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12/01/2021 5:32 PM  #1


Question - What is the life expectancy of a flat tappet engine

I was just remembering that it used to be a big deal when a car rolled over the 5 digit odometer.  I remember my dad telling me that an engine with 100,000 miles usually needed the engine rebuilt.  So what is the truth about the life expectancy one can expect for a flat tappet engine?


1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
 

12/01/2021 6:14 PM  #2


Re: Question - What is the life expectancy of a flat tappet engine

Are we talking in the 60's or today. I am currently running a flat tappet engine and it has 371,000 miles and still runs strong. Granted, it be a diesel.


Gary Zilik - Pine Junction, Colorado - 67 Coupe, 289-4V, T5
 

12/01/2021 6:37 PM  #3


Re: Question - What is the life expectancy of a flat tappet engine

EFI makes the bores last effectively for ever but the flat lifters need proper lube...a bit 'o  zink, I think.  So if we had had EFI back in the day I think those engines would have been like today's...good for 250K + with proper a maintenance.  Now, you are gonna have to make sure those lifters are broke in properly and get the right oil.  Then if you have EFI....who knows.  Should be as good as a roller.  With a pot...not so much.

BB1
 


"you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
 

12/01/2021 7:28 PM  #4


Re: Question - What is the life expectancy of a flat tappet engine

I swapped my first 289 at 200,000 miles only because the car was my daily driver, and I did not want to break down while on the road.  I sold it to a guy who put it into a 4-cyl BMW because he wanted more power.  Several years later I ran into him, and the car and engine were still going strong.

289 #2 was also swapped at 200,000 miles, and still ran well.  I only did it because I put in the 351w it now has.  It's around 100,000 now and the last compression check showed all cylinders at 150-160 psi.

I agree with BB.  They could go way over 250k miles


Original owner - 351w,T-5, 4whl disks, power R&P
 

12/02/2021 6:01 AM  #5


Re: Question - What is the life expectancy of a flat tappet engine

There is no answer, as there are too many variables.  In the '60s they seemed to think 100,000 miles for a typical street driven vehicle was good.  Granted, the oil back then was nowhere near as good as it is today, and carbs inefficient fueling tended to wear the bores out considerably faster.  Once EFI came around we started to expect 200,000 miles from an engine.  Concurrently the oils got better, which also helped. 

The more performance you want out of an engine typically the shorter its life between rebuilds.  In racing its not uncommon to refresh an engine every year.  That engine may only have traveled 50 miles.  In super high end racing they freshen them after every pass (Top Fuel, etc.).

There are exceptions to any number thrown out there though.  I've seen carbed, flat tappet engines go 300+K.
 

 

12/02/2021 8:48 AM  #6


Re: Question - What is the life expectancy of a flat tappet engine

In the late 50’s, early 60’s  a local auto machine shop and Ford enthusiasts found that Quaker State oil and Rislone was the combo that got 125,000 miles from a V8-60.
I continued that regimen well into the OHV engines that I owned. I quit with the Rislone when I started using multi viscosity oils.
  Nowadays I use synthetic oils almost exclusively. From what I have read Mobil 1 euro spec oils have the most desired qualities.
Of course, YMMV.


Good work ain't cheap, Cheap work ain't good!   Simple Man
 

12/02/2021 9:22 AM  #7


Re: Question - What is the life expectancy of a flat tappet engine

Very interesting testimonials.  It is good to hear these stories of long lasting engines.  The remarks about the benefit of EFI, or proper constant AFR to be more specific, was a surprise.


