Another 302 Head Question

Discussion in 'Small Block Mopar Engine' started by JJH, Oct 7, 2018.

  1. JJH

    JJH Member

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    Hey all! I'm new to this group but have read through many of your posts. I finally joined, not because I have an A-body, but because you guys seem to be some of the most knowledgeable when it comes to 318s. My vehicle is a '69 D200. 727 trans with 3:54 D60 sure grip out back. When I started the project, my had an engine shop inspect the original motor, it checked perfect so they had a new cam, intake, 4bbl carb, headers, timing chain and the pertronix ignitor installed. Keep in mind, I was 13 at the time. Anyways, this last summer was the first summer for the truck being completed, I put a few miles on 'er to say the least. But the head gaskets appear to be leaking. So I'm pulling the heads sometime the spring so I can have it ready for the summer; i'm away at school for months at a time.
    Sorry for the novel, I just like people to have all the info when I ask a question lol.
    I was offered a set of 302 heads, no cost to me. I pulled them yesterday and they look to be good. I'm going to get them magnafluxed, and if they are good, I will do some home porting. Free horsepower is never bad, no matter how small. Anyway, i've read and wondered if these castings are thick enough to follow 1wild&crazyguy's thread for porting?
    Also, is it worth my while to have the heads milled? Looking to run a thicker head gasket, cause I can't tolerate leaks.
    Truck Specs are as follows:
    318
    Stock internals
    Eddy performer intake
    QFT 580 cfm carb
    Long tube headers
    Comp 252H cam (small, I know, but runs real nice in a truck)
    3:54 gears
    A727
    I know naysayers will come with "no gain in 302s" but I can visually see a difference, plus if the heads are coming off I believe there's value in improving what you have. Thanks!
     
  2. clifftt

    clifftt Well-Known Member

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    What heads were on before? AJ might chime in soon. He’ll crank out some calculations for you.
     
  3. JJH

    JJH Member

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    Okay, the heads on the motor now are the originals from '69. Not sure the casting number, just your normal pre-smog port cast head with an open chamber. Thanks!
     
  4. MOPAROFFICIAL

    MOPAROFFICIAL Well-Known Member

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    Follow the 1wild porting thread.
    Fyi They are the same ports as the heads you have now, just with a closed chamber.
     
  5. JJH

    JJH Member

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    Thanks! As I said, I have. The question I had regarding that thread was if the walls are of equal thickness. Like can I go as deep? I know the port size and shape is the same, but I was unsure about the casting being of equal integrity to the original head
     
  6. MOPAROFFICIAL

    MOPAROFFICIAL Well-Known Member

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    As deep as what , what's done in the thead?and which ,int or exh?
     
  7. JJH

    JJH Member

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    Yeah, when grinding in the actual runners (both int and exh) are there any areas I should be more careful of when working on newer 302 castings? I must apologize, I worded that question weird... just because it sounds right in your head, don't mean it sounds right in text:realcrazy:
     
  8. MoparLeo

    MoparLeo NRA PATRON LEVEL LIFE MEMBER FABO Gold Member

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    I see in your profile that you are now 18. So engine has sat for 5 years ? Was the engine just sitting on an engine stand or was it installed back into the truck back when it was " assembled ?" If it was installed back then, did you put any water in it ? If so it probably will need more than a head gasket set. So an engine shop inspected the motor and it was perfect ? What does that mean ? Did they do a compression check, oil pressure check ? Leak down test ? Did they remove the heads and oil pan and inspect the cylinder walls, pistons, bearings, cylinder head chambers, valves, deck and head surfaces ? Thicker head gaskets do not seal better than thin gaskets unless something is wrong with the surfaces you are trying to seal. The only time anyone uses a thicker gasket is when their headers are leaking. Usually because the header mating surface is not true and gaskets are easier, if they work. The more that you machine the head surface, the thinner the surface will be. The thinner it is, the more likely it is to warp when heated. Just like brake rotors that are machined too thin. Vibration when hot because there is not enough material to absorb the heat. Get an extra set of top end gaskets in case your "porting job " does not give you the results you were hoping for and you can put the good set back on. If you are determined to do the port job, remember that you can't put any material back that you take off and the most common mistake is going too far. Don't change the shape of the ports, just smooth out any casting flaws. Do not touch the combustion chamber. You will only lower the compression which will lower your HP. Do a port match to the intake and exhaust gaskets. Good luck and it takes many years to get the experience doing this stuff. You are still very young. Take your time. Get good tools, good service manuals and read a lot.
     
