Looking for a little more power out of a 318

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ColeTrickle74

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Its almost completely stock, besides a cam (not sure of its specs) and dual exhaust. Noise isn't a concern, MPG is a little concern, would like to keep it in the same ballpark. Its a 74 Dart 2 door. Would like to reach somewhere near 350-375hp, without any machining or spray. The motor and trans were recently rebuilt. I'm thinking an intake manifold and headers for now. Anyone have experience with electric fans or water pumps? Would like to free up as much power as possible. Any comments or recommendations would be very helpful. Thanks ahead of time :rock:
 
I've got a 318 in my Barracuda. I used a Comp Cams he 260 and the Eddy performer (port matched) . A 3 angle job on the heads and 340 exhaust manifolds. I figure it's about 275-280 hp. To get to 350-375 you'll need alot more cam and more then my 9-1 comp. Why not build a mild 360, that would be a piece of cake and alot more streetable! The problem with the 318 is any major changes kill the torque. It's a great motor but you'll have to run a tall set of gears and forget about gas mileage...but it will fly!
 
Yeah, I knew I would have to replace the gears. I was just looking for some little bolt-ons and what not for a little more power this summer. I plan on building a 360 this winter when the car is garaged.
 
Robbie has a point. But you cold probably do well in the HP department without to much work. I don't know about 375 HP.

Try this, one of 2 ways, on the cheap or one with some extra dough for new parts;


Mill 318 heads down for a better ratio, 9.0-1 would be the min. ratio and good enough to use. Port to match 360 head w/1.88 valves back cut and continue with a bowl porting, add small primary T-Q w/headers. Cam speced on or about 224 intake duration @ .050 and more on the exhaust.
An excellent example is the Comp XE268, though I'd like more lift myself.

You'll need about this much cam at a min. to make the 350 HP mark with this set up.

For more power and a bit more on the price tag without piston replacement, try a Comp XE274H or the Magnum series280H cam and a Magnum head conversion, Edel. RPM (Magnum style intake) 750 Carb of choice. Edel. or Holley etc.....Headers

Remember the new rocker ratio gives new and higher lift.

This should get you to 375 HP and better with proper tuning.

Thats the HP soulution IMO and you'l have some mileage, but not like you have now. For a well set up car combo, your going to need a stall converter to match and some gear back there.

I would also look into a 4spd auto. trans like the A-500, a 904 based overdrive. You could run 3.91's in the rear while, with the overdrive, the final ratio would be 2.6979.
 
Oh, I did a Perma cool electric fan. Nice fan. I didn't do an electric water pump.
 
That reply is why I posted here instead of searching 8) Thanks very much. I'll look into some of those options. You think it would be cheaper and a better over-all drive just to swap in a 360?
 
In a nut shell, yes.

The 360 will provided much more torque over the 318 and it's peak HP will be a few hundred RPM's sooner due to the extra throw of the crank.

Other plus markers of the 360 are cheaper pistons, use of stock heads rather than porting out the 318 heads and port matching them for best performance from them.
Most OOTB parts will be good to go rather than not so many OOTB parts for the 318, which are commonly to large for mild 318's. Your HP level sought for the teen is still mild IMO, though getting up there for it's particulr displacment.

For a decent mileage and powered 360, you'll require less cam and stall.

Pistons are a bit cheaper as well.

The only draw back on going to a 360 at this point is the purchace of the 360 itself. Also, there extrnally balanced and require a different drivers motor mount.

The external balance can be overcome via a modded flex plate from B&M or others that allow the use of neutral balanced torque converters without problems.

Off hand, besides Schmaucher creative serives, I do not know where to get a drivers motor mount, and there pricey. Great and beautyful stuff, but a tad pricey.
http://www.engine-swaps.com/
 
I would start with some hedders & a intake for now. See what that does & go from that point. You might be surprised! Good luck!

What kind of muffs. are you running?
 
So besides the mount it would "drop right in"?

