Stock 318 bolt on performance modifications

Small Block Mopar Engine

  1. zhandfull

    zhandfull Well-Known Member

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    As I'm pulling parts off this 1975 Valiant 318 to transplant it from a four door parts car to a 72 slant 6 Swinger. I'm wondering if it would be worth it to add headers, intake, and a small four barrel carburetor.

    I'm actually fine running the motor as is with the 2 barrel carburetor and stock exhaust. This car is just going to be a cruiser, but if I could increase mileage or Hp noticeably. I have an open mind and a small budget.:D

    Any input from the 318 guys? Remember this would just be a couple bolt on items. Were not talking about getting into the engine.
     
  2. terzmo

    terzmo Well-Known Member

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    a 600 cfm 4 barrel would get You about 25 ponies...headers,in My opinion aren't worth the cost vs HP on a stock motor....I had a 2 door hardtop dodge phoenix(1960) with a 318/4 barrel/stock and it would chirp the tires from first to second at 60...
     
  3. 273

    273 Well-Known Member

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    ya something like an Eddy performer, 600 cfm carb, headers and high lift 256 or 262 cam should give ya 250+hp with no loss and maybe a litte bump in mileage.
     
  4. OldmanRick

    OldmanRick Well-Known Member

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    Carb and intake will make a nice upgrade as far as performance. Shouldn't be too expensive either. Keep your eye out for a used Eddy Performer and a 600cfm Holley/Edelbrock. To save a few more bucks, i'd run a nice dual exhaust off the stock manifolds, much less hassle. Run as much initial timing as you can and it should be a nice cruising package and get as good or better mileage then stock. Jmo.
     
  5. Johnny Dart

    Johnny Dart Well-Known Member

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    Stock 318
    Ede Performer
    Ede 600cfm
    340 manifolds
    Dual exh
    Mopar Performance elec ign.
    :burnout:
     

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  6. dustinmoran91

    dustinmoran91 Well-Known Member

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    find some 302 casting heads that are used, but still in good shape and dont need rebuilding. that'll bump the compression up and make it a little peppier with the intake 4 barrel and small cam if you choose to go that far with it.
     
  7. BillGrissom

    BillGrissom Well-Known Member

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    For low rpm cruising, the 2 barrel is fine. Most Mopars came that way for a reason. You could theoretically get a little better mileage with a small 4 barrel carb, but only with a dual plane intake. You wouldn't notice the 4-barrel horsepower unless you scream the engine (>4000 rpm), and doesn't sound like you care to drive like that. I would put the motor in as is for now since changing the intake isn't any easier with the engine out than installed. Wait until you have the money and know exactly what you want to do. EFI would give you the best driveabilty and mileage.

    If the V-8 engine harness plugs directly to your slant bulkhead connector, I would keep the Mopar ignition as is. If you must hack up the wiring harness, I would consider wiring in an HEI module and better coil. The ready-to-run HEI distributor is simple and inexpensive.
     
  8. bad440

    bad440 everything,all the time..

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    x2 what bill said,put efi on it and dual ex and be done.
     
  9. jarvitron

    jarvitron Well-Known Member

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    Second dual exhaust, don't waste the money on the "340 manifolds", they're worth 3-4 horsepower tops, see here http://www.moparmusclemagazine.com/techarticles/engine/mopp_0307_mopar_crate_engine_exhaust/photo_17.html, expensive to ship, preposterously dear for what they are and there's better places to put money. If you are OK with cheap headers get cheap headers and a summojegsalocalmufflershopomatic dual exhaust, or have a muffler shop build some downtubes from your stock manifolds (delete the EGR flapper wheel nonsense with some jbweld and bolts or all thread and washers or whatever level of ghettoness you are comfortable with) piped to a dual system.

    As a dude who is putting a 4bbl into a car that originally had a 2bbl, I can tell you this. It's not as "put them there 600 four burrel on and whoop she go" as it sounds in a forum thread or article. You're gonna be pulling the distributor and the intake manifold, which is a beast to do yourself without a crane or a young, vital backbone, strong and wide. As well as disconnecting all the sensors and hoses that go along with that process. Then, once you get the sucker back into place, you will realize that all of your linkages are now worthless. Your throttle cable doesn't reach right, the kickdown linkage isn't in the right place. So you need to get a stocker 4bbl setup or a Lokar kit (which is pretty cheap and pretty nice, TBH, I had a lot of haterade before it showed up in the mail, it feels nice and strong), and switch out to that.

    If I had it to do again, maximizing dollar to horsepower, I'd probably do dual exhaust, a shift kit, a new cam, DIY HEI on a recurved distributor, and either rebuild the BBD or replace it with a motorcraft 21xx, on a "big holley" adapter plate, which is what the BBD-affected performance jeep folks appear to favor. That would be a big kick in the shorts <$1k even if you aren't shopping for sales and being frugal.
     
  10. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    The first thing to do to it to gain performance is to run dual exhaust like 2 1/4".

    Then look into 4 bbl and headers secondary.

    It is useless to run headers with single exhaust. The biggest performance restriction on a stock 318 is the single exhaust. Start there and work on intake next.
     
  11. AdamR

    AdamR Big Member

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    dual exhaust, LD4B or Performer intake, small cam like an XE256.
     
  12. 273

    273 Well-Known Member

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    If your gonna stick with manifolds at least grab a set of 360's manifold Magnums being the best theres a certain years that better than the others, but any is a step up.
     
  13. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    I just DID this very thing. The 360 I bought (used) developed a knock, and I didn't want the car down for the rest of this very short summer.

    Found a comPLETEly stock 318 about 73 on Craigs for 200 with evidently less than 40 K claimed by the seller. Plastic cam sprocket looked like new, cam and lifters looked like new, and BARELY any wear from the seal on the balancer. Blue painted VC and intake gaskets had NEVER been off!!!! Frankly I'd say it has less than 20K on it!!

