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Old 03-17-2011, 04:07 PM   #1
Dave in Boise
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Default Standard engine "Redline"?

Hi All,

What is the recommended Max for a stock A with Babbit?

With Inserts?

Babbit and Balanced Crank

Inserts and Balanced Crank?

Kind of a wide open question, but I'm afraid I might be driving my car too hard in traffic.

- Dave in Boise
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Old 03-17-2011, 04:26 PM   #2
Dave in MN
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Default Re: Standard engine "Redline"?

Dave,
Yes..wide open question. (Did you intend the pun?)

These are my practices and many will not agree.
Stock: 45-52 Max 55 (in my '28 pickup) with stock engine with high speed rear end assuming stock gravity oiling (This would equate to about 52mph with a standard ring and pinion)
With inserts: I do not have an inserted non-counterweighted but I would suggest the same as babbitt assuming gravity oiling for the inserts
Babbitt and Balanced crank: Same as below
Inserts with counterweighted and balanced crank: 60 (in my '29 Phaeton) with standard rear end and 65 with overdrive assuming again standard gravity oiling.

One more you did not mention: Pressure oil to mains and rods...more pressure...more rpms...

Brakes: The best you can build if you are pushing modern highway speeds!

Speed is fun once in awhile but 35 to 45 is much more pleasant!

Just my opinions....others will have their own.

Good Day!
Dave in MN

Last edited by Dave in MN; 03-21-2011 at 03:28 PM.
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Old 03-17-2011, 05:07 PM   #3
Special Coupe Frank
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Default Re: Standard engine "Redline"?

Going by Ford's own engineering data, the Model A makes its peak HP at 2200 RPM, which equates to about 53 mph road-speed in my '28 with 3.78 rear & 21" tires.

SAE defines "red-line" as the speed at which maximum HP is developed.

Therefore, Model A red-line is about 2200 RPM for a stock engine.

This is probably a conservative definition, but "conservative" probably doesn't blow-up as many engines as "edgy".

Dave made a good point about the brakes too.
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Old 03-17-2011, 05:22 PM   #4
Dave in Boise
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Red face Re: Standard engine "Redline"?

One thing I do do first is the brakes on my A's.. Still all mechanical, reinforcing bands on the drums, woven linings and all adjusted properly.. I'd put them up against modern brakes any day Going fast is not as fun if you cannot stop!

I have a 31 coupe that seems to have a sweet spot at around 54-58 mph. It's an H&H with a balanced crank and flywheel and a tollitson carb.. Other than that I believe it is pretty stock. My 30 Tudor has a standard, no modifications motor on it with about 500 miles on it and it seems to be happier about 5 mph lower.. As far as I know, both have the same 3:78's out back..

Someone told me (not sure I believe it) that you cannot blow up the motor, as the stock Zenith has enough air restriction so as to work like a governor..

Not sure I'd want to really test if that is true
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Old 03-17-2011, 06:51 PM   #5
Don/WI
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Default Re: Standard engine "Redline"?

Quote:
Originally Posted by Dave in MN View Post
Dave,
Yes..wide open question. (Did you intend the pun?)

These are my practices and many will not agree.
Stock: 45-52 Max 55 in a '28 pickup with stock engine with high speed rear end assuming stock gravity oiling
With inserts: I do not have but I would suggest the same as babbitt assuming gravity oiling
Babbitt and Balanced crank: Same as below
Inserts with counterweighted and balanced crank: 60 in a '29 Phaeton standard rear end and 65 in overdrive with standard gravity oiling.

One more you did not mention: Pressure oil to mains and rods...more pressure...more rpms...

Brakes: The best you can build if you are pushing modern highway speeds!

Speed is fun once in awhile but 35 to 45 is much more pleasant!

Just my opinions....others will have their own.

Good Day!
Dave in MN
I am in total agreement with the info above. 35 - 45 is much more pleasant. If I'm in a rush, Ill jump in my modern car. Also, stopping is equally important. Unless you can stop don't even think about making it go! Don/WI

Last edited by Don/WI; 03-18-2011 at 10:30 AM. Reason: corrected spelling error
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Old 03-17-2011, 11:25 PM   #6
Jim/GA
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Default Re: Standard engine "Redline"?

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Quote:
Originally Posted by Dave in Boise View Post

<snip>

I have a 31 coupe that seems to have a sweet spot at around 54-58 mph. It's an H&H with a balanced crank and flywheel and a tollitson carb.. Other than that I believe it is pretty stock. My 30 Tudor has a standard, no modifications motor on it with about 500 miles on it and it seems to be happier about 5 mph lower.. As far as I know, both have the same 3:78's out back..
The difference in the sweet spot is probably the cam being used in the two engines.


Quote:
Originally Posted by Dave in Boise View Post

<snip>

Someone told me (not sure I believe it) that you cannot blow up the motor, as the stock Zenith has enough air restriction so as to work like a governor..

Not sure I'd want to really test if that is true
I have heard the same thing.

Jim
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Old 03-18-2011, 10:49 AM   #7
Special Coupe Frank
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Default Re: Standard engine "Redline"?

"Someone told me (not sure I believe it) that you cannot blow up the motor, as the stock Zenith has enough air restriction so as to work like a governor..."

There's probably some truth to this, given that some folks like to bore-out the intake throat in stock A intakes for better breathing...

Had my Coupe out on a local cross-town "expressway" today and the best she'd do was 60 MPH on the level. But, that's an unrestored engine with 85,000 miles...
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