I've got a 74 318 from a dart, its got around 150HP and 220 pounds of torque and I'm looking to increase the Hp and torque for as little money as I can. The engine runs fine and I don't want to open the bottom end up. The only ways I can think of for making more hp and torque with out opening up the whole engine is a cam shaft swap, intake manifold swap and working on the headers. Its got a eldelbrock performer rpm intake on it, but other then that its stock. Correct me if I'm wrong but would porting, polishing and other modifications to the heads would be the way to go?
Yes,you can port and polish the 318 heads but it is time-comsuming and you need to know what you are doing.If you can afford it I would swap to stock 360 heads,they have bigger ports & valves and will bolt right on. They will breathe much better in combination with a four-barrel intake & carb. This will give a big improvement,even with a stock cam. Also,stick with a stock replacement four-barrel intake manifold for better driveability. Use a 600 cfm carb,no bigger.
If your going to go the 360 head route you will want to machine .060 off an La head to increase the compression ratio to a livable #. Also don't worry about the large 2.02 intake valves, the 1.88 will flow plenty for a 318 and make it more driveable. Nice dual plane intake with a holley 600 cfm will do wonders. Other areas of improvement, a mild performance cam like a 340 automatic car cam with and a nice set of 1 5/8 headman headers. Have fun.
The only thing I would worry about with the 360 heads is the larger chamber volume will hurt performance a little bit by dropping the compression ratio.
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Thats why I'm worried about going to a 360 head, the compression ratio. I've heard that when you put a 360 head on it and its taken down .060 that you have to modify the valve stems so that they are sorter other wise they will hit the pistons and I've heard you don't at places.
I've gotten a lot of good advice from this forum and would feel guilty if I did'nt pass it on. One of these fellas who know more than I about 318 mods offered this advice, put 1.88 int 1.60 exh valves in the 318 heads and you wont have to worry about the compression. I picked mine up off of craigslist fairly cheap. I did some info searching on this idea and asked alot of questions before I went this route. Some agree and some say nay but its your motor. Good Luck
What is required to do that? I'm guessing you have to machine the valve guides and seats for the correct sizes right?
I'm right behind you an a budget 318 build for my Valiant. Keep the info coming. Thanks.
After doing some research it seems like putting on some swirl heads off of a 87-89 318. Any ideas?
New to forum with question: I have a 1989 Plymouth Fury with 318 and would love to put headers on it. Does anyone know where I may find them?Thanks,
summitracing is where I got mine
I have gone through this exact process, and I love the way the engine came out. You can hear it run on YouTube under My 1970 Dodge Charger 500, posted by RUMBLEINN.First, I overhauled the 318 shortblock with new rings, bearings, cam bearings, etc. I cross hatched the cylinders with a dingle berry hone. I used the Crane "Beast" Cam, Edelbrock LD340 Maninfold, 600 CFM carb, refurbished "J" heads and MP electronic ignition. It also has a double roller chain and MP high volume oil and water pumps, Heddmen Hedders and Flowmaster exhaust.The whole build was rather inexpensive and I think I actually got better results than the build they did here in the magazine. And this was 11 years ago. The engine is still running strong and I have spun the heck out of it, a time or two. I would do the same thing over again, if I was just starting out.
new to the post please forgive me I must tell it like it is my 1988 D100 W/230000 miles factory computor controled EFI has a mind of it's own I've put Summit shortty headers on a flame thrower HV coil summit 8.5 wires bunged in the o2 pluged air holes for header install no cat flowmasters duel ex NGK Iridium plugs ,power improvements are noticable my thing is there are not a lot of people out there who truly understand how this engine works or how to keep the the computor hook up ,this roller cam engine could it take a set of 1.6.1 roller rockers and some larger valves from it's sister 360 and some slight porting just to smooth out the air hump and gasket area .researched 360 heads would drop comp. any one out there know trully know about this engine? Please understand giving bad advise is the worse thing that could happen to my babby.I need a true mopar head to anwser these things to give this 318 more GET UP!!!
without pulling the whole engine down and starting fresh, there's not much you can do that will make a huge differance. if you check out in the tech section on the 318 budget build, part 3 and 4, pretty well tells you what you can do and what to expect.
318 peforamance problems my coments are directed twards anwsering some real issues related to the 1988 EFI w/318 computer control system .seems to be little info and alot of open smack without backup .My objective is what can be done for power gains with the computer hooked up? yes every thing done so far emproved performance but understand the computer will only let you do so much .so after reserching what is avable out there ain't no geek's got there hands dirty inventing a chip or box .sorry to put you thru all that .I may go as far as freshen up the motor only with what it needs port the 302 heads then 1.88/1.60 valves installed then tell ya'll about it, All because it realy run good and has gotten me A to B and B to A 230000miles worth .NO pun intended to anyone in the link This one is on me. I am not the first and wont be the the last this Mopar will get me were I need to go.