@Bigmac, 2 Flowmasters, not sure which series. Haven't gotten the car over a pit or on a lift yet
 
Haha, thats indeed a nightmare. I guess I'll grab an intake and some headers, and just concentrate on body work/paint for now. Thanks a lot. May still consider building up the 318 though. Who makes up there mind that easy?

Opps, one more thing. What gears you recommend in the rear end for now? Would be nice to get quicker out of the hole. I got 2 somethings in there now. Might not wanna go 391's with the 3 speed, RPM's already get kinda high
 
Well, it kind of depends a whole lot on what RPM you OK to cruise at. And a few other things like cam size and if your willing to change out the converter.

What speed do you normally run at on the Hwy.?

My Duster has a small Crane in it. 272/284 - .454/.480 on a 112. (Re-see thread for figures @ .050)
I have 3.21's on a stock size tire and the 318 is a '79 with stock everything except intake and carb with headers. No converter swap. No comprsion upped via piston or milled heads.

It's not to bad. I'm hoping to finish enuff soon so I can take it to the track for fun just to see. I'm not expecting much at all. It's currently built just to cruise and cruise far with some pep.

Later, I will have the heads worked on.
 
This is the only thing that sucks about buying cars without any other paperwork. I'm assuming it was just rebuilt to stock specs, other than the cam.

Gotta get to bed, 'Ill update tomorrow. Thanks for the replies so far everyone.
 
From your engine pic, it already looks like you have a Torker manifold and an Eddy carb.

As stated above, 350-375 will require compression in the 9.5 or higher range with a matched cam.
 
rick_rawker said:
Eddy 600 for mpg's, ported/polished intake,flows.
Click to expand...

A totalllly disagree with that entire statement.

500 cfm on a 318 is enuff to feed it well at all RPM's on a stock engine and do very well for mileage. The engine in a hopped up state has trouble sucking down 600-650 cfm's on the big end on the rpm scale and track.

Blanket statement on the next sentence. Stock heads also flow.

Polishing the ports after porting them is not the great idea of the century for a street car with limited Hwy. useage and mostly around town driving rather than a track only car.

OMG!!!!!!!!!!
 
Everything is stock in and on the motor besides the cam. I think I'm gonna leave the motor as is for the rest of the summer. Will try to finish up some trim hunting and body work for now. Save up some money for paint and some new wheels and tires.

I'll probably start looking for a 340/360/383 crate or block soon, opinions or advice anyone? Would also like to change out the trans.
 
You'll need to shorten the drive shaft a little for the 727, which is the same length for big or small block, but it's the only trans (Auto) for the big block.

Schumacher creative services has a swap kit for the big block and headers.
 
:sign2::banghead:
rumblefish360 said:
A totalllly disagree with that entire statement.

500 cfm on a 318 is enuff to feed it well at all RPM's on a stock engine and do very well for mileage. The engine in a hopped up state has trouble sucking down 600-650 cfm's on the big end on the rpm scale and track.

Blanket statement on the next sentence. Stock heads also flow.

Polishing the ports after porting them is not the great idea of the century for a street car with limited Hwy. useage and mostly around town driving rather than a track only car.

OMG!!!!!!!!!!
Click to expand...
That's probably why I remain a shade-tree mechanic. I'll stay away from the performance issues. Sorry for any bad info. What works for me might not work for someone else. Keep 'er safe...............................rick
 
The answer was to "In General" and could leed one down an ill path without knowing the full extent of the build.
 
Well I feel my 318 does pretty good for what little money I put into it 15 years ago. It has 9.0:1 compression, gasket matched stock heads with 1.88 int. and 1.60 exhaust, a comp cams 280H cam, Thermoquad carb on a 4 bbl 318 intake from the '70's also with a 2500 stall converter and 3.91 gears it ran a best of 13.55 @ 102 mph in Pomona. Here in Germany it has run a best of 14.185 @ 97.19 mph 11 years later. I plan to put some 302 heads on it and a single plane intake and also a 3500 stall to maybe get the times back down. Talk with BJR racing, he is a member and he knows what he is talking about. I hope that helps you a little if you decide to keep the 318.
 
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