The Venerable Slant 6 vs Our Beloved Flathead 6s

[55 Fargo]

Now was lurking on the Slantsix forum and its a great site.

Its apparently not difficult to get 200 to 250 hp out of a Slanty without going bankrupt.

With our engines even a 265 getting 200 to 250 is a huge deal getting 150 to 175 is doable.

Difference is that 6 port intake overhead valve head, plain and simple..

 

[55 Fargo]

Hers another interesting tidbit, on the smaller Slant 170 with its 1 inch shorter stroke, could be made to be a little revver. It being an over square engine, has the shorter stroke.

 

Now with our Flathead 6s, in say the long block Canadian versions,  the 218 with it's 3 3/8 bore and 4 1/8 stroke, ( closer to square than the others like the 228, 250 or 265)  should be a better candidate to make power and rev, say than the 250/265s with there much longer strokes.

 

But of course they do not, as the displacement increases and longer stroke torque increase seem to reign in this arena.

 

Smokey Yunik declared at 1 time, he has never seen an engine respond to simple bolt on parts as the 170 Slant 6 does, very interesting statement..

 

Here is a Furd back in the day with a Chrysler flathead 6

Edited February 3, 2018 by 55 Fargo Spitfire

[Dozerman51]

I have heard that the Desoto 236.6(237) with it’s 3&7/16” bore x 3&1/4” stroke is also a good rever. But like they say, “there is no replacement for displacement”. 

[55 Fargo]

56 minutes ago, Dozerman51 said:

I have heard that the Desoto 236.6(237) with it’s 3&7/16” bore x 3&1/4” stroke is also a good rever. But like they say, “there is no replacement for displacement”. 

Not to be picky but....LOL

Its a 4 1/4 stroke same as the 228 with its 3 3/8 bore...

For what its worth have not ever heard or known anyone who has souped up a Canadian long block 218 or 228, so who's to say they can't be like a 250 or 265, this is unknown.

Hey my Fargo has it's stock 228, and there is no indication it has been over bored or rebuilt, no tags, no oversizes marked on the piston tops.

I'm building a 265 so yes no replacement for discplacement

[Dozerman51]

I had a nice conversation with Tim Kingsbury recently about my IND-7(237). I gave him the specs to the cam I have in it. He stated that the profile is basically one for a 1952 Chrysler with a bit more duration but not much more. Looks like I will have to change the cam if I want to increase the horsepower or more importantly the torque. 

[55 Fargo]

13 minutes ago, Dozerman51 said:

I had a nice conversation with Tim Kingsbury recently about my IND-7(237). I gave him the specs to the cam I have in it. He stated that the profile is basically one for a 1952 Chrysler with a bit more duration but not much more. Looks like I will have to change the cam if I want to increase the horsepower or more importantly the torque. 

Whats the spec .375 lift 260 duration?

[Dozerman51]

The lift is .376 and the duration is 238 degrees.

[55 Fargo]

Just now, Dozerman51 said:

The lift is .376 and the duration is 238 degrees.

Yes that makes sense, a 260 duration with a .375  lift may be closer to a 3/4 mile track type cam, more RPM for the turns...LOL

How about putting in a .410 lift 270 duration, warm it up a bit...

[Dozerman51]

I guess that is what I should have done to begin with. I just don’t want too hot a cam where the motor is really chugging at idle.  I should have done more research on cam profiles. Oh well. I do plan on returning to the 750-16 tires and wheels from the 900-16’s I have on the truck now. This should lighten up the load some for the 237. Along with the wheel change,  I will be switching out the 4.30 ratio third members to 4.10 ratio third members. 

[55 Fargo]

17 minutes ago, Dozerman51 said:

I guess that is what I should have done to begin with. I just don’t want too hot a cam where the motor is really chugging at idle.  I should have done more research on cam profiles. Oh well. I do plan on returning to the 750-16 tires and wheels from the 900-16’s I have on the truck now. This should lighten up the load some for the 237. Along with the wheel change,  I will be switching out the 4.30 ratio third members to 4.10 ratio third members. 

