how to get power from a 318

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scampgt440

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hi im new to this forum and i own a 1973 scamp 318. since its getting tired im lookin in to how and how much power i can get out if the 318. im considering rebuilding it. if i do its not going to be stock. i already have headrs and a 4bbl. hat else can i do to make her fast yet streetable. is there any thing i can do to the stck heads???

any thing would help
thanks
wayne
1973 plymouth scamp
 
Install 360 valves in the head. 1.88 - 1.60. Pocket port the head and match the port windows to the intake being used. Roof and divider walls are important.
What 4bbl. do you have and carb size? What is or will be the rear end ratio & Tire size?
Alot has to do with the rest of the car.
 
im runnig a edlebrock 700cfm with a performer intake i have a 2.70 gear right now with a 904 trans thanks.

wayne
 
You definitely need to lose that 2.76 and get something higher in there if you want any kind of hole shot and see if you can find a set of 68-71 340 heads,that`ll wake her up!Welcome to the site.
 
Longgone said:
You definitely need to lose that 2.76 and get something higher in there if you want any kind of hole shot and see if you can find a set of 68-71 340 heads,that`ll wake her up!Welcome to the site.
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Be carful with those 340-360 heads, bigger combustion chambers = less compression. the 318-360 magnum heads, small combustion chamber- great ports & valve size, seem to be the way to go on the 318, remember you need torque. go with an edelbrock airgap int manifold, 600cfm edelbrock carb, a mopar perf cam for the stock 340, 1 5/8 headers with 2 1/4 size exhaust, a good ignition system, i prefer a msd 6al, at least a 3:55 rear gear. this should make a nice pkg.
 
I would stick in the Summit cam, and then swap gears long before I went the rebuild route.
 
This is just my opinion, not if I'm not mistaken the chambers are the same size on the magnums as the others as they made the depth of the chamber different even with the closed or quenched head. I think that they had to do this for emissions to keep the compression low enough to satiaify the cam and the fuel systems. But they do have a better valve to head and port combination. If people would look at what the factory is doing the rest would be simple, this is the thought that I came up with a few years ago. Just use the factory against themselves,.............look they have the money and the techs and knowledge to get everything to the best that it can be for the street, so just improve what they have and learn from them, kind of a can't beat them join them. So I got close to the engineers! A very good learning experience from my stand point. Just a thought.

BJR Racing
 
BJR, if you wanted to build this 318 for street and occasional strip duty within a reasonable amount of money, what heads, cam, intake, etc. do you think you would put together? I ask you because I respect your opinion. Mike
 
Stick with the stock 318 head and port them or use the Magnum heads stock. The problem with the 302's is head cracking between the valves. I here lots-o-problems finding them without cracks.
Queery? Edelbrock doesn't make a 700. They have a 600 and 750, 800.
The performer and 600 are a good combo. The gear ratio is very low, so if a change isn't coming, a small cam is in order.
For a off the shelf cam, Comp Cams has the XE256H. I would recomend this because it will work with the gears and converter without problem while retaining excellent vaccum for brakes and anything else needing vaccum.
 
Rumble, It wasn't the 302 heads that have the cracking problem, It's the magnum heads that have the problem. Now I'm sure that the heads will crack but haven't had that kind of problem as of late. They are fairly thick between the seats, or they have been severly over heated. I do agree with you on the rest of the comments, but he could stand a little more cam, something like a 280H comp. good vacume and torque, lots of low end power with the intake and carb combo. stated.
I agree with the stock heads (318s) and valves as this will be a big gain in the performance department with some minor work, bowl blending and gasket matching. This should be fun for the street!

BJR Racing
 
Then too I would run a 3310 carb with some adjustments, as the engine would run on a 2bbl until needed with the right parts.
With what is stated above this will run very good on pump gas. Most comp cams are 4 degrees advanced so the cam stated is 106/114 with a 110 lsa and 60 degrees of overlap, this is why I said this cam. But the smaller cam would work also if the rpms are going to stay down. The 280H is good to 5800-6000 rpms in a 318.



BJR Racing
 
BJR, 280 Magnum cam with a 2.76 gear?
I'd say ya with a min. of 3.23's and stock tire height.
 
Rumble, They do build lots of torque, and he did say that it would be for occasional strip use this is where I was comming from, taking for granted that he was going to change the rear gear to something taller.
Your right with the gears that he has, good choice.

