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04-19-2021, 11:43 PM | #1 |
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Max Speed of a Model A with 26% OD and HC Head
For member with a Mitchell 26% overdrive and a HC Head at 5.5 or 6.1.
What is the max speed you had your car at and at what speed do you feel comfortable at for extended periods of time. I have a feeling that the max speed will be quite high. Ron |
04-20-2021, 02:05 AM | #2 |
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Re: Max Speed of a Model A with 26% OD and HC Head
All I can tell you is that I run sustained 68 mph in my Model A (per Garmin GPS readings) with a standard Model A 3-speed trans. I have 12 volt modern point system, a lightened flywheel, balanced crankshaft, and a Weber Two barrel carb with the modern intake. I also add Lucas lubricates in both the engine and in the trans. I have had enough sports cars to 'know' that it does make a difference.
I am also running 1935 wide-rims and radial tires with a piston stabilizer on the steering and 'float-a-motor' rubber engine mounts front and back – past 55+ the car handles with limited vibration and little perceivable shimmy. I have read here and other places that I can add an additional 5+ mph if I use a cast iron header exhaust and different muffler system, but have not done that as of yet. I use a four blade fan for cooling here in Florida, but I have also read that the use of a six blade plastic fan will work better and reduce the drag on HP and speed. Another advantage to consider. Lots of changes that can really perk up the wonderful Model A. |
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04-20-2021, 12:22 PM | #3 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Gear ratios can be deceiving. Just because mathematically it will raise your speed, if you don't have the horsepower, you won't go as fast as you think you can. Pushing a Model A thru the wind is like pushing a barn.
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04-20-2021, 01:40 PM | #4 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Remember what kind of brakes these cars have. Especially if you’re not using cast drums.
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04-20-2021, 01:55 PM | #5 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Ron I am sure many will disagree but I am quite surprised that a new owner such as yourself seems to be obsessed with attaining excessive speed. Maybe you should have purchased a type of race car instead of a 90 year old classic. JMO, Wayne
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04-20-2021, 11:08 PM | #6 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
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Quote:
I have multiple cars for that kind of driving and regardless of how fast they go I never exceed 5 to 7mph on the interstate. That said I have no intention of ever using my Model A on the interstate. I am interested in hearing what people can attain with 6.1 head and a 26% Mitchell as this is what I will be running. By knowing what the max performance is with an otherwise stock car I am trying to judge an optimum max cruise speed without causing damage to my engine for long distance driving. I do think the best speed for a Model A is 40 to 50mph but secondary roads tend to be 55 to 60 when you get out of town. In my opinion my car is safe at 60 as my steering, brakes, suspension and front end have been refreshed but the engine is turning just a little to fast to hold that speed in my opinion. I am not trying to build a race car out of my Model A rather make her a little more drivable. I am the kind of guy that would love to drive across the country someday in a car that's pushing 100 years old. I know that may be strange for some but to me that's a great way to get out of work and spend my vacation experiencing Small Town America. Ron Last edited by Model A Ron; 04-20-2021 at 11:51 PM. |
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04-21-2021, 01:59 AM | #7 |
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Re: Max Speed of a Model A with 26% OD and HC Head
My 1930 Town Sedan has a 5.5 HC head, standard 3.78 rear end, and a 26% Mitchell OD. The previous owner restored the car and had the engine re-built, so I do not know exactly how well things were balanced. My steering, brakes, and tires are all very good, and I feel quite comfortable doing a sustained 55-60 mph. I’ve never tried running it as fast as it will go....I’ve hit 65 a few times, but 60 is my upper limit for comfortable cruising.
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04-21-2021, 03:04 AM | #8 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Back in the day my car did 65
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04-21-2021, 08:04 AM | #9 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
Quote:
Ford marketed the model a as a car 'to meet todays (1927) demand for speed and comfort'...With modification it still does,90 years later.. |
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04-21-2021, 09:35 AM | #10 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
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04-21-2021, 09:39 AM | #11 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I have a 6.1, larger intakes, model B carb with bored out intake, touring cam, lightened flywheel, 26% overdrive, cylinders bored .60 over, electronic ignition, 3.78 rear end.
