How many miles on your flatheads?

[Matt Wilson]

Hi folks, I'm just curious how many miles you guys have gotten out of your flatheads since they've been rebuilt.  Especially as related to the small block, such as 230 cid like mine.  Or how many miles you've heard of other people getting.  I'll post a similar question on the truck forum.

As I said, just curiosity...

Thanks!

[knuckleharley]

Not sure you are really going to learn anything. Almost nobody uses an antique car as a daily driver these days regardless of the weather or the distance involved, Because of this almost nobody will put 100k miles on their antique Mopar in 10 years,or maybe even 20 years,even if it is the only antique car they own. For casual "weekend in nice weather" drivers none will live long enough to put more than 100k miles on their cars.

I will say I have a general impression/recollection from youth that nobody seems concerned about vehicle mileage until it topped 100k miles back when I was a kid and it was common to see 40's and 50 cars on the road as daily drivers every day.

Given how much the lubrication properties of oil has improved since the 40's and 50's,I'd be surprised if there were any reason for concern today about mileage on a well-maintained flat 6 Mopar right up to 150 k miles if it weren't abused. Especially if you were to add a full-flow modern oil filter to the system.

[Young Ed]

I think mines been about 12 years now and it's got 24K miles on it since then. Truck engine is even more years but only about 6k miles. 

[dpollo]

I have been using cars powered by these engines for over 50 years.   It was not unusual that a well maintained flathead would travel 100000 miles but most needed service by 75000 .    I drove my first  50 with a Canadian 218 from 56000 when I got it, to 179 900 but that involved three overhauls, the second and more thorough included a rebore at 95000 miles,  At 150 000 I went through it again.  I never had any crankshaft problems  but did put new shells in at each overhaul.  The engine still exists and is in good running order.

  I had a nice 55 Plymouth which needed a valve grind at 70 000 and a chain at 75000.   My present 51 Convertible has travelled over 50 000 since its restoration in 1983 and runs just fine.   A rebuild done in 1990 for a customer who used his car daily logged over 70 000 miles on unleaded gas and without any intelligent care at all  before a tree fell on the car.  That engine is in another car now and is well past 80 000 miles.  The most trouble free crankshaft-wise were the Chryslers with a full flow filter.  The highest mileage car I have seen is a 48 Dodge Limousine whose owner used it commercially and did his own repairs logged 650 000 miles on three engines, each with one  overhaul and the last a preventative teardown and rebuild when the owner was over 80 years old.  These were the Canadian 25 inch engines.  The owner, Gretton Brown of Victoria BC changed oil at 2000 mile intervals.

 By 1957 when the venerable flathead was required to haul around a much heavier car and at higher speeds, some owners found that the engine was worn out by about 25000 miles, but others , perhaps gentler drivers got the usual 77 to 100000 miles.

I have repowered some of my cars, one with a 283 Chev and another with a 225 Slant six but while these swaps had merit, I always returned to the flathead.  I even put a flathead in a 57 truck which was a  v 8 and it worked really well since the 8 came with a 3.73-1 rear axle.

[meadowbrook]

My 50 was never rebuilt as far as I know and has 80000. But compression is below spec. Runs great and does not smoke.

[lizmcl527]

I use my 1941 Dodge D20 as a daily driver except during the winter and during inclement weather, and generally put about 2300 miles a year on it. The engine, a 218 Canadian long block, was rebuilt in 2012 at 92030 miles, and I'm just getting ready to lay it up for the winter at 101473, so that's 9.443 miles in four years since the rebuild. I use maybe half a quart of oil between changes, and get about 18 miles to a gallon.

[50 coupe]

86k on my 218. I assume all original. Runs ok but compression is low and misses when idling. All new plugs, wire, points, distrib wiring. Plan to reset valves this winter and see if that matters. 

[Dan Hiebert]

Our D24 has 256K miles on it.  We've put less than 1K on it per year.  It has the original engine which I know was rebuilt sometime before we got the car, but no clue at what mileage, but it wasn't all that recent to when we got it, as it had obviously aged quite a bit already.  It runs well, but compression isn't all that great, and you can tell everywhere I've been by the blue cloud...

[55 Fargo]

On 12/10/2016 at 10:10 AM, dpollo said:

I have been using cars powered by these engines for over 50 years.   It was not unusual that a well maintained flathead would travel 100000 miles but most needed service by 75000 .    I drove my first  50 with a Canadian 218 from 56000 when I got it, to 179 900 but that involved three overhauls, the second and more thorough included a rebore at 95000 miles,  At 150 000 I went through it again.  I never had any crankshaft problems  but did put new shells in at each overhaul.  The engine still exists and is in good running order.

  I had a nice 55 Plymouth which needed a valve grind at 70 000 and a chain at 75000.   My present 51 Convertible has travelled over 50 000 since its restoration in 1983 and runs just fine.   A rebuild done in 1990 for a customer who used his car daily logged over 70 000 miles on unleaded gas and without any intelligent care at all  before a tree fell on the car.  That engine is in another car now and is well past 80 000 miles.  The most trouble free crankshaft-wise were the Chryslers with a full flow filter.  The highest mileage car I have seen is a 48 Dodge Limousine whose owner used it commercially and did his own repairs logged 650 000 miles on three engines, each with one  overhaul and the last a preventative teardown and rebuild when the owner was over 80 years old.  These were the Canadian 25 inch engines.  The owner, Gretton Brown of Victoria BC changed oil at 2000 mile intervals.