As Tim K or Earl Edgy could tell you these bigger cams make the idle higher, more than a big lumpy idle like a big block V8..

[55 Fargo]

Okay here is a 225 Slant 6 and a 904 installed into a 1956 C series Dodge pickup, easy install and no firewall chopping according to the owner.

It fits nicely, looks good and is a nice little cruiser engine..

[classiccarjack]

If you find a 1960 Slant six powered truck, I have seen 1 slant six town wagon, you can use the bell housing and the engine mounts to bolt everything into the post pilot house trucks.  I did this many years ago.  I have never been able to find another early slant six truck since.  Almost all of them I find is a flathead or a poly V8.  

 

The 1961 and up, I am not sure if they would work.  The frame was drastically changed in the 1961- trucks.  I haven't swapped one yet, or been asked to.

[55 Fargo]

19 minutes ago, classiccarjack said:

If you find a 1960 Slant six powered truck, I have seen 1 slant six town wagon, you can use the bell housing and the engine mounts to bolt everything into the post pilot house trucks.  I did this many years ago.  I have never been able to find another early slant six truck since.  Almost all of them I find is a flathead or a poly V8.  

 

The 1961 and up, I am not sure if they would work.  The frame was drastically changed in the 1961- trucks.  I haven't swapped one yet, or been asked to.

Yes that would work nicely.

In fact a front style mount can be adapted to a LA 318 Ive heard but do not know for sure..

[Tim Keith]

On 2/1/2018 at 7:11 PM, Flatie46 said:

Tim your right about the L-heads liking propane.  The Yale forklifts we use to have at our plant did very well on this. The engine in my '46 coupe was a Jasper re-man engine that was suppose to go in a fork lift but they signed a rental agreement on a new fleet before it was used.  ( It was actually set in a forklift but never put into service, long story, anyway I got a new engine for free )  Propane  burns much cleaner in the combustion process and promotes longevity.   I saved the propane set up and tank in case I ever wanted to run it like that again. 

Propane is better for the oil.    L-heads often coke up the rings .   I think that annual use of a top engine cleaner could help a flathead motor.  Some older engine manuals recommend that the cylinder head be removed periodically and the carbon be removed.   I doubt that many flatheads ever had that service done.  I think that modern gasoline direct injection would help an L-head, that would be radical         The LF-39 aircraft flathead is designed to be trouble free, there must L-head tricks in that motor, which has only been in production for a couple years.   One of the advantages of the LF-39 is if a valve fails the engine keeps running, -a dropped valve in an OHV motor can cause a crash.

[Flatie46]

10 hours ago, Tim Keith said:

Propane is better for the oil.    L-heads often coke up the rings .   I think that annual use of a top engine cleaner could help a flathead motor.  Some older engine manuals recommend that the cylinder head be removed periodically and the carbon be removed.   I doubt that many flatheads ever had that service done.  I think that modern gasoline direct injection would help an L-head, that would be radical         The LF-39 aircraft flathead is designed to be trouble free, there must L-head tricks in that motor, which has only been in production for a couple years.   One of the advantages of the LF-39 is if a valve fails the engine keeps running, -a dropped valve in an OHV motor can cause a crash.

I wonder if the direct injection from the LF-39  would work on a Mopar car or truck.  I know in this day and  age where  people have Bridgeport  mills and Tig set-ups in their shop out back you can make most anything work.  But I wonder since the engines are so similar if it might be  a good fit. I would think it would up the power,  MPG's and longevity.  ( longevity because fuel injected engines tend to last longer due to the more ideal atomization and proper metering of the fuel )  It would be neat to see anyway but they're prob few and far between, in my area anyway.

