218 flat six max RPM

[OUTFXD]

Just out of curiosity,  what is the Redline on a 218 flathead six?

 

I mean. .. I dont CURRENTLY have a tachy-o-meter,  but I am thinking of temporarily hooking one up for academical purposes.

[TodFitch]

I recall seeing a factory test horsepower/torque curve that went up to maybe 4000 or 4200 RPM. Power dropped off pretty dramatically after 3600 RPM (RPM for max horsepower).

 

Personally, I'd rather not abuse my nearly 90 year old engine that much.

[FarmerJon]

Peak horsepower from the factory was at 3600.

 

If you think your speedometer is about right, you can see what RPM you are turning at various road speeds using a calculator like this.

 

 

[Booger]

Thats a really good question. A few factors and you can chart up with your tire size and gear ratio and mph. But your ears know when when your pushing it. 3600 is max. 2800-3000 should be your sweet spot. Buy a Westach for 140. 

[Loren]

Lee Petty said his 49 P17 could do 92 mph.

He used Imperial wheels, tires, shocks and springs.

The Imperial tires were very large diameter so he changed the final drive gears to 4.3.

We worked it out that little 218 must have been turning 5,200 rpm!

Which must have been really flogging it.

But then he only had to do it for 500 miles.

Peak output is listed as 3,600 rpm so….

Maybe that’s why he got torn down 15 out of 19 races.

 

Enzo Ferrari loved his race cars and he didn’t put much effort into his street cars even though they paid the bills.

So you don’t see many Ferraris at the supermarket. The reason is the cars he spent his time perfecting only had to last 24 hours.

The typical “licensed” Ferrari was lucky to make it to its first or second tune up before major work.

Lee Petty’s P17 I am certain was pushed beyond all reasonable limits. So kids, don’t try this at home!

I would think a redline at or near 3,600 rpm is good unless you do some serious work to the engine.

[OUTFXD]

5 hours ago, FarmerJon said:

Peak horsepower from the factory was at 3600.

 

If you think your speedometer is about right, you can see what RPM you are turning at various road speeds using a calculator like this.

 

 

 

My Speed-o is pretty juttery. I think the cable needs to be lubed.  I have been using a GPS till I get around to fixing the speedo cable.

[FarmerJon]

My speedometer was like that when I first picked it up. A drop or two of CLP oil in the gauge side of the cable and it has been smooth and quiet ever since. A nice 'No tools required' job. Your milage may vary

 

Keep in mind that max safe rpm when the car was fresh off the showroom floor, and max rpm when 70+years old are likely to be different.

Wear, loose parts, tired fasteners, sludge, deposit build up, state of the carb and distributor.

 

You have good oil pressure on your engine. How's the compression?

Have you adjusted the valves? 

Is the oil pan full of sludge?

Does it smoke? 

Rattle?

Does the distributor vac advance work, or suck air?

 

Edited February 9, 2022 by FarmerJon

[keithb7]

These long stroke engines were originally designed for torque with minimal transmission shifting. My understanding is back in the day it was considered luxury quality to be able to drive around in only 1 or 2 gears. The less shifting the better the car. So torque was king. Not necessarily top end speed for the average car owner. The old square cars plowed through wind resistance best they could. Air flow design had not been considered until the early 30's.  Soon after the Chrysler Airflow was released. The flat head six in mass production by the early 1930's, there became less demand for the 4 cylinders engines. Henry Ford even had to relent eventually. The Mopar flathead 6 saw little change until it was replaced by the V8 in about 1954. Compression numbers rose over the decades, stroke changed and grew bit. The basic foundations of the engine design, still the same since the 19-teens. High revving, was not part of the design for these mass produced people movers.

[OUTFXD]

4 hours ago, FarmerJon said:

My speedometer was like that when I first picked it up. A drop or two of CLP oil in the gauge side of the cable and it has been smooth and quiet ever since. A nice 'No tools required' job. Your milage may vary

 

Keep in mind that max safe rpm when the car was fresh off the showroom floor, and max rpm when 70+years old are likely to be different.

Wear, loose parts, tired fasteners, sludge, deposit build up, state of the carb and distributor.

 

You have good oil pressure on your engine. How's the compression?

Have you adjusted the valves? 

Is the oil pan full of sludge?

Does it smoke? 

Rattle?

Does the distributor vac advance work, or suck air?

 

Oil pressure runs about 60 psi.  I am told this is almost dangerously high and I should check the oil pressure spring.

 

I have not adjusted the valves.

 

Have not checked the oil pan.  I am running seafoam through the engine to flush out any sludge.

 

It blows grey smoke (steam) for about 30 seconds after a cold start.  It cold starts in about 1.5-2 revolutions.  After "warming up" for about 15 seconds it runs butter smooth.

 

No rattles, even when cold.

 

First thing I did after buying the car,  It was having ignition problems.  Cracked open the distributor thinking to adjust/replace the points.  Found the roller Bearings  for the spark advance (!) was seized solid.  ended up rebuilding the Distributor.

