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how to hop up you slant 6 (hot rod mag)

Discussion in 'The Hokey Ass Message Board' started by gasjockey101, Oct 7, 2011.

  1. gasjockey101
    Joined: Mar 7, 2011
    Posts: 40

    gasjockey101
    Member

    i know its not really the engine of choice for hamb but i have a 66 plymouth valiant and its has the leaning tower of power in it and i rember someone saying that hot rod mag did one does anyone know what year,issue... it was in
     
    Last edited: Oct 7, 2011
  2. RodStRace
    Joined: Dec 7, 2007
    Posts: 2,521

    RodStRace
    Member

    Best bet is to go over to www.slantsix.org
    They have been wringing power out of these and know what works.
     
    rockable likes this.
  3. offenhauser made some goodies, and Mopar I believe had what they called the scat pack of something along that line... That was a fast little slant six..
     
  4. jipp
    Joined: Jun 20, 2011
    Posts: 1,112

    jipp
    Member

    yeah the slant six can be pumped up.. good engine.
    chris.
     

  5. Hello, hello ? Did someone say slant six hop up? Have done several. Both hot street and race.
    Don
     
  6. sledkid
    Joined: Oct 7, 2011
    Posts: 20

    sledkid
    Member
    from mansfield

    direct connection had catalogs in the mid 80's that gave you part numbers and peices you would need
     
  7. Normbc9
    Joined: Apr 20, 2011
    Posts: 1,122

    Normbc9
    Member

    There is a Slant six Mopar here in my town in a '41 Plymouth coupe and it is coupled to a A-727 with a Clifford intake and Weber #38 carbs. It isn't a slouch either. Nice runner and when it has to, it hauls the mail!
    Normbc9
     
  8. I dont know how serious you are but the "hot rod build" was not particularily wonderful.And to their credit that they tried but it is a special case engine not well understood. Not a lot of what we normally know applys. It was one of the first ram tuned production engines . It has a huge stroke and is an oversquare engine (stroke is way bigger than the bore. at3.4" bore X 4.12" stroke. This gives the engine very different characteristics. Before all the "experts" jump in here I want you to stop and think for a minute. Pick the engine most info talks about, the small block Chevy. Make its bore and stroke ratio the same. 4 inch bore X 4.874 "inch stroke. That would be a very different engine than the one we are familiar with today and would want very diffferent cam shaft just for starters. Why? Because piston speed is very high and piston on the intake stroke reaches very high speed much earlier on in the stroke than an normal 3.48 inch stroke engine.(stock stroke for a 350 chevy) because of this three factors arepresent that would not normally be the case. FirstRPM is limited because of the long stroke. (There are limits to everyhing in life. ) Secondly because piston achieves significant piston speed in feet per minte earlier in the stroke than normal engines would we can open the intake valve and need to earlier so as not to lose this benifit. iI we dont then it becomes a neg facor. Thirdly because the piston moves away from TDC so rapidly we CAN open the valve much faster without any fear of it smacking the piston because it is already out of the way due to the long stroke (travels further per degree of rotation.) . I say all this to say this. These engine need a lot of valve timing to achive significant RPM ie 6000RPM. Probably in the area for that would need a hydraulic of 272 @050. a solid would be even more approx 14 degrees more for the same RPM (Which is why I get custom made hydraulics ground for .904 lifter rise rates. ) I have one I had made at 241/247 duration@050 and it pulls to about 5300 for its peak. It will as will most cams run beyond that another 500 rpm so would show in the average cam catalog as being for 2500 to 5800 RPM but at the track you need to cam for your peak HP. The fact it wil run higher is imaterial because your MPH in the lights will be at your Peak HP. This may require some rethinking but a motor has no opnions . It only does what it is asked to do by the cam. If Horse power is falling then speed is not rising in the 1/4 mile. However if this was for a street car it would be a fairl decent cam with the right set up. Other than a ragged idle it has good characteristics and power. The slant six engine in general terms can make a wonderful lower RPM motor with a milder cam and power below 5000. It can more than hold its own there. And for a street car with good manners that is the way to go. The old slant six marine camshaft and a 500 Holley 2 barrel with headers make a good combo for a daily .driver. But as you can see it requires a bit of out of the box thinking because it is not a normal engine as we are used to them. You learn with these with experience. They require a slightly different approach. These are some of the reasons why.
    Don
     
    Last edited: Oct 9, 2011
  9. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,038

    Truckedup
    Member

    I'm no engineer or have modification experience with Slant 6's...But I think the small bore and long stroke was chosen by Mopar to fit the space under the hood of the new cars of that era.Small bore means the engine can be shorter.And to get the displacement you need a long stroke that makes the engine taller so you lean it over.My opinion based on US car makers spending little design money on inline 6's appealing to "cheap" car buyers.
    They might have lasted longer(debatable) than the other inline 6's of the day.But stock "tuned" performance wasn't any better than the 230-250 Chevy or the 240 Ford 6.I drove lots of pick up trucks and from my experience the Slant 6 was no better in performance.And they didn't tolerate being run low on oil :D
     
  10. OUCH!
    They were maybe no better but just as good and were the smaller engine. No engine of your choice or mine will tolerate running low on oil. Nothing is idiot proof. I sit behind one every racing weekend with the trans between my knees. Have spent a lot of time with them and know them very well. 170s 198 and 225. They were not leaned over for hood clearance. They were leaned over for the manifold. They are no taller than you favourites. And tis true a 230 chev would have its hands full with a 170 or 198 slant six next to him at the stop light. :D)))))))))))))
    Don
     

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  11. damagedduck
    Joined: Jun 16, 2011
    Posts: 2,342

    damagedduck
    Member
    from Greeley Co

  12. damagedduck
    Joined: Jun 16, 2011
    Posts: 2,342

    damagedduck
    Member
    from Greeley Co

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