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The Venerable Slant 6 vs Our Beloved Flathead 6s

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Hey all

For those of us who have owned both slant 6s and flathead 6s.

Share your stories, comments, good times and bad.

Ive owned a few slant 6s 225s 1 with a 1bbl carb the other a 2bbl carb.

Both A904 transmissions neither super fast but tough reliable and peppy.

Many articles discuss the evolution to slant from flat.

The big change over head valves 6 intake ports and long runner manifolds.

Lets have fun..

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Not much to discuss. The slant 6 is the most reliable gasoline engine ever put in a automobile or truck.

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When my old dual carbed flattie went south, I installed a SL-6/904 in my P-15 with dual Carter single barrels. I gained an easy 50 hp. and a much better car. Since I'm using a  Satellite 273 rear axle, its a slug of the line but has lots of go after I'm moving. The mileage is about the same. I imagine, that if I had a lower rear ratio, It would be a screamer. 

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22 minutes ago, knuckleharley said:

Not much to discuss. The slant 6 is the most reliable gasoline engine ever put in a automobile or truck.

Yah i know but lets tell stories and share hop up secrets.

I have a 1971 in the wings. For a future project.

Or lets compare  a slant 6 stock to a warmed up 265?

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Wife was driving our old truck slant 6, 4 speed. She was on the freeway and heard a loud explosion and pulled over thinking blew a tire.

Everything was fine and it was running fine, she went on her way.

That weekend I went to check the oil. The dipstick was a inch shorter and curled up.

Old carb had been leaking gas into crank case, drove it for a couple years before selling it the new owner drove for long time and said truck was shot not worth fixing and sold. The running motor.

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6 minutes ago, Los_Control said:

Wife was driving our old truck slant 6, 4 speed. She was on the freeway and heard a loud explosion and pulled over thinking blew a tire.

Everything was fine and it was running fine, she went on her way.

That weekend I went to check the oil. The dipstick was a inch shorter and curled up.

Old carb had been leaking gas into crank case, drove it for a couple years before selling it the new owner drove for long time and said truck was shot not worth fixing and sold. The running motor.

I have a cousin that put over 200,000 miles on one in a dump truck,and he was in the scrap metal business and loaded the HELL out of that thing by shredding the metal before loading the truck to haul the steel to the buyer.

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27 minutes ago, Reg Evans said:

I prefer the sound of a flattie over the /6

Me too Reg.

And the look too.

Hows that 251 in Old Yellar going these days?

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Many,many years ago, I out run a 58 Ford 352 V8 with a 61 Dodge Lancer 225. Wasn’t even close. Sure was glad, he was one of my high school teachers and I did not want him to know who it was. There will be no discussion on why he was chasing me. 

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8 minutes ago, Mike36 said:

Many,many years ago, I out run a 58 Ford 352 V8 with a 61 Dodge Lancer 225. Wasn’t even close. Sure was glad, he was one of my high school teachers and I did not want him to know who it was. There will be no discussion on why he was chasing me. 

Uhhhhh,don't want to burst any bubbles,but he was trying to scare you,not outrun you.

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29 minutes ago, Mike36 said:

Many,many years ago, I out run a 58 Ford 352 V8 with a 61 Dodge Lancer 225. Wasn’t even close. Sure was glad, he was one of my high school teachers and I did not want him to know who it was. There will be no discussion on why he was chasing me. 

Did you have Long Haired Louise in the car..

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22 minutes ago, knuckleharley said:

Uhhhhh,don't want to burst any bubbles,but he was trying to scare you,not outrun you.

Nope disagree that Teacher was afraid to blow that old Furd.

That old Furd 352 did not make the top 10 list of best engines in the world...lol

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55 minutes ago, 55 Fargo Spitfire said:

Nope disagree that Teacher was afraid to blow that old Furd.

That old Furd 352 did not make the top 10 list of best engines in the world...lol

The original FE was a 1958 332,and it didn't last long, but the FE's sure lasted long in both production and usage,and IIRC,were finally replaced in 71 with the 429 series engines.

Even the 332 would have had no trouble running down a 6 cylinder anything,with the exception of XKE Jags and that type of car.

 

And the 332 descendant ,the 427 had no trouble running down anything anywhere. Even in a crude old English  AC body.

