Most reliable engine?

[Larenc]

Which engine is the most reliable, the flathead V-8 or the OHV V-8? Which is better for town driving and which is best for freeway driving?

[Otto Skorzeny]

OHV V8 of course. It's a modern engine with more hp and torque.  They're well designed, extremely reliable and relatively fuel efficient.

I use my 56 regularly aand take it on 1000+ mile trips. It's never let me down or overheated. It get about 17 or so on the highway and 10 in the city. Less chance of vapor lock on the ohv as well I believe.

[Owen Nacker]

 The flathead was never designed for running long distances at a steady and wide open throttle. Remember, driving situations were a lot different than they are today.

 My nod would go for one of the OHV engines as well. But in my opinion, the 472 is one of the best long distance engines ever built. This engine will run 80-90 MPH for days on end.

 Mike

[kgray39011]

Which engine is the most reliable, the flathead V-8 or the OHV V-8? Which is better for town driving and which is best for freeway driving?

As quoted from Cad Company:
http://www.cad500parts.com/catalog/page6.htm

"Lets start with the advantages of using the 472/500 engine family as a basis for your next engine. This engine family has earned a reputation for longevity and power, partly due to the high initial build quality. You are starting with an engine with tighter specs than many new 'high end' cars, to include the square-ness and uniformity (lack of casting shift) usually expected only in high dollar full race engines, from the bore centers, to the deck surface, to the rotating parts centerlines, to the exceedingly high nickel content of the castings (like a 'Bow Tie'™ block that costs more bare than your complete core engine).

These engines are also very light for their size, being within 60 Lbs of a small block Chevy, while still being tougher and more wear resistant due to the high quality materials and castings. They have numerous other advantages, including easy access to the distributor and oil pump, dry (no coolant passages) intake, individual ports (not siamesed to lower production costs while hurting flow), conveniently angled spark plugs (easy access in the tightest of installations), and internally balanced, eliminating the need (and inefficiency) of external balancing.

Another prime advantage is that due to the stock 11 degree valve angle, and well designed chambers and ports, It is not unreasonable to expect in excess of 700 real HP out of a normally aspirated engine, with common ported production heads - no exotic machine work or aftermarket castings required. For the milder builds, this means that you are well within the range of easily attainable power, without stratching the limits of the stock block and heads."

OHV without a doubt!

Ken

[Mike Josephic CLC #3877]

I think the 331 V-8 engine, which debuted in 1949, is one of the best designed
power plants that Cadillac ever did.  It was the first overhead valve offering from them
and it's basic design was bored out and used for years after which was a testiment to it's
design, engineering and quality.

It was used as a race car / stock car engine in the 50's and blew everything else
away that it came up against.

Absolutely reliable and a strong, well thought out design in my opinion.

Hard to argue with success like that.

BTW, I also like the 500 series engines as well -- smooth running with power to spare
but my nod for #1 goes to the 331.

Mike

[TJ Hopland]

Was the 331 where the 390/429 came from?

[The Tassie Devil(le)]

The first 390's ('59 to '62) were from the same Family as the 331.   The '63 390 and 429 were a totally different kettle of fish.

Bruce.

[Owen Nacker]

 The '63 390 was a totally re-engineered variation of the earlier 390 which can trace it's heritage back to the 1949 331, However some parts were still interchangeable with the previous engine. It was not an "all new" engine.

 These engines were lighter by 50 lbs. This was accomplished by using the latest thin wall casting techniques. Also by using an aluminum front accessory drive in which the distributor and oil pump was moved to the front of the engine.

 The '64-'67 429 was essentially a bored out '63 390. The '67 429 also had some unique design characteristics not seen on the '64-'66 429's such as the "T" pedestal rocker pivots and oiling through the pushrod tube instead of passages in the heads. This was a precurser to the valve arrangement used on the 472 which debuted in '68. It also featured Cadillac's first use the new 4MV Quadra-Jet carb, which required a unique intake manifold.

 The 472 was an all new engine design. This basic engine family which included the 500, 425 and 368 was used in regular production cars until 1981, and until 1984 in the commercial chassis and Seventy Fives. The regular production cars received the all new aluminum HT4100 in 1982.

 Mike

[EAM 17806]

I personally consider the 500 CU, 8.2Ltr engine in 1976 to be one of the finest put together by GM because of its durability, easy access to engine parts and all the updates from the early years when they started. The carburetor, air cleaner intake direction, HEI ignition (1975) and quite a few more improvements  that made this engine purr like a kitten when it is tuned up properly. When you drive these engines you can feel the power and command it has especially when driven up around 65 MPH. Just my opinion, and not because I have one.  The gas mileage could have been better, about 12 in city and 15 on the highway.  EAM

[Owen Nacker]

 I have to agree on many points on the 500, however the power of the high compression 472's was beyond comparison. These were truly heroic performers, and engines that ran as smooth and quiet as any when just cruising around town. Add HEI as I did with mine, and you have that added touch in performance and durability.

 Mike

[CarFreak]

I personally consider the 500 CU, 8.2Ltr engine in 1976 to be one of the finest put together by GM because of its durability, easy access to engine parts and all the updates from the early years when they started. The carburetor, air cleaner intake direction, HEI ignition (1975) and quite a few more improvements  that made this engine purr like a kitten when it is tuned up properly. When you drive these engines you can feel the power and command it has especially when driven up around 65 MPH. Just my opinion, and not because I have one.  The gas mileage could have been better, about 12 in city and 15 on the highway.  EAM

Does anyone know the mpg of a 1976 Lincoln?  Chevette was about 30 mpg.

