How fast in 2nd gear?

40 Deluxe said:
Would like to back up the bus a bit here. Ford came out with the 5.4 (330) engine in 1997 with a bore of 3.55" and a stroke of 4.17". Definitely under square! The 6.8 V10 had the same bore and stroke.
Thus stroke is 5/8" larger than bore. By contrast a Model A's stroke is only 3/8" larger than bore. So the A is more nearly "square" than a late model F-150!
A lot of other modern US gasoline engines are also under square, though by not nearly as much.
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Three eighths of an inch is huge in engineering terms. Saying that an A engine is nearly square is a bit like saying that your girlfriend is a bit pregnant. Both things are black and white.
 
Chippy Minton said:
Three eighths of an inch is huge in engineering terms. Saying that an A engine is nearly square is a bit like saying that your girlfriend is a bit pregnant. Both things are black and white.
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My comment was referring to post #54 which said a 5/8" difference was 'fairly close to square'.
 
40 Deluxe said:
Would like to back up the bus a bit here. Ford came out with the 5.4 (330) engine in 1997 with a bore of 3.55" and a stroke of 4.17". Definitely under square! The 6.8 V10 had the same bore and stroke.
Thus stroke is 5/8" larger than bore. By contrast a Model A's stroke is only 3/8" larger than bore. So the A is more nearly "square" than a late model F-150!
A lot of other modern US gasoline engines are also under square, though by not nearly as much.
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I'm surprised.

Apparently there has been some what of an about-face in the last 20 years or so.

Except for particular vehicles that I own / have owned, I pretty much stopped paying much attention to "modern" cars and trucks.

Maybe automakers figured-out that "torque" has some value after all.

I'd still bet someone a hot lunch that the majority of engines designed and built since 1960 are over-square, short-strokers that will tolerate high revs better than our heavy, old long-stroke, 3-main Flivvers.
 
Art Newland said:
My car has some vibrations here and there but at higher revs it's quite smooth. It will easily attain 50+ mph on the flats, but can't say that I feel comfortable at that speed... 45 seems happier.:) There is talk of a drive being put together by some local clubs beginning in Blaine, WA and traveling to Mt. Baker. It's a bout a 70 mile trip but the last 20 miles climbs 4000+ feet in elevation, and the last 8 miles has a lot of switchbacks as it climbs even more steeply. Sounds like maybe some sustained 25mph in second gear is doable?
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Art,

Looks like fun! Are we starting in Blaine, Benny's newsletter said it would start in Deming? At any rate, I think we would be fine. I have had the misfortune of being on the freeway on 5%+ grades out on the Olympic Peninsula, and while I didn't make many friends at the end of the day I never felt that unsafe and only got flipped off once (and yes, I used the pullouts whenever available & I was holding up traffic). I'm glad I did it.

One of these years, I'd love to start on the Pacific on the Summer Solstice & see how far across the state we can make it.
 
Ian, we thought Deming would be more centrally located for the folks down South. Watch moonona.org for more info on the Artist Point drive. Should be plenty of time for testing second gear speeds! 8^)
 
40 Deluxe said:
My comment was referring to post #54 which said a 5/8" difference was 'fairly close to square'.
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As opposed to my '48 Chrysler straight-eight which has a bore of 3-1/4" and stroke of 4-7/8", for example.

Essex - Terraplanes / Hudson Super Six had a 3" bore and 5" stroke as late as 1946.



Thus, 5/8" is fairly close to "square" in my book...

It's all relative, I guess.

For those that feel their Model A can spool-up past 2500 RPM and like it, it's your car. If you're confident that it's "at factory spec" or better, then maybe there's nothing to worry about.

If your engine is "tired iron", proceed with caution.
 
The thing that would prevent me revving my Model A too high wouldn't have anything to do with the cylinder configuration as were hardly talking about high revs here. What I would be more worried about would be the basic valve system and the efficiency of the valve springs in particular.
 
Chippy Minton said:
The thing that would prevent me revving my Model A too high wouldn't have anything to do with the cylinder configuration as were hardly talking about high revs here. What I would be more worried about would be the basic valve system and the efficiency of the valve springs in particular.
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What sort of damage or catastrophic failure are you anticipating from the valve train ?

If anything, the Model A's valve train and design of the induction system would help to limit its potential revving by restricting its "breathing".

Isn't "high-revving" a somewhat relative term ?

In his 1950 "bible", "Souping the Stock Engine", Roger Huntington, spends a fair amount of time discussing reciprocating mass and its effects on engine performance.

Most reports of Model A engine damage / failure pertaining to speed are related to bearing failure, or failure of the rod / piston, not valve issues.


Today, the most expensive parts of the Model A engine to fix (besides the block) are the bearings and crank.
 
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