headder question

M Body General Discussion

  1. kingoftooland

    kingoftooland Active Member

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    soon I am going to be getting some heads and headders for my 1984 5th ave now the thing I am trying to figure out is I hear that the aspen/volare has the same k frame/engine compartment as the m bodies is this true?? because i'd love to get some full length headders for it. my 5th ave has the stock 318 la in the heads gotta go their smoked valve guide seals leak so bad it's nuts so getting edelbrock performer heads for it but you guys know if aspen headders whould work on a 5th ave?? n this is the babby that's getting the goodies

    my car.jpg
     
  2. jasperjacko

    jasperjacko Well-Known Member

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    yes
     
  3. kkritsilas

    kkritsilas Well-Known Member

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    If you haven't bought the Edelbrock heads yet, look at the EngineQuest heads. May (or may not) be cheaper, and are great performance heads, even un-ported. They flow a little bit better than the Magnum heads, but don't have the cracking potential of the Magnum heads, and some versions can be had with the same bolt angles as the LA heads, so you can use any LA intake manifold.
     
  4. Aspen500

    Aspen500 Well-Known Member

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    All F/M/J bodies have the same chassis, suspension and steering. Only real difference between all models and body styles is the wheelbase.
     
  5. Camtron

    Camtron Well-Known Member

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    A body headers fit nicely too. Is your engine stock otherwise? Most aftermarket heads are going to make that thing a dog from a dead stop if it’s got stock smog pistons and highway gear ratio in the rear axle. If you can find some 302 swirl port heads off a late model 318LA with a roller cam for cheap, that could be a better option depending on what you’ve done/haven’t done/plan to do to the engine. That would give a little bump in compression, better flow and pair real nice with a 4 barrel intake and headers, even with stock pistons.
    But I digress lol
     
    Last edited: Mar 18, 2020
  6. Mikes5thAve

    Mikes5thAve Active Member

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    Your money would be better spent on a set of 302 heads and cam swap over putting Edelbrock heads on a smogger 318.
     
  7. AJ/FormS

    AJ/FormS Well-Known Member

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    I think the pistons are about .080 down in the hole so that's 15.74cc, add 6.2 for .028 gaskets, and 63cc for the Eddies, and that comes to ~85cc and so the Scr maths to ~8.7..
    IMO, this is not enough improvement to warrant the expense. Better to stick to closed chamber iron heads, with smaller chambers like the 58cc ones; which could maybe get your total chamber volume down to 80cc, and thus 9.15 Scr.
    That's probably a lil high for the factory cam and the no squish chamber, but if you could keep it out of detonation would be just the ticket..

    The big thing with those cars is the crappy hi-way gears in the back, and the low-stall TCs.
    The convertor starts the car off at a low-torque place on the curve, and the rear gears keep it there, seems like forever.
    Those would be my first targets for performance improvements.

    Think of it this way;
    on the start line at zero mph, what can you expect from headers and a 4bbl?
    Say you have an 1800 stall TC. You punch it and the Rs jump to 1800...... at which point your teener in factory trim has um say a max available , foot-to-floor, 190 ftlbs (65 hp) . The 4bbl will not open at 1800,and even if it did, the 2bbl can handle the engines air requirement at 65hp.The headers are not yet on-line. Yeah they are better than the factory logs, but lets be generous and say 5% or 3hp. So you are up to 68hp tops, foot in the carb..... ; remember this number;plus 3%.
    Some guys will jump the headers to 10%, so what; that's still only 71.5hp@1800rpm.


    Now lets get rid of that 1800TC, for a 2800. Now when you nail it, the Rs jump to lets say 203ftlbs which is 108 hp, a 67% improvement; before the addition of any headers or 4bbl.
    See what I mean? 68hp versus 108hp,3% versus 67%; and without headers or a 4bbl.
    The TC should be your first go-to.
    My specific numbers could be wrong, but when expressed as a percentage. the point is the same ......... plus BIG %
    And the car hasn't even started to move yet,lol

    Lets see what happens as the tire makes it's first revolution.
    First with the 1800TC and say 2.45 gears;
    So out the crank is coming 190 ftlbs, and the trans multiplies that by 2.74 (A999), and the rear by 2.45, and the TC is gonna start off at 1.8-ratio. Ok so;
    190x2.74x2.45x1.8=2300 ftlbs to the pavement, almost a chirp, maybe more like a squeaky suspension bushing, right?
    Second with the 2800, and say 3.23s; Torque is up to 203 now (108hp). and,
    203x2.74x3.23x1.8=3234 ftlbs now; So now, at 3234, you have broke the tires loose.
    What's next?

    That would be the sustain; can she keep spinning the tires?
    Well the stocker cant hardly squawk one tire, never mind spinning them very far.
    But with the 2800/3.23 combo;
    as soon as the tires break traction, the 1.8 TM ratio drops to close to it's minimum, I'll guess 1.4, so;
    203x2.74x3.23x1.4=2515, yeah, that should be plenty to sustain
    The engine is now making 108hp and the rpm is rising. If you have kept your foot in it and the rpm has climbed to 3200 say to peak torque of 209, so 2590 ftlbs .
    Ok well 2590 @3200 is a tuff call, as the car is accelerating, and torque is now gonna start to fall, I think she's done. 3200 @10%-slip will be 26mph, sounds about right.

    So to recap;So far; the 2800TC and 3.23s have transformed your 318 into a tire shredder up to around 26 mph; a thing which the 4bbl and headers, by themselves could never do.

    But we're not done yet; she's only up to 3200 rpm@26mph.
    The factory 2bbl combo with single exhaust is gonna power peak at 4000 or so, which ,with 3.23s will be about 34 mph. But yur not gonna shift until 4400/37mph, so as to get the most out of first gear.
    Compare the above combo, to the current combo with 2.45s.
    3200 will NOT be until 35 mph! 4000 not until 44, and shift-rpm is 4400@48 mph.By 48mph, the 3.23s will be in Second at ~3260, having put down considerably more average power, and that means, considerably quicker in the doing.
    And we still haven't touched the engine.
     
    Last edited: Mar 20, 2020
  8. kingoftooland

    kingoftooland Active Member

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    hmmm true it's got the 7 1/4 axel /w hwy gears n stock cam main reason for new ally heads is 1 the stock smoggers are shot valve guide seals leak oil into the cylenders BAD and smokes every time on start up and #2 I want to leave meat on the table for improvement next year gona get rid of the smogger pistons n do a full rebuild at that time
     
  9. Duke5A

    Duke5A Well-Known Member

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    Valve seals are cheap and can be installed with the heads on the car. I got to agree with everyone and say the loss in compression isn't worth the increase in flow - this is especially true if you don't plan on replacing the cam at the same time. That stock cam is a broom stick and is all done at 4500 RPM. Eddie heads will do nothing more than look really nice under the hood.

    I do know you want the heads to support future mods, but this really isn't a good order to go in. Put new valve seals on the valves first, do your exhaust next and then tackle the rear axle.

    Since this is a daily driver, I would be really apprehensive about using long tube headers. They hang under the steering link and you WILL flatten them on Michigan roads. Shorty headers would be my advice. Maybe a set of Tri-Y headers from Schumacher.

    Any improvement on the motor that shifts the power band up is going to make the car a bear to drive with 2.24 gears. You can try and find a Mopar axle, either an 8.25" or 8.75", but these are hard to find anymore. A Ford 8.8 is probably the best solution here and it an be pulled with disc brakes. Grab the 8.8 from Parts Galore. Get the measurements for the existing axle and have Warren Gear & Axle set it up for you.

    At least this is what I do.