Edited by knuckleharley

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3 minutes ago, knuckleharley said:

The original FE was a 1958 332,and it didn't last long, but the FE's sure lasted long in both production and usage,and IIRC,were finally replaced in 71 with the 429 series engines.

Even the 332 would have had no trouble running down a 6 cylinder anything,with the exception of XKE Jags and that type of car.

Oh I have driven a few.

Sure they have more power than a stock slant 6.

But  we are comparing slants to lheads..

Not apples to grapefruits...lol

 

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5 hours ago, knuckleharley said:

The original FE was a 1958 332,and it didn't last long, but the FE's sure lasted long in both production and usage,and IIRC,were finally replaced in 71 with the 429 series engines.

Even the 332 would have had no trouble running down a 6 cylinder anything,with the exception of XKE Jags and that type of car.

 

And the 332 descendant ,the 427 had no trouble running down anything anywhere. Even in a crude old English  AC body.

You are right about it being a 332, in the over 50 years since it happened I had forgotten about that engine. In 79 I bought a new Dodge aspen with 225 engine. Other than looks, it in no way resembled the 61 engine. Those pre emission engines would run hard. The teacher was not trying to scare me, he wanted to know who it was. 427 had no trouble running down anything anywhere? Unless it was a blue Plymouth with a 43 on the door.

Edited by Mike36

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2 hours ago, Mike36 said:

You are right about it being a 332, in the over 50 years since it happened I had forgotten about that engine. In 79 I bought a new Dodge aspen with 225 engine. Other than looks, it in no way resembled the 61 engine. Those pre emission engines would run hard. The teacher was not trying to scare me, he wanted to know who it was. 427 had no trouble running down anything anywhere? Unless it was a blue Plymouth with a 7 on the door.

Maurice Petty is a pretty sharp cookie. I know some of the guys that work for him. One of his guys built the headers for my 32 Ford coupe for me.

Still,they didn't always win,and the Holman and Moody team kept them on their toes.

 

And we all know the street cars of all brands were very distant cousins to the factory race cars from everybody.

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52 minutes ago, knuckleharley said:

Maurice Petty is a pretty sharp cookie. I know some of the guys that work for him. One of his guys built the headers for my 32 Ford coupe for me.

Still,they didn't always win,and the Holman and Moody team kept them on their toes.

 

And we all know the street cars of all brands were very distant cousins to the factory race cars from everybody.

Knuckle its a thread on slant 6s and lhead 6s please and thank you.

I enjoy your stories so dont take it the wrong way...

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In October 2016 I drove my 1965 Barracuda with a slant six , 904 automatic transmission, and a 2:76 rear end on Route 66 from Joliet IL to Santa Monica CA. The total trip from Michigan to California and back 5889 miles. I ran 60 to 70 MPH for most of the trip and got 21MPG average mileage. The slant six is a great motor.

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My slant spanks a lot of V-8's...  I raced a 5.0 Mustang with a 5 speed at a quarter mile track.  I won 2 out of three races on a dare and some $$$ and beer involved.  I lost the time slips from this race, which was over 20 years ago!  My 1969 2 door Valiant has a 8.75" rear end with 3.73 ratio from US Gear, over .500" lift camshaft(not going to give away the actual specifications), headers I built using Clifford and a vintage set of Edelbrock headers I found, a A833OD transmission, and a Holley 4 BBL.  

 

When I raced the car, I had a 465 CfM Holley.  For the last decade, I stepped down to a 390 CFM 4 BBL.  I think that the 390 is more efficient than the 465, at least according to my spark plugs.  But the engine really screamed on the top end more with the 465....   I temporarily put 3.55 gears in the car for now too.  The 3.73's are the way to go!  So I will be putting them back in at some point.

 

I have earned a lot of respect from naysayers over the years.  And I want to see what I can do with a flathead next.  So far, the flatheads that I have built have all been stock....  That will be changing soon...

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6 minutes ago, classiccarjack said:

My slant spanks a lot of V-8's...  I raced a 5.0 Mustang with a 5 speed at a quarter mile track.  I won 2 out of three races on a dare and some $$$ and beer involved.  I lost the time slips from this race, which was over 20 years ago!  My 1969 2 door Valiant has a 8.75" rear end with 3.73 ratio from US Gear, over .500" lift camshaft(not going to give away the actual specifications), headers I built using Clifford and a vintage set of Edelbrock headers I found, a A833OD transmission, and a Holley 4 BBL.  

