318 Mods, looking for suggestions

Fuel and Air Systems

  1. Plymouth71

    Plymouth71 Waterslide Decal Artist FBBO Gold Member

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    I have a 1971 Plymouth Satellite with the factory 318. I have received a Holley 650 ultra double pumper part number 76650 BL which if I can make it work reliably I would like to use on my setup. I also have a four barrel intake from what I believe is a police interceptor 360 part number 4100340.

    I need to figure out if I can make this combination work. The carb is a square bore and the intake is a spread bore I've heard that you can get an adapter. I also have a skip White HEI distributor with included coil part number JM 6513 BK. I was trying to install it with my factory air filter, but there is contact and I would need to cut the air cleaner assembly. I have two and a half inch exhaust with MagnaFlow mufflers running from the stock exhaust manifolds. I was thinking of getting a mild cam again not sure what I should look at. I also have a Rochester quadrajet that came with the intake. It had been used on a 318 out of a 68 satellite, however the engine and intake were not factory. One other thing tl mention is I do have a Mopar Orange box and electronic distributor that came with that engine as well. almost forgot I also have a
    Proform Extruded Aluminum Roller Rocker Arm - 1.5 Ratio. The car sat for a long time but runs good except for smoke on start up which I expect is from the intake valve seats. I am wondering if the newer heads would have hardened seats. The engine that came off of is a 1976 to 1984 318. The Exhaust manifoldsImanifolds are marked 77. I have included pictures of the parts. I have not checked the camshaft information on that engine either, not sure if it would be an upgrade or not. It's still in the engine.

    I look forward to your suggestions thank you for your time.

    1596135482796.jpg 145766-700238aa499b76313f9c73772376cf26.jpg
     
  2. Bad B-rad

    Bad B-rad Well-Known Member

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    I have heard that there is a slight port mis-match when the 360 intake manifold is placed on the 318 heads, but I am not an "LA" guy, I love the 318, but I never hot rodded one.
    650CFM carb also may be a little on the large size.
    I have read some of the best heads for a 318 are the ones right before the switch to the "MAGNUM" set up, Like "302" 1987-1989 heads, for the combustion chamber shape.

    I am sure that guys who know more then I will chime in.
    Good luck with your project!!!
     
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    • 493 Mike

      493 Mike FBBO Gold Member FBBO Gold Member

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      DP Holley is not a good choice for you. Vacuum secondary type is better and a 600 CFM is plenty big. Or, use the Q-Jet and save $.
      If the manifold ports are larger than the cylinder head ports it will cause a reversion condition, not good.
      Unless the OEM rockers and/or shafts are damaged I would use them. They won't break but, aluminum can and then there's the geometry issue. The OEM rockers were designed to fit. The Proform's should be checked for correct contact pattern.
      If you want more cam, stay on the mild side. Ask the cam manufacturer for a recommendation.
      Good luck! Keep asking questions.
      Mike
       
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      • VitaMeVas

        VitaMeVas Well-Known Member

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        I’m not much help bc I don’t build engines, nor did I have a hand in building the 318 in my 68 Satellite. I know that a builder in CO took the original 318 from my car (under previous owner), stroked it to 4”? (not bored) to reach 390 and added Edelbrock Aluminum heads (which he had to machine flat), a Weiland intake manifold and a Holley 600 or 650 carb. He ported and polished everything for flow and threw on long tube headers to 3” collectors down to duel 2 1/2” exhaust (H pipe). MSD HEI ignition upgrade and ‘aggressive cam. End result was 400 plus hp (calculated 450 ish). It was all professionally done and sounds amazing with tire shredding power. Conclusion: Don’t underestimate the bottom of end if the 318. It has crazy potential. I only know the finished product is amazing as I was always into the 383 or 440 route. Best of luck.

        4F3001BF-1E29-451E-979F-562077CE14A5.jpeg 670C64F1-0011-4C12-9B92-6699D958FD0A.jpeg
         
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        • myk r sanchez

          myk r sanchez Well-Known Member

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          Maybe my math is wrong, but you'd have to bore the block .30 over and combine that with a 4" stroke to get 390 CI. Nice motor though-you're 318 could outpull my tired 440...
           
