318 horsepower

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You don't need a single-plane,get yourself a Air Gap dual plane i've seen test where it outperformed most single planes...

As far as getting the same power out of a 318 that you can from a 340/360 for the same amount of money,i'd like to see that without spraying it...i've owned basically nothing but 340's don't recall any 318 running anywhere what my 340's could,without spending more money....
 
....i always wonder why people bother with little 318's when theres so many 360 blocks out there.."


Probably because there are so many MORE 318's out there... ;)
 
Well my original plan was to go with a 360. But I got duped by this guy that had the motor, he had it listed as a running 360 and I trusted thathe knew what he was talking about, silly me, so I didn't unbolt all the accesssaries that are necessary to look at that engine code to verify it. So when I got it home I found out that it was indeed a 318 and not a 360. So I called the guy and told him that what had happened and what I found. So he gave me back 100.00 for the problem so I ended up getting the 318 for 200.00. That is my story as humbling as it may be but I learned something from it and now I intend to learn how to build a 318.
 
All well, leason learned. Crap happens. At least he was a bit stand up and gave you cash back. That was cool.

I agree, a set of Magnum heads would do very well on top with a RPM. See how far in the hole the piston sits. Then the rest of the math will fall into place with head gasket thickness and head chamber cc amount. Once the compresion ratio is known, we can see what will need to be done to improve it or if you can just run with it.

What year 318?

Good work Mopar nocar.

Mguner, your words are very true. Many do not have extra money just to go out and purchase a 340 block. I myself find it hard to drop $700 on a used bare 340 block and then ship it off to the machine shop. The price of a 360 is OK for the most part. And OK if the car is allready running/needed.
 
It is a 1987 318 I did look at the head casting numbers and they are 302 castings and from what I hear that is a decent head. You said find out how far down the piston sits in the hole, ????? Just how do I go about that? Is it as simple as measuring the distance from the top of the head to the top of the Piston at TDC ???? If so, what should I use to measure it???
 
The best way to do it is get a bridge and a dial indicator and do so math. IIRC the factory measurement for deck height is 9.59"
 
The simplest way (and fairly accurate) is a straight edge (like a steel ruler or a level) placed accross the bore, and basic feeler gages. Measure it in line with the pin (meaning in the middle, near teh dot or notch that marks the front of the piston. The 302 heads have value, but I think I'd rather use Magnums ona a build like yours.
 
That's it.Trust in your 318!And you can have a lot of fun with his HP's!!!!! :burnout: Good luck.

The Dart-Nº3,5.jpg
 
A dail indicator and a bridge (Dusterb318) is the way to do it. Mopers way is fine if the piston is high in the block, but, I have seen pistons sit .102 below deck. Thats a lot of feelers. But possible. And cheap!

Factory listed deck height is 9.58 - 9.60, what rolled out the door may vary....greatly.

LOL @ Low Dart.
 
I was told that the 302 heads are the ones to have on a 318 due to the smaller combustion chambers and ports making better flow and more compression without changing pistons or milling heads, etc. What advantage would a Magnum head give you? I'm not saying they don't,and I am not by any means an authority, but what would the advantage be, and wouldn't the magnum heads lower his compression? Mike

P.S. If you decide to switch heads let me know, I'm looking for a set of 302s.
 
I agree with you Mike...I'd use the 302 heads....the magnums are good heads but I just do not like the stud mount rockers.....they are to "Chevy" for my liking. I like the stability of the shaft mount rockers. The other thing I don't like about swapping to the magnum heads is the lack of intake choices out there....yes they are out there but there are so many mor LA style intakes. You also don't have to swap out the lifters and pushrods for the oiling.....I'd keep the 302 heads if it was me.
 
thanks rumble...

as for the -302 heads. they work FINE! just stick a set of 360 valves into them. i only ported the exhaust side on mine! i didn't want to mess with the velocity on the intake side, so i just cleaned up the casting imperfections.

IF you already have them use them. i have never messed with magnum heads, but if you don't have -302s, might as well buy magnums. downside for magnums is the rocker assembly, but for a mostly street car NOT an issue.

sb
 
Val-Mike, If all goes well, I'll let you know the compresion differences of the 302 vs. Magnum heads on a teen. I have both.
I want to port the 302 vs. a standard Magnum.

The 302 port window will be opened up to 340/360 sizes. Very much like a Magnums head. The thing is a Magnum head flows very well for the window size. So does the 302, but it's window size is smaller and less. The 302 head can be ported well with a opening of the ports to a larger size.

This enlarging of the port window puts it on par more with the magnum head. And the performance potentail. Keeping the port window small on the 318 will be fine for most cases. If street bound only without a big care of max output, they'll be fine. In the end results and mods, it will be closer to a apples to apples compare rather than a small port vs. large port.
Save the one serious advantage of the Magnum, 1.6 rockers.


The cam I have in the car is a Crane, 218/226 @ .050 and lift is low. But this will also change later. A cam of this size can bennifit from a larger port window, in the right arena.
Engines have an area (Size regurdless) were a larger port will perform better to feed the engine and release more power. I am experimenting with this size cam. Previously, I would have said a larger cam, but I have been wondering if I can get better results with a smaller cam.