 By 1957 when the venerable flathead was required to haul around a much heavier car and at higher speeds, some owners found that the engine was worn out by about 25000 miles, but others , perhaps gentler drivers got the usual 77 to 100000 miles.

I have repowered some of my cars, one with a 283 Chev and another with a 225 Slant six but while these swaps had merit, I always returned to the flathead.  I even put a flathead in a 57 truck which was a  v 8 and it worked really well since the 8 came with a 3.73-1 rear axle.

While the 57/58 Plyms were in the 3550 lb range while the 51-53 Plyms were in the 3200-3400 range. The early 50s Plyms were 218 95 hp while those laters would be 228s or 250 with about 110hp.

I think perhaps if they needed a ring and valve job by 25k they were driving the $hit out of them, or running them low or outta oil....

I do respect your love of these engines though, and I also think they are great, ever see 1 in a fox body Mustang....LOL told my son we should put 1 in his....

[knuckleharley]

1 hour ago, Rockwood said:

I do respect your love of these engines though, and I also think they are great, ever see 1 in a fox body Mustang....LOL told my son we should put 1 in his....

That would be a real hoot.

Remember back in the 70's during the first gas crisis,and suddenly full-fendered T's  and A's with OHC 4 cylinder Pinto engines became popular? One guy had his car in Rod and Custom back then that reversed the flow. He put a Model A engine into a Pinto.

[dpollo]

I am sure that the flathead has been swapped into many more applications than I am aware of.  For my part, I have seen one in a Morris Minor and another in a late 40's Vauxhall !  I never heard either one run.   I read of one which was swapped into a 52 Chevrolet sedan with good results.  The whole power train from a 48 Plymouth went into the Chev for the simple reason of necessity and no money.  Same reason why I swapped one into my 57 half ton Fargo when the V-8 croaked.  It may have cost me in excess of $150 to repair !  A long time ago now.

By the 50s these engines were definitely yesterday's news, but I like the way they run and they will run a long time if treated with respect.

[Matt Wilson]

Thanks for the responses, guys.  It sounds like one can expect 75 - 100K before an overhaul, if the engine is cared for and not driven hard, and maybe some will go beyond 100K.  Not that I will ever drive mine that many miles.  I just thought it would be an interesting topic.  There is a section on L-6 Engine Rebuild at the back of Don Bunn's book on Dodge pickups, and the author of that section says that his experience is that some engines have over 100K miles on them and are running well, while others are completely worn out at 40,000 miles, and that an average life is about 70,000 miles in his experience.  This seems to agree with what you guys are saying.  Some years ago, when I spoke with George Asche, he told me that he runs synthetic oil in his flathead and at that time, he had over 200,000 miles on it since the last rebuild.

[knuckleharley]

16 minutes ago, Matt Wilson said:

  Some years ago, when I spoke with George Asche, he told me that he runs synthetic oil in his flathead and at that time, he had over 200,000 miles on it since the last rebuild.

Good oil and good filters make a difference,and frankly,the old non-detergent oil everyone used back then was crap.

[dpollo]

Matt,   check out who wrote the article in the Don Bunn book.

  I first wrote it in 1980 for the WPC news then revised it for the Plymouth Bulletin who then permitted the Dodge truck book to use it.  There it suffered some BAD editing and some pictures of what appears to be a Hudson six.

Also, George Ashe is completely correct .  Just as the limousine driver I mentioned earlier  Good clean oil is important.

[DLK]

My 50 Wayfarer went about 66000 original miles before I had it rebuilt. By then it still ran fine but its weak power was evident climbing hills and it smoked like a mosquito control vehicle and burned a quart about every 150 miles.   Since I only put about 2-3000 a year on it this rebuild should long outlast me.

[James_Douglas]

I use my 1947 Desoto LWB Suburban here in the middle of San Francisco every week.  I also dive it a couple of times a month, about 160 mile round trip, to our place in a small town.  That has a lot of 65-70 MPH running.

I have over 50K miles on my rebuild which was done about 2005.  I am noting some dropping of oil pressure. Just a little.  I also have started to see in the last year some oil pulling by when going down Waldo Grade at 60 MPH and allowing the engine to compression brake down the hill in 1:1 gear. With the OD in and the RPM's lower not so much.

I suspect that the guides are starting to wear and I am sucking oil under high vacuum - high RPM situations.

When I had the engine open a couple of years back for the melted plug (see old posts), I did put in new rings and ground the valves.  Although how good the hone was leaning over the engine bay is an open question.

In about 20K more miles, I suspect that I will have to pull the block and rebuilt it.

Given that this car is over 4000 pounds, only has a 251 six,  see's San Francisco Hills, and long freeway runs on a constant basis, I think I am doing good.

