Register now to get rid of these ads!

willys L head to f head engiine swap

Discussion in 'The Hokey Ass Message Board' started by h2omonkey, Apr 2, 2011.

  1. h2omonkey
    Joined: Dec 8, 2008
    Posts: 165

    h2omonkey
    Member
    from vegas

    Any one swapped these motors? Been trying to get the l head in my truck going in time for viva, but its not happening. So I'm going to swap a running f head into it for now. Can i just pull the motors and swap, or do the bell housing (flywheel clutch etc) need to get swapped too? Hope I can just do the motors. Found lots of info saying motors can be swapped easily but nothing mentioning bell housing components cross compatibility. thanks

    Sorry for the confusion, i was refering to swapping the whole motor, not just the heads
     
    Last edited: Apr 2, 2011
  2. xlr8
    Joined: Jun 26, 2006
    Posts: 651

    xlr8
    Member
    from Idaho

    I'm no expert but I thought that the F head can even be installed on the older flathead engine. I was always under the impression that the engines were the same except for the head, but I sure could be wrong cuz I've never actually done it.
     
  3. RichFox
    Joined: Dec 3, 2006
    Posts: 9,720

    RichFox
    ALLIANCE MEMBER

    For what it is worth I did look at the older pre-war Willy four and the F head switch. There was one bolt hole that had been moved and would not line up. I understand that bolt was moved in the Mil. Spec. design and remained that way after '41. Attached a picture of the stock flathead manifold turned upside down and the hot spot opened up for more carburation. At the same time I made an adapter plate to correct for bolt hole misalignment caused by flipping the manifold.
     

    Attached Files:

    Last edited: Apr 3, 2011
  4. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,713

    hillbilly4008
    ALLIANCE MEMBER
    from Rome NY

    I believe its a direct take out and put back in conversion. My buddies are flat fender freaks, after overheating there L-heads they just yank em and drop in the F-heads. Biggest issue is carb to hood clearance. But thats in a CJ2A.
     
    Register now to get rid of these ads!

  5. h2omonkey
    Joined: Dec 8, 2008
    Posts: 165

    h2omonkey
    Member
    from vegas

    Thanks hillbilly, i thought that it as a direct swap, my cj had a hole in the hood when i got it, if it dont clear the hood of the truck i'll run it without one, dont want to cut it up. Just finished cutting holes in the floor to get to back to bolts, and unbolted everything. Having a heck of a time figuring where to chain the motor for lifting, everything on the L head is a stud with a nut, no bolt holes to secure the chain with, may have to get lifting straps and just wrap them around the motor, only think I can figure.
     
  6. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,713

    hillbilly4008
    ALLIANCE MEMBER
    from Rome NY

    I had a '43 MB that had lift points attached to the head bolts. Remember these engines are damn heavy for a "little 4banger", heavier than a SBC. I've been people use the oil filter mount as a lift point, seemed to work OK. Got the job done anyways...
     
  7. porsche930dude
    Joined: Jan 5, 2008
    Posts: 262

    porsche930dude
    Member

    i think there were a few different flywheel ring tooth counts and starter differences. Its definatly questionable. check out earlycj5.com i know its been discussed there before
     
  8. RichFox
    Joined: Dec 3, 2006
    Posts: 9,720

    RichFox
    ALLIANCE MEMBER

    I just recived the most amazing amount of information concerning Willys engines that I think exists. Which I will try to duplicate here.
    <<For what it is worth I did look at the older pre-war Willy four and the F head switch. There was one bolt hole that had been moved and would not line up. I understand that bolt was moved in the Mil. Spec. design and remained that way after '41. Attached a picture of the stock flathead manifold turned upside down and the hot spot opened up for more carburetion. >>


    Rich
    It is always entertaining when the subject of Willys engines come up on chat groups.
    The cylinder head bolt pattern was changed for the 1939 model year. It had nothing to do with Mil. Spec design. The bolt hole was moved over out of line with others in the centre row to equalise expansion stresses across the head to overcome a head cracking problem. Moving the water outlet forward in the head also aided in this.