 

all in all it runs better than it has any right to.  I suspect someone rebuilt the engine not to long ago.  It is a rollercoaster of workmanship.  a long time ago.  somebody LOVED this car and sunk tons of money into it,  Then  it fell to a group of kids who tried to turn it into a rat rod, complete with using a sandblaster to artificially patina the paint. as to the electrics... well...

[Sniper]

Not sure why you think 60 psi is dangerously high, it isn't.  If you have Facebook search out The Freewheeling Tony Smith and read up on his oil system work.

[greg g]

Factory max recommended oil pressure is 50.  Chrysler used to pull random flathead six engines off the line, mounted them in a water brake dynamometer  and run them under load at 3600 rpm for 24 hours, as part of their quality control procedures.  My car was running 3280 rpm at 65 indicated on the speedo which showed as 62 on the GPS.  When I had the engine at the machine shop, I asked the fellow what his recommendation for sustainable cruising rpm.  He said for long stroke engines that was 80 to 85% of peak hp rpm, assuming good operating conditions regarding engine temp, oil pressure, and oil quantity and condition. My rpm at 60 to 65 fell within the 85% brackets. He also said that exceeding 4000 rpm for more than a couple minutes without modifying oil supply to crank and cam could result in expensive noises.  

 

Use the calculator for your specifics and operate accordingly.

 

Our car has the 4:11 rear, before the od was installed, we did several 500 plus mile trips at 3300 rpm sustained with no problems.  But checking the oil level at every fuel stop was part of the routine.  This after the re build.

[Sniper]

Depends on what manual you look at, early ones call for 40-60psi

 

Later ones up to 53 psi

 

Also depends on what oil you are running.

 

 

 

[OUTFXD]

24 minutes ago, Sniper said:

Not sure why you think 60 psi is dangerously high, it isn't.  If you have Facebook search out The Freewheeling Tony Smith and read up on his oil system work.

 

What I remember of the quote it was "Ten pounds pressure for every thousand rpm is an engineering standard proven by years of experience."

 

and That over 40-45 psi will " overload and prematurely wear the oil pump and the timing chain, It will also contribute to flooding the cylinders with too much throw off from the rods."

 

Aaaand I dont have facebook

[FarmerJon]

the discussion involving the oil pressure.

 

 

[OUTFXD]

Thank you FarmerJon.  I'm still new here and didnt know how to cross-thread quote!

[Sniper]

2 hours ago, OUTFXD said:

"Ten pounds pressure for every thousand rpm is an engineering standard proven by years of experience."

For a small block Chevy maybe and as a MINIMUM.  Heck the factory recommended oil pressures are above that guideline anyway.  IIRC, the Mopar Perfomance engine book called for less pressure than 10 psi per 1000 rpm, but I'll be darned if I can recall the exact amount anymore.  I;m not even recalling where the book is that has the info anymore.  lol

 

Not all engines are the same.  The flathead has two sets of oil control rings, the SBC one set.  The timing chain on the flathead is twice as wide as the SBC as another example.  One cannot automatically assume that what limitations a specific design has is applicable across the spectrum of all engines.  Lots of variables, but if you are seeing that kind of pressure with a thick oil, change viscosity. 

[OUTFXD]

Well.. I'm seeing that kind of pressure, but I have no idea what weight oil is actually in the engine.  I have only JUST started driving it and I am letting some seafoam circulate in the oil supply hoping to nock loose any sludge.  I have a new filter and 10-40 ready to go in.  I kinda assumed 10-40 for an older vehicle.  My Mopar knowledge only goes as far back as the mid 60s.

 

out of curiosity what wait oil are you using?

[kencombs]

11 minutes ago, OUTFXD said:

Well.. I'm seeing that kind of pressure, but I have no idea what weight oil is actually in the engine.  I have only JUST started driving it and I am letting some seafoam circulate in the oil supply hoping to nock loose any sludge.  I have a new filter and 10-40 ready to go in.  I kinda assumed 10-40 for an older vehicle.  My Mopar knowledge only goes as far back as the mid 60s.

 

out of curiosity what wait oil are you using?

before taking any action on the oil pressure issue (question), I'd confirm with an independent gauge.   I wouldn't assume the original is accurate.

[47 dodge 1.5 ton]

Back to the max rpm— I have seen these engines make 5k if allowed to breath. My biggest concern is cylinder ridges on later life engines. If the engine spent any amount of time at lower rpm’s,  cylinder bores most likely are worn there, stretching rpm’s may allow a few extra thousands above the ridge, potential cause for ring failure. If ran in at high rpm’s from the start, think they are capable. Question is— where you feel comfortable.

[Sniper]

25 minutes ago, OUTFXD said:

out of curiosity what wait oil are you using?

 

Lol, you like to live dangerously.

 

I use 10w30 detergent oil.  Others use what they like. 