  9. BigBlockMopar

    BigBlockMopar BigBlockMember

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    Home porting does not equal free horsepower. Especially with no experience. Most likely even the opposite, or you get cocky and grind and break right through a wall, turning the head into a 'free' doorstop.
    Porting is a science. Based on knowing what an air flow/fuel mixture will do at certain speeds and a lot of hours of experience with porting AND testing them on a flowdyno. Fuel particles don't always travel in the same manner as the air does.
    Heck, even just 'removing' all the casting roughness could end you up with a port that flows less then before.

    You have a truck, so 'horsepower' is fairly irrelevant.
    You want to build for torque. This also means a high(er) airflow velocity will help better than wider ports (which lower that airspeed if the engine-size is not up for it).

    A port match would be the smartest thing to do, besides maybe increase the compression-ratio. But the 302s being closed chambers your CR will already be 'up' a bit.
     
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    • stixx

      stixx FABO Gold Member FABO Gold Member

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      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^All of this.
       
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      • JJH

        JJH Member

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        MoparLeo, the motor sat for 15 years with fluids in it before I even found the truck. It was my great grandfather's. My parents sent the motor to an engine builder. At the time, I knew very little about any of it, so I am unsure as to what was done. The engine did sit for about 3 years after assembly, before being started for the first time. It sat without fluids, on the floor, in the garage linked to my house. It has ran perfect all summer, besides for these leaks.... and I understand about the thin vs. thick gaskets. Sure I'm in college for Marine Engineering now and some of those big 2-stroke diesels don't even utilize head gaskets. My primary reason for that is the possibility that the block itself may not be true. Thanks for your insight!
        BigBlockMopar, I have learned very much over the past few years. I agree with what you're saying, and I understand the concepts of fuel suspension and "rough" surfaces. As for being cocky, I am ambitious but I don't get away from myself lol. I wouldn't go near as far in depth into a "home porting" job than described by 1wild or the other thread that had videos. But being my first time, I was looking for insight on whether or not there were any DANGER areas compared to the older castings. 302s seem to be a head that like to warp or crack; is this because they are thinner? lower quality metal? or a side effect to the lean burn and emissions, running too hot? Thanks
         
      • nm9stheham

        nm9stheham Well-Known Member

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        OP: Do you know what head gaskets are/were in there? Where were the leaks located? What thicker ones are you considering? A warped deck won't likely be fixed with just thicker head gaskets. Getting good, even compression across a head gasket won't be achieved with just a thickness change.

        Are you going to 302 to compensate for the thicker head gaskets and try to keep the static CR the same? Your original heads were very likely 675's. The 302's are 5-6 cc's smaller in the chamber, and that increases your Static CR. Your cam is small and torquey and the higher SCR will help the low RPM torque more. Not any real chance that it is too high with stock 318 pistons.
         
      • 4spdragtop

        4spdragtop FABO Gold Member FABO Gold Member

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        I did my 1st DIY port job on a set of 273 heads in my cuda. 1st time doing it. I dont regret it, I took my time and followed the same thread(1 wild n crazy).
        If you are "uncertain" do a DIY on the heads that are coming off(or junkers) and install the 302's with no portwork? Do the 302's later.
        Good luck and welcome aboard
         
      • MOPAROFFICIAL

        MOPAROFFICIAL Well-Known Member

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        I remember when everybody told me I was too young to know what the hell I was doing, next thing you know... lol

        Do whatever you are comfortable and confident with. Research, short turn shape, go to shows and physically touch the short turn of an edelbrock head.

