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Technical Olds guys, what’s the difference between the 371 and the 394?

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Feb 18, 2021.

  1. Roothawg
    Joined: Mar 14, 2001
    Posts: 22,045

    Roothawg
    Member

    I may have a chance to pick up a 371 cheap. Not sure if it is a boat anchor or a good base for a hot rod power plant?

    Performance parts interchange?

    Shorter stroke?

    Dog or gem?
     
  2. rusty rocket
    Joined: Oct 30, 2011
    Posts: 4,409

    rusty rocket
    Member

    I would like to know also. I picked up a gmc cab forward truck but don’t know the exact year of it because of no title. I has an Oldsmobile power plant.
     
    Last edited: Feb 18, 2021
  3. I'm not an expert but I had a '63 394 Ultra High compression '88.
    The bore is bigger on the 394.
    The real thing about these Olds engines is they have 400+ ft/lbs
    of torque usually maxing at under 2800 RPM as I remember, (STOCK)
    Pulled that heavy '88 like a freight train.
    Here's an old thread, but a lot of good info!

    MOTOR, Early Olds Rocket tech summary.
     
    Last edited: Feb 18, 2021
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  4. oldolds
    Joined: Oct 18, 2010
    Posts: 3,220

    oldolds
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    I searched for the ultimate rocket thread but could not find it. That will have the answers to your question. If I remember right the 371 uses older style water pump and pullys ect. The 394 uses it's own water pump and accessory mounting brackets.
     
    1934coupe likes this.

  5. belair
    Joined: Jul 10, 2006
    Posts: 8,803

    belair
    Member

    One thing is the 371 was available from 57-60, the 394 from 59-64, so there might be more 394s around. Don't seem to hear a lot about the 371, except as a J-2. Kind of like the 364 nailhead compared to the 401. Nothing wrong with it, it just got superseded by a bigger, more often available engine.
     
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  6. flatheadpete
    Joined: Oct 29, 2003
    Posts: 10,213

    flatheadpete
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    from Burton, MI

  7. Moriarity
    Joined: Apr 11, 2001
    Posts: 22,271

    Moriarity
    SUPER MODERATOR
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  8. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,390

    sunbeam
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    1/8 more bore
     
  9. oldolds
    Joined: Oct 18, 2010
    Posts: 3,220

    oldolds
    Member

  10. From my old TRW catalogue: The 371 has a 4" bore, the 394 is 4.125". Very few parts are listed as being the same. Same cam and timing chain, different rocker assemblies. There is a year change on the 371: 57-58 versus 59-60 also.
     
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  11. tubman
    Joined: May 16, 2007
    Posts: 5,908

    tubman
    ALLIANCE MEMBER

    I believe this is true and important. I seem to remember that the late 371's have more in common with the 394's than with the early 371's.

    Odd; when I think 371, I think "Olds Rocket"! When I think 394, I think "Late Model stuff".
     
  12. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,608

    Rusty O'Toole
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    57 58 371 was the final development of the original 1949 Olds V8. In 1959 they came out with a revised design in 371 and 394 cu in. The smaller engine for the Olds 88, the larger one for the Super 88 and 98. The earlier model has bolts in the middle of the valve covers, the newer one around the edges. Either is a good engine, heavy powerful and remarkably tough. Both could be taken out to 480 cu in.
    There were some top fuel dragsters that used blown Olds engines, they would run with the Chrysler hemis.
    Any 371 will make a good hot rod power plant. They were popular in their day and I would expect things like intake manifolds, cams, etc to be available.
    Later... The last 371s were in 1959 - 60 Olds 88s. The 394 continued until 1964, for 1965 Olds got an entirely new engine, a 425 that grew into the 455. This was the same family as the 330 that debuted in 64 and later became the 350.
     
    Last edited: Feb 18, 2021
  13. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 8,157

    Bandit Billy
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    Not quite the Ultimate Answer, but damn close! :cool:
     
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  14. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    As already mentioned above, the 57-58 371 is a totally different design engine compared to the 59-60 371. (The cubic inch is the same because the bore and stroke are the same)

    The later one has little to no value to most rodders for several good reasons. One is that there won't be much variety or availability of old speed parts like decent intake manifolds or even valve covers.

