Basic 318 Mods

[CFD244]

If he's was gonna swap to larger engine might as well buy one with the larger engine in the 1st place. For some reason his dream seems to mildly hop up a 318 A Body.

A great dream to have

 

[Dan the man]

Been quiet on here today, is everyone okay?

 

[moparlvr166]

When I buy a driver, I always go through the complete brake system, cooling system, fuel
system Fix all leaks (Hate fluid leaks after destroying mom's driveway when younger) then tune as needed, if any cash left over do what you want.

 

[AJ/FormS]

Wish me luck as I'm going to be checking out a couple of duster's next week. I'm only asking these questions as a quide, both are 318 cars but one is a 2 barrel. Once the car is home I'm going to check it out completely and if everything checks out okay I'd like to do a 4 barrel swap and was wondering what size carb and intake manifold to use. I thought about a better coil and module. A curve kit and a good dual exhaust system. The car will be a cruiser only and probably the engine will never see more than 4500 rpm's. I'm open to a stall converter and a different gear ratio. Maybe even a mild cam.

IMO, for your stated usage;
The best cam for this application is the stock one.
Any other cam, with no other changes, is pretty much a waste of money/time.
If it doesn't already have a 4bbl, but does have the typical 2.76 gears, and a stock stall, then installing a 4bbl is for your stated usage, a waste. The reason is that with say a 26.5"tire, 2000rpm in 2.45 low gear, is gonna be about 21 mph. Your 2bbl is not gonna roll off the power until maybe 3000 rpm, which would then be 30ish mph.This is about the time a 4bbl will begin, I said begin, to make power over the 2bbl.
Are you willing to wait?
By far the best bang for the buck for your your 318 Duster is a 2800 stall.
And next best is, 4-series gears; But, I don't suggest that lol. With a 2800TC, 3.23s would be adequate in your combo, and you can still hit the hiway.
The higher stall will allow the engine to spool up and find at least 20/25 horsepower over a sub-2000 stall. The 4bbl will not even begin to touch that at 2000 stall. nor will any streetable gears at zero mph. Nor will a cam until say 4500 rpm or more.

Only after the Convertor and gears are in, would I think about a 4bbl, and at no time, for your combo, would I consider a cam with a later closing intake. If you install a 4bbl, then more than likely you will need dual exhaust, but the iron log manifolds may still be a choke-point.
These are my opinions based on 50 years experience.

Lets say you put a 4bbl on it and it makes plus 15hp at 4400rpm which with 2.76 gears will be about 45mph. and it didn't START making power until 30/35 mph When you stuff it into Second at say 4600, the rpm will plummet to 2700, and that takes care of performance. tuck tail and slink off the track. Cuz at 2700, the 4bbl is not making any hp over the 2bbl, unless it's like maybe 2hp, lol.
Lets say you are a lil disappointed and install 3.91 gears. Now the 4bbl will START making power at 22mph, going to 38 mph. When you shift, the Rs will again fall to about 2700, and so now, yur done 7 mph sooner.
So now yur really ticked
And finally, you install a convertor, unlocking your 318 from it's drudgery of lack of footpounds, the engine spools up, finds a bunch of more footpounds and begins it's Rapid Transit to shift rpm.

Since I already told you this would happen, just do it first. Maybe you will be satisfied with what you get, and postpone the other mods. I mean, you said it was a cruiser; right?

Ok one more; Say you are idling down the road with those 26.5 tires and a 2000 stall, doing 35mph at 1200rpm, in top gear. Let's say you wanna impress the raging-hormones teenager in the POS tuner-car in the next lane, who is incessantly burping his throttle to keep his tiny dick hard. So then, as soon as you floor it, your engine spools up to around 2000, well not much power there yet, so the trans calls for a downshift, and hits oh say 2000 at 35mph, now in Second gear, Hmmm. So the trans goes to First gear and at WOT, the Rs jump to 3600, there ya go but, the tuner-creep is long gone.
Next, lets install a 2800 TC and 3.23s
Ok so, at 35mph, yur cruising at 1400 in Drive. On the downshift into First at WOT, the rpm jumps to 4200, oh chit, yur just about at shift rpm, but screaming at or near peak power, none the less; so you are kicking that tuner-boy, at least for a second, lol, as the engine races to shift rpm. But hey, the smile on your face is hard to ignore.
The 2bbl is still on it, as is/are the single exhaust and factory cam.