    Ran it a week stock, ran good, so I put my "little" cam and Edelbrock Performer, 650CFM AFB The cam is an unknown reground, was supposed to be about the same as the factory HP 340 cam except in a mechanical grind

    That little 318 is AMAZINGLY snotty. No head work, nothing else was touched. Car has headers and mediocre dual exhaust.

    REGULAR FUEL!

    If I get time, maybe I'll do an "in car" vid.
     
  14. zhandfull

    zhandfull Well-Known Member

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    Some good advice so far. I sure like that little blue 318 Johnny Dart posted it's pretty.
     
  15. TT'74

    TT'74 Well-Known Member

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    Magnum engine (efi~$500-600) + twin turbos(~$800). Manual steering, magnum manifolds (flipped left to right), U-pipes up for turbo mount, Used mustang SVO turbos with internal waste gates, FMU, air hat, charge cooler(I used water/meth).

    I got 16/20 mpg with a 727, could spin 275/60/15s at 50mph with an unmodified 5.2l+TT.





    [​IMG]
     
  16. TT'74

    TT'74 Well-Known Member

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    '92s are the good ones, and they can be 318 or 360 there isn't any difference.
     
  17. Inspector71

    Inspector71 Well-Known Member

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    Sounds like you want some simple bolt on mods and nothing too fancy. My brother and I did the same with a low mileage 68 Charger that came with a 318 2bl. We changed it to a 4bl intake (be careful dropping it in place. if you "pinch" the gasket moving it around, it will leak...I made that mistake), a 600 cfm carb, hotter than stock cam, headers, and low restriction muffler. It had stock 318 heads and no other work was done. It ran good and fast and fooled a lot of people who swore it had a big block.
    I forgot to add that modifications had to be made to make the throttle linkage work. It was a 3 on a tree so not as much work as if it had been an auto trans.
     
  18. zhandfull

    zhandfull Well-Known Member

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    Very cool engine! I can see this engine under a flat 70-71 Dart hood getting fresh air from the factory dual scoops. The twin turbo set may be in my future someday. Even though you have a very budget build. I'm hoping to just win the lottery and buy Maddart's twin turbo Dart when he's finished building it and gets all the bugs out.
     
  19. zhandfull

    zhandfull Well-Known Member

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    I actually like the EFI ideal, but have no ideal whats out there. Are people using a factory set up and controller? Any threads with a how to install?
     
  20. scott2683

    scott2683 FABO Gold Member FABO Gold Member

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    My dad and I just got done building the 318 out of my duster, punched the engine out 30 over, KB pistons, 268H compcam, I found a set of reworked heads, performer intake and 600 eddy, and cheap summit headers, and she's a screamer now! I was completely surprised by the performance difference it made! Initially I wasn't going to have it bored over, but the cylinders weren't in as good of shape as I hoped!

    We made a throttle cable bracket and lengthened the linkage rod ourselves, instead of buying the Lokar kit. It worked out really well for us, but that was the biggest issue we had installing the 4bbl. Everyone is right, the 2bbl cable and linkage is pretty much useless.
     
  21. SirDan

    SirDan Well-Known Member

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    FWIW mine ran great with, a 340 cam, headers, ld4b,600 cfm carb, dual exhaust. with 3.23 gears and 275/60/15 tires i am confident it was in the 14 second quarter mile range. It would roast the tires at 6,000 rpm in first all day long. When i had headers and just small glasspacks after them, i pretty much made purple hornies out of 30 dollar glasspacks. but anyway EVERYONE thought the motor was hot stuff. sounded amazing at 6,000 rpm. when i put a dual exhaust on it only pulled to 5,700 rpm but gained a ton of down low. high mileage motor 200k at least, i think i spun a bearing after 2 years of abuse.

    I also agree that forced induction would wake a 318 up!!

    hoping to boost my motor at some point.
     
  22. OldmanRick

    OldmanRick Well-Known Member

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    zhandfull, i'm glad you liked Johnny Dart's engine combo. It's a good clean build and is what you asked for. Economical bolt on's with no internals.
     
  23. jimjimjimmy

    jimjimjimmy lobsterman FABO Gold Member

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    sweet
     
  24. Abodybomber

    Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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    My .-000002 cents,lol.Simply a good,honest double roller chain.The chain ,possibly shot .Might make 20 to 40 ft lbs more torque,across the board.
     
  25. mopardude318

    mopardude318 Well-Known Member

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    while not the most "budget friendly" approach....i took a stock bottom end 318...ball honed the cylinders, threw in new cast iron "rebuild" rings, new cam, main and rod bearings, (emory clothed the crank journals....) used the stock cast crank, rods and and cleaned up the heavy stock replacement keith black silvolite pistons it had in it. (which were approx. .070 down in the hole) and slammed it all together in my living room. (using the "how to rebuild SB mopar" book)

    -i used a melling HV oil pump, and added a MP windage tray
    -cam is an Edelbrock RPM 234/244 dur. @ .050, lift is 488/518

    -Prepped RHS heads by brian @ IMM engines. 202/160 with 5/16 valve stems, beehive springs. 62 cc close chamber

    -hughes roller rockers 1.5 ratio
    -performer RPM manifold
    -holley 650 spreadbore carb
    -tti headers
    -MP viscous fan

    transgo 2 kit in my 904 with a PTC 3000 stall converter. 355 sure grip rear...

    this little engine in this combo works REALLY good. idle sounds mean, it revvs to the damn moon, everything works and runs so damn good...pump gas on 87, no pings. (low compression anyway lol)

    i wish i could take it to the track to see what itll do..on the street itll smoke rubber any time, and gets my barracuda sideways with ease...
     
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