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View Poll Results: What sustained car MPH will babbitt bearings in a stock Model "A" reliably withstand?
50 MPH 54 49.09%
55 MPH 29 26.36%
60 MPH 14 12.73%
65 MPH 6 5.45%
70 MPH 7 6.36%
Voters: 110. You may not vote on this poll

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Old 05-13-2018, 07:50 PM   #21
Chuck Sea/Tac
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Default Re: How Fast Will It Go?

Quote:
Originally Posted by Kurt in NJ View Post
from the crankshaft print--
shaft must be in balance dynamically within 3 ounce inch at any one point of reference, shaft must be in balance statically within 3 ounce inch

on the rod print there is a weight tolerance of +/- 1 gram at each end ----modern engines mostly have larger tolerances

what percentage of rebuilt engines do you think have been restored to original tolerances
Quote:
Originally Posted by George Miller View Post
babbitt is lost because of bad babbitt jobs, loose bearings, lack of oil to the bearing, lugging.
I use to race chev 6 cylinders with babbitt rods and babbitt line inserts in the mains. never lost the babbitt, did break a couple of pistons.
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Old 05-14-2018, 07:24 PM   #22
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Default Re: How Fast Will It Go?

Someone explain if these engines were so well balanced leaving the factory why do we now add large counter weights to smooth out vibrations.
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Old 05-14-2018, 08:58 PM   #23
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Default Re: How Fast Will It Go?

156 kph flat head 4 in stock cpe body but not stock engine , we run our stocker delivery 95-100 kph with Mitchell . Its an old car, reno MAFCA meet in a few weeks be there,
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Old 05-15-2018, 12:15 AM   #24
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Default Re: How Fast Will It Go?

I was going between 55 and 58 when I lost the babbit. It wasn't the speed that caused the problem, but the oil tube(s) feeding the mains were clogged and the mains got little or no oil.
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Old 05-15-2018, 07:28 AM   #25
BRENT in 10-uh-C
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Default Re: How Fast Will It Go?

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Originally Posted by wmws View Post
Someone explain if these engines were so well balanced leaving the factory why do we now add large counter weights to smooth out vibrations.





In a nutshell, how the engine left the factory, ...and how many people rebuild them today are totally different. For example, when you measure the weights of today's typical replacement piston vs. the weight of an original piston, there is a huge difference. The same applies to the wrist pin. Matter of fact, today's typical replacement wrist pin is nearly 100 grams heavier than original pins.


Next consider how the connecting rods are rebuilt today. Most rebuilders add WAY more shims between the cap & the rod (-over what Ford originally did) in an effort to make the engine owner feel like he has much greater service life. Next, factor in the crankshaft pin journal is smaller, and something must take up that difference between the cap/rod and the pin journal. That 'something' is babbitt which is heavy by comparison.


The 3rd thing is most Model-A engine rebuilders are selling on a price point (--because that is what their customer wants them to do!!) and there is typically not money budgeted in the rebuild cost to do an accurate balance job. By percentages, there is only a small amount of A engines out there that have an aftermarket counterweighted crankshaft. General logic will be that if an owner is paying for the C/W crankshaft, then in all likelihood they are paying for a quality balance job too. This as a combination makes one engine much superior to the other type of 'budget-built Model-A engine'.


Does this answer your question??
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Old 05-15-2018, 09:35 AM   #26
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Default Re: How Fast Will It Go?

Thanks for the explanation Brent. So you are saying that with a well balanced engine that 3000 RPM is no problem.
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Old 05-15-2018, 03:09 PM   #27
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Default Re: How Fast Will It Go?

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Originally Posted by wmws View Post
Thanks for the explanation Brent. So you are saying that with a well balanced engine that 3000 RPM is no problem.




Well, don't take my word for it, let's think it thru together. What do you feel is the weakest link, ....and why exactly? If the Babbitt is correctly installed (peened, etc), align-bored & clearance correctly, and has adequate lubrication, it will support a spinning crankshaft at likely twice the RPMs as you mentioned. So in reality, we can rule-out the Babbitt as the weakest link.


