318.what to expect?

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74dodge

74dodge

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hey guys im pretty new at the whole working on cars i have a basic understanding of how stuff works and i was just wondering what kinda numbers to expect from a 318(early 70s motor) with a nice set of headers a decent cam some 340 heads with new rockers and rods and a new intake and carb? ive been thinking of starting a 318 build to replace the ole slant 6 so just curious as to what kinda power it would be making.thanks for any info
 
You can expect anywhere of something @ about260 HP depending on set up, health of engine and cam used. IMO, the 340 heads are not the way to go on a stock 318. Even the smaller valve 360 head is a bit much.

I did a 318 in my Duster that was 14 sec. capable (Sea level) with a few bolt on parts and a small Crane cam. Since Crane is no longer in biz, use this Comp Cam as a sub. or this Lunati. The specs are very similar.

Comp Xe262H; http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=626&sb=2
Lunati's 60402; http://www.lunatipower.com/Product.aspx?id=1544&gid=287

Top it with a 4bbl. intake, 600 cfm Carb or a small primary TQ, headers w/dual exhaust (Got mine from Jegs @ 2-1/2 inchs for $200 ) and a good ignition set up.
I added a sure grip equiped rear w/3.21's and off I went.

The heads were left stock and only used the matching springs for the cam.
OOTB with these parts, I ran 15.14 @ 89 mph in the 1/4.

Upgrade your brakes and your in good shape.
 
My friend is running a "smog" 318 in his '70 dart nothing more then a stock bottom-end,comp .477/.480 cam,dual plane intake, 600 carter carb and a set of headers and with a set of 3.91's has gone a best of 13.75 not bad for what it is..
 
I am currently in the process of pulling my engine to drop in a new cam and heads on it, but it sounds like pretty much the same set up as I will have.
A freshly rebuilt 318 everything new down bottom, stock pistons, with 2.02X1.60 heads milled down to a 61cc chamber, mopar performance cam .484/.484 lift and 248 duration at .50. A set of hooker headers, weiand high rise dual plane manifold, and holley 650 carb, hoping to have it done and back in by the end of this year. Send me a pm and when I get numbers I will let you know.
 
Crane is back in business just to throw it out there
 
thanks guys well i was either gonna go the 318 route or do a cheap turbo build on the slant six havent decided yet but ive always wanted to do a mild 318 build plus i mean you cant beat that v8 sound
 
ive never even heard of someone turboing a 318 but it sounds like it would be kinda cool lol
 
I can say car for sure because that is where I got my Roller Cam from with a cast iron gear on it (only company I could find after 4 hurried hours of searching).
 
I think if you build on the mild side with fresh parts you can get 280HP at the crank pretty easy. Just don't go to big on the heads(340 and some 360), the 318 seems to like a lot of port velocity.
 
I almost missed this one.

Agree the teen loves port velocity.

Two stock heads do this well. The 302 casting and the magnum. The mag will give up torque on the bottom compared to the 302 stock to stock. It has bigger ports than the 302 and bigger valves. Both heads have a heart shaped combustion chamber with raised quench area's.Fast burn combustion chamber,good for todays pump garbage.

The mag is prone to cracking,hard to find 2 good used heads,but there are VERY nice aftermarket heads,including the new rhs la/mag hybrid.

302 can make good power but if you want 400 h.p start porting.

Theres a lot of debate about what heads to use. If I had $1200 or so Id go for the new RHS. Sold here by OU812 btw:yawinkle:

I have mags at hand, and 78 360 truck heads but Id use the mags over those. They will just run....better due to the chamber being more efficient.So thats my vote really. Work with what you have. Even the stock teen heads can be made to perform well with some $$
 
thanks for all the info guys ya i was just thinking a mild build i dont want to run 10s or anything lol just a fun sunday driver with some pep something around 275-300hp
 
300 h.p is no problem. You can get away with stock heads even allthough you'd need to find another way to bump compression.

I think either the 302 or mag will do it no problem as well.

