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need a little more power out of a 134 F head

Discussion in 'Early CJ5 and CJ6 Tech' started by dougimes, Jan 19, 2012.

  1. Jan 19, 2012
    dougimes

    dougimes New Member

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    Hey Gang,

    I finished an m38a1 restoration last fall, and use the jeep as my daily driver. I have the original 134 and a warn overdrive. It runs pretty well, but i could use a little more power on some of my SouthCarolna hills. Not much, but another 10% would make a noticable difference.

    Just need to be able to pull 50 or so over the rolling hills.

    At the moment, everyting is stock. I am willing to make mods that can be un-made

    Can anyone suggest some things I can do to boost HP a little.



    Different carb?
    Ignition
    exhaust?



    below is a website where I posted pix of the restoration process and final product.

    http://wartimetrucks.com


    Thanks for advise.
     
  2. Jan 19, 2012
    Mike S

    Mike S Sponsor

    Cameron Park Ca.
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    Last edited: Jan 19, 2012
  3. Jan 19, 2012
    mb82

    mb82 I feel great!

    Charlottesville Va
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    A few extra things will help us be able to help you. Like what axle gears you have and what size tires. I know you said restoration but well that means a lot of things these days.
     
  4. Jan 19, 2012
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Don't mind them. 8)

    Good work Doug! From the link you posted, I would guess it has 6.00-16 NDTs and 5.38 gears.

    Seems to me that the F134 is not very receptive to hop-up efforts. Likely the most rewarding mod would be turbocharging.
     
  5. Jan 19, 2012
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Last edited: Jan 19, 2012
  6. Jan 19, 2012
    duffer

    duffer Rodent Power 2019 Sponsor

    Bozeman, MT
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    http://www.summitracing.com/parts/NOS-05101NOS/:twisted::twisted:

    Seems in one of the 134 turbo threads I have seen, the engine developed a knock shortly after installation.

    If you actually want to keep it together, I think finding one of the high compression heads, a bit of a cam grind and possibly headers would be about it. The long stroke and long, rather weak rods limit what can be reliably done.
     
  7. Jan 19, 2012
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    Back on topic......

    No one loves the F head more than I do, but I have realized that it is a tractor motor.

    I still will one day run a supercharger on one.
     
  8. Jan 19, 2012
    SFaulken

    SFaulken Member

    Renton, WA
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    Put a fogger nozzle on it, and just give it a little of the juice on those long hills? Nitrous is fun stuff.
     
  9. Jan 19, 2012
    Vanguard

    Vanguard Chief Cook and Bottlewasher Staff Member

    Brighton, MI USA
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  10. Jan 19, 2012
    Petesponies

    Petesponies Banned

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    You have a flathead exhaust design. You are seriously exhaust limited. Anything to help the head breathe on the exhaust side is going to have the most change in power. Read that as a performance valve grind and split profile camshaft followed by a properly sized exhaust system.
     
  11. Jan 19, 2012
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    and here lies the biggest problem.........Where do you find a cost effective camshaft for an F head? I would also be very leary with exhaust size changes. Sometimes bigger is not better...at least with a tractor motor.
     
  12. Jan 19, 2012
    duffer

    duffer Rodent Power 2019 Sponsor

    Bozeman, MT
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    Not that I know of. The engine we know is the direct descendant of that designed for the 1926 Whippet and that engine looked nearly identical to the L134 (to the point I strongly suspect that there are a lot of common parts). In the context of time, it was quite advanced when a lot of engines were still using poured babbitt bearings. What we (at least the obstinate of this forum) are dealing with is just 86-87 year old technology in a engine that was never designed for high output. Sort of parallels Harley's:rofl:
     
  13. Jan 19, 2012
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    I’d think nitrous to a 134 would be a bad idea. If turbo’s are making them knock nitrous would probably be worse.
     
  14. Jan 19, 2012
    jwjeep60

    jwjeep60 in process

    Sedalia Mo.
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    please don't turbo such a nicely restored jeep, Too pretty.
    and if its engine has been rebuilt, too much to risk.
    Drop the windshield, wear a helmet, loose (18" x 60" @ 15*) 100lbs of wind resistance, carry as little weight in it as possible, ie ditch the spare tire, 5gal jerry, empty the tool box, etc.
    the weber, and headers are the only bolt-ons
    pertronics won't work with the military 24v distributor
    angle milled head would be an option

    BTW it's the inability to keep the timing anywhere near optimal when it is only mechanical advance, you need to retard timing once in boost and that takes some fab on the distributor to make that work. There is a vac advance mod that improves economy. combined with an adjustable vac diaphragm this might be the fix for timing issues under boost.
     