    Next big drawback is that nearly all 59-up were A/T engines that need to have the crank drilled for a standard shift pilot bushing, and they also used an external balanced flywheel which would be nearly impossible to find. So you'd need to have the engine internally balanced to use an original pre-57 Olds neutral-balance standard shift flywheel or a $$ repro flywheel. You'd just spend far too much $ on those mods even before finding a vintage stick bellhousing to fit the trans you want, or a new repro bell which will also be $$.

    Also , like Tubman hinted above, the 59-up Olds engines look more like a modern engine compared to the far more desirable early Olds Rockets.

    Most (Olds powered) hotrods built in the 50s to very early 60s used 49-56 303/324 engines, and that is why there are so many different brands/varieties of vintage speed parts and valve covers still out there for those. That also explains why there are so few 59-up old speed parts to be found, as most old "street driven" rods rarely used the 59-up Olds engines....Chevy Sbc popularity was affecting the aftermarket demands by then as well.
     
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  15. Roothawg
    Joined: Mar 14, 2001
    Posts: 22,045

    Roothawg
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    So, it sounds like a polite "no thanks" is in order.
     
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  16. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,274

    Truckedup
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  17. Paul
    Joined: Aug 29, 2002
    Posts: 15,585

    Paul
    Editor

    You didn't say what year the engine is or what your end use would be.
    But does sound like responders have made your decision for you.
    Get an sbc, they will be happy with your (their) choice.
     
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  18. Paul
    Joined: Aug 29, 2002
    Posts: 15,585

    Paul
    Editor

  19. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,993

    flamedabone
    ALLIANCE MEMBER

    You are a wuss if you don't buy it.

    -Abone.
     
  20. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,188

    d2_willys
    Member
    from Kansas

    The most obvious difference was the deck height. The 57 and 58 371's had a different deck height from the 59-60 371's. Even though the 59-60 371's did not have the pilot bushing location, it was very simple to have one bored and installed. The flywheel/flexplate that would be needed on these engines are pretty simple to have counterbalanced.
    As far as which 371 to use, I prefer the 59-60, since they are just a de-bored 394. Some of the 394 performance parts do fit in the later 371. The only performance part that is not available is the tri power (J2 option) for the 59-60 engines due to the different deck height.
     
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  21. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,681

    1934coupe
    Member

    Roothawg what do you consider cheap? I don't really want to know how much your paying just that I have a 394 complete but completely apart with a 4bbl carb and manifold plus some 371 stuff and I wanted $300.00 I still have it. I thought that was a cheap price. My brother Mike was going to use it for his comp coupe but sold the car.

    Pat
     
  22. nochop
    Joined: Nov 13, 2005
    Posts: 2,385

    nochop
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    from norcal

  23. Roothawg
    Joined: Mar 14, 2001
    Posts: 22,045

    Roothawg
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    Like $250
     
  24. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,681

    1934coupe
    Member

    If you can use it that's a good price for a complete motor. If it's going to sit for a future project your better off adding $250. to your IRA? contribution.

    Pat
     
  25. Roothawg
    Joined: Mar 14, 2001
    Posts: 22,045

    Roothawg
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    It's not a Pontiac.
     
  26. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,003

    mgtstumpy
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    Roothawg likes this.
  27. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 8,130

    junkyardjeff
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    I had a 59 371 in a 53 Olds and it was a great engine,plenty of low end torque and plenty of top end and got decent gas mileage if I kept my foot out of it. Only modification was a 4 bbl off a 59 394 and it also ran good with the 2 bbl.
     
  28. Dan Waldrop
    Joined: Oct 5, 2015
    Posts: 5

    Dan Waldrop

    The 371ci Oldsmobile is a great engine for a Hot Rod. As far as parts interchange if you run heads off the 324ci you can run the early intake. We ran this one at Bonneville the last 2 years. [​IMG]


    Sent from my iPhone using H.A.M.B.
     
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  29. getow
    Joined: May 9, 2016
    Posts: 297

    getow
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    Id buy it. But thats me. They dont grow on trees, and if you dont use it, you wont lose on it.
     
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  30. gsjohnny
    Joined: Nov 27, 2007
    Posts: 169

    gsjohnny
    Member

    met a guy at the dover drag reunion racing a fed with either a 371 or 394(forgot). but it was running a hilborn on it. he said his engine guy told him he could run up to 8k rpm with no problems. WOOF!
     

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