318 Performance Mods

markmine · Apr 28, 2013

I've been researching some performance mods for my 318 and I’m hoping for suggestions from all the knowledgeable people here….. I have a low mileage bone stock 318, 904 in my Satellite, single exhaust with 2.76 gears and a $1,500 budget for some performance mods. I was thinking of upgrading to a 4bbl, dual exhaust, cam and gear change to 3.23. I have a stock 340 4bbl intake manifold that I planned on using, but was told that the intake ports don’t match the 318 heads – not sure if this is an issue. I would like a set of TTI headers and exhaust, but that would kill the budget. So, I’m thinking of running the stock manifolds on duals (possibly 2.5” TTI exhaust, depends on cost). Any suggestions would be great!

HT413 · Apr 28, 2013

But rustyratrod's motor. He just built a nasty 318 that is looking for a home. Or at least I bet he'll chime in with some advice.

RustyRatRod · Apr 28, 2013

Literally tens of thousands of 318s came from the factory with the "mismatched" intake ports. Chrysler must not have thought much of it. If it bothers you, you can certainly have the intake port windows opend at the entrance to match the intake.......or use the big port heads.

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HT413 said:
But rustyratrod's motor. He just built a nasty 318 that is looking for a home. Or at least I bet he'll chime in with some advice.

Yeah, that would be nice. Thanks for the thought.

markmine · Apr 28, 2013

RustyRatRod said:
Literally tens of thousands of 318s came from the factory with the "mismatched" intake ports. Chrysler must not have thought much of it. If it bothers you, you can certainly have the intake port windows opend at the entrance to match the intake.......or use the big port heads.

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Yeah, that would be nice. Thanks for the thought.

You think the 340 manifold will work fine with the 318 heads?

RustyRatRod · Apr 28, 2013

Yup. Chrysler did it with no mods to the 318 heads at all. Lookin at the size difference, you'd think there would be a restriction......but most of the 4 barrel cop 318s hauled ***. If "I" was gonna do it, I would let a machine shop open the port openings up to match the intake, but it's not necessary. Plus of course you'll want to use the 340/360 intake gaskets.

rumblefish360 · Apr 29, 2013

Here's my take;

Sell/trade the 340 intake for ethier a Edelbrock Performer or a Weiand Action Plus.
A Edelbrock 600 AFB or better yet (IMO) a 650 AVS.
There inexpensive and reliable.
Open air cleaner

Summit headers into there own (Summit) dual exhaust.
Summit also sell inexpensive cams though what ever cam you get, get the whole package!
This is where you will spend the bulk of your budget! And call it "Money well spent! Not just spent."

markmine · Apr 29, 2013

rumblefish360 said:
Here's my take;

Sell/trade the 340 intake for ethier a Edelbrock Performer or a Weiand Action Plus.
A Edelbrock 600 AFB or better yet (IMO) a 650 AVS.
There inexpensive and reliable.
Open air cleaner

Summit headers into there own (Summit) dual exhaust.
Summit also sell inexpensive cams though what ever cam you get, get the whole package!
This is where you will spend the bulk of your budget! And call it "Money well spent! Not just spent."

A package sounds appealing because I just don't know which cam will work best. I found this kit http://www.jegs.com/i/Edelbrock/350/2176PK/10002/-1 Any thoughts on this configuration? Thanks!

YY1 · Apr 30, 2013

That's an awful lot for that kit.

I'd build my own from swap meets.

I've bought three Eddy 1405/6 carbs for between $50 and $75 each this past 2 years.
All bolted on and ran.

I've bought 2 performer intakes for the same price, and got the older castings with less core shift on the port alignment. Just check for craks, stripped stud holes and pits on the thermostat housing.

The only things I'd buy new is the cam, lifters and timing chain... I don't know about Jegs, but Summit has some decent "in house" grinds that can be had for around $100-$150 with lifters.

rumblefish360 · Apr 30, 2013

That is half your budget. I do not like the Edelbrock cams. You can do better.

