318 REBUILD IN 67 BARRACUDA

Small Block Mopar Engine

  1. 67BARRICONVERT

    67BARRICONVERT Well-Known Member

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    Hi everyone,
    I just pulled the 318 out of the car so i can paint the car including the engine bay. The engine ran ok so originally I was not planning on a complete rebuild but after doing a compression test (120 psi low to 170 psi high) and disassembling the engine I don't have a choice. There is a piston ring ridge at the top of the cylinder wall that will catch your finger nail and the nylon tooth timing gear was the loosest I have ever seen. You could almost walk the chain off of the gears even though all the nylon teeth are still there. I am going to have to make some decisions on some things like cam choice, and valve size.
    engine pull.JPG
    First let me tell you about the car and what direction I am going with it. Its a 1967 Barracuda 273 with the commando option, 904 trans, 7 1/4 axle with open 2.76 gears. The original owner (I am second owner) swapped the original 273 for the 318 years ago. Other than the engine the car is very original and I would like to keep it as original looking as possible. The car will probably never see a drag strip (maybe?:)), just a nice driver. In fact i am building this car for the wife. I understand with its 7 1/4 rear end and 904 trans we cant get to crazy.

    So, back to the engine.......The block is a 1969 casting # 2586030 and the open chamber heads are what I believe to be original to the block (sorry, i dont have the casting numbers in front of me but they are 1969 castings also). I would like to improve performance but I realize the limitations that will hold it back. One would be the exhaust because I would like to use the original exhaust manifolds and the Accurate exhaust Hi-Po system (already purchased) with the optional Magnum muffler which should flow better than the original single exhaust. Accurate claims this system will out perform dual exauhst but I am not going to bank on it. The exhaust manifolds are part number 2843953 and 2780946 which I believe are the original 273 manifolds which came with the car.

    So my plan with new pistons is to raise the compression to around 9.5 to 9.75:1 (has to run on premium pump gas) and since the heads are going to be rebuilt install larger valves. How large should I go? I have seen as large as 2.02 intakes, is that a possibility or should I go with more like 340 or 360 size valves? I do think I want to keep the stock rocker shafts and push rod length because I don't want it to get too complicated.

    head 1.JPG
    block.JPG
    nylon timing gear.JPG
    I am going to run the LDB4 aluminum intake which was already on the car. It says Chrysler on it and has a Chrysler part #. It leaked coolant at the thermostat housing because there was pitting on the aluminum mating surfaces and one of two bolt holes threads were pulled out. I machined the mating surfaces, installed a 3/8" heli-coil in the stripped hole and glass bead blasted the intake.
    I have two carbs to choose from. On the car was a Carter AFB #9626S which is 625 CFM. I would assume its been on the car since the 1970s and it ran fine with it but it is kinda crusty looking so I would rebuild it. The other option is a Edelbrock #1406 600 CFM that I have which is new and has the "Endura shine" finish on it.

    The distributor has a electronic module in it and a Direct Connection orange box.

    I was planning on using the the stock crank and rods if they are serviceable, and doing some port matching on the intake and exhaust manifolds if needed.

    So that leaves the camshaft and that's where I get a little lost. What do you guys recommend for a build like this???? Any help on a camshaft or advice on the rest of the build is greatly appreciated since this is my first LA small block build.
     
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    • jazak5

      jazak5 Well-Known Member

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      stroke it to 390 and after a few months tell her she broke the axle:rofl: or convince her that your already doing a lot of work and order a blue print 408 be a lot faster turn around to being back on the road and most likely with the machine work and parts a wash a member here has 340hp manifolds for sale now.... reasonable price
       
      Last edited: Sep 15, 2021
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      • toolmanmike

        toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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        Just a freshening up will do it good. The LD4B is a great intake and it sounds like you have that under control. Either carb would be fine. Cam's for a stock 318 have been discussed here to death. Unless you want to add a higher stall converter and possibly rear gears don't go too big. I recommend keeping the @.050 duration below 230°. A simple off the shelf Comp cam that many have had good luck with is the 252H. Here's a thread of interest. (post #5) THere's mild Sealed Power cams, Summit, Jones. Crower and the like. Many say the 340 cam is a good choice only to find those guys have headers, converter, and/or gears to make it work well. If you are going to bore it get some flat top pistons close to zero deck to raise the compression. Keep it around 9.5/1 or so and it will be pump gas friendly. (KB167) KB KB167-030 Keith Black KB Performance Pistons | Summit Racing
         
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        • furrystump

          furrystump Well-Known Member

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          There are a bunch of smart 318 guys who can help with cams, but I might be biased but I like the tips from the 68 cars. You are already doing body work and making the valence cutouts isn’t that hard. I just did it on my 68.

