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Make power with low comp. 440 ?

Discussion in 'The Hokey Ass Message Board' started by cornpatch, Apr 20, 2011.

  1. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    I have a low mileage 1978 440 with low comp engine (low 8's stock.) I dont want to take off the stock heads (452) or replace the stock pistons. I will use a Pertronix ignition for a points style dist. with their stock looking coil.

    I do have Edelbrock performer RPM intake ,750 Holley, using stock 383-440 magnum exhaust manifolds, and can change the valve springs if needed. Car is 3800 lb. 4 speed, 3:55 rearend.

    What cam specs would give me the best performance with this low compression engine? I know what lift, duration, overlap means, but not good with knowing just hjow the different combos work for specific purposes.

    Thanks for any input............MO
     
  2. DirtyThirty
    Joined: Mar 8, 2007
    Posts: 2,396

    DirtyThirty
    Member
    from nowhere...

    Why not just mill the heads a bit, before trying to go with anything other than a very conservative cam choice, due to loss of cylinder pressure??
    It's fairly cheap if you have a decent machine shop buddy, I'd do that first I imagine.
     
  3. joes55belvedere
    Joined: Mar 18, 2011
    Posts: 20

    joes55belvedere
    Member

    Years ago I built a low comp 440 stock 452 with mopar hipo springs mopar 284-484 cam Holley street master, 750 holley, 1/78 headers 3.91 gears and 3500 convertor. I dialed in the suspension and tuning I ran a best of 11.89 at 115mph. It was a consistant low 12 sec car. Weight will hurt you a bit I was around 3400.lbs. But with the stick and 3.55-3.91 and tuning it will run. I would go with a slightly smaller cam, something in the 270-274 range.
     
  4. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    Yes, I do agree that milling the heads would make a big difference, but I just dont want to do that at this time. This will be a temporary engine and The parts I have can be used with my 413 build, later. For now, I want the best performing cam with the engine comp. I have. Thanks for your input................MO
     
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  5. ddawg16
    Joined: Apr 10, 2011
    Posts: 60

    ddawg16
    Member
    from So CA

    When you say "Low 8's", do you mean Compression ratio? If your talking ET's....that would only be possible in the 1/8th mile....

    Anyway.....changing your cam is not really going to gain you much if anything. My best friend on a 68 charger with the same engine....stock...pass anything on the road except the gas station...ate a quart of oil every night....but the bitch was fast....

    Without changing other items....not much else you can do....those engines were pretty much dialed in. To really gain anything, you also need head work....exhaust work....etc.

    If your looking to improve your quater mile times....re-gear.....that will do more for you than anything else.

    But if you really want to change the cam....go pull up the specs for the cam manuf you want to use. They will list the power range for each grind...decide where you want your power to come on and how high you want your RPM's to go.
     
  6. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    Good question?

    I have a late 70s 440 with low miles on it and I just can com up with a way to do it right using those stock parts even with using a .018 head gasket. Those motors are actually 6.2:1 if you do the math with a .020 head gasket. I dont know where the factory came up with that 8:1 stuff but the math just doesnt jive!

    Hughes engines sells a sweet cam for low compression motors called the whiplash.

    www.hughesengines.com

    Im going to put some different pistons in mine (to get around 9-9.5:1 compression) along with a forged crank I have. I have the Hughes 1928BL cam for it, ported 67 GTX heads, performer RPM intake and 750 Holley. Should get over 400 hp and over 500 ftlbs torque.
     
  7. pcterm2
    Joined: Aug 25, 2009
    Posts: 554

    pcterm2
    Member

    before you do anything check with Dolmetsch here on the board.the man knows alot about mopars
     
  8. bREWcITYbIRD
    Joined: Apr 7, 2011
    Posts: 16

    bREWcITYbIRD
    Member

    I would go with a cam grind from Hughes Engines. Maybe their Whiplash cam:

    http://www.hughesengines.com/Index/...V2hpcGxhc2ggTXVzY2xlIENhciBjYW1z&partid=25116

    Most of the new cam designs are made to build more cylinder pressure with lower compression engines.

    The 452 heads are good heads they are basically the 69-70 906 heads with hardened exhaust seats. The magnum exhaust manifolds flow good. The Performer RPM intake is a great intake, but on a 440 usually seems to like a 850. The only other thing would be the ignition this should have had electronic ignition from the factory. The stock distributors in these years are pretty much the same as the Mopar Performance units they sell today, so if you have it i'd stick with it.
     
  9. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    I am very familiar with Don, I am hopeing he chimes in on this . I asked him about this a while back and his basic reply was to mill the heads 60 thou. In this particular case, I don't want to do that..