This kit by Competition cams includes what you need for a close to No-Brainer set up. The only draw back to comps valve springs is the head needs to come off to machine the head for there springs. This cam will work well with 3.23 gears and the stock converter.

http://www.summitracing.com/parts/cca-k20-222-3/overview/make/plymouth

I have used this Crane cam twice. The kit is just cam and lifters. Crane does have a valve spring to work with this cam. It just needs to be sought out separately. A walk through there catalog (On-line or in book) will show the springs to use. This also works with the stock converter and 3.23's (Like my old Duster had) The best part is the valve springs swap right in and they can use the OE retainers and locks for the valves. Just plug in some air to keep the valve up and swap springs. BAM! The lobe separation is @ 112 vs. the Comp's 110. This means it will idle smoother.

http://www.summitracing.com/parts/crn-693942/overview/make/plymouth

The 340 intake will work fine. The Performer will be a tiny bit better. You can save the money and use the 340 intake. The port mismatch isn't a horrible thing. But, IF, if your interested, I have a Edelbrock Performer ready to bolt down painted Chrysler blue. Just get gaskets to the intake and head.
And, again, IF, if your interested, I have a older Carter 9636 Comp Series AFB that I used for a while. It is in generally good clean shape and in good working order when I drained it to shelf it. I'll include a Edelbrock "Thick" gasket to protect from heat and the studs that go with it.

I'd sell for $250 shipped, I'll post some pictures in a minute.

RustyRatRod · Apr 30, 2013

A stock thermoquad intake is almost as good as that overpriced POS. Please don't buy that. You can do much better. Hell, buy my motor. I caint go 1500, but I can come close. Shippin is another issue.

rumblefish360 · Apr 30, 2013

Here's the Carter 9636 with the thick Edelbrock heat gasket & the Edelbrock Performer freshly painted in Chrysler's MoPar blue engine paint.

redchihuahua2004 · Apr 30, 2013

I'm also planning to upgrade my '67 318 at some point. Here is what I'm planning (also on a budget!):
Heads: stock with exception of hardened seats for exhaust valves (original to car)
Cam: Mopar Performance cam with 1968 340 manual transmission profile (bought)
Intake: stock 1966 273 Commando 4 bbl intake (bought)
Carb: stock AVS from a 1968 383 (bought)
Trans: stock 727 (original to car)
Rear: stock 3.23 non-Sure Grip (original to car)
Exhaust: stock exhaust manifolds with TTI dual exhaust system (with H pipe)(yet to be bought)

Total estimated cost: $800.00 (most of this cost would be from TTI exhaust system)

Hope this is helpful to you. Any comments (positive or negative) for this setup would be appreciated.

Good luck with your upgrades!

RustyRatRod · Apr 30, 2013

rumblefish360 said:
Here's the Carter 9636 with the thick Edelbrock heat gasket & the Edelbrock Performer freshly painted in Chrysler's MoPar blue engine paint.

Looks great, Rob.

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Where did you get that cam?

redchihuahua2004 said:
I'm also planning to upgrade my '67 318 at some point. Here is what I'm planning (also on a budget!):
Heads: stock with exception of hardened seats for exhaust valves (original to car)
Cam: Mopar Performance cam with 1968 340 manual transmission profile (bought)
Intake: stock 1966 273 Commando 4 bbl intake (bought)
Carb: stock AVS from a 1968 383 (bought)
Trans: stock 727 (original to car)
Rear: stock 3.23 non-Sure Grip (original to car)
Exhaust: stock exhaust manifolds with TTI dual exhaust system (with H pipe)(yet to be bought)

Total estimated cost: $800.00 (most of this cost would be from TTI exhaust system)

Hope this is helpful to you. Any comments (positive or negative) for this setup would be appreciated.

Good luck with your upgrades!

rumblefish360 · Apr 30, 2013

Which cam? Both are a available at Summit racing.
The Crane ran my '74 duster equipped with well over 300,000+ mile 318 untuned and spinning tires to a 15.14 in The 1/4. It also had the Hooker headers, Jegs exhaust (just like Summits), a 600 AFB on top of a LD4B.

It could have used wider tires and more compression than the D.O.A sub 8-1 ratio from '79.
I just used the Crane cam and lifters with the recommended spring.