BJR Racing
 
Also I have to say that our engines hold 13-14 lbs. vac. with mild porting and the 280-H cam. But I wouldn't go any further than this for the street, and this is the max for the stock converter.


BJR Racing
 
hey there are some good ideas but im kinda lookin for a hot street strip car thanks
 
"This is a Good Thread" Im Planning on Doing the Same with my car,Its a Early 64 Valiant,Weight 2980 lbs, I Have a 318-3 Block, steel crank Bored .040 with Torque Plates & Decked,What Pistons should i use as .040 is a odd size But i think i can get KBs Hyperuetectics in that size But am Open to Suggestions,"Im Not too worried about Fuel Consumption or having to run a Blend,& I dont mind if its a Little Bit Cammy on the Street as its only a Weekend Toy.But I want to Run Low 12s on the 1/4 as I live only 40 mins away from the Track & would prefer to drive there Uncork the Headers & Run,"I have 12 sets Heads all Rangeing from 360s std,360s J,360s fully ported & fitted with 2.02 intakes,& countless 318 Heads, I know about Velosity & slow is Not Good But what if i pump the Compression up to 10.1 or 10.5.What Heads do i use?I Prefer Solid cams as I have Solid Rocker gear,Looking at a Hughes Grind??,(Dont Like Hydraulics anyway Just Me)Also what Ratio in the Diff should I Run as I have at my Disposal 2.9,3.23,3.50,3.70,3.89,4.11 the Street Wheels are 26inch & for the Drags I was thinking 28inch if they will fit??I Run a Manuel Gearbox,What would be the Best manifold & Carb size to use & what type of Ignition system should i run,"Why the 318, The cores are Plenty"P.S. I dont Run Boosted Brakes But have already converted to discs, So Vacume isnt a Problem, Sorry for the Ramble.. :thumblef:
 
If the block is bored +.040, you should already have the pistons. The honing step is what properly sizes the bore to the pistons you are running. My .02, if it's already bored, buy forged pistons, Speed Pro or similar ,run as much compresion as you can..10.5:1 at least..You may need to mix fuel, or retard the timing on the street. I'd run the ported 360 heads if they flow decent, or have the J heads re-done to flow well if they dont. I'd run the Comp XE274S cam. Make sure the springs match it. For gears, I'd be running at minimum the 4.11s..But look at 4.30s with a 27" tire.
 
moper said:
If the block is bored +.040, you should already have the pistons. The honing step is what properly sizes the bore to the pistons you are running. My .02, if it's already bored, buy forged pistons, Speed Pro or similar ,run as much compresion as you can..10.5:1 at least..You may need to mix fuel, or retard the timing on the street. I'd run the ported 360 heads if they flow decent, or have the J heads re-done to flow well if they dont. I'd run the Comp XE274S cam. Make sure the springs match it. For gears, I'd be running at minimum the 4.11s..But look at 4.30s with a 27" tire.
Click to expand...
"Thanks for your Imput Moper" Your Right Originally I Bored the Block +.040 for Some cast Pistons that i had But seem I want to step it up a bit I was thinking of Going Forged or Hyperuetectics, "To go Forged Pistons it seems I may have to get some Specially made in those sizings as ive been searching the Net & They Not that common if i was to go +.030 then Not a Problem? Thanks.. :thumblef:
 
My line of thinking was with forged, you cant get away with more slop in the bores between the pistons and wall..in fact, many like more clearance. Hypers wont fit right at .040 over..but forged ones willjust swell up and fill the extra..plus, they are a lot tougher if things do rock around a little. The extra is still prob less than re-boring or honing..lol.
 
"Thanks Your Right" But I will Need to Recheck the Bore size as the work was Done By the Machine Shop,Just to Make Sure its Truely .040 over? I will Go the Forged Route,"Now What Brand?Also I Have Standard 273 Ajustable Rocker Gear But I dont think these are Suitible in the Long Run?What do you suggest?"I was thinking Going Comp Cams Stainless Roller 1.5 ratio?A bit Pricey But if they Good & Reliable,I dont Mind?Also Valve & Spring Lenghts Standard or Should I go Next size up?As ive Been told Maximum Lift with stock Guide Height is 0.450" more Lift Requires Shortening the Valve Guides??"Also with Valve Train Reliability should the Intake Valve Be smaller in Diameter?(meaning stem)"One more thing Which brand of Valve Seals?I dont Ask for much Do I,"Its just that Im New Here & there is Some Good Wisdom in these Forums & as much info i can get the Better Before I part out with my Hard earned cash. :thumblef:
 
Whats up man. Dont know if this'll be worth anything to ya but I was in yer exact position when I was in High School. I had a stock-as-a-rock 1970 Duster w/a 318/904/8-3/4" drivertrain. It was so slow that some dude put a whoopin' on me with his 65 Barracuda... with a slant six! That was pretty embarrasing for me, but kudos to him though! (I found out later that he had a cam, intake, carb, ported head, headers, exhaust, a 4speed, & a 3.91 sure grip in that thing LOL) Anyway, this is what I ended up with before I sold it about a year after I graduated High School in '95.