          98F233F6-5EB0-48C6-966F-F3BE970A329E.jpeg

          D5099EED-5767-47FD-B433-5F149275CD87.jpeg

          5855C6CC-7C67-41B9-AD0E-9ED87478478E.jpeg

          E1B35D1B-4AC4-48F6-A00E-1A135407C9F3.jpeg
           
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          • furrystump

            furrystump Well-Known Member

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            or you could just put the second half circle in.
             
          • 67BARRICONVERT

            67BARRICONVERT Well-Known Member

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            Would those manifolds bolt up to the Accurate exhaust that I have already purchased?
             
          • toolmanmike

            toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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            I bet not
             
          • 67BARRICONVERT

            67BARRICONVERT Well-Known Member

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            Thanks Toolmanmike, I was looking at those exact pistons and was thinking on going .030 over which should clean it up. I saw an article where Steve Dulcich used those pistons at zero deck but with 58CC closed chamber heads and a .040 gasket for a ratio around 10:1. I will check out the 252H cam. One thing I didnt mention was that this car has factory air so I want to make sure that I dont kill the manifold vacuum which the A/C and power brakes need and that cam should not affect vacuum much, right?
             
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            • 67BARRICONVERT

              67BARRICONVERT Well-Known Member

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              I thought about modifying the rear valance for dual exhaust but because of the gas tank mounting on the 67 there is not much room on the passenger side.
               
            • toolmanmike

              toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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              It should be ok for vacuum.
               
            • Dartswinger70

              Dartswinger70 make it 3 yards and well have us a automobile race

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              If you think the engine ran ok before wait till you replace the timing set...Id venture to say that's stock, last time I saw a nylon tooth timing gear was in a 69 Coronet 500 I owned that had a 318. This was way back in like 1990, around when they all should have been replaced LOL!
               
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              • 67BARRICONVERT

                67BARRICONVERT Well-Known Member

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                I think your right Dartswinger70, I checked the bore and it is standard so I don't think the engine has ever been rebuilt. The original owner is still alive and I have been meaning to ask her where they got this 318.
                 
              • cudamark

                cudamark FABO Gold Member FABO Gold Member

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                Looks like some items from the 273 ended up on the 318. Did the solid cam adjustable rockers and push rods? If so, I'd reuse them and keep/make it a solid cam engine and use a cam similar to the 273 4bbl specs. Opening up the heads for bigger valves can be more expensive than buying new aftermarket aluminum heads. If you have that kind of budget, I go aluminum so you can bump up the compression ratio and still run pump gas. If it were me and keeping the costs down, I'd just clean up those head with a nice 3 angle valve job and maybe some minor porting. Using the stock exhaust manifolds would kill most of the flow advantage of the big valves anyway. I'd rebuild the 625 carb and use it. I'd also keep an eye out for a stronger rear axle assembly.....eventually you will need it! Oh, and one more thing.....a question about how they mated the crank to the converter. The original 273 would have had a small register in the end of the crank for the small button converter. A 318 would have had a large register. Did they put a reducer bushing in the end of the crank? Make a custom converter? Now's the time to address that too.
                 
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                • Brooks James

                  Brooks James Dustoff

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                  I wouldnt spend the money on heads other mods are much more cost effectively. Like a 150 hp nitrous kit for $400, which if set up correctly wont fry the motor
                   
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                  • cudamark

                    cudamark FABO Gold Member FABO Gold Member

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                    It'll just grenade the rear end! :lol:
                     
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                    • Dartswinger70

                      Dartswinger70 make it 3 yards and well have us a automobile race

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                      Check out the cam kits on this page. I have used the SUM- K6901 with manual trans on 318. It ran good with stick heads and valvetrain There are plenty out there but these are budget friendly

                      CHRYSLER - Summit Small Block cam shaft kit KEYWORD Parts & Accessories | Summit Racing

                      IMO what you have to watch out for is getting to .500 lift with stock heads and springs. Im sure someone will chime in on this, but i ran that .444 cam with stock springs and no issues on the street not racing...I wouldn't know what it would do at max rpm LOL!
                       