Very comfortable at 55MPH, 60 is OK but the rpms are getting up there, 65 no problem but it seems a stretch. |
04-21-2021, 09:48 AM | #12 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
Quote:
"It was my desire to prove the basic model a platform relevant in todays driving conditions, to run anytime without the protection of a convoy." |
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04-21-2021, 05:24 PM | #13 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
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04-21-2021, 07:19 PM | #14 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
Quote:
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04-21-2021, 08:59 PM | #15 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Without getting into the details of the physics, it takes a certain amount of power to push a car along at any given speed. As the speed rises, the resistance increases till you reach a point where the available power is all used to maintain what is the maximum speed of the car. So long as there are no silly gearing issues etc, O/D or not will not make much difference to the top speed. The O/D does not increase the power available. The HC head makes a bigger difference.
That said, if you want to travel at say, 60 mph, the car is happier with the O/D. Things are not so busy under the hood.
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04-22-2021, 01:01 AM | #16 |
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Re: Max Speed of a Model A with 26% OD and HC Head
If you want to travel at 60mph you need a V8
you got your new engine yet Arnold. My shed is full of them Lawrie |
04-22-2021, 08:04 AM | #17 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
Quote:
Ron Last edited by Model A Ron; 04-22-2021 at 08:10 AM. |
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04-22-2021, 08:16 AM | #18 |
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Re: Max Speed of a Model A with 26% OD and HC Head
With stock wheels and tires 62 requires real good roads.. even with 16's and modern radials you have to 'give her her head'.. don't try to hold her on a string, just 'herd' it down the road. Everyone agrees the car is comfortable at 45 no matter how much you do to it.
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04-22-2021, 08:21 AM | #19 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
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04-22-2021, 10:01 AM | #20 |
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Re: Max Speed of a Model A with 26% OD and HC Head
My Fordor has an overdrive, 5.5 head, Weber, insert bearings, cam, etc. I have had it up to 70 with more to go but I like driving it at 55. It has excellent brakes and steering so I do not feel threatened at 55 or even 70. The engine HP was estimated at 90 by the builder but I suspect it is more in the 70 range.
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04-22-2021, 08:34 PM | #21 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I’ve install a number of overdrives and have them in both my sedans
31 slant window std head currently with 26 Mitchell . I did 76 with it last fall on a trip. A could easy cruise is 55-62 in the highway. My 30 tudor has a 5.5 head and a 3.54 rear end and a 23 percent Ryan overdrive . It is a wonderful mix and is a great highway cruiser. Top speed beat my town sedan. But only wrapped the speedo once . It has been up pikes peak and many miles . 55-62 is still a great freeway speed as well. I think the overdrive and 5.5 head is the best thing you can do to make them cruise a little easier and lower your engine rpm’s so it’s a little less strain on the engine and you. Yes you MUST have the brakes and front end in top notch condition . My cars screech to a stop and handle superbly.... but that’s what I do. I also have never balanced Model A wheels and tires and have never had issues at higher speeds. The reason for the overdrive and the head should be for drive ability and not for speed. I’m not necessarily a fan of the synchro overdrive trans units although understand why some like them. With the correct ratios they are a pleasure to drive and help with those who have trouble double clutching for one reason or another. We are blessed to have the options out there we have. The Model A community is truly a great thing. Happy motoring! Larry Shepard Last edited by larrys40; 04-22-2021 at 08:41 PM. |
04-23-2021, 02:49 AM | #22 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Larry, your wheels must be better than the ones we see in NZ. I have an electronic balancer that mounts the wheels through the 5 stud holes. I have balanced many front wheels that were bouncy at as little as 50 mph, especially light speedsters. Our Tudor and roadster both needed banancing. I find a dynamic balance not necessary with the narrow wheels and usually only do a single plane balance on these, using stick on weights split 50/50 inside and outside.
But for wider 16 inch tubeless radial tyres on V8 rims, which many use, a dynamic balance works better. My cars have good new springs and Stipe shocks, but they need balancing for a bounce-free ride. Some with 1/8th diametral throw are unbalanceable. I see many of these that previous owners get rid of and the new club member owners then bring to me and I have to reject them. 1/8th axial wobble at the rim is the norm and these balance up ok. I always enjoy you factual to-the-point posts, so it is interesting your findings are different from mine. SAJ in NZ Last edited by SAJ; 04-24-2021 at 06:30 AM. Reason: Changed single plain to single plane |
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04-23-2021, 10:10 AM | #23 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I have most of the modifications mentioned and have regularly taken long trips from weekends to a 7 week round trip, 40 state, jaunt some years back. With my antiquated but dependable 25% Borg Warner OD I drive all day every day at 1900-2000 RPM at 60-62 MPH per my GPS. How fast will it go? I don't know but it has drifted up to 74 MPH before I noticed and slowed down.