If you rebuilt a flathead WELL, as if you are doing a race engine, I see no reason why it will not go 50K to 60K without any issue. Mine has.

James.

 

 

[Matt Wilson]

On ‎12‎/‎12‎/‎2016 at 10:25 PM, dpollo said:

Matt,   check out who wrote the article in the Don Bunn book.

  I first wrote it in 1980 for the WPC news then revised it for the Plymouth Bulletin who then permitted the Dodge truck book to use it.  There it suffered some BAD editing and some pictures of what appears to be a Hudson six.

Also, George Ashe is completely correct .  Just as the limousine driver I mentioned earlier  Good clean oil is important.

Aha!  I didn't make that connection till you mentioned it, Dave!  Glad to see you are still driving flatheads.  Yes, those OHV engines are indeed just a passing fad.  I appreciate your and everyone else's input.

[DrDoctor]

   I agree completely with knuckleharley’s comment that [sic] good oil, and good filters, make a difference, and that the non-detergent oil everyone used back then wasn’t as good as contemporary lubricants. To that formula I’d add “good maintenance”. A well taken care of car will last much longer than one that’s not so well taken care of, but that’s stating the obvious. As to synthetic oils, it’s my understanding that the molecules in synthetic oil are much smaller than those in petroleum-based oils, thus they provide a significantly greater lubrication factor to the engine. However, along with that, also due to the smaller molecules in synthetic oil, they tend to work their way around the engine’s seals, and thus leak more than petroleum-based oils do. My only experience with synthetic oil is with our Corvettes (neither of which we now have), and we never had a problem, but those engines were designed for synthetic oil. So, would you suspect that a flathead engine, designed well before the expanded usage of synthetic lubricants (I’m not including the Nazi usage of coal-based synthetic lubricants during WWII, and their equipment was famous for leaking . . .), would be a leaker of major proportions??? Just curious . . .  Thx.

[T120]

I don't mind a vintage car dripping a bit of oil  over a period of time and I generally provide for that where the vehicle is parked, providing either a drip tray or something to absorb drips. As others have found, changing to a synthetic oil may cause more of a problem with oil drips...I don't use synthetic oil for that reason

 

[knuckleharley]

I suspect,but don't know that synthetic oil would be fine if you had a newly totally rebuilt engine with modern seals. I also know it will sometimes swell old,hardened,and shrunken seals to stop oil leaks. What I don't know is which seals it will "heal" and which it will make worse. I have personally had it stop leaks as well as stop smoking in one old engine I put it it,but that "old engine" was a 70's engine,not an original 50's or older engine.

I used it exclusively in my 06 GMC turbo diesel 2500 HD 4X4,and have since the day I bought it used off of a Texas used car lot 6 years ago when the odometer read 96k+. It now reads 130k+,and I never even have to add a quart between oil changes at 25k miles, Not even when I drove from NC to Minot,ND a couple of years ago pulling a 4,000 lb equipment trailer,and came back home hauling a 39 IHC and a 37 Dodge truck at 75 MPH. Weighted a little over 19,500 lbs leaving out of Minot.

BTW,my 2500 has the optional 365 hp,665 ft lbs of torque engine instead of the standard turbo diesel,and a Allison 6 speed auto with what amounts to a trans brake in it for slowing going down hills,and 3:73 gears. My transfer case,transmission,and differentials are all also filled with synthetic lubes.

My plan right now is to run synthetic oil in my flat 6's once I rebuild them. Until I tear them down and get rid of all the old caked in 30 and 40 wt non-detergent crud,I will continue to run 30 or 40 wt non-detergent oil in them. I definitely don't recommend dumping it in a engine that has a lot of miles and a lot of that old non-detergent waxy oil clinging to ever internal surface because it will set that stuff free to flow though your oil journals.

Edited December 18, 2016 by knuckleharley

[Tom Skinner]

I seem to remember an old Mechanic named Bob (that worked on old flatheads) starting out in the 1940s telling me (in the 1970s)

Our old flatheads were good for about 60 - 75K then would need rings. Of course proper valve adjustment improved their life as well.

 

[T120]

Don't want to get into a discussion about the merits of different engine oils. I totally agree with regular oil and filter changes. I do use approved multigrade detergent engine oils in all my vehicles. If I was still a resident in the arctic I might use synthetic engine oil... I am kind of fussy and I don't like oil drips on my concrete driveway. A couple of years ago one of my sons bought a used 2004 Chrysler PT Cruiser and parked it in my driveway. It ran fine and didn't drip oil, although it wasn't entirely clean as a whistle underneath. It was driven and parked in my driveway for a month or so without any noticeable drips. Anyhow, he changed the engine oil, thought he would spend the extra bucks for the better synthetic oil which he uses in his trucks and left the PT Cruiser parked in my driveway. It was dripping oil - not a lot, but enough to annoy me. I parked it out on the street until the next oil change and then did it myself using a 10/30 oil. The annoying drip disappeared. That is my experience with synthetic engine oil. That is not to dispute the fact that it may be a superior engine oil and as I mentioned, if I was living in the arctic,i would probably be using synthetic oils; at present I don't see the need for the added expense.