          Last edited: Jul 31, 2020
        • VitaMeVas

          VitaMeVas Well-Known Member

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          You're math is probably fine. It might be stroked some, but when I called the shop for the 'details'.... the builder's son had just been put in the hospital after a mining accident. He said he'd send me the build numbers (from 2016) but he has to dive into his filing cabinets. Nice guy and seemed pretty distracted with his son's health.
          Whether it's a 320 or 420, it sure likes to go. But the suspension and steering are all over the place. Previous owner built it for power, but didn't do anything with suspension/steering/braking. But that's what I like to do....so I'm having fun. But mopar's are new to me, so I'm learning little by little. Can't wait to get the power planted to the ground!
           
        • toolmanmike

          toolmanmike Moderator Staff Member FBBO Gold Member

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          390, 392. They are whatever they end up being. a 390 stroker is a great engine. Like all engine builds, it needs the right combination of parts but really nothing more fancy than a 4" throw crank and the right pistons. All parts are off the shelf items.
           
        • RJRENTON

          RJRENTON FBBO Gold Member FBBO Gold Member

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          Personally, I do not like the idea of a spread bore to square bore carb adaptor. Due to the drastically different bores, turbulence during the transition will likely cause a flow restriction. I also agree with the premise of using a vacuum secondary carb is the better choice.
          Perhaps you can locate an aluminum 4 bbl square bore manifold, Edelbrock or similar, in lieu of the spread bore manifold. Thermoquad carbs are very good, but are difficult to tune because of limited availability of jets and metering rods plus the semi fragile plastic fuel bowl. But be aware of the potential head to manifold port mismatch. Perhaps gasket match the head ports to the manifold runners.
          But in spite of all the previous great suggestions, HOW MUCH $$$$ do you have to spend and how nuch time do you have to allocate? The old addage of: horsepower costs money....how fast do you want to go? Only you can make that determination. Just my opinion of course.
          BOB RENTON
           
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          • toolmanmike

            toolmanmike Moderator Staff Member FBBO Gold Member

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            An old Edelbrock LD4B works great. Weiand has one with 318 sized ports as well. A 600 Edelbrock is perfect. Easy to tune with jets and metering valves and springs. The AVS has adjustable secondaries and the new 650 AVS2 has annular discharge venturi's for added efficiency. A smooth flowing dial exhaust and a re-curved distributor (contact @HALIFAXHOPS ) will all help the cause. The roller rockers aren't needed (and don't add hardly any horsepower) until you get pretty serious with other racy parts. 318's usually lack compression. The 69's I believe had close to 9-1. As good as it gets.
             
          • rumblefish360

            rumblefish360 Well-Known Member

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            Keep the 650 DP and use a thick gasket to get it off of the hot intake. A police interceptor intake is exactly 100% the same as any other. It is not special in any way shape or form. Find an egr valve and it’s high temp gasket, install it and leave it un hooked up. (Or make your own block off plate) The unit works via vacuum. No vacuum? No work! So if you think about it for a second, anytime you flood it, the egr valves closes and is rendered ineffective & not working.

            An adapter plate like the Edelbrock part?
            Yup!

            HEI? Like a GM distributor?
            You can use there off set air cleaner. Instead of it having a centered hole in the base plate, it is off set to clear the huge distributor cap.

            I can help with a cam if you can give details about not only what you want but also about the car.
            Car Weight
            Type of transmission & model number
            Would a purchase or modification to the relays converter be OK?
            Gear ratio
            Tire size (not wheel size)
            Intended usage?

            Oh jeez, a slew of information all jumbled up and out of order... ugh! LMAO!

            Not braking your chops but try and organize your thoughts a little better.
            Rochester carb, if it works fine, that would be an excellent carb for a dual purpose machine.

            The orange box is on longer needed with the HEI from Skip White as it is self contained.

            The heads should have hardened seats.
            [/QUOTE]



            @Bad B-rad , do not take my reply as an insult or ridicule.

            While it is true there are port size differences between the 318 & the 360 intakes and heads, I have also found this to be true among just 318 heads and just 360 heads. Though smaller. The answer can be done at home with a die grinder. BUT I do not recommend a novice porting a 318 head out to gasket size unless there is someone w/experience behind him.

            Id skip the 302’s.

            A 360 intake on 318 heads untouched isn’t as bad as people make it out to be. This however also depends on the level of performance sought. For a minor upgrade, it’s fine.

            A 650 cfm carb size is fine. BTDT.


            @493 Mike , do not take my reply as an insult or ridicule.
            Not a thing wrong with the DP. If you step into it and I becomes to much, pull your foot back a little bit and learn where the engine likes to consume it all.