In reference to recent posts on wheel balance, I have used Dynabeads for several years with good results and all my Model As have front and rear anti sway bars. Richard Anaheim CA |
04-23-2021, 10:23 AM | #24 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Richard,
Please post photos of your anti sway bars. Also the details.
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04-23-2021, 11:15 PM | #25 |
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Re: Max Speed of a Model A with 26% OD and HC Head
SAJ ,
I admittedly my wheels are stellar and straight and do well on my cars . Your are right some wheels are worse than others and could be better with good balancing . My 40 Ford when installing new tires on original wheels was difficult to get them balanced well. I found solace that had a Hunter road force balancer and a fellow flathead guy running it that didn’t mind taking the time. I found out I had the worst tire mounted to the worst rim. After a some remounting and expert balancing they were fairly decent. I would love to see your electronic setup you use. I know balancing ( or not) can be a problem at times and maybe I’ve been lucky! I appreciate your comments.... as you know it’s a continuing learning process from us all. Post some photos or open a new thread on your balance method . I would love to see it. Any details how we could duplicate out here in Model A land would be most grateful and appreciated. By the way how many A’s in New Zealand ? Larry |
04-24-2021, 12:41 AM | #26 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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The sway bars are the standard ones sold by the major parts dealers. They keep the body from swinging on the shackles around corners. I'm sold on them. Richard Anaheim CA |
04-24-2021, 04:50 AM | #27 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I see Snyder's sells Panhard Bars, is that what you have?
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04-24-2021, 06:51 AM | #28 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Larry, my electronic balancer is just an old Italian Corghi. Nothing special. It has the usual cone mountings which are no good for a Model A, plus adjustable 4 and 5 stud mountings for the different wheels and a double cone for knock-off while wheels.
There were 130 Model A's at our rally last week. About 10 cars from America could not come or could the Australians. I am guessing there are 400 or so running Model As in NZ and many more hidden on farms and in sheds. Someone else from here may like to correct that. I may have made my wheel balancing sound more clever than it really is. The main problem is tyre fitters these days don't want to dismount the cones they use on all moden wheels to put on the adjustable stud mountings for older cars. This means they remove the Model A hubcaps to mount with cones through the centre holes. And I have heard it said these pressed holes do not always mount accurately like those in modern cast alloy wheels do. I have 2 Jaguars, a 1952 Riley, a 1953 Alvis and 2 Model A's. the English cars are all 100 mph saloons so wheel balancing is critical and tyre companies will not take the time to do any of them properly. SAJ in NZ |
05-03-2021, 10:44 AM | #29 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Attached Chart showing RPM-MPH for given Rear End Gear Ration
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05-03-2021, 04:33 PM | #30 |
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Re: Max Speed of a Model A with 26% OD and HC Head
Correction to my post above about Larry's question. I was told there are 1200 registered Model A's in NZ.
And the belief is there may be about the same number or more unregistered, hiding in barns and sheds all round the country. So my estimate of 400 is way out! SAJ in NZ |
05-03-2021, 05:20 PM | #31 |
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Re: Max Speed of a Model A with 26% OD and HC Head
That's all very nice but what tyre size relate to those figures? A 5.00X19 tyre is about 3.3% smaller than a 4.5X21 tyre.
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05-03-2021, 05:24 PM | #32 |
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Re: Max Speed of a Model A with 26% OD and HC Head
103.7 mph
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05-03-2021, 05:37 PM | #33 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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05-03-2021, 06:52 PM | #34 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I saw 70mph in my 29 fordor once and it was a little scary. I have an inserted engine with oversize intake valves, B cam, 5.9:1 Brumfield head, dual B carbs, and a Borg Warner overdrive. 55-60 on the highway feels ok. Those front fenders act like wings and create lift if you go too fast...
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05-06-2021, 07:56 PM | #35 | |
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Re: Max Speed of a Model A with 26% OD and HC Head
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Ron |
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05-06-2021, 09:26 PM | #36 |
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Re: Max Speed of a Model A with 26% OD and HC Head
I saw 70mph on my Model A speedometer once, but that was when I had it disassembled in my hand playing with the dial.
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05-06-2021, 10:35 PM | #37 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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05-06-2021, 11:16 PM | #38 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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05-06-2021, 11:31 PM | #39 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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05-07-2021, 12:26 AM | #40 |
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Re: Max Speed of a Model A with 26% OD and HC Head
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