 

[Dan the man]

IMO, for your stated usage;
The best cam for this application is the stock one.
Any other cam, with no other changes, is pretty much a waste of money/time.
If it doesn't already have a 4bbl, but does have the typical 2.76 gears, and a stock stall, then installing a 4bbl is for your stated usage, a waste. The reason is that with say a 26.5"tire, 2000rpm in 2.45 low gear, is gonna be about 21 mph. Your 2bbl is not gonna roll off the power until maybe 3000 rpm, which would then be 30ish mph.This is about the time a 4bbl will begin, I said begin, to make power over the 2bbl.
Are you willing to wait?
By far the best bang for the buck for your your 318 Duster is a 2800 stall.
And next best is, 4-series gears; But, I don't suggest that lol. With a 2800TC, 3.23s would be adequate in your combo, and you can still hit the hiway.
The higher stall will allow the engine to spool up and find at least 20/25 horsepower over a sub-2000 stall. The 4bbl will not even begin to touch that at 2000 stall. nor will any streetable gears at zero mph. Nor will a cam until say 4500 rpm or more.

Only after the Convertor and gears are in, would I think about a 4bbl, and at no time, for your combo, would I consider a cam with a later closing intake. If you install a 4bbl, then more than likely you will need dual exhaust, but the iron log manifolds may still be a choke-point.
These are my opinions based on 50 years experience.

Lets say you put a 4bbl on it and it makes plus 15hp at 4400rpm which with 2.76 gears will be about 45mph. and it didn't START making power until 30/35 mph When you stuff it into Second at say 4600, the rpm will plummet to 2700, and that takes care of performance. tuck tail and slink off the track. Cuz at 2700, the 4bbl is not making any hp over the 2bbl, unless it's like maybe 2hp, lol.
Lets say you are a lil disappointed and install 3.91 gears. Now the 4bbl will START making power at 22mph, going to 38 mph. When you shift, the Rs will again fall to about 2700, and so now, yur done 7 mph sooner.
So now yur really ticked
And finally, you install a convertor, unlocking your 318 from it's drudgery of lack of footpounds, the engine spools up, finds a bunch of more footpounds and begins it's Rapid Transit to shift rpm.

Since I already told you this would happen, just do it first. Maybe you will be satisfied with what you get, and postpone the other mods. I mean, you said it was a cruiser; right?

Ok one more; Say you are idling down the road with those 26.5 tires and a 2000 stall, doing 35mph at 1200rpm, in top gear. Let's say you wanna impress the raging-hormones teenager in the POS tuner-car in the next lane, who is incessantly burping his throttle to keep his tiny dick hard. So then, as soon as you floor it, your engine spools up to around 2000, well not much power there yet, so the trans calls for a downshift, and hits oh say 2000 at 35mph, now in Second gear, Hmmm. So the trans goes to First gear and at WOT, the Rs jump to 3600, there ya go but, the tuner-creep is long gone.
Next, lets install a 2800 TC and 3.23s
Ok so, at 35mph, yur cruising at 1400 in Drive. On the downshift into First at WOT, the rpm jumps to 4200, oh chit, yur just about at shift rpm, but screaming at or near peak power, none the less; so you are kicking that tuner-boy, at least for a second, lol, as the engine races to shift rpm. But hey, the smile on your face is hard to ignore.
The 2bbl is still on it, as is/are the single exhaust and factory cam.

Car is totally stock. Probably a good dual exhaust system would be first thing

 

[junkyardhero]

If he's was gonna swap to larger engine might as well buy one with the larger engine in the 1st place. For some reason his dream seems to mildly hop up a 318 A Body.

because 318 cars are cheaper than 340/360/stroker cars

 

[AJ/FormS]

Car is totally stock. Probably a good dual exhaust system would be first thing

not if it was mine.
your stock 318 will not outrun the single exhaust with 2.76 gears, until screaming in top gear at/or near the torque peak, which translates to 77 mph or so..... unless it has been crushed, or the Y-pipe was welded up poorly.
But, if that's where you want to start, I've said my piece.

 

[318willrun]

not if it was mine.
your stock 318 will not outrun the single exhaust with 2.76 gears, until screaming in top gear at/or near the torque peak, which translates to 77 mph or so..... unless it has been crushed, or the Y-pipe was welded up poorly.
But, if that's where you want to start, I've said my piece.

dual exhaust is the forerunner to the 4bbl he wants to add. Also, just for the conversation (and not argument), our '77 van with a stock 318 2bbl dropped 3 tenths and gained 2 mph in the 1/8 mile by going from a true dual exhaust to headers and duals. So 318 2bbls do appreciate more flow too......

 

[273]

If you look at a stock 318 dyno chart it may peak at 4500 rpm but it practically flat from 3500-5000+ rpm’s with a small bump at 4500 rpm’s. Imagine exhaust, 4bbl adds through out that whole range and lower so you don’t have to wait to 4500 rpm’s before you get into the power (lol) of the engine.
Even at 2500-3000+ rpm’s it down a good bit but still not too far off peak hp.

 

[Dan the man]

not if it was mine.
your stock 318 will not outrun the single exhaust with 2.76 gears, until screaming in top gear at/or near the torque peak, which translates to 77 mph or so..... unless it has been crushed, or the Y-pipe was welded up poorly.
But, if that's where you want to start, I've said my piece.

Where would you start?