RustyRatRod · Apr 30, 2013

The 68 4 speed cam. I didnt think they were available anywhere. The MP 340 cam is the later one. The 68 340 cam was a split pattern that used a big block lobe on one side. Or maybe that is the one they make. Hell I don't know. lol

redchihuahua2004 · Apr 30, 2013

Where did you get that cam?[/QUOTE]

I bought it about 10 years ago (my project is taking a loooong time...), so I'm going off of memory, but my guess is that it was through Summit or Jeg's. My understanding (again based on memory) is that it has the same specs as the stock 68 340, but maybe that is not completely correct. I need to check to see if I still have the part number and/or specs for what I bought to confirm either way.

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Another possibly helpful source:

http://www.allpar.com/mopar/4bbl.html

There is a section in this which mentions the 68 340 hi po cam:

"Camshaft is the next best upgrade you can do for the 318.
They really like the 340 hipo cam, which is still very mild, but is just enough to wake a 318 up. It has a lift in the .440 range, so any aftermarket camshaft between .430 and .455 work really well and mileage will not suffer, won't have to be high compression and doesn't require any high torque converter. Any more than that and you will kill the bottom end and the 318 will run like junk. This is an excellent cam for the 318.
318s get a little radical with a cam larger than .450 lift on 270+ duration, 360s get radical when you get up to .485 and 290+ duration, so a .450 lift and 270 degree duration in a 360 screams, idles pretty smooth and will get a little better mileage without any sacrifices. "

Original is at Chrysler, Dodge, and Plymouth LA (273-318-360) V-8 engine and carburetor performance upgrades http://www.allpar.com/mopar/4bbl.html#ixzz2Ry5Oq3bm
Follow us: @allparcom on Twitter | allparcom on Facebook

rumblefish360 · Apr 30, 2013

markmine said:
You think the 340 manifold will work fine with the 318 heads?

Not until you start putting some good zest into the 318 will it matter!

markmine · Apr 30, 2013

Thanks for all the great advice!! You guys are the best!

Now, I’m gonna feel pretty stupid…. I took the 340 out of my roadrunner about 3 ½ years ago and put it in the back of my garage, covered it and haven’t looked at it since. (I had medical problems and did nothing with my mopars since then – I guess that’s my excuse for being stupid!) Well….I knew it had an edelbrock manifold but never thought the previous owner would install a 2176 on the 340. Nice!

So, based on what everyone has been saying, I’m thinking the 318 will get the 2176 intake over the stock 340 manifold, along with headers, 2 ½” TTI dual H-pipe exhaust, edelbrock performer 600 cfm carb and the crane cam rumblefish360 recommends and used in his Duster….. the article redchihuahua2004 linked to is interesting and recommends a 340 cam. Is there much of a difference between the crane cam and the 340 cam? Am I over thinking this??

YY1 · Apr 30, 2013

What are the bore sizes on that thunder series?

rumblefish360 · Apr 30, 2013

Well, as faras the cams go, a lot of this is personal usage and preference. I have not used a 340/4spd cam. Off hand, I can not remember all the specs to it. The cam I mentioned will idle smooth after warm up for the most part, provide good power and remain very streetable so well, your mom ain't gonna know the difference when it's all warmed up and she's driving it until she hits the go pedal.

The other cam I have no known knowledge of. But, I can recommend 3 or 4 more cams right in the ball park (Or within a few degree's @ .050) that act, sound and perform very similar to very differently. Of course, this is in all how they are ground. Being that it is a street cam, I'm sure itll be good as well.

Try not to over think cams. The basic idea you and everyone that have little experiance with cams but have a good hand about wrenching on a car should do is simple.

Read the grinders notes
understand where the cam makes power and at what speed your cruising at should match the cam's cruise area (RPM)
Knowing how much lift your head will handle, might as well get a cam that can take advantage of the heads abilities right?!
Ask the been there and done that or at least an honest smart guy who's been around the block and a good fella that wont lie to you.

Small changes in duration are small changes in the power band. Sometimes, it is splitting a hair, sometimes it is not.

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