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Lee Petty and the 1949 Plymouth Business Coupe

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There's been some questions about wheels and tires lately and because of my activities with brakes I've had to study up.

I knew I had read about Lee Petty and his 49 Business Coupe and for the longest time I couldn't find it again.

I found it last night and had to read pages of Petty Enterprises history....fascinating!

He talked about using Chrysler Imperial springs (front and rear) shocks and wheels.

Surprisingly he used 4.78 final drive gears! He said the little Plymouth would only go 92 mph!

Now I maybe wrong but I had to calculate it out.

C64 Imperial wheels are 15x6 with 8.20x15 tires

C66 Crown Imperial Wheels are 15x6 1/2 with 8.90x15 tires

Using the Crown 8.90x15 tires (31 inches tall) with a 4.78 final drive means the little Plymouth was wound up to 5,000 rpm at 92 mph!

If that doesn't get your attention he said because the car was so light he never took his foot off the throttle.

The Oldsmobiles had to slow down for the corner then try to accelerate out but because he never did slow down he had the edge on them.

Imagine lap after lap at 5,000 rpm for 500 miles....in a flathead Plymouth!?!?

We know he did it and so did others.

So I don't think we can call B.S. on that.

He said the car handled better than the big engine V8s, didn't use tires and was easy on fuel, so he made fewer pit stops and had fewer accidents because of blown tires.

He just motored around lap after lap his objective was finishing in the top 5 where he could make money racing.

This is what I am talking about!

This is what gives me satisfaction with these old things!

There's a story, a history and we can actually drive one.

It's a different experience if you crane out the flathead 6 and install a V8.

I personally think you lose something when you do that.

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I agree. Driving my Coronet is satisfying because it takes me back to a different time. Johnny Mantz won the southern 500 in a 50 Plymouth. Back in the day flathead fords were prevalent but many people were using stovebolt chevs and flathead Plymouths for rods. Horsepower wise they were pretty equal.

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I gotta be honest. 5,000 rpms for 500  miles in a flat 6 Plymouth scares the hell out of me.


50 miles at those rpms scares me.


Then again,you can bet your bippy the Petty crew had the bottom end balanced to the point that friction was just a rumor.

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It does make you wonder how they did it.

I am sure the engine came apart every race and was crack tested everywhere.

They said he had post race inspections 15 times out of 19 races. They used to pay you around $100 (enough for a gasket set, rings and bearings) if you passed the inspection. That had me wondering if they called for an inspection just to help him with expenses.

Petty more than the rest was doing this as a business.

Using Plymouths fit his business model. A low priced car reliable enough for taxi duty with good handling because it was light. The ability to use heavy duty parts from other Chrysler cars (the Imperial springs, shocks and wheels). It all fits.

The list of things they could do besides NDT and balancing might have included Nitriding the crank shaft (to harden the bearing surfaces).

The 92 mph figure agrees with the magazine road test data I've seen in several places as the top speed of a Plymouth.

All of Lee Petty's strategy was to get to the finish line in the money (5th place and above) at the end of the race.

How long it took to get up speed didn't matter if he could stay at his race speed longer than the others even if it was slower.

It's the old tortoise and the hare story with the added twist that he was doing this as a business.



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So heard that 5hey used 6 or 8 ply truck tires which also lengthen his time between pit stops. I think the tires were probably 31 inch diameter the numbers I just ran suggested around 3200 for 65 mph so maybe 5000 is a bit high. Still over 4 grand.


As an aside, I have read from several sources,  that all brands of Chrysler Corp engines were pulled at random from factory build lines, hooked to a water brake dyno and run for 24hrs at 3600 (peak HP RPM) Roughly 60 mph.  So a mile a minute for 24 hrs with no break in procedure.  

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48 minutes ago, kencombs said:

Doesn't work for me either.  Maybe one has to be an Outlook user?   I'm not.

Doesn't work with Outlook,either

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I was kinda lost with the link. Sometimes we add a few extra doo hickeys at the end by mistake ... removing them will get the link to work.

But then it just brings you to this same thread @Loren started ...  obvious boo boo somewhere.  Not the link the poster intended to share.

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Was LP racing on the beach in Daytona? How cool would that have been! Whoa! Tides coming in.

God bless ya Loren...those are crazy #s, bro

Edited by Booger
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