318 REBUILD IN 67 BARRACUDA
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.
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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.
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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.
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
