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Old 06-09-2019, 05:16 PM   #1
Pandersen33
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Default OD power

I have fresh rebuilt 29 engine, snyder head, weber carb, Fs ignition... when i shift into 3 high with my Mitchell (55mph?) it doesnt quite seem to be able to accelerate too well. Is this the experience most have or should it be able to pull a bit more? Tach says ~2500 rpm and 62 mph. Timing set right around 28 at full advance.
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Old 06-09-2019, 05:57 PM   #2
MAG
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Default Re: OD power

Based on 2500rpm, 62mph and 26% Mitchell would guess it has a 4:11 ratio differential. If so you are about on the top of it.
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Old 06-09-2019, 06:27 PM   #3
CWPASADENA
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Default Re: OD power

55-60 MPH is plenty fast for a basically stock Model A.


I would keep the revs down around 2000RPM when at cursing speed.


At 2500, you are working the engine a bit too hard.


Again, this is just my opinion and I am sure others may have something different to offer.


Chris W.
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Old 06-10-2019, 10:24 PM   #4
Bruce of MN
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Default Re: OD power

Quote:
Originally Posted by CWPASADENA View Post
when at cursing speed.

W.
For me, that isnít very specific!
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Old 06-10-2019, 10:50 PM   #5
TerryH
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Default Re: OD power

As others said it sounds like you must have 4.11 rear axle ratio, and at that speed you are already well past the power peak. I also have a Mitchell 26% OD, and I usually shift into 3rd OD at about 45 mph, and on somewhat level ground, it does accelerate decently up to 65 or so. I have the standard 3.78 rear end and also the Snyder 5.5 head. Even with the OD I prefer to cruise at 60 mph most of the time.
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Old 06-10-2019, 11:11 PM   #6
Railcarmover
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Default Re: OD power

Ive seen the FSI module breakdown without failing,resulting in timing scatter...are you running a fuel pump with the weber?
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Old 06-10-2019, 11:46 PM   #7
Tom Endy
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Default Re: OD power

It has been my understanding that the Model A was designed to run all day long at 45 mph with the engine turning over at a nominal 2000 rpm. With an overdrive you can increase the speed of the car and still maintain the engine turning over at 2000 rpm.

My Victoria has a 378:1 ring & pinion and a 23% Ryan overdrive. A while back I installed a tachometer and wrote an article about it. The article includes some speed\tac observations.

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Old 06-11-2019, 08:40 AM   #8
katy
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Default Re: OD power

Quote:
Originally Posted by CWPASADENA View Post
55-60 MPH is plenty fast for a basically stock Model A.


when at cursing speed.


Chris W.
Who's doing the cursing? The Model A driver? Or?
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Old 06-11-2019, 08:46 AM   #9
CWPASADENA
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Default Re: OD power

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Originally Posted by bruce of mn View Post
for me, that isn’t very specific!


55-60 mph

Last edited by CWPASADENA; 06-11-2019 at 08:48 AM. Reason: TYPO
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Old 06-11-2019, 08:52 AM   #10
CWPASADENA
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Default Re: OD power

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Originally Posted by katy View Post
who's doing the cursing? The model a driver? Or?

both!!!

Last edited by CWPASADENA; 06-11-2019 at 08:53 AM. Reason: TYPO
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