Willys six cylinder questions - 148 versus 161 versus ?

scramboleer

Super Moderator
Staff member
All-Star
Aug 16, 2011
9,036
San Francisco, California
First Name
Dan
Willys Model
  1. Wagon
Willys Year:
  1. 1964
Hi all,

These questions come from my Dad who is selling his 1942 Willys MB next month and getting a 1948 - 1951 Jeepster with overdrive. He just wants something to cruise around town in, although he recently met a few Jeepster owners who were part of that recent Jeepster caravan across the USA. But I digress. Here are the questions:

1. How do the L148 Lightning and L161 six cylinders compare in everyday driving against the four cylinder F134? The specs are nearly the same, but what are they like in the real world? He's quite familiar with the L head 134 (he also has a 1945 CJ2/Jeep salad with the L134), but was wondering about the sixes compared to the F head four cylinder.

2. And this might make you laugh...how would a 226 or the 230 OHC fit in a Jeepster? He's seen a few Jeepsters for sale that are missing an engine. There is the possibility that he'll buy an already-modified Jeepster that has a V8 or non-Willys V6 in it, but he's more likely to get a stock one with the F134/L148/L161.

We'd love to hear your thoughts. Thanks in advance!


Scramboleer
 

Oliver Hevvy

Precision Fit
Jun 21, 2013
628
San Francisco Bay Area, California
First Name
Oliver
Willys Model
  1. Pickup
Willys Year:
  1. 1951
Sixes are inherently smooth motors - good primary and secondary balance. Fours have inherent secondary vibration -2x crank speed. I don't have any direct experience with either engine, but it would be interesting if some owner did a little porting work on the block and head. In general, a six will have more valve area per cubic inch, and so will make a little more power.
 

Possum

Gear Grinder
May 16, 2012
17
near Lexington, Ky
First Name
Greg
Willys Model
  1. Wagon
Willys Year:
  1. 1948
I have owned the 148 L head, 161 Fhead, 226 Lhead, and the 230 OHC powered wagons. The 148 only makes about three more hp than the 4 cylinder, but the four has a long stroke, over four inches, the stroke of the 6 cylinder is just over three inches, so it is quite a bit smoother and happier at high RPMs. The 161 Fhead makes about 20% more power, and in my opinion is one of the sweeter, and more interesting engines that they made. The 226 makes more power ad quite a bit more torque, but is a physically larger and heavier motor that requires modifications to the firewall. The 230 "Tornado" overhead cam engine makes plenty of power, but this seems to be a motor that people either love or hate. I had a good one and so I liked it, but as I recall, it really liked gas.
IMHO a well chosen final drive ratio can have as much effect on driving quality as the engine. The overdrive really helps with that.
 

diggerG

Well Oiled
Oct 2, 2011
5,365
Wrentham Ma.
First Name
Greg
Willys Model
  1. Wagon
Willys Year:
  1. 1963
A version of a V6 GM (either) would be a good fit, and both are popular with Jeepsters. IMHO a V8 is way too much weight and power to add to those wimpy tin foil frames. Jeepster frames (all planar frames) were junk when new. Sorry planar fans. That's what I've observed. Leaving one stock would be better than you may think though.
diggerG
 

scramboleer

Super Moderator
Staff member
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Aug 16, 2011
9,036
San Francisco, California
First Name
Dan
Willys Model
  1. Wagon
Willys Year:
  1. 1964
Yeah my dad's goal would be to find one with the 148 or 161 in it... or find an engine-less Jeepster and either factory six separate and install it.
 

scramboleer

Super Moderator
Staff member
All-Star
Aug 16, 2011
9,036
San Francisco, California
First Name
Dan
Willys Model
  1. Wagon
Willys Year:
  1. 1964
Related, would the 1952-1954 F161 six fit in a Jeepster? As far as I understand it the F161 was first offered in 1952 in the wagon, after Jeepster production ended in 1951 (it was offered with the L161). So would the F161 fit in place of an L161? Would it be a drop-in replacement or would you have to change motor mounts, transmission input shaft, etc.? What about hood clearance?
 

second_floor_lo

Sharpest Tool
Sep 27, 2013
359
North Carolina
First Name
Paul
Willys Model
  1. Pickup
Willys Year:
  1. 1949
Related, would the 1952-1954 F161 six fit in a Jeepster? As far as I understand it the F161 was first offered in 1952 in the wagon, after Jeepster production ended in 1951 (it was offered with the L161). So would the F161 fit in place of an L161? Would it be a drop-in replacement or would you have to change motor mounts, transmission input shaft, etc.? What about hood clearance?

Yes it'll go right in. May be necessary to re-route the throttle linkage but the rest is a bolt in
 

scramboleer

Super Moderator
Staff member
All-Star
Aug 16, 2011
9,036
San Francisco, California
First Name
Dan
Willys Model
  1. Wagon
Willys Year:
  1. 1964
Thanks Paul. I'll pass along the info to my dad. There's a local Jeepster that's missing the engine and transmission as well S a F161 on eBay that he's interested in.
 

second_floor_lo

Sharpest Tool
Sep 27, 2013
359
North Carolina
First Name
Paul
Willys Model
  1. Pickup
Willys Year:
  1. 1949
just one word here... (or several words) If he decides to swap the motor, he'll be many hours and several pulled muscles ahead if he takes the grill, fenders and hood and front bumper off before he starts. These things were built to accommodate any of several Willy's motors and it seems evident that the design/engineering departments preferred to refrain from making new parts. The result is that there are a variety of "extra" mounting holes for motor and transmission mount locations. Likewise the front motor mount plate which bolts to the front of the motor... He might need to trim the original radiator fan shroud...might not... It's pretty obvious what needs to be done once you get the motor hanging just above the frame and later when you put the grill back in place. You can't just throw it in, but it's pretty close to that.
 