    Last edited: Jan 19, 2012
  15. Jan 19, 2012
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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  16. Jan 19, 2012
    jeep2003

    jeep2003 Well-Known Member

    Vestal NY
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    i dont know how much overlap these engine have when theyre in spec but do yall think a looser adjustment would keep the valves closed longer and boost compression. I know it works like magic on my little briggs and tecumseh engines :)
     
  17. Jan 19, 2012
    dougimes

    dougimes New Member

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    I am overwhelmed.
    Here are a few more details:

    Wheels are 700-16, stock for the M38A1

    Timing - Military manual says 5 BTDC . I have it set for 10 maybe 12 BTDC, using a timing light. Seems to idle best here, doesn't knock, but still not sure what is optimal, hard to tell.

    Exhaust pipe is 1 3/8 " ID. seems pretty restrictive. Military muffler. Intake is stock military oil bath. I have run without a filter at all, makes no difference.

    Carb is rebuilt Carter, starts idles runs well. I presume it is working as well as it can, but who knows.

    When youi are driving at 50 or so, slight hill, and step on it, you get a BWAAAAAA sort of sound. feels like timing is wrong or it cant breath.

    I have an m38, that has the flat head. it seems like it has maybe a little more go than the a1, but it has no overdrive, so it is not apples to apples.


    There are still a few "motor slick butter" products at the autoparts store that I have not tried over the years. (but not many). So far the crankcase oil in the A1 is just oil, but I am a sucker for "improve HP" stuff, expecially it is gooey and a strange color. Love dumping that stuff in. Poured some bright blue stuff into my M38, I am sure it doubled my HP and extend the life of the engine by 50 years, but it is hard to tell on a vehicle that red-lines at 42mph.


    Anyway- can someone recommend a source for an improved exhaust system if we colllectively thing that would help?
     
  18. Jan 20, 2012
    66cj5

    66cj5 Jeep with no name

    NorthWest Indiana
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    synthetic gear oil in the axles, learn to live with the :hurrican:
     
  19. Jan 20, 2012
    garage gnome

    garage gnome Rust polisher

    Western MA
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  20. Jan 20, 2012
    oldtime

    oldtime oldtime

    St. Charles,...
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    Primarily the standard engine must be in top condition.
    It will do one very little service to modify a worn out engine.
    The best means to test an engines internal condition is via compression and vacuum testing.

    By far the easist and the most cost effective gain for a standard Hurricane is to increase the compression ratio.
    The standard CR ratio was set low to adapt the Jeep for use with very low octane fuel.
    Uncracked fuel could be as low as 68 octane.
    The standard CR for CJ and Military F-134's is only 6.9 to 1.
    Engines with 7.4 to 1 CR heads were usually installed into the SW's and PU's.
    The optional 7.8 to 1 CR heads are few and far between.

    The specific CR for a given Hurricane engine may or may not be noted on the top of the head.
    When rebuilding a Hurricane I always deck the block and shave the head.
    Burning 87 octane fuel I believe one could "CC" the combustion chamber to yeild 8.2 to 1 CR before detonation occurs.

    The next best thing following the CR increase will be a change of distributors.
    The vacuum advance Autolite IAT is a very do-able and an easily reversable addition.
    Custom built distributors along with increased voltage are another possability.

    If the block is sleeved the bore can be increased up to .120 oversize.
    I never bore a block any more than necissary because it narrows the head gasket area and potentially leads to overheating.
    W/O wisely limited the oversize bore to .040".

    The throat bore of the standard YF 938 can become a limiting factor.
    Increasing the CFM flow will be mandated if some modifications are made.

    The Hurricane already uses an industrial designed camshaft yeilding maximum torque output.
    The exhaust sizing is already near optimum promoting maximum torque.
    If one wants to increase the HP then the torque may or may not be effected.
    To further increase HP the camshaft lift duration is increased plus a small lift increase.
    The exhaust valve diameter should then be increased along with port polishing.
    Finally the exhaust is opened up with a header.
     
    Last edited: Jan 20, 2012

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