So what are you thinking is going to fail at 3k RPM??
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Old 05-15-2018, 04:57 PM   #28
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Default Re: How Fast Will It Go?

I would think that if valve float didn't limit the RPM before 3000 the next thing to go would be the crank. I'm not worried about the babbitt. But there is a lot of weight reversing direction twice a revolution. I'm talking about an engine right off the assembly line, not a modern rendition. But your the expert on these engines. I just feel that Henry never intended for them to be turning that high on a regular basis.
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Old 05-16-2018, 12:45 AM   #29
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Default Re: How Fast Will It Go?

xxx

Last edited by apbright; 05-16-2018 at 09:11 PM. Reason: answer n/a
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Old 05-16-2018, 07:05 AM   #30
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Default Re: How Fast Will It Go?

Quote:
Originally Posted by wmws View Post
I would think that if valve float didn't limit the RPM before 3000 the next thing to go would be the crank. I'm not worried about the babbitt. But there is a lot of weight reversing direction twice a revolution. I'm talking about an engine right off the assembly line, not a modern rendition. But your the expert on these engines. I just feel that Henry never intended for them to be turning that high on a regular basis.





Again, it seems like we have been thru this a million times, and while Bob has changed the verbiage thus IMO screwing up this entire poll, the original question was what speed can a stock engine's babbitt reliably withstand. Over of the voters believe they were only capable of 50 MPH which always seems to bring an argument.


While I doubt this will change anyone's mind, let's see if we can logically get to the bottom of this discussing facts and not fabricated opinions which this site seems to always have many of. If as you say that Henry never intended for them to be driven that fast, then why did he publish in his Sales Literature that he did?? Matter of fact, this statement was made well into the Model-A production, ...so if there was any doubt or claims of misinformation, he had 2 years of prior production to retract his claim.


For all the naysayers, I have enclosed a page below right out of the 1930 Ford Model-A Sales Manual. Please read the highlighted paragraph from that literature and then tell us where it says anything about needing overdrives, or a high compression head, or 16" tires or any of the other 'items required for touring' nonsense to be able to drive a Model-A safely & reliably at 60 mph. So if Ford advertised it could run safely and reliably at 55-65 MPH --or even at greater speeds, surely to goodness if someone wants to claim their Model-A is restored, then it should capably be able to duplicate the speeds as when it was new.


...and for the over 50% who voted that a Model-A engine when new was only capably of operating reliably at 50 mph or under, please tell the ones of us that voted for 55 mph or faster where we are wrong.


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Old 05-16-2018, 09:04 AM   #31
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Default Re: How Fast Will It Go?

I was told by my good friend and mentor, Bill Coleman (RIP), that a stock Model A engine is limited to about 3,000 RPM by it's air flow through the stock carb, intake manifold, valves, etc. In other words, the air flow. He never mentioned the babbitt. You can figure out road speed at this RPM for a stock car.

If you have modified the above, which is common, then this restriction is raised some.

I have concerns, on a stock engine, about rod lubrication in the dipper trays being able to keep up at higher RPM. You are slinging a lot of oil out of the tray at very high RPM and I'm not sure the oil pump and gravity feed to the tray can keep up. I have no evidence (hard to see in there while the engine is running at high RPM) so it's a concern, not a fact. I know that's why designers went to pressurized cranks in later engine designs.

I have driven a few original, low mileage, engine never been opened up or worked on, Model A's. They are amazingly smooth. They put modern rebuilders of the same engine to shame. Of course, you can't get away from the harmonics that are inherent to the engine design itself. But except for that, they are smooth. As Brent said, if you take the time to balance everything to the original specs (and I mean balance to be more than just weighing components... I mean balance everything, like combustion chamber volume, valves, proper cam specs, etc.) you should be able to reproduce it.
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Old 05-16-2018, 11:14 AM   #32
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Default Re: How Fast Will It Go?

http://www.fordgarage.com/pages/rileysos.htm
So back when the car was new there wasn't much concern about Babbitt doing higher compression ratios, oiling center main, splash lubed rods--- and 100 mph---- it does say that babbited brass insert for only upper center main can be improvement

100 mph is well over 3000 rpm----- to does say stock rotor comes apart over 85 mph
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Old 05-16-2018, 12:56 PM   #33
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Default Re: How Fast Will It Go?