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                      • toolmanmike

                        toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                        Nitrous. How many engines can't handle the stuff? Most of them.
                         
                      • Dartswinger70

                        Dartswinger70 make it 3 yards and well have us a automobile race

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                        I can say Id like to try playing around with it, but really don't know much about it, Id probably run a "fogger" with a carb spacer and see what happens...:)
                         
                      • 67BARRICONVERT

                        67BARRICONVERT Well-Known Member

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                        Hi Cudamark, Thanks for that info, I did not know about the converter and crank differences. I will check the converter when I get back home late tomorrow. The converter thats in it is painted blue. I rebuilt the trans and reused the converter because it seemed to work fine. The crank is at the machine shop so I would have to go by there to look at that. Unfortunately the solid cam and rocker assy did not make it into the 318. I have considered aluminum heads and I could paint them so they look more original but my head guy said it wasn't going to be that expensive to put in larger valves....We will see about that.
                         
                      • 66fs

                        66fs FABO Gold Member FABO Gold Member

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                        On the camshaft I'd shoot for around 260-268 duration and .450 to .490 lift. Honestly, call Racer Brown and any other cam grinders and honestly tell them what you want. Get valve springs to match the cam you pick. You should have a nice 318, so I'd just rebuild what you have. Have the big ends of the rods redone .0002 undersize with ARP rod bolts. They should be the early light weight, bushed rods. Make sure the decks are equal on the block, bore and hone with torque plates with mains torqued to spec also. Add a windage tray, high pressure oil pump, and a true roller timing chain. I like Speed Pro ductile, file to fit, moly rings. Have your bottom end balanced. Mill the heads .020 and .019 on the intake side of the head, that should give you around 64 cc chambers. You can run stock valve sizes, or bump them up to 1.88 intake and 1.60 exhaust (360 sizes) not really necessary though. I would run stainless steel exhaust valves and the later Viton positive valve seals from Fel-Pro. Spring for a Competition valve job, and just clean up the bowls under the valves. Find true TDC and centerline your cam while the heads are off. On the exhaust, delete the heat valve on the passenger side manifold and consider "Jet Hot" coating the manifolds to keep the heat down in the engine bay. You will like the Accurate Commando exhaust. Your intake is great and either carb will work. I think the 9626s was designed for a 383, so it might be a tad rich. Play with both and pick the one you like best. When port matching, just do the top and sides. The Commando 904 has some nice parts from the factory. You could probably just reseal it, adjust the bands, change the fluid and filter, and be done for the next 100,000 miles. HP cars usually had 3.23 gears but we used to swap in 2.76 gears for highway cruising. We ran a 67 Barracuda like yours, except we kept the 273, for about 50 years and 300,000 miles. What a great car, still have it. Good Luck!
                         
                        Last edited: Sep 17, 2021
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                        • 67BARRICONVERT

                          67BARRICONVERT Well-Known Member

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                          Thanks 66fs, I like all your ideas and I appreciate your input. Your right about the 3,23 gears. I found 2 build sheets in the car , one under the seat and one on top of the glove box and they said the car came with a 3.23 gear. I will have to research the best way when deleting the heat valve on the exhaust to plug the shaft hole.
                          LDB4.JPG
                           
                        • 67BARRICONVERT

                          67BARRICONVERT Well-Known Member

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                          So the converters button is 1.55 inches and has the numbers 287 6 1 on the opposite side.
                          convert front.JPG
                          convert hub.JPG
                           
                        • 66fs

                          66fs FABO Gold Member FABO Gold Member

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                          If you can get the flapper off the shaft you can usually grind the high spots/welds on the shaft and slide it out. Then I tap both sides of the manifold with a size that fit the shaft bore. Then install button head bolts from the outside to seal it up.

                          That looks like a 67 torque convertor, so use the adapter in the register in the crank. What are the numbers on the pan rail of the 904?
                           
                        • furrystump

                          furrystump Well-Known Member

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                          The fuel tank mounts the same as a 68, but you are right. There is not much real estate back there so the location of the cut outs is pretty important. If you are interested I can make a set of templates for each side located off the frame rail. Which is what the tips mount to. I have an original 68 340 car to make templates of.
                           
                        • 66fs

                          66fs FABO Gold Member FABO Gold Member

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                          Actually 67 cars had one gas tank strap across from left to right. 68 up had 2 straps front to back.
                           
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