied most cars with it. The flathead engines don't produce maximum torque until they get above 2,000 rpm. The low ratio prevents getting enough "grunt" to get off the line. Your new engine may improve when it gets some hours on it, but I wouldn't expect a whole lot. Hilly country called for a 4-11.
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| TomO | -- 11-12-2012 @ 8:23 AM |
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Peder, do not use a copper line for gasoline. The fuel line from the tank to the firewall is steel with a copper coating on the inside and outside to protect the line from rusting. The line from the firewall to the fuel pump is a flexible line made of gasoline resistant rubber and the line from the fuel pump to the carburetor is a copper coated steel line like the one from the tank. As to your lugging problem, is your idle speed correct? Is your gasoline mixture right(check the plugs to determine this)? Has your distributor been timed on a distributor machine? Has your vacuum brake been correctly adjusted? Tom
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| supereal | -- 11-12-2012 @ 2:02 PM |
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Again, my friend Tom (my Mercury go-to), is correct. Many assume, since to correct fuel line looks like copper tubing, that it is. The proper tubing is, in fact, copper coated steel. Copper tubing will crack due to vibration., causing a fire hazard. Buy ikt pre-bent from a good vendor.
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| Peder D | -- 11-27-2012 @ 12:24 PM |
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Thanks to everyone for all the good advice. As far as the overdrive goes, are there any other well known overdrives that are offered for the early Ford V8's other than Mitch*ll in the United States?
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| Peder D | -- 01-02-2013 @ 12:39 PM |
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Still contemplating buying a Mitch*ll overdrive. Question: My Mercury has the 118" wheelbase...and the Ford 114"? Do they share the same "length" with regards to the torque tube? Just to be sure that I get the correct overdrive unit for my car...thanks...
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| TomO | -- 01-04-2013 @ 8:37 AM |
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Yes they share the same length torque tube. The extra 4 inches are from the cowl forward. Tom
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| jal9846 | -- 01-09-2013 @ 12:01 PM |
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Not sure when in the 46-48 model year cycle...but my understanding is that original OEM tire for that run of Mercury was 6.50-15. Unfortunately...that die was lost long ago, and the available options are now 6.70 and 7.10-15. I know my 48 convertible came with 6.50-15 wide white walls, as I still have an original off the car.
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| TomO | -- 01-10-2013 @ 8:14 AM |
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You are correct in the original standard tire size being 6.50x15. The 6.70 x 15 size was more readily available and used for replacement tires. 6.50x15 tires are still available for trucks and farm vehicles. Tom
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| Peder D | -- 01-29-2013 @ 11:16 AM |
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I will be ordering the Mitch*ll overdrive soon. They require the exact length from the rear to the transmission to get the correct overdrive. Would appreciate getting the correct measurement if anyone has it? Thanks...Peder
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| supereal | -- 01-30-2013 @ 1:38 PM |
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I don't quite get where the length should be measured. They should have a correct unit for a '46 Mercury, unless it has been modified. The extra length of the Mercury chassis is ahead of the cowl, and the driveline is the same as Ford. I have Ford torque tubes lying around here and can measure one if that is what is required. Perhaps they are concerned that a non-US car would be different.
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| Peder D | -- 01-31-2013 @ 12:42 PM |
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This is originally a Minnesota car. Not modified. To my understanding they need the correct length. Mitch*ll has made these o.drives for model A's. They might not recognize the Mercury being the same as Ford? Would appreciate it if you could measure your torque tube and get back to me...Thanks again! Peder
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| Peder D | -- 02-08-2013 @ 11:13 AM |
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Question: Are there several suppliers of overdrive units serving the Early Ford V8 in the U.S.? Would also appreciate getting that measurement from you when you get around to it. Thanks again! Peder
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| Peder D | -- 02-09-2015 @ 12:44 PM |
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Where can I buy a pre-bent copper coated steel fuel line from the fuel pump to the carb. for my '46 Mercury? Thanks!
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| TomO | -- 02-10-2015 @ 7:33 AM |
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Joblot in New York or Little Dearborn in Minneapolis might still have some left. Most vendors do not have any of the pre-bent lines left. Tom
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| Peder D | -- 02-11-2015 @ 11:44 AM |
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Ok, thanks. Checked with Joblot, they have the line, but not pre-bent. C&G Ford Parts advertises one, but not sure if this is correct. Will check with them. Peder
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