73 Valiant 318 performance build Ideas.

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C2ndLTpigeon

C2ndLTpigeon

Mopar or no Car!
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So im looking to do some work to my 318 in my 73 Valiant.

So far here is a list of upgrades I've been thinking about.
I plan to keep stock heads and do a little bit of port work and smoothing some of the casting imperfections.
I was looking into a hughes performance 318 whiplash cam. From what I read they are good in a stock internal engine. I will be getting it as a kit so cam, lifters and springs.
Intake I think im going with the Edlebrock performer RPM Air gap.
Carb would be either an Edlebrock 600 or 650 CFM.
Headers would be either a set of hooker or headman headers 1 5/8 runners to 3 in collector reduced to 2 1/2
As for the transmission it is a 904, plan to rebuild it and throw in a shift kit.
Sourced out an 8 1/4 rear with 3.55 gears. at the moment it is an open rear but will eventually make it a suregrip.

Has anyone had any experience with any of these as a combination? This is my first performance build since all of my other cars require smog tests.

Thanks
 
Sounds good, depends on the specs of the cam your talking about.
 
If I was you I think about upgrading to magnum heads, I would guess at least 50hp more over 318 heads, 318 heads were designed to work on a 273.
 
I like the magnum heads on this one too, especially if you can find a used set of EQ's for sale.
 
C2ndLTpigeon said:
Would anything else need to be changed by adding Mag heads?
Click to expand...
Your local Pick-n-Pull should have an entire Magnum 360 4 around $200....
If you get Magnum heads you're going to need an intake manifold for a magnum. I bet by the time he bought Magnum heads you could just go ahead and buy an entire 360 Magnum. And then all you would need is a manifold. You'd probably need a couple hundred dollars worth the accompanying Parts but then you would really have an upgrade..
Food for thought and that's probably what you're looking for food for thought...
 
It’s hard to beat the magnum on a low dollar build, 5.9l or even 5.2l make 300 hp with 4bbl and exhaust manifolds. Add mild cam and headers your at 1 hp per cid, add more aggressive cam for 400 hp.
 
One of these days I am going to build a 318 stroke engine. You get the plain looking 318 with the punch of a mild big block. Nobody will suspect that.
Heh heh heh....
 
I would like to get a little more HP out of the 318 with above modifications. 360 would be nice but I chose to stick with the 318. If I end up doing an engine swap I have a 72 400 that could be a nice stroker build but not looking for that at the moment. Just want something with a good sound and more power than stock.
 
Kern Dog said:
One of these days I am going to build a 318 stroke engine. You get the plain looking 318 with the punch of a mild big block. Nobody will suspect that.
Heh heh heh....
Click to expand...
You might find it cheaper to do a 360 than a 318 and you can just tell people it's a 318...
 
C2ndLTpigeon said:
I would like to get a little more HP out of the 318 with above modifications. 360 would be nice but I chose to stick with the 318. If I end up doing an engine swap I have a 72 400 that could be a nice stroker build but not looking for that at the moment. Just want something with a good sound and more power than stock.
Click to expand...
Sound good...lol..
 
C2ndLTpigeon said:
I would like to get a little more HP out of the 318 with above modifications. 360 would be nice but I chose to stick with the 318. If I end up doing an engine swap I have a 72 400 that could be a nice stroker build but not looking for that at the moment. Just want something with a good sound and more power than stock.
Click to expand...

The magnum head is the most important part. You don’t need to swap in the short block.
 
In the case of a mild performance build, I'd probably go with a factory four barrel intake, Ededlbrock base performer, or a weiand stealth (preferred, 318 sized runners from plenum to port). I'd probably run the dougs D-453 headers. If your going to rebuild the transmission anyway, a good converter (probably a quality reproduction of a factory high stall) would be worth some improvement, especially with the 3.55s. But, have you done a compression check yet? 8.5:1 is probably a stretch for this engine. Can you get any specs on that cam you can share with us? By virtue of 3.55 gears, you may be able to run just a shade more cam in it. It would take some guide to retainer and possibly spring seat work, but this cam is looking really good for this on the Howards lobe list with 128 degrees at .200 lift. I don't know the ICL on it yet but given the design parameters it looks to have had four or more degrees of advance ground into it.
Howards Cams Hydraulic Flat Tappet Camshafts 711381-10
 