    . Thanks alot folks, all input is appreciated.....................MO
     
  10. bREWcITYbIRD
    Joined: Apr 7, 2011
    Posts: 16

    bREWcITYbIRD
    Member

    From what ive seen the pistons on these later motors are .100 - .120 in the hole which should come out to 7.9:1-8.2:1 it you were to put a set of 915's (67 GTX HP) heads on a later motor it should bump the compression a full point which would put you at 9.0:1 without a piston swap.
     
  11. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    The closed chamber heads are around 75cc and lets say you mill those to 70cc you would only get it up to 6.8. Not woth the effort pluss you have hosed a good set of 452 heads. Its too bad those pistons a cast because it would be a perfect candidate for a street 671 blower motor!
     
  12. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    .100-.120 would be nice but ive miked mine several times and they are .150 in the hole. Ive used several calculators on line and done it on paper and they all come out the same.
     
  13. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    I am enjoying the input. I don't know where to look to find factory compression ratio figures for a 1978 440 engine. The only source I did find, quoted ( I think) 8.2 :1 And I do not know what thickness head gasket that would be with. I would be shocked to find that it was substancially lower than THAT. .........................MO
     
  14. das858
    Joined: Jul 28, 2010
    Posts: 348

    das858
    Member

    Like several others have suggested, the Hughes whiplash cam is the way to go on low compression 440's. If it was mine I would bite the bullet and put 9.5-10.5 compression pistons in it, but I understand being on a budget.
     
  15. el Scotto
    Joined: Mar 3, 2004
    Posts: 3,363

    el Scotto
    Member

    I have a forged crank 440 engine out of a '73 motorhome so I'll stay tuned to this thread. I don't want to toss a bunch of money or time at it, but I love burnouts and this engine may end up in my Model A.
     
  16. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    We a difference in opinion here and I think you are both right. My bet is , the 440 with 150 thou below the deck is below a 8 :1 comp. ratio because it is a motoehome engine. I'm thinking at 110-120 thou below the deck would be the 8.2:1 ratio , Both having the same cc heads.

    Thanks for the input folks, Please more replys. I am learning some more 440 things here. I would like to have some more cam specs and what they should accomplish..............MO
     
  17. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    My .150 motor is out of a 1975 pickup, probably a sweet gas sucking low power rig when new :D

    I dont know why you would have less compression on a motorhome. Those motors had heavy duty rods for a reason.
     
  18. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    Ok guys! DO I FEAL STUPID NOW!!

    I had "F"ed up this whole time and had fogot to put a zero some place!

    Anyhow,
    88 cc head
    flat top piston
    .020 gasket
    4.35 gasket bore
    4.32 bore
    .150 in the hole
    3.75 stroke

    = 7.98 compression (we can call it 8:1)

    When choosing a cam for compression you want to look at the intake closing point to up your cylinder psi. The "range" i found from reading a hot street cam is between 7.5 and 8.5 dynamic compression ratio (found by using intake closing point @.050 + 15 deg and your rod length). Anything beyond 8.5 is time for race gas.

    So I plugged in my Hughes Engines 1928BL cam that has a 52.5 closing point and the 6.768 440 rod and came up with 6.93 dynamic compression. With my closed chamber heads it gets me to 7.5. Too low for me, thats why im changing my pistons to get it up to 8+ dynamic. The whiplash cam has a good intake closing for dynamic compression and more duration than mine which makes it a better hot rod cam. There are some good videos on youtube and the Hughes website. Check it out!
     
  19. porknbeaner
    Joined: Sep 12, 2003
    Posts: 25,737

    porknbeaner
    Member

    Problem with milling the heads is that the rockers are not adjustable. The only adjustable rockers for your setup from MOPAR would be for a 426 max wedge, pretty basically they are made from unobtainium. The other option is after market rocker arms not unobtainium but made from expensium.

    WEe have used the 383 road runner cams with good success or MOPAR purple cams the middle of the road or the tamer version hydraulic cams with the low compression motors with pretty good success.

    Either can be purchased from your favorite catalog speed shop at a reasonable price.
     
  20. el Scotto
    Joined: Mar 3, 2004
    Posts: 3,363

    el Scotto
    Member

    I heard the Engle K56 cam is pretty nice in a low compression 440 with an intake and headers, but I have never looked it up to see what the specs are.
     
  21. cornpatch
    Joined: Jan 21, 2007
    Posts: 53

    cornpatch
    Member

    Thanks for the input folks. I haven't been on the board for a while. Is the comp ratios in your last paragraph what you intended? My confusion is probably cause I don't know the difference between static and dynamic compression.

    I know that a 413 Motor home engine has dished piston tops and are low compression. I have bot seen a 440 with a dished piston top, so would guess they lowered the compression by puttimg it lower from the deck. Thanks for you'uns help and I welcome more input...........MO
     

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