diggerG

Well Oiled
Oct 2, 2011
5,365
Wrentham Ma.
First Name
Greg
Willys Model
  1. Wagon
Willys Year:
  1. 1963
I believe he will have to either get a 6 cyl. grille or alter his 4 cyl one. The 6 is, after all, at least 6" longer than the 4. Paul is correct on the bolt up however. The 6F is just a 4F with 2 extra cylinders, as the 4L with 2 more is a 6L. Internals would be different of course.
diggerG
 

peewee

Bigger Hammer
Oct 23, 2019
94
Buckley WA
First Name
Bill
Willys Model
  1. Other
Willys Year:
  1. 1949
I believe he will have to either get a 6 cyl. grille or alter his 4 cyl one. The 6 is, after all, at least 6" longer than the 4. Paul is correct on the bolt up however. The 6F is just a 4F with 2 extra cylinders, as the 4L with 2 more is a 6L. Internals would be different of course.
diggerG
I have owned the 148 L head, 161 Fhead, 226 Lhead, and the 230 OHC powered wagons. The 148 only makes about three more hp than the 4 cylinder, but the four has a long stroke, over four inches, the stroke of the 6 cylinder is just over three inches, so it is quite a bit smoother and happier at high RPMs. The 161 Fhead makes about 20% more power, and in my opinion is one of the sweeter, and more interesting engines that they made. The 226 makes more power ad quite a bit more torque, but is a physically larger and heavier motor that requires modifications to the firewall. The 230 "Tornado" overhead cam engine makes plenty of power, but this seems to be a motor that people either love or hate. I had a good one and so I liked it, but as I recall, it really liked gas.
IMHO a well chosen final drive ratio can have as much effect on driving quality as the engine. The overdrive really helps with that.
 

peewee

Bigger Hammer
Oct 23, 2019
94
Buckley WA
First Name
Bill
Willys Model
  1. Other
Willys Year:
  1. 1949
Does anyone know if the L 148 is the same block as the L 161? only a little more bore and/or stroke? Or is it actually a different motor?

peewee
 

PTV

Precision Fit
Jan 3, 2020
544
SW Pa.
First Name
John
Willys Model
  1. Pickup
Willys Year:
  1. 1958
I believe the blocks are the same, just a slight increase in bore on the L161.
 

second_floor_lo

Sharpest Tool
Sep 27, 2013
359
North Carolina
First Name
Paul
Willys Model
  1. Pickup
Willys Year:
  1. 1949
I'm not an authority by any means but given the propensity toward frugality by the folks at Willys, I'd bet it's the same block is the same. The stroke is the same on both engines but the bore for the 161 is 1/8 inch larger (3 1/8 inch) than the 148 at 3 inch.

Regards:
Paul
 

peewee

Bigger Hammer
Oct 23, 2019
94
Buckley WA
First Name
Bill
Willys Model
  1. Other
Willys Year:
  1. 1949
I'm not an authority by any means but given the propensity toward frugality by the folks at Willys, I'd bet it's the same block is the same. The stroke is the same on both engines but the bore for the 161 is 1/8 inch larger (3 1/8 inch) than the 148 at 3 inch.

Regards:
Paul
I am seriously considering switching my L 134 for one of the flathead 6's. Would love to cruise comfortable at 60 to even 65. I just want to make sure if I had to buy a L 161 it would slip in as easy as the L 148 and pass appearance wise as a L 148. Hoping to find one near Western Washington.
 

51delivery

Sharpest Tool
Oct 10, 2018
286
Fond du Lac Wisconsin
First Name
Gary
Willys Model
  1. Wagon
Willys Year:
  1. 1951
Probably how they salvaged oversized and scored bores. ( around 1993, Harley oil filters were under the transmission, why buy a chrome filter when it can't be seen? When I change my oil and filter, the black filters paint was eroded from the road grit. It was Chrome under the black paint. Salvage your blemished Chrome by painting it.) so you paid less for a Chrome filter that was painted.
 

peewee

Bigger Hammer
Oct 23, 2019
94
Buckley WA
First Name
Bill
Willys Model
  1. Other
Willys Year:
  1. 1949
I am seriously considering switching my L 134 for one of the flathead 6's. Would love to cruise comfortable at 60 to even 65. I just want to make sure if I had to buy a L 161 it would slip in as easy as the L 148 and pass appearance wise as a L 148. Hoping to find one near Western Washington.
Peewee...If you're going to do that, find the F head 161. It'll go in just as the L-161 would and add a few more horse power.

Regards:
Paul
Yes am thinking what I really want to do. The L 148 would keep my 49 Jeepster totally 49 Jeepster stock and I would love to do the L 148 if I could find one. But I do like getting the power from a 161 hurricane or the lightning 161's. When it gets down to it I probably will jump on the first local 16 I can find, but I will go no bigger than that size.

peewee
 

diggerG

Well Oiled
Oct 2, 2011
5,365
Wrentham Ma.
First Name
Greg
Willys Model
  1. Wagon
Willys Year:
  1. 1963
If you guys want to swap in an L or F 161 or 148 see if you can find an exhaust manifold or distributor for either one. Parts availability is a monster for those engines, that is the parts that are different from the 4 cyl.
diggerG
 
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