Indio?
Have Brian at IMM do a couple few hundred in porting and flow test 'flow sheet or not' ..just as long as he knows he has them where a 360 head would be. You're in his neck of the woods.
Add 340 cam or faster rate version, headers, you do the 360 port window gasket match for that intake to save $ ... it'll be all you need. A 2400-2600 stall torque convertor would be good idea too.
 
no way on a whiplash
way too much exhaust duration
I like the howard mentioned above
or a similar spec lunatinn700- 701
a factory 340 is a dog in a low compression 318 unless you use deep gears and a really loose converter
I would not use one even if free- so use the faster rate version the 340 ramps are way too long
check heads for seats and guides
would not put money into stock heads except late 318 or magnum
do some searches- many threads on this topic
 
273 said:
The magnum head is the most important part. You don’t need to swap in the short block.
Click to expand...
The problem comes how much will you be paying for the heads? How much will you be paying for new pushrods? When you could swap in the entire block and heads and pushrods and you are still going to have to buy a magnum style intake manifold for a carburetor....
He doesn't have to do anything he's just looking for different ideas... But honestly I think he's more into having it sound like it has horsepower then really having it...
 
I want the car to have more horsepower but not looking to make this a drag car.
What is the difference in 360 and 360 Mag heads? Can these bolt to a 318 and what else would need to be changed to accommodate them?
Im mainly looking for a little more power on about a $2500 budget.
 
C2ndLTpigeon said:
I want the car to have more horsepower but not looking to make this a drag car.
What is the difference in 360 and 360 Mag heads? Can these bolt to a 318 and what else would need to be changed to accommodate them?
Im mainly looking for a little more power on about a $2500 budget.
Click to expand...

The thing is a 318 head with low cr and a mild cam is good for 280-300 hp. You could swap on a regular 340/360 1.88 or 2.02 valve head but there gonna really drop your cr, The magnum is gonna bump cr a bit nothing major but it won’t at least take any away.
And there able to support 400 hp stock, so with them and your combo be at 330-350 hp. Maybe more depending on cam.

Or you could just drop in a stock 5.9l with 4bbl and headers for 320 hp choice is yours if 280-300 hp is fine stick with 318 head.
 
j par said:
Your local Pick-n-Pull should have an entire Magnum 360 4 around $200....
If you get Magnum heads you're going to need an intake manifold for a magnum. I bet by the time he bought Magnum heads you could just go ahead and buy an entire 360 Magnum. And then all you would need is a manifold. You'd probably need a couple hundred dollars worth the accompanying Parts but then you would really have an upgrade..
Food for thought and that's probably what you're looking for food for thought...
Click to expand...
This is good advice especially if you have a budget of $2500.00.
I don't know why you are stuck on the 318........
This is bang for the buck, and it leaves you money to buy a converter and intake.
It's a win/win situation for you.
If you were considering a big block down the road, then originality isn't a prime consideration for you.
So, why not?
 
C2ndLTpigeon said:
So looks like a 360 may be the smart way to go.
Click to expand...

It’s why everyone recommends 360, sure 318 can be made to work with more rpm and gear, but 360 gonna Is gonna be better idle-5000 rpm street rpm.
 
The small whiplash cam might work in the right engineered 318 combo, but that ridiculously long exhaust duration will steal any chance of fuel economy. In a 318 it is nothing but a poser. In a low compression 318, not even a good poser.
 
Last edited:
AJ/FormS said:
The small whiplash cam might work in the right engineered 318 combo, but that ridiculously long exhaust duration will steel any chance of fuel economy. In a 318 it is nothing but a poser. In a low compression 318, not even a good poser.
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:(
 
I had a mid 11 sec stock stroke 318 with iron heads.
No matter what you tell anybody, if it gets out of its own way, nobody will believe you when you tell them its a 318
The 360 magnum suggestion is great advice
 
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