            While I agree the 600 cfm is enough, there is no sense in getting a new carb. A QJ for the smaller primaries would be a good move. I like spreadbore carbs a lot for stock engines to some semi seriously hot rodded engines. I like the TQ better but getting a good one that doesn’t need a rebuild is a PIA on top of a PIA or getting tuning parts for them.

            This is not a huge issue. It also does not cause “Reversion.” That is an issue of cam over lap & timing. What does happen is the air and fuel crash into the head and then puddle into the head and cylinder. While that is not a desirable condition, it is not a huge issue. To be honest, you wouldn’t know the difference if I had otherwise two identical cars for you to test drive and figure out which one had what set up.

            Stock rockers are fine for low lift and minor spring pressure upgrades. It is the rockers pushrod cup area that is the weak point. I would not worry about an aluminum roller rocker. As long as there not stressed under heavy loads and rpm abuse, they will last.
            I have zero experience with Proforms though.
            A good idea. Though 10 phone calls will yield 10 different answers from the 10 cam grinders.
             
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            • rumblefish360

              rumblefish360 Well-Known Member

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              This is incorrect. No matter what, the amount of turbulence under the carb has less to do with carb type to intake type but just the simple fact of the engines firing order. It is a turbulence maker. Nothing can be done to fix it. Unless you want to do a port fuel injection set up. There isn’t anything there that will limit cfm consumption or limit the carbs ability in cfm terms.

              An Edelbrock LD for the 318 or the Performer would be the intakes to look at. However, the Performer doesn’t perform any better than the OE iron. IDK about the LD 318 series of intakes. The did have one on my Dusters 318. It was very good. So is the Weiand intakes. The Action plus (spreadbore) or the Stealth (a square bore)

              Without question, the OP should measure the heads port window and then do some shopping around for “Other Intakes” to look up there specs on the windows port size. There may be a surprise in the specs.....
               
            • rumblefish360

              rumblefish360 Well-Known Member

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              I like the thoughts. The older LD and a AVS-II is an excellent combo. Recurring the distributor is a great idea that will help wake up that engine.

              Roller rockers do not add power vs one another however they will show a power gain over the OE rocker since there stated ratio of 1.5 isn’t always accurate & sometimes fall to 1.4. The best thing about an upgraded rocker is they actually have the stated ratio! Thus restoring the missing power that should have been there to begin with.
               
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              • HALIFAXHOPS

                HALIFAXHOPS MSGT(ret) and MOPAR only distributor rebuilder! FBBO Gold Member

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                OK I am not doing a plug here but the right recurve gives it a serious acceleration like a 50 shot of nitrous. What's your curve now? Simple to change it.
                 
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                • 451Mopar

                  451Mopar Well-Known Member

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                  Not sure if I would mess with the 360 intake unless the budget is really tight.
                  Done it before when I was 16, but the intake is still very heavy, you need to make an EGR block Off plate, and I even tapped and plugged the EGR holes inside the intake (or maybe back then I plugged them and brazed then closed?
                  The holley carb should be fine, need the spead bore to square bore adaptor, and a Chrysler throttle lever adaptor for the carb.
                  I would use an aluminum intake that does not have EGR, and accepts a square bore holley carb. They are way lighter than the cast iron intake.
                   
                • DeltaV

                  DeltaV Endeavor to persevere FBBO Gold Member

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                  I used to have a '71 Satellite with the indestructible 318. Here is what I did to it and I would do it again if I had one:

                  Stock heads freshened up with new valve stem seals and knurled the valve guides. Kept the stock springs/hardware. Replaced 2 exhaust valves. No 3 angle valve job...kept stock seats/angles.
                  '70 Dodge 340 dual plane intake.
                  Holley (600?) vacuum secondaries. I think it was a spread bore?
                  Direct Connection purple shaft cam
                  2-1/4" dual exhaust all the way back.
                  Turbo Flow (name?) mufflers for a '71 Fury I 440 (2-1/4 in and out)
                  B&M shift kit
                  Drained trans and converter; refilled with B&M Trick Shift fluid (name) an odd blue color.

                  I did not do anything to the stock single point distributor. SEE EDIT 3 BELOW. However, I tried a capacitive discharge box...twice. The car ran better with it, but they stopped working correctly after long distance runs over 100 mph (30 to 45 minutes at speed). Probably not good enough heat sinking to the firewall. The CD box would make the car miss slightly after the high speed runs. I could switch off the CD box and the car would run fine. It would miss again when I turned the box on again. Same story the next day...slight miss during normal driving. Tossed the CD box in the trash both times.