1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     Thread Starter
 

12/02/2021 11:39 AM  #8


Re: Question - What is the life expectancy of a flat tappet engine

Years back....I pulled the 289 from my 66 and there was zero ridge at the top of the bores! I was the 3rd owner (I tink).
Now....the oil gauge would bottom out at a stoplight butt it never rattled or made weird noises.(I guess that was from the worn bearings...low oil pressure)
I have all ideas that was the original engine soooo it was 32 years old?!! Using old skool oils and fuel.
Proper oil changes.....carb and ignition properly tuned....with today's oils and ethanol laced gasoline I would 'guess' 300,000+ miles.
Keep in mind....those flat tappets are NOT sliding along the cam lobes! They are riding in a microscopic layer of oil. Hardly any friction at all.
Same with bearings to a degree. Rings are a different story.
6sal6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

12/03/2021 5:50 AM  #9


Re: Question - What is the life expectancy of a flat tappet engine

Rudi wrote:

In the late 50’s, early 60’s a local auto machine shop and Ford enthusiasts found that Quaker State oil and Rislone was the combo that got 125,000 miles from a V8-60.
I continued that regimen well into the OHV engines that I owned. I quit with the Rislone when I started using multi viscosity oils.
Nowadays I use synthetic oils almost exclusively. From what I have read Mobil 1 euro spec oils have the most desired qualities.
Of course, YMMV.

That's interesting because the machine shop I used to use once told me that Quaker State was responsible for the engine I took apart that looked like a volcano erupted inside it.  Every nook and cranny was packed with sludge.  I mean, the rocker boxes and valley had imprints of the covers and intake respectively  in the sludge.  The shop owner said he saw it all the time.  So I must wonder if the Rislone was keeping that from happening. Rislone from what I've heard is a great detergent.  I've heard of guys loosening up stuck stuff by soaking it in Rislone.  The machine shop owner said the issue with Quaker State was too much paraffin.  It makes me wonder if the Rislone was keeping the paraffin liquified.

As far as oil goes IMO you simply cannot go wrong with Amsoil.
 

 

12/03/2021 5:54 AM  #10


Re: Question - What is the life expectancy of a flat tappet engine

6sally6 wrote:

Years back....I pulled the 289 from my 66 and there was zero ridge at the top of the bores! I was the 3rd owner (I tink).
Now....the oil gauge would bottom out at a stoplight butt it never rattled or made weird noises.(I guess that was from the worn bearings...low oil pressure)
I have all ideas that was the original engine soooo it was 32 years old?!! Using old skool oils and fuel.
Proper oil changes.....carb and ignition properly tuned....with today's oils and ethanol laced gasoline I would 'guess' 300,000+ miles.
Keep in mind....those flat tappets are NOT sliding along the cam lobes! They are riding in a microscopic layer of oil. Hardly any friction at all.
Same with bearings to a degree. Rings are a different story.
6sal6

I think its hard to say now, because nothing except old engines and hobby vehicles have flat tappets.  Only very early EFI engines still used flat tappets.  By the late '90s everything was roller, and those vehicles are getting close on to 30 years old.  Regardless, you are right, that oil film is the life of any engine, and why ZDDP is so important to flat tappet engine survival. 

 

12/03/2021 9:55 AM  #11


Re: Question - What is the life expectancy of a flat tappet engine

Had a few cam & lifter failures on my 77 chevy pickup over the years, Chevy SB are known that. Never had that kind of problem with any SB for Fords. I used the same oil for both. Most ford dealer used Quaker State back in the 70's and so did I for a number of years. I quit using QS after lifting a few valve covers off and seen the gunk build up inside. 

 

12/03/2021 10:45 AM  #12


Re: Question - What is the life expectancy of a flat tappet engine

Back in the 60s Ford rented Daytona Speedway for about 40 days. They ran several Fairlanes I think, and averaged over 100 mph for over 100,000 miles. There's a you tube vid on it.


Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
 

12/04/2021 7:12 AM  #13


Re: Question - What is the life expectancy of a flat tappet engine

Bearing Bob wrote:

Back in the 60s Ford rented Daytona Speedway for about 40 days. They ran several Fairlanes I think, and averaged over 100 mph for over 100,000 miles. There's a you tube vid on it.

They still do all kinds of testing like that, but problems not evident in testing still crop up.  I think its because mileage is one factor, but the effects of the environment and age simply can't be sped up. 
 

 

Board footera


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