[The Tassie Devil(le)]

Does anyone know the mpg of a 1976 Lincoln?  Chevette was about 30 mpg.   

I don't think the numbers go low enough for the Lincolns.

Bruce.

PS.   Oh, that's right, there are still single digit numbers to consider

[Otto Skorzeny]

I don't know about the 1976 Lincolns per se but the '77-'79 Mark VI got only 7 mpg on average. If you romped on it, that figure was cut in half! You get better mileage with a Patton Tank!

[Owen Nacker]

 Ford engines could never claim anything like economy in the 70's. However, if you properly tuned a 472 or a 500, the mileage was pretty decent.

 Many of you will not believe this, but I could get 24MPG (imperial) with my 75 CDV with a 500. I did not believe it at first, but after I ran the numbers 3 times, I had to.

 Mike

[EAM 17806]

MIKE!  I have a 76 CDV and you just can't make that engine any more perfectly tuned and on the money. I personally perfect the carb to its exact specs, in accordance with its shop manual, and hit the timing right on target along with new plugs, wires, ignition module and everything else you can think of and the best mileage I'm able to get is about 12 city and 15 highway. I hope you test the mileage by filling the tank to its brim, mark the mileage on the odometer, then drive at least 150 miles and then fill the gas to the brim once again.  This would be the exact method, as I'm sure you know, to determine the correct MPG after dividing the gallons needed to fill the tank into the number miles driven. If you determined your MPG in this manner WOW what a golden car you have and good luck always with that beauty. I always rebuild my carbs with precision instruments and they run like a charm.  EAM

[Otto Skorzeny]

EAM, I'm pretty sure Mike knows how to figure his mileage.

Note that he said Imperial Gallon not US gallon.

A US gallon is about 83% of an Imperial gallon.

19mpg(US)  is still not too shabby.

[S Passmore]

The flathead was never designed for running long distances at a steady and wide open throttle. Remember, driving situations were a lot different than they are today.
 Mike

I think all you guys have slightly missed the point here and let your hearts run away with you, I cant see how you can compare a flathead engine with other engines of the 70s and later, engineering was bound to improve.
I have proved time and time again that overheating problems with these flathead engines is all down to blocked rad cores or crud in the water jackets, once owners accept that and get them cleaned out with a new rad core they run real cool.     My take on the original question was between the flat heads and OHV of the 40s.

I also have to completely disagree with with certain comments like the one from Mike above, Cadillac tested their Flatheads By running them flat out for days, and don't forget they were in tanks during the war, and Id bet they were run flat out in hot desert conditions in battle, they had to do their job, and if you had a Panzer chasing you, you gunned it. and sorry Mike, but the leader on most stock car circuits in the 50s were the Hudson Hornet, surpassed eventually by the Olds 88. don't see many Cadillac engined cars in there.  There are plenty of good OVH engines out there now, but I think Cadillacs flat head was a milestone engine in its day, was never beaten for power to size ratio and smoothness if a little on the heavy side, and I love them to bits.

[mgrab]

Don't forget the Chrysler 300 of 1955 and 1956......

[Owen Nacker]

 Of coarse you are right in what you are saying. However, driving conditions were quite differant in the time of the flathead than what cropped up in the 50's with the new interstate system.

 The Cadillac flathead was a very advanced engine for its' day, however the OHV engine completely eclipsed it and left flathead technology looking like yesterday's laundry. It was not unusual for many manufacturers to test engines at WOT for days on end to check wear and potential problem areas. These were controlled tests done in laboratories, and even with these tanks, the lifetime given for them was reasonably expected to be in months and not years.

 I am also well aware of the Hudson Hornet. However it was not solely the performance of their 308 CID L-6 that made them winners, it was their superior centre of gravity that allowed them superior stablilty in the turns. Again, these were specialised engines that were designed really to last the length of the race. Hudson was the first company to adopt a performance program to facilitate these engines for competition, one that would be adopted by Pontiac in 1959 with their Super Duty program.

 However, it is everyday driving that I am referring to. The driving of the day included many stops, starts, slowdowns and speed ups. Not constant RPM for hours on end which would be the norm for the later interstate driving. The cars were geared accordingly, generally having lower gearing to facilitate this sort of driving. It was a rare case when even 70MPH could be acheived for any more than a few minutes.

 A technical study of the design of the OHV engine compared to the flathead will show it's superior design and how it is more suitable to high speed driving over long periods of time.

 Mike

[Wayne Womble 12210]

Mike, I agree that the later OHV engines were great, and an improvement, especially in higher compression and HP to weight etc. BUT, there is no reason a flat head cant run just as dependably for extended periods.  My knowledge of engines and mechanics tells me once its running there is very little wear, and it will last longer that way than stop and go. There is no reason it would wear or fail any faster running for extended periods. As a matter of fact, many early Cadillac engines, specifically the 355`s and others, were used to power stationary equipment, long after they had worn out their old car bodies.  Long duration heavy use is just the condition found in this application, and they were very reliable and sought after. Because of the short simple and straight valve train, they could even conceivably be more reliable than an OHV on average.