      I think the only drawbacks of propane are it makes a tad less power from combustion and it's harder  to start in cold weather.  If you run a propane set up in a car or truck and needed fuel you could pick up a grill tank at any convenience store. lol

[55 Fargo]

3 hours ago, Flatie46 said:

I wonder if the direct injection from the LF-39  would work on a Mopar car or truck.  I know in this day and  age where  people have Bridgeport  mills and Tig set-ups in their shop out back you can make most anything work.  But I wonder since the engines are so similar if it might be  a good fit. I would think it would up the power,  MPG's and longevity.  ( longevity because fuel injected engines tend to last longer due to the more ideal atomization and proper metering of the fuel )  It would be neat to see anyway but they're prob few and far between, in my area anyway.

      I think the only drawbacks of propane are it makes a tad less power from combustion and it's harder  to start in cold weather.  If you run a propane set up in a car or truck and needed fuel you could pick up a grill tank at any convenience store. lol

And a bbq grill in trunk or box tapped in for roadside burgers and dogs....lol

Edited February 4, 2018 by 55 Fargo Spitfire

[55 Fargo]

LF 39 is  short stroke engine too at 3.11 inch stroke..

[Flatie46]

22 minutes ago, 55 Fargo Spitfire said:

And a bbq grill in trunk or box tapped in for roadside burgers and dogs....lol

Might work better for a truck and "tail gating".

[Tim Keith]

15 hours ago, Flatie46 said:

I wonder if the direct injection from the LF-39  would work on a Mopar car or truck.  I know in this day and  age where  people have Bridgeport  mills and Tig set-ups in their shop out back you can make most anything work.  But I wonder since the engines are so similar if it might be  a good fit. I would think it would up the power,  MPG's and longevity.  ( longevity because fuel injected engines tend to last longer due to the more ideal atomization and proper metering of the fuel )  It would be neat to see anyway but they're prob few and far between, in my area anyway.

      I think the only drawbacks of propane are it makes a tad less power from combustion and it's harder  to start in cold weather.  If you run a propane set up in a car or truck and needed fuel you could pick up a grill tank at any convenience store. lol

 

 The propane is so much cleaner burning than gasoline.    Synthetic oil ought to help a flathead. 

[55 Fargo]

Hey all,

Okay so picked up this 225 Slant 6 the other day 200 bucks.

It is supposedly has 39 k mileage ( like I believe that)...lol

Its out of a So Cal car that sat for many years like close to 25 years at a body shops compound.

The guy i bought it from got it a while back with the intention of a 440 transplant which they finally did this winter.

The var and this engine were driven as late as summer 2017.

Pulled valve cover rockers filthy inside of cover clean, someone was in there.

Pulled oil pan black filthy oil and some sludge, oil pickup screen fairly clean and not clogged.

All sparkplugs newer but carbon fouled.

New looking ignition parts rotor point etc.

Compression turning over by hand seems good no stuck valves.

Did not expect too.much for the price

Seller phoned me about another matter and was adamant this engine runs well and did not smoke or knock..ive heard that before....lol

 

Edited February 10, 2018 by 55 Fargo Spitfire

[55 Fargo]

The good news it had a forged crank and rods.

Dirty is heck but may or may not run well.

[55 Fargo]

Okay so played around with the Slant 6, pulled oil pan for inspection and clean out. Cyls nice and cross hatched patter still visible, oil pan filthy.

Pulled rockers and push rods and cleaned them up.

No immediate plans for the engine, have another 1 in the wings as well as 3 - IND 265s, investments....LOL

[55 Fargo]

So its always been suggested or believed that a Slant 6 will either not fit in easily or would demand your sheetmetal would get a haircut.

So here are measurements for the 25 inch long block engines versus the Slant 6.

Canadian built cars and light trucks of course all had the longer engines.

It appears the slant 6 is only slightly longer than a 25 inch engine.

[Dozerman51]

How about shipping down one of your 265’s so I can Install it in my WC-12. LOL.

[55 Fargo]

2 hours ago, Dozerman51 said:

How about shipping down one of your 265’s so I can Install it in my WC-12. LOL.

Meet you at Pembina ND $400 USD....lol