 

When I raced the car, I had a 465 CfM Holley.  For the last decade, I stepped down to a 390 CFM 4 BBL.  I think that the 390 is more efficient than the 465, at least according to my spark plugs.  But the engine really screamed on the top end more with the 465....   I temporarily put 3.55 gears in the car for now too.  The 3.73's are the way to go!  So I will be putting them back in at some point.

 

I have earned a lot of respect from naysayers over the years.  And I want to see what I can do with a flathead next.  So far, the flatheads that I have built have all been stock....  That will be changing soon...

I know they will do that Jack. My cousin used to shut down 283 Chev’s with his, as well as several 318’s. 

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I have a couple good stories.  FIrst, at one point in time I owned a 1964 W-200 Crew Cab with a slant six, and also a 1966 D-200 step-side, and finally a '73 Dart.  The dog liked to ride in the back seat of the dart because the sound of the engine would lull her to sleep.  She'd growl if you tried to move her LOL.  The 2 trucks were both ex-Air Force, and I owned them in the 90s when they were plenty old, but neither burned any oil and they ran perfect.  

 

I used to work for a guy that always made fun of my Dodges (I also had a 68 Plymouth Sport Satelitte...poor man's Super Bee) with a 383 and a 4 speed with a Hurst shifter at the time) and finally one day I had enough of his **** so I called him out on his BS.  I challenged him to a floorboards contest.  He had a Ford truck, nearly new.  I told him, we will each sit in each other's trucks and hold it to the boards until one of the engines blows up.  Last man standing wins.  Maybe it wasn't a smart move, but I told him if his truck engine outlasts my slant six I'd work for him for 1/2 pay for a whole year.  If I win, he gives me a $5/hr raise. Yes, I actually said that.  But I knew his Ford engine would never outlast my slant six.  Hell, if I drained the oil out of my engine it still probably would've outlasted his.  Anyway, he didn't think I was serious at first.  Then he realized I was serious and told me that his truck was worth a lot more than mine, so he had more to lose.  So I offered to put it up against the shop's Chevy S-10 which had one of those tough little 4 bangers in it, and the truck was a $500 junker anyway.  He STILL wouldn't do it, and then he got pretty quiet after that.  He never made fun of my Dodges again.  

 

Around the same time, my next door neighbor, whom was a big Chevy guy (and was about 20 years older than me) told me a story that I almost didn't believe, but I knew he wouldn't lie to me because he didn't like Mopars and would never go out of his way to talk a Mopar up or give credit to one.  He told me one day back in the late 70s a friend of his had an old rusted out Dart from the 60s that he was gonna junk.  But he wanted to have some fun and blow the motor up first.  So he and some pals gathered around while the guy drained the oil out of the slant six.  Then he started it up and wedged a stick between the gas pedal and the seat.  He said it ran for 25 minutes wide open before it shut down, with no oil mind you.  He said the next day they went out to the car for sh*ts and giggles and his friend thought he'd try cranking the engine over.  It started up and ran.  Turns out my boss in my previous story probably wasn't as naive to Mopar engines as I might have thought, otherwise the dumbass would've taken me up on my bet.  Long live the slant six :D

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I killed the 7 1/4" within a day, hence the reason I needed a 8.75".  Then a week later, the 904 went...  Then I found the 4 speed.  Finding two different driveshafts  in one week was the tough one for me!  LOL. Would be even tougher now!  At least in the early 1990's, junkyard's still had A Bodies in them.  No more...

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5 hours ago, classiccarjack said:

I killed the 7 1/4" within a day, hence the reason I needed a 8.75".  Then a week later, the 904 went...  Then I found the 4 speed.  Finding two different driveshafts  in one week was the tough one for me!  LOL. Would be even tougher now!  At least in the early 1990's, junkyard's still had A Bodies in them.  No more...

Great stuff Guys keep.em coming.

Also anyone can share there experiences on flathead Chrysler 6s versus slant 6s.

Say the monster 265 performance compared to the more modern slant 6.

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Another option for posts on this thread could be.

Who has swapped out  a small displacement for a large say 250 or 265.

Tell us how much more power and driveability pleasure this created..

I am hoping to rebuild my IND 265 this year and swap out the tired 228.

I can hardly wait to see how much difference in power it might be.

With a full 1/2  inch stroking it should be fun..

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