[Bryan]

46 minutes ago, OUTFXD said:

Well.. I'm seeing that kind of pressure, but I have no idea what weight oil is actually in the engine.  I have only JUST started driving it and I am letting some seafoam circulate in the oil supply hoping to nock loose any sludge.  I have a new filter and 10-40 ready to go in.  I kinda assumed 10-40 for an older vehicle.  My Mopar knowledge only goes as far back as the mid 60s.

 

out of curiosity what wait oil are you using?

Will use 5W30 Quaker State “Full Synthetic”  dexos 1 Gen 2, ILSAC GF-6A, API SP = 152,674 psi in about a year. 

[keithb7]

I'll join the fight. 10W30. I might go xxW40 when it 90+ around here in July and Aug. Just this week in my fresh 237 rebuild I saw 43 ish psi at idle with 10W30.  I dumped it and installed SAE30. Idle psi was up to 50-ish. 

Edited February 10, 2022 by keithb7

[Bryan]

11 minutes ago, keithb7 said:

I'll join the fight. 10W30. I might go xxW40 when it 90+ around here in July and Aug. Just this week in my fresh 237 rebuild I saw 43 ish psi at idle with 10W30.  I dumped it and installed SAE30. Idle psi was up to 50-ish. 

Pressure builds with resistance to flow.   A garden hose with the nozzle open has low pressure. Nozzle closed, hose swells.  

[Matt Wilson]

On 2/8/2022 at 10:55 PM, Loren said:

Lee Petty said his 49 P17 could do 92 mph.

He used Imperial wheels, tires, shocks and springs.

The Imperial tires were very large diameter so he changed the final drive gears to 4.3.

We worked it out that little 218 must have been turning 5,200 rpm!

Which must have been really flogging it.

But then he only had to do it for 500 miles.

Peak output is listed as 3,600 rpm so….

Maybe that’s why he got torn down 15 out of 19 races.

 

Enzo Ferrari loved his race cars and he didn’t put much effort into his street cars even though they paid the bills.

So you don’t see many Ferraris at the supermarket. The reason is the cars he spent his time perfecting only had to last 24 hours.

The typical “licensed” Ferrari was lucky to make it to its first or second tune up before major work.

Lee Petty’s P17 I am certain was pushed beyond all reasonable limits. So kids, don’t try this at home!

I would think a redline at or near 3,600 rpm is good unless you do some serious work to the engine.

I know this is an older thread, but I am really curious about whether Mr. Petty was using stock 218 rods and rod bolts.  I don't suppose there's any way for us to know for sure, unless it was known that he said that stuff was stock.  But I'm curious.

[Loren]

From what I've read in the early days of NASCAR stock meant stock.

So that would mean the Pettys used Plymouth rods and rod bolts. The forging numbers were right there for all to see.

 

The biggest cheater of all time, Smokey Yunick told a story of why his Hudsons ran so well.

American race tracks all turned left at the time and all car engines turned clockwise when looking at the front of the car.

This meant the torque of the engine pulled to the outside of the turn and reduced the traction and cornering power of the car coming out of the corner.

His cheat in this case was to change the camshaft so that the engine ran counter clockwise and thus the engine torque pulled to the inside. It gave his drivers a significant advantage coming out of the turn into the straightaway. The driver could apply power sooner and harder.

He never said if he even bothered to tell the driver.

Chrysler racer Carl Kiekhaefer could smell a rat and protested Yunick's Hudson often. He knew that camshaft was somehow suspect but not what was wrong with it. After Yunick threw a fake tantrum one day and broke the cam in several pieces, he picked one of the pieces up and handed it to Kiekhaefer and said "Here's all you need to check it yourself!" Of course he could check the profile but not the direction of rotation.

 

When I read that story I wondered how the NASCAR "experts" and an engineer of Kiekhaefer's calibre could miss what Yunick had done.

Looking at a camshaft you can tell which way it is supposed to turn by the arrangement of the lobes. The rule is Intake follows Exhaust. Chain driven cams turn with the crank and a gear driven cam turns the opposite direction. Put a gear driven cam in an engine with a chain and it will run counter clockwise. Twin engine boats can have engines that turn opposite directions to counter the torque on acceleration.

Now before you jump to the conclusion Lee Petty did the same thing, I can tell you he didn't. Photos of his car coming out of a turn show it leaning heavily to the outside. Also the Plymouth had a hypoid ring & pinion which couldn't be "flipped" to turn the right direction, like an "on-center" R & P can.

 

Petty didn't mind the frequent tear downs because they came with a protest fee which was intended to pay for a set of gaskets and a little more.

I am certain he tore the engine down every race. Yes he abused them but they only had to last at most 500 miles. NASCAR rules said the parts had to be stock. They did not say how you were to assemble them. To get more oil pressure to the rods you could be "sloppy" with the installation of the cam bearings. Put them in with half or more of the oil hole covered by misalignment with the galley.