                  Edit: I had the transmission rebuilt (clutch packs, etc.) before I added the shift kit a few months later.

                  Edit 2: The trans rebuild was at around 58k miles.

                  Edit 3: @HALIFAXHOPS post jogged my memory. I did change the centrifugal advance...I replaced ONE factory weight with an aftermarket lighter weight. I did not replace BOTH factory weights, only ONE. I don't remember any details...weight size.

                  Also, I've dealt with @HALIFAXHOPS and he is a good guy. :thumbsup::thumbsup:
                   
                  Last edited: Aug 1, 2020
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                  • Montclaire

                    Montclaire Well-Known Member

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                    Sounds like you have a mix of parts there. You honestly do not need more than a 500 cfm carb unless you are racing. The older Edelbrock 318-360 performer intake (not the air gap, has two thermostat housing locations) is easy to find used and will fit the 318 heads better. There are many modern cam grinds out there but in the past the stock 340 cam was the way to go. And ditch those aftermarket rockers, the factory stuff is more than good enough for what you are doing and is 100,000 mile dependable. Lots of horror stories about aluminum rockers on the net.

                    Personally, I would look around online and see if there are any small blocks for sale in your area. You might find something for a lot less than what it will take to get yours humming. 318s can be good motors but they are also a little picky when it comes to mods.
                     
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                    • Plymouth71

                      Plymouth71 Waterslide Decal Artist FBBO Gold Member

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                      ok, a bit more info. All of these items except the HEI Distributor were given to me, so they owe me nothing. The Holley was won in a raffle, it is brand new. I'd like to get a bit of a power boost. I'm not looking to Race, I ain't got the time or the money. This car is my summer driver, and sunday night family cruiser. It has 8 & 1/4 diff. I don't have a lot of money to spend at this point, especially with me being in Canada, the exchange rate hurts as much as the shipping. However, I am willing to save. The car has 55,000 original miles. I don't believe the engine has ever been apart. I had the transmission rebuilt at about 44,000 miles because second gear was slipping. Put in a Mild shift kit at that time. The rear tires are 255-60-15 the fronts are 225 x 70 x 15 if that makes a difference. I have Hi-Jackers installed. The car has the A/C components, but it is not functional at this time. The car originally came from San Antonio Texas, and it is solid. I think it was owned by a little old lady, because I keep finding hair pins. Car is a 3 speed automatic, (904). Replaced the rear Leaf springs 2 years ago as well.

                      Trying to find used Mopar parts in my neck of the woods is like finding a needle in a hay stack. Nobody lets anything go, and if they do, they want top dollar. Basically I like the small block for the weight savings, the gas mileage is decent, but it's all show an no go. I don't have a big garage at this time either, so until I sell the house and move to the country, I need to pick a job, and get it done on the weekend, or I risk the possibility of it sitting indefinitely. I think I'ma little ADHD. I can lose interest pretty quick which is another reason I'm not looking at a 383 or 440 to put in.

                      RR.jpg
                       
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                      • 493 Mike

                        493 Mike FBBO Gold Member FBBO Gold Member

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                        I just wanted to mention that your reference to knurling valve guides is the first I have seen in this forum. I have a knurling set and use it on most of the valve jobs I do here. Of course that has slowed down as I age but. I knurled the guides on the poly 318 in my 65 Coronet in 2018.
                        Mike
                         
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                        • toolmanmike

                          toolmanmike Moderator Staff Member FBBO Gold Member

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                          I would agree. A intake, 4 barrel,a distributor curve, and dual exhaust are a great stage 1 modification. 318's are easy to over cam. Even a 340 grind can make your idle to 25oo rpm performance soft. (where you spend most of your time on the street0. Too big of a cam and you will need a higher stall torque converter and higher ratio rear gears to make it sing. The roller rockers are not needed for a basic engine like this. Stock valve train works fine. Then you are still working against the low compression in the stock short block. (often around 8:1 static, 7:1 dynamic). Then you still have the small port/small valve heads. If your goal of 350-400 horse out of a teen it has to be purposely built and the rest of the package has to match to make it work. We have weekly discussions on FABO. Stop on over and type 318 cam or the like in the search box. There are enough threads to keep you busy studying for weeks. Remember there are no magic bullets.
                           
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                          • DeltaV

                            DeltaV Endeavor to persevere FBBO Gold Member

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                            That is a fine looking car you have there! Given your situation I would be driving it, driving it, and driving it some more!!!
                             
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