So if someone were in the market for a rebuilt engine as close to an original Ford example as possible, where should you look/who should you talk to?

Not sure how much longer mine will last, the rods are in sorry shape (#4 is missing a good chunk). But it's still reasonably quiet, and pulls my 2500lb Fordor up to 60-65 without much fuss. Been told by a lot of guys to just run it. And I will.... for as long as I can.
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Old 05-16-2018, 02:37 PM   #34
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Default Re: How Fast Will It Go?

Brent, I think Henry may have been stretching truth in advertising a bit, but as I remember they did run a Model A from I think it was LA to Phoenix and averaged 60 MPH. As an ex motorcycle road racer I know that even racing engines run near there maximum RPM for long periods tend to blow eventually. We used to rebuild the bottom end and check over everything at least every 500 miles of racing.
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Old 05-17-2018, 04:44 AM   #35
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Default Re: How Fast Will It Go?

Quote:
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Brent, I think Henry may have been stretching truth in advertising a bit, but as I remember they did run a Model A from I think it was LA to Phoenix and averaged 60 MPH. As an ex motorcycle road racer I know that even racing engines run near there maximum RPM for long periods tend to blow eventually. We used to rebuild the bottom end and check over everything at least every 500 miles of racing.
Here we go again. Folks often choose to believe opinions over facts which generally leads to confusion.

So exactly what is the fastest speed 'one needs to drive to average 60 mph? How long does it take to drive from LA to Phoenix?? Did the A engine require rebuilding upon arrival in Phoenix???

Believe what you like but most rational people would agree that if you can drive from LA to Phoenix at an average speed of 60 mph in a Model-A, then Ford's claim of driving 60 mph for extended periods would NOT be stretching the truth!
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Old 05-17-2018, 08:03 AM   #36
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Default Re: How Fast Will It Go?

I don't remember all the exact details, I think it was 62 mph, and that was after 500 miles on the salt flats averaging 65 mph, and the car had over 60,000 miles without being rebuilt, and it was done to advertise a brand of oil ----the car had observer riding in the back seat---must have been a wild ride

many roads weren't good enough to go 60+ ----but still people drove as fast as the car would go
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Old 05-17-2018, 09:28 AM   #37
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Default Re: How Fast Will It Go?

Driving the A fast is easy ... it's the stopping it from those speeds that can be life shortening.
With the brakes setup properly the tires don't have the adhesion capacity to stop & control the car at speeds over 50 mph, any dirt or water on the road... not a pretty sight for the grand-kids. More sticky rubber on the road helps here. ( newer tires, fatter tires )

or... Another view would be please drive them fast, it will leave more $ in the Social Security trust fund for me.
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Old 05-17-2018, 11:04 AM   #38
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Default Re: How Fast Will It Go?

I agree with Brent. If the model A is in like new condition or even real good condition it could be driven 60-65 MPH for extended periods . This certainly doesn't mean that a person should ALWAYS try to average these high speeds or drive the model A that fast at all . the point is that the model A could do it !!! Does anybody remember the advertisements on TV that the early small block Ford engines were testes at 100.000 miles at 100 miles per hour . This was just a test to show their durability, not to say that they should be driven at such speeds .
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Old 05-18-2018, 12:16 PM   #39
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Default Re: How Fast Will It Go?

Why do we keep hearing that Model's have bad brakes. My 1928 Sport coupe had 26,000 miles since it had been restored. It would still slide all 4 wheels, what more do you want. Some say they drive bad. I never found that to be true.
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Old 05-18-2018, 01:02 PM   #40
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Default Re: How Fast Will It Go?

I agree with George !!! My mechanical model A brakes wqork just as well as more modern hydraulic drum brakes . I think that a lot of the problem is in the way the brake rods are set up. It doesn't make a lot of difference how much money has been spent or how good the brakes have been rebuilt if the brake rods haven't been setup correctly . Slack in the brake rod connections is a major cause of poor brakes .
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