        Dont gasket match the exhaust.
        Dont grind the 'intake bowls' straight to the seats, think venturi, google is your friend.

        Do your homework.
         
        Last edited: Oct 8, 2018
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        • JJH

          JJH Member

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          Thanks guys!
          Just the original head gaskets, and I'm not sure which ones i'll use. I'll probably go with one of the thinner ones upon reconsideration. The current heads are leaking at the front on both sides, and possibly at the back, even though I have a feeling the rear main is weeping too.
          Thanks for the welcome! And I hope that once I get this done and over with that I'll find it to be worth it as well.
          MoparOfficial, I have messed up on things before, will mess up, and always will. But I will certainly take my time on these. 302s are rare up here in NL. And I don't have the experience to go messing with the SSR, nor would I want to. The biggest thing I would like to see is to get the air coming in as fast as possible, as that is one benefit of smaller ports. Velocity is my friend. So, gasket match the intake (this eddy has 318 sized ports I believe), and clean up the casting (I don't mean make shit smooth, but any flashing and that), take some material away from where the valveguide comes out. I like strength so I'm not going crazy there. Why shouldn't I gasket match the exhaust? Will I lose much velocity coming out? I assumed that the headers having such large ports that it wouldn't hurt to at least flare the exhaust ports a little? Please correct me if i'm wrong.
          Now, the main purpose behind this is to fix my leak. But, do you guys (ya'll got the experience, I don't when it comes to this) think that there will be a slight gain? Switching to 302s with a lil port work, will it be slightly noticeable? I'm gonna do it anyway, i'm just curious
           
        • 4spdragtop

          4spdragtop FABO Gold Member FABO Gold Member

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          Depending on current heads, I bet the difference will be noticeable. Have fun, I did.
           
        • mderoy340

          mderoy340 Well-Known Member

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          Leave the exhaust floor alone.
           
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          • skrews

            skrews Well-Known Member

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            Aftermarket stainless valves, a good performance valve job, followed with a bowl blend will get you the best results.
             
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            • JJH

              JJH Member

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              I was going to just re use stock valves and lap them in.... what benefit do stainless offer? And is a valve job worth it on a street motor?
               
            • skrews

              skrews Well-Known Member

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              The factory valves don't flow very well and are cupped on the chamber side. Aftermarket valves are flat IE nailhead, thus reducing chamber volume by 2-3cc each, and flow better than the OE valves. The factory valve job doesn't flow well either, and is likely in need of freshening up anyway. A 3 angle valve job will increase the flow in the lift range of your cam more so than opening up the ports. It will be money well spent if its in the budget.
               
              Last edited: Oct 9, 2018
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              • JJH

                JJH Member

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                It's in the budget.... so are eddy aluminum heads lol. I'm just trying to see what I can get from what I've got, but i'm fine with having a valve job done. I could get my hands on a grinding machine but that's past my comfort zone right now
                 
              • AJ/FormS

                AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                You gotta look at the whole combo.
                What size tires are you running? My guess is 28s, and so those 3.54s and probably an 1800TC are gonna lock your engine into a low-rpm mode. Heck 4000 rpm in first is gonna be 37mph, and when you shift, the Rs drop to 2360.Then second will pull to 4000=62mph
                Personally I wouldn't spend a minute on home-porting.
                Before you bolt those 302s on, do some measuring and math. Those 69 engines where the highest ever compression LA318s at a rating of 9.5. that makes the total chamber volume to be 76.7cc. If nm9 is right and we assume a 5.5cc loss with 302s that makes your new chambers 71.2. But your new headgaskets might be 8.6 versus ~4.2 on the original .020steelies, for a final number of 75.6, and so a new Scr of 9.6...... hey it works out good to go no wins no losses right? Not so fast; the engine went from having zero quench to .039 plus the piston in the hole measurement of perhaps .012= .051, meh that might work as well.
                Good deal slap the 302s on and ...................
                wait,what
                No compression gain; not a meaningful improvement on the Q without a compression gain;otherwise same heads soooooooooooo did I miss something here?
                Oh I know; you can mill the 302s a lil less to boost the compression the same amount........... but you don't want to mill.
                I got an idea, How about just retorque the heads and put some sealer in the coolant, and continue to abuse the old girl, cheap as chicken broth.
                I see you spending a week and finding immeasurable improvement, and kicking yourself for having gone thru the motions.
                You want more fun? increase the rear gear 5% or drop the tire size 5% or ...... hyup BOTH!!!
                 