The car; '74 Duster, '79 stock short block 318, 904, 8-1/4,w/3.21's and suregrip. Stock tires on ralleys.
A total (Well, damn close) sleeper. A done on the cheap thing. While trying to extract better performance. How far I'll push it is a time will tell thing.

But for right now, it's going to be a few head and intake swaps with this cam and test it going to and from the track while checking out times.
 
rumblefish360 said:
The thing is a Magnum head flows very well for the window size. So does the 302, but it's window size is smaller and less.

Save the one serious advantage of the Magnum, 1.6 rockers.
Click to expand...

I'll add, the 302's chamber has shrouding issues with larger valves. So you have to make the chambers slightly larger to help that. Not a huge deal, but it will make a measurable difference.

So, you have to port the 302s, and push back the chamebr walls slightly to get them to flow what the Magnums already do, and they are still "limimted" by 1.5 rockers. My point being, in a dollar for dollar build, the Magnums will make more, from less. You're still buying cam, lifters, and pushrods. Complpete heads come with rockers, and you can complain all you want about CHevy designs, but adding screw in Chevy studs and Checy rockers is cheaper than the cheapest 1.5 ratio stamped steel MP shafts and rockers. Plus, the lighter beehive retainers and springs help too. Teh 302s work when you need compression, and when torque is the goal. A drag car, torque is not as important, and the Magnums will make better power for less money. Also, the magnum chamber is slightly better shape too.
 
Thanks Rumble, Moper, for the explaination. I can see some benefits of the Magnums, although port velosity would have to be better with the 302s. Rumble, it will be interesting to hear the results of your tests on both. Mike
 
ValiantMike said:
although port velosity would have to be better with the 302s.
Click to expand...


The important question is at what lift, and what flow rate? The Magnums should flow better with no work than the 302s with some porting $$ incurred. The 302s should have better low lift velocity and flow rate, but you'll need to spend money to keep the numbers climbing thru the whole lift range, especially when larger valves are installed. Magnums in cleaned up form will make up to about 450hp pretty easy on medium sized cams. 302s will need a bit of work, and much more cam to make numbers near that.
 
moper has a point. This is all for fun though. Anyone here can poke fun or whatever and say things about money spent, this verse that, why bother when...

Part of this is since I have 302 heads, I was wondering how they would do. So I'm finding out. My waste of money? YEP! Now you don't have to.
Everybody here can whip out there calulators and think out loud. I don't care. Knock your selfs out. It's all good.

I will be doing alot of "Wrong" things on purpose. When this actaully happens, it will be in a seperate thread, apart from this and my project thread.
The whole idea is to show alot of people here what works and what doesn't. Theres often people that show up asking some questions that some of us "More seasoned" people know about.

A note on the 302 heads or any 318 head sitting around in the shed or the ones on your car now.
If you can or can not port a head or want to, I'll snap a few shots of the work when it is all done. Show a few dimentions. Give you a general idea. Heck, you may even want to try it yourselfs. And why not. If the ride goes faster, you did something right.
After you have tried to port yout own heads, you'll understand why head porters charge what they charge.

The magizies show how to do this alot. Get a back issue and give it a shot. Go get some saftey glass's and tools. Have at it.
 
I agree with your ideas. I am going to try the 302 head option and see what happens. I was always told by a very wise old man, my Grandfather god rest, that it is only money so don't fall in love with it as you can't take it with you. Now on to the tech questions.

I took the straight edge and laid it on the block like you guys said to in the center of the piston at the mark. I took a feeler gauge and measured the distance between the top of the piston as high as it would go and the straight edge. I came up with a gap of .063 what does that tell me?????
 
That you need to cut some off the block via milling to get the piston (closer) to zero deck IF you are using those pistons (or the same compression hgt oversize) in your rebuild. OR you can get a set of pistons with some more compression height to take up that space.

i would want a more accurate method of measurment before i ordered any sort of machine work. that being said, if you are getting new pistons, i like these for a street build: KB167

http://www.kb-silvolite.com/performance.php?action=details&P_id=134

the number you came up with will let you use calculators (along with accurate chamber volume & compressed gasket thicknes) to map out your planned static compression ratio.

sb
 
okay I am not going for a street build. we are going straight strip build. goal is a 12 second bracket car
 
those pistons are ok for strip use, too if you aren't going to be using power adders like Nitrous and you follow the instructions about piston ring gap and piston to cylinder clearance.

i have heard of people using NOS with these pistons, but seems a bit risky to me.

i guess i forgot the goal of this build....get those pistons, build your shortblock, then check how far in the hole you are. you should be purty close to 0 deck. if not, measure it, and have the machine shop cut enuff to make it 0 deck. you'll do well with that.

sb
 
Okay so after doing a lot of thinking, reading, and talking to my wife, I have decided what it is that I am going to do. Since she has never raced before I am going to leave the bottom end of the motor as is for now. Put some sorta cam in it new timing gears and chain, new lifters, and push rods. have some head work done on my 302s, 360 valves and port/polished, and new springs and seats. put the edlebrock performer back on it with a holly 780. I will get a 2500 stall and put all back together and let her run it that way for a year. then build it to the 12 second class. that way she gets it out there sooner and gets a little seat time before going 12's.
I will still put the car on a major diet and tub it and all of that good stuff. Any suggestions on what cam to go with? should I use geat timing set or stay with a chain?
 
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