Increasing Compression

I have a 73 Dart with a 318. I want to try to increase the compression. From what I've read the best way would probably be to get some KB167 flat top pistons. But I have no money and my dad is a machinist so I was thinking I could machine the heads down, but I don't know how much to take off. I want to take as much off as I can but I don't want to screw up my pushrods. Also, is it worth it to put bigger valves from a 360 in?  

As long as the 318 is an LA motor from the 73 Dart you can take off up to 60 thousands. Be sure to machine the intake side of the head the proper amount or the intake will not fit. You will lose the end gaskets on the intake, use silicone.
push rods will be fine unless you are changing to a larger cam.
I don't think installing 360 valves will do much for you. A set of headers and a mopar performance 340 type cam will wake the 318 up along with a 4 barrel intake and a 600 holley.
Doc  

Thats more work than necessary. If you look in the TRW catalog, just order pistons for a 1969 or 1970 dodge truck 318. the compression is set at 9.4:1 instead of 8.2 or 8.4 like the passenger cars. Trucks were rated as heavy duty because of this. they are true flat top pistons and use the same stock ring sizes. they actually come out of the block by about .010 so use flepro permatorque gaskets whick are about .040 and all will clear perfectly fine. I have this in my 1974 dart and it does perfectly fine on regular pump gas. All for less than $90. When you start machining the heads you will throw off the geometry and before you know it things blow up major league at higher RPM's.  

Thanks for the help. I hate to sound stupid but what is the TRW catalog? Where can I find It?  

Not sure how replacing the pistons is less work than machining the heads.
I have .040 thousands off my 360 heads and the motor has been drag raced for 5 yrs. with zero problems.
The young lad says his Dad is a machinist and he doesn't have much money to work with.
Bottom line is removing the heads with a free machine job and a set of top gaskets is the cheapest and quickest way to up the compression. I also had .060 removed from a 440 with 10 yrs. of racing on that motor and again, zero problems.
Doc  

If I get a Comp Cams XE262H
 RPM range 1300-5600.
 .462/.470 valve lift.
 218/224 Duration at .050.
 262/270 Adv. duration.
 110 degree lob.
how much could I take off?
I am getting headers and I have a edelbrock 600 carb. I read on here that they added almost a 100 HP to a stock 318 by using this cam and a 4 barrel carb. Would there be a better cam to use? Thanks for the help.  

Ok, that is a good cam for the 318, however I would be tempted to go one step higher in duration and lift, especially if you are increasing the comp. by 1.5 points. This is accomplished by removing .060 thousands, use the thin head gaskets.
Here is my break down on what your power increase should be if you have a solid bottom end.
milled heads .060, up to a 30 hp gain.
recommend port and polish
the heads,              15/20 hp  
cam you mentioned,         20 hp.
headers,                   20 hp.
Performer intake for 318,  20 hp.
and 4 barrel, if watching
cash, a used 318 4 barrel
intake will do.
final piece of the puzzle
an MSD 6AL ign.          5/10 hp.  
Cam I would recommend
comp cams.
224/230 duration
477/480 lift
advance 4 degrees        25/30hp over stock.    
 
This will make for a killer set up and the potential for a 100/130 hp increase is real.    
Note, you will have to run the highest octane rating available at the pumps to help this engine work properly.
Set timing at 10/12 degrees initial, and 35 degrees total.
Good Luck
Doc  

Thank you for the help. I am planning on following your advice as close as I can. But I have a couple more questions. If I machine .060 off the heads and have a bigger cam, will I need adjustable rocker arms? And should I get a different stall converter?  

You will be fine with the rockers you have.
Stall converters are not cheap, and with the mild set up you are building it may not be necessary. However for a street car I would consider an 11" after market converter that stalls around 3200 RPM.
Good Luck
Doc  

measure the cylinders, if they are worn out the block needs to be bored and honed oversize to make power, then u buy new flattop pistons. use moparperf .026" p4120094 orange head gaskets. a big cut off the heads lowers the ports, race heads have raised ports. cutting .050" off the heads and using stock pushrods and rockers increases hydraulic lifter preload, not the hot setup for high rpm action. the doc also failed to ask a very important question or 2, what rearend gear ratio are u gonna use? where are u gonna run this thing? street, highway, 1/8 or 1/4 mile drags or what? money is tight but it is cheaper to do it right the first time.  

Measure the cylinders, why, do a compression test. If you got 125 lbs and all cyls. are within 10 lbs. start machining.
Ideal is a $10,000.00 investment in a complete new engine, economical is what I recommended and what the man asked for.
My motto, always make the customer happy.
In the end it really doesn't matter what the car is for, he is looking for an increase in power the cheapest way he can.
Doc  

phelpsja and his dad the machinist must have the tools to measure the cylinders, do they have a compression tester? they will have the heads off to machine so if u have the tools why not? I have seen stock 340's push a pushrod thru stock rockers. sometimes to make a happy ending u need to tell the guy to scrape up a few bucks (not $10,000.00) and build a good total combination!  

I'm not sure what gear ratio I have. It is a stock 73 dodge dart swinger with a 318 and a 904. It's just going to be a street car. Maybe an occasional drag race. I will probably be driving it everyday. Is there better gears I should have? I just want a good strong engine with plenty of power. Anything will be better than the 4-cylinder ford i'm driving now. I do have a job now so I will have a little bit of money, but my car needs plenty of other things besides engine parts.  

73 Dart will have a lousy rear gear ratio for performance, something like 2.54 ratio.
The good news is the 904 has a first gear ratio of 2.74 or so.
For a Daily street car with a 318 a ratio of 3.21 or 3.55 would be ideal.
Check and see how many bolts are holding on the rear cover, if it is a 10 bolt this will be strong enough for a street 318.
Finding a rear end with the improved gear ratio however will be difficult. But not impossible, I found a 10 bolt rear end with 3.21 gears in a wrecking yd. for a tow vehicle of mine.
The other option is to order a set of gears from a performance shop but this can get expensive. Especially if you are not able to do the job yourself. Another area of consideration is a sure-grip for the third member, [same as a posi]. This of course gives improved traction and may be necessary if you start getting close to the 300 horsepower mark.
Good Luck
Doc  

check the rear gear, jack it up and rotate a tire 1 revolution and count driveshaft revs. or pop off the cover and count teeth, befor we assume ratio. 3.55 - 3.91 is good. when u rotate it if both tires go forward it is a good sign of a suregrip. a compression tester that screws in (not cheap press in) say from sears is a good investment.