    The F head first released in 1950 did indeed have the central head bolt hole offset but that is not the only thing stopping it from being a direct bolt-on. The exhaust section of the combustion chamber, in the F head, actually overlaps the existing L134 inlet valve seat so the head gasket will not seal. The inlet valve opening in the sidevalve block needs to be machined, as if fitting a hardened seat, and a disc that has a hole drilled for the pushrod inserted.

    After machining the block and new inserts flat the F134 head gasket will seal. Obviously sidevalve camshaft needs the inlet lobe reground to suit the F head inlet operation. The F head camshaft can be installed in the early block but its fibre camshaft gear drive also needs to be used instead of the chain drive due to the F134 cams opposite rotation. Regrinding the sidevalve cam is the best option as the chain drive is more durable
    . >>
    The F head first released in 1950 did indeed have the central head bolt hole offset but that is not the only thing stopping it from being a direct bolt-on. The exhaust section of the combustion chamber, in the F head, actually overlaps the existing L134 inlet valve seat so the head gasket will not seal. The inlet valve opening in the sidevalve block needs to be machined, as if fitting a hardened seat, and a disc that has a hole drilled for the pushrod inserted.

    After machining the block and new inserts flat the F134 head gasket will seal. Obviously sidevalve camshaft needs the inlet lobe reground to suit the F head inlet operation. The F head camshaft can be installed in the early block but its fibre camshaft gear drive also needs to be used instead of the chain drive due to the F134 cams opposite rotation. Regrinding the sidevalve cam is the best option as the chain drive is more durable.

    The F134 head onto L134 conversion has been done many times and works but horsepower potential is limited by the inlet manifold being cast integral with the head. Plus compared to the sidevalve motor the extra valve train weight (push rods and rockers) of the F134 limits RPM potential over that of the sidevalve L134. The shape of the integral inlet manifold does not lend itself to just boring holes in from the side and welding in individual manifold stubs either. Been there played with all this Willys stuff. Unless it is necessary to retain the pre 1950 engine block to meet a class rule (enshrined to ensure Model A/B Ford dominance) it is best to use the complete F134 engine.

    Regards your showing the upside down manifold conversion could you please add a note each time that the manifold to block bolt pattern must also be modified as it no longer will line up. I recall that you have previously mentioned using an adapter plate but new viewers will take it that it still bolts up as per the factory. Cutting off the flanges and welding them back on rotated to match again the block bolt pattern also works but requires cast iron welding which seems to scare some rodders.

    h2omonkey also asked about bellhousings and flywheels etc and not modifying the engine (yet) so here is the gist. The bellhousing to engine block bolt pattern is the same from 1933 up until the end of L134 and F134 production which I think was sometime in the 80's in France. Flywheel to crankshaft bolt pattern is also the same from 1933. Over the years ring gear tooth count and flywheel diameter did vary but if a matched bellhousing, flywheel, engine separator plate and starter motor set is used the L134 and F134 engines will interchange. The F head has the carburettor on the other side so the linkage will have to be adapted or swapped over from the F134 donor truck . Exhaust header pipe is the same shape for both. If the F134 engine is pulled from a wagon or Jeep and not a truck he may also have to swap over the front engine mount plate. Front pulley, timing gear/chain cover and camshaft gear have to be removed before the plate can be swapped.

    Not relevant to his questions but handy for the search function should the question come up in the future is that the L134/F134 bellhousing and flywheel bolt patterns are also the same on the Willys designed and manufactured L148, L161 and F161 six cylinder engines. Note this does not include the Kaiser/Continental L226 and later 230 OHC engines used post the Kaiser take over of Willys. The Willys six cyl engine can therefore be bolted up to any 4 cyl bellhousing, flywheel, starter etc combination for a 'factory' engine swap into an early Willys or the six cylinder gearboxes similarly swapped in behind a Willys 4 cyl. I should also note that these sweet running Willys six cylinder engines were a new design and not just stretched L134/F134 engines. The only interchangeable parts of note are the Bellhousing and flywheel.Attached is photo of a 1933-35 Willys 77 engine I updated a few years back with later L134 and F134 parts as well as adapted oil pump with full flow oil filter and a 5 speed Isuzu gearbox. F134 exhaust manifold has two mounting ears trimmed to allow it to fit up with a 1935 inlet manifold that has had the exhaust gas heat exchanger trimmed off for clearance. Test run carby was later changed to a Stromberg BXOV series carby which was used on Holdens in Australia. Also a less restrictive air cleaner fitted. The owner is pleased with the way it runs and drives..