550-600cfm 4 bbl,air gap or crosswind intake

268 XE comp cam

! 5/8 hedman headersfor cheapies,Dougs or TTI if you have deeper pockets. Heck you probably dont need headers at that h.p level. Maybe just some 360 pass car manifolds or those Dakota magnum ones I keep seeing threads about

El cheapo duals and really loud annoying mufflers! Not! I like the dynomax hemi turbo..such a deep rumble!
 
ya i like a nice rumble at idle other then that i could care less about the noise the quieter the better less suspious lol
 
HUH? Did someone say rumble.... what?!?
 
Im glad i stumbled on this too!. I recently took out a 71 318. I wasnt sure if i should rebuild it or go with something else.HUMMMMMMMMMMMMM:read2:
 
Nite Moves said:
Im glad i stumbled on this too!. I recently took out a 71 318. I wasnt sure if i should rebuild it or go with something else.HUMMMMMMMMMMMMM:read2:
Click to expand...

This is the way I see it.

The only modern muscle car...which doesn't make the grade of muscle, but gets the nod my millions as a great platform to build up a nasty street car on, is...ugh! The Mustang.

For years, this pony has been powered by the 302. IF they can run quick on a 5.o, then why can't you on a 5.2?

Lets look at the Ford power plant a second.

Tiny 3 inch stroke, 4 inch bore.

MoPars 318 has a 3.31 stroke which is more and means more torque and a 3.91 bore, which can be bored out bigger. How far you can safely go is just a sonic check away.

Hensley performance takes selected 318 to punch out to 4 inchs. HELLLO!

Typical overbores are done at .020, .030, .060 while Hensley has found a few every now and again that will take .090. YIKES, not really recomended, but do able.

At .020 it's 321 (3.93)
@ 030 it's 323, (3.94)
@ 060 it's 328 (3.97)
@ a 4.00 inch bore 333 cubic inchs.

Pistons are the cave eat for this size engine.

OH, if the Ford guys get cute and threaten you with a 347 stroker, then perhaps one day, you'll play ruff too with a 318 stroker that displaces 390 cubes. At a .030 overbore.

LOL, ha ha ha ha sit on there head and fart! Loudly!!! :toothy10:

Better heads, abilty of stouter cams due to the larger lifter, great intakes! Vic Edelbrock even sez so!
 
rumblefish360 said:
This is the way I see it.

The only modern muscle car...which doesn't make the grade of muscle, but gets the nod my millions as a great platform to build up a nasty street car on, is...ugh! The Mustang.

For years, this pony has been powered by the 302. IF they can run quick on a 5.o, then why can't you on a 5.2?

Lets look at the Ford power plant a second.

Tiny 3 inch stroke, 4 inch bore.

MoPars 318 has a 3.31 stroke which is more and means more torque and a 3.91 bore, which can be bored out bigger. How far you can safely go is just a sonic check away.

Hensley performance takes selected 318 to punch out to 4 inchs. HELLLO!

Typical overbores are done at .020, .030, .060 while Hensley has found a few every now and again that will take .090. YIKES, not really recomended, but do able.

At .020 it's 321 (3.93)
@ 030 it's 323, (3.94)
@ 060 it's 328 (3.97)
@ a 4.00 inch bore 333 cubic inchs.

Pistons are the cave eat for this size engine.

OH, if the Ford guys get cute and threaten you with a 347 stroker, then perhaps one day, you'll play ruff too with a 318 stroker that displaces 390 cubes. At a .030 overbore.

LOL, ha ha ha ha sit on there head and fart! Loudly!!! :toothy10:

Better heads, abilty of stouter cams due to the larger lifter, great intakes! Vic Edelbrock even sez so!
Click to expand...

Hahaha, this sounds like the argument I have every other day with the two mustang guys at my work. But they always get me with: when is that dart ever going to be running again... one day... I will prove the 318 power again

And did you say deep rumble:
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I love a chance to post that ;)
 
..........I've bored 318s out to the 4.04 bore to use standard bore 340 pistons in them........took out 8 lbs of metal......never 1 had an overheating problem, always a recored rad though........kim........
 
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