              • JJH

                JJH Member

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                AJ, the tires are closer to 30's, rear is a suregrip 3.54. I would like to go to 3.73s or similar, but highway driving would dislike me lol. I am highly considering pulling the motor, changing to a 2000stall converter and throwing in a shift kit.
                Now, I am not opposed to milling the heads. Another member mentioned the fact of warping, but if you believe it is not of concern, I definitely will consider. But you believe that mild blending/porting, a good valve job with stainless valves, port matching, and a converter change is not worth my time? I don't expect to have a tire-eating fire-breathing monster, but is it truly not worth the effort?
                 
              • JJH

                JJH Member

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                And actually, I believe the tq converters were tighter than 1800 on these trucks... probably closer to or below 1600
                 
              • AJ/FormS

                AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                ow and ow!
                30s will make 4000 to be 41 mph in first and 70 in second.
                You would be way more excited with a 2800TC and more rear gear;
                than with any home -porting.
                Those 3.73s would get you 65=2723 zero slip.
                Typically you will want to blast off at a tic under 30 mph. With your current combo, this will be;1250 in drive,1820 in second and 3070 in low.
                Here is a Magnum 5.2 curve, just an example..............

                power-318.gif

                Check out the torque at 1600,maybe 264ftlbs
                Check it out at 2800; maybe 292ftlbs.
                Now multiply those numbers by your rear gear and low gear and then by 24/30=.8 to get the ftlbs the tires are gonna see.
                >>First the current combo
                264(at 1600)x2.45x3.54x.8= 1832ftlbs at the road . not too bad. But look at the horsepower; about 80hp.
                Ok now imagine what the homeporting will do for you.From peak torque(3200) to shift-rpm(say 5700), the homeport might help with power. So the port work if works at all, will work from about 31mph to 55 mph. Now, ask yourself how often are you gonna go thru that zone, in first gear, at WOT. Then decide if it's worth your time to wear your fingers out on something that may or may not have good results, and you can't prove it with out before and after flow-tests, And in any case the gears and TC (see below) will eclipse any improvement.
                >>Next AJ's pick; the 2800 and 3.73s;
                292(at 2800)x2.45x3.73x.8= 2135ftlbs, Whoa! That is plus 16.5% more torque, and enough to fry both rear tires so make sure the SureGrip is working. Now look at the horsepower, about 183hp.
                With the 3.73s now your rpm at 30mph will be 3230. Go look on the graph; what are the ftlbs there? I'll go with 298. Ok so 298x2.45x3.73x.8=2179ftlbs at the road, at 30 mph.
                >The Magnum numbers were likely made with the stock engine, so your numbers may be slightly different, no worries.
                >The first point is that the 2800TC will more than double your horsepower to the rear wheels, over the 1600 on the start-line. And the 3.73 gears will let the engine spool up quicker, allowing you to get into second sooner. and put down more average power during the 30 to 65 mph run. And the combination of the two will incinerate the tires,off the line.
                > The second point is that IMO, the home port with the 1600TC is a total bust, compared to even just the 2800TC.:)

                So my advice for the biggest bang for your dollar, get a higher-stall TC and I have had great results with the 2800.
                For a little more improvement the 3.73s offer plus 5.36% TM on the start-line, and throughout the working rpm, with a quicker spool up. I would save this for after you have driven the 2800; you may find the 3.54s satisfactory with the new TC. If you need new tires, 28s will offer a cheaper alternative to the 3.73s. Tires offer a 30/28=7.1%TM improvement.
                 
                Last edited: Oct 10, 2018
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