    Rich if you could pass this information on it might help a few lateral thinking rodders in the future.

    Best Willys Regards
    Ted Robinette
     
    Last edited: Apr 2, 2011
  9. willys1950jeepster
    Joined: Nov 3, 2009
    Posts: 75

    willys1950jeepster
    Member
    from pdx

    Just try to get the complete throttle linkage with the f-head. L-head carb is on drivers side, f-head is on passenger side thats the only hiccup I can think of.
     
  10. RichFox
    Joined: Dec 3, 2006
    Posts: 9,720

    RichFox
    ALLIANCE MEMBER

    If anybody is thinking of flipping the intake manifold as i showed in an earlier post. I had to make an adapter/header plate to correct what would have been misplaced bolt holes. It's not just a flip and cut.
     
  11. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,842

    Truckedup
    Member

    I rebuilt the F head four in my avatar Willys last winter.Like mentioned,there is a lot of little differences over the years but the swap will work.
    One thing I suggest is to pull the head off the F head and closely inspect the block around the areas of the side valve exhaust seats for cracks.
    Walck's 4x4 in Pa in a wealth of information on Willys Jeeps.The people you talk to on the phone are Jeep nuts with greasy hands.
     
  12. RichFox
    Joined: Dec 3, 2006
    Posts: 9,720

    RichFox
    ALLIANCE MEMBER

    I didn't get Ted Robinette's full "Everything you ever wanted to know about interchange on a Willys" letter to copy on this thread. If you want or need a very informative Willy letter Email me at V4GMR@yahoo.com and I will froward it to you.
     
  13. h2omonkey
    Joined: Dec 8, 2008
    Posts: 165

    h2omonkey
    Member
    from vegas

    Just an update on my engine swap, the f head will fit under the willys truck hood without cutting a hole with a few inches to spare. Motor mounts on frame are way different, made plates to adapt f head temporarily but it looks like front motor plate from L head will work if swapped onto the f head engine.

    I did swap out the flywheels because they are different tooth numbers (124 L head/129 F head) but the clutches and pressure plates appear to be the same. Reason for the swap is the starters wont interchange, didn't pull trannys because of different linkages, wanted to keep the 3 on the tree in the truck.

    I did end up using lift straps wrapped under the motor then ran a chain through the four ends to get a even lift point, worked great.

    If it starts up it should be at Viva in all its rusty, crusty glory!
     
  14. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,713

    hillbilly4008
    ALLIANCE MEMBER
    from Rome NY

    Oh man, I forgot about the mounting plate being bent differently! I been there before, I should've remembered that one...

    My bad.
     
  15. wmc
    Joined: Feb 5, 2014
    Posts: 13

    wmc
    Member

    I realize this is an old thread, but in hopes of saving someone a lot of grief time and money I will say my piece about the whole Willys Overland adaption craption situation that went on back then...

    One thing is for sure, don't let anyone tell you they have the same clutch housing! and never mix match block plates and housings, always replace as a "set". Back of engine "block" itself is same, but nothing behind it ever is... even depths can vary depending on transmission used and it's input shaft length. I currently have four totally different clutch housings for Willys engines and every one of them is a little bit different than the other, depth diameter, bolt pattern etc. all very close but not same. be careful.

    On a side note, I used to have a handy informative link to a wealth of info online about these and I have somehow lost it. I need to know how to read the date code cast into the head... I forgot how :( thanks.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.