Motor:
600 cfm carb (vacum secondary)
Edlebrock Performer intake
Stock heads (rebuilt, 3 angle valve job, ported-matched to the intake manifold)
Hooker Headers (bought em used, I think they were the Comp as opposed to the Super Comp headers)
2-1/2" x-pipe (I was definitely able to tell the difference between these & an H pipe btw)
Dual 2-1/2" Flowmasters (2-chamber)
The cam was stock

Tranny
Shift kit
Replacement gearset with a lower 1st gear (this really made a difference off the line)
Mild converter that I bought used off one of my buddies that swapped over to a 4 speed gear box

Rear End
3.55 Sure Grip

Suspension
stock /6 torsion bars
90/10 front shocks (looking back, I cant beleive I used to drive around with this set up... with the stock drums no less!)
slapper bars on the back
pinion snubber


Weight Savings
'Glass fenders, hood, bumpers & deck lid
removed the a/c & heater, switched to manual steering, switched to 15" Big-N-Little Centerlines

The moral of the story? I was pretty much stomping on the 5.0s & Camaros (that didnt have any major work done) in my town. I never put it on the track but id say that with a pair of slicks im pretty sure it would have been in the high 13s/low 14s. Interestingly enough, the buddy that I bought my converter off of ended up beating me every single time from the time he swapped to the 4speed & our cars were set up EXACTLY the same up to that point. Ever since then, ive never owned a Mopar with an automatic.

Anyway, I dont know how hot of a street car you plan to have but if your thinking about going much faster than this, I suggest you use a 360 as your foundation. Besides the fact that you only have to change 1 of the motor mounts to make it fit, youll have better head & intake choices & every mod that you make will net you more power gains over the 318 because you'll be 42ci ahead of the game which is pretty signifigant.

hope this helps out!
 
Just my input which isn't much....however...cheap mega power. My kids Duster had a very used sick 318. He had the motor rebuilt, which came with the 30K over, new flat top pistons etc. He also picked up and used 360 heads and had the builders port and shave the heads. They ensured there was a excellent match with the new duel performer intake. A new 340 aggressive cam, Holley 600 CFM. My kid ended up putting a 2600 stall while apart. Headers of course with crossovers and 391 out rear... Go's like hell..and very snappy. Never seems to run out of top end steam as well :salut: . I have "No" idea what the HP is but it sure feels pretty good.

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"Thanks Guys Good Info"I Know what your saying about the 360 as I have one for my Other Project But When you have nine 318s sitting Under your Bench & Four that are Complete its Time to start Using them & I Like the 318s Because they Screem with the Right mods,"Also I like the Challenge" Most always Discard the 318 in Favour of the 360 as there is No Subsitute for Cubic Inches.But You Guys Have Got to Remember that I Live in New Zealand on the Other side of the World & 360s are Not that common like over Their, In Fact 340s are Rearer still,Some ask $1000 just for a Block :sad2: But 318s are Plenty,Will they were Plenty they starting to get Harder to find to Now! going up in price as well!I also Love the 313,318 Polys as they are a Fantastic Cylinder Head Design Shame they dont make much Performance Gear for them!!Anyway we Have some Clever Engineers Over Here if it works out Cheaper to Manuafacture Forged Pistons Here for my Application then I get them done Here,Otherwise Ill will Get them Through Summit etc.. :thumblef:
 
Dude you in NEW ZEALAND?! Whoah, I didnt realize that! Have you ever seen that movie "Once were warriors"? Its one of my favorites.

Anyway, back to the subject @ hand here. Man, if you have that many 318 blocks lying around then you should DEFINITELY make a stroker motor out of one of them. Mopar Performance sells a 360 crank thats modified to fit in the 318 block. Talk about a sleeper!

Anyway, good luck with yer endeavor!
 
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