 

[273]

How about follow 318willrun’s 318 car that performs somehow even though some say you can’t add a cam carb etc.. to no stall and gears and get results.

 

[rumblefish360]

Where would you start?

I think, at least the way I read it, he wouldn’t.

As far as my two cents, even with a 2.76 rear gear, dual exhaust w/a H pipe, 600 cfm carb on a Performer intake with an open air cleaner, upgrade the ignition to a CD, open the plug gap to .050, limit the timing advance to 36* and bump the initial to 15*.

Call it a day there.

Camshaft wise, on a stock 318? Probably wouldn’t do it myself. At best, a cam at 210@050, at the most 216*@050. This may take away a little mileage.

This cam or equal if it is available; https://www.monicattichrysler.com/comersus/store/comersus_viewItem.asp?idProduct=397

 

[318willrun]

My first posting in this thread addressed Dan's carb/intake question. But, let me say the very first thing I'd do to the 318. THE first:

1. Check to make sure the heat riser flap is opening in the exhaust manifold. More than once I've seen these freeze (rust) shut. Bad gas mileage and very poor performance is the results as well as burnt valves/seats if run too much like this.
2. And number 2 is to make sure the valves are sealing. I say this till I'm blue but I will say this again: Add all the 4 bbls and cams you want to an engine, but if the valves are leaky all over the place and the a few cylinders are around 90-100 psi, it's a waste of time. Good sealing heads is where it starts in my book.

 

[273]

Could always get a custom cam with around stockish + intake duration and more exhaust with decent lift, and a fairly tight lsa with stock or better intake closing point. Should add a few hp and mid range tq while at least keeping bottom end.

 

[rumblefish360]

That’s a small Comp Cam, I wouldn’t bother with a custom cut at such a low performance level. Just add 1.6 rockers and Rhodes lifters on the intake only.

 

[273]

That’s a small Comp Cam, I wouldn’t bother with a custom cut at such a low performance level. Just add 1.6 rockers and Rhodes lifters on the intake only.

True but seems the OP wants to science out a 200-250 hp 318.

 

[AJ/FormS]

Where would you start?

already said it.
and already did it,
every dumb way you can think of, I've done it.
I bought my First Mopar in 1970 at the age of 17. I bought a manual trans car with 3.55s, cuz I could "stall" it at any rpm I wanted to. The 3.55s were not in there long, coming out to make way for 4.10s. Stall and gears baby.

I went thru the low-compression, hi-way geared, no-performance era. My sheds are full of low-mileage 3.23>2.73 gears, and factory stall convertors. They are almost always the first casualties. I bet I have over a dozen of those. and probably the same number of low-compression, smog-era, 150hp, freaky, low-perf. 318s.
You wanna wake up a street 318?
Just slide a 340 under the 318 top end, and stuff a 318 cam in her. Instant tire-shredding capability with any rear gear, any 318 convertor; just drive it. Lemmee know if you need one of those for a core. lol.

 

[273]

If you really want street friendly power add replacement magnum heads and beer barrel intake with headers and duals.

 

[forphorty]

How about follow 318willrun’s 318 car that performs somehow even though some say you can’t add a cam carb etc.. to no stall and gears and get results.

Yep. I remember AJ being the naysayer , didn't align with his math.

 

[rumblefish360]

If you really want street friendly power add replacement magnum heads and beer barrel intake with headers and duals.

Ouch! LMAO!

Yep. I remember AJ being the naysayer , didn't align with his math.

Yep! 318 hater. For good reason. It ain’t easy waking up a low compression 318 and even worse when it’s a smog era 318. They will perform good for what they are but they’ll never perform well. Not until you change the pistons and heads to something much nicer.

AJ nailed it. While you can shake up a smog 318 OK, it’s what I out lined above. It is a lot of work that should be done on a 340 or 360.

If one would want to do a 318, it’s because it’s ether a budget build what ya got or you wanna do a 318 because of the limitations and challenge yourself. Ether if fine by me and I won’t bash you for ether. However, if you have a few extra bucks to get a 360 core engine to build up, you’ll be happier.

@Dan the man, seriously, don’t add a cam to the low compression 318. If and when you want to try and build an engine, grab a 360 or 5.9 and have at it. It’s just a better bang for the buck with no to little down time with the car.

 

[junkyardhero]

318WR hit the nail on the head: if you're starting with dog ****, no amount of sugar is gonna make it ice cream. comprehensive diagnostic to start. always.

from there, i personally think that a dual plane with a reasonable 4bbl carb and headers is a viable path-- despite some naysayers. is it a world beater with the 2bbl cam? no. but it's a reasonably priced path to something that's decent and all of that will directly attribute to any build going forward.

if you're going small cam, get the 340 repop. you're not building a race motor, it won't suck out too much compression, it doesn't have enough lift to need special springs or machine work, it doesn't have enough duration to need a converter or gears. even with a 2bbl it makes for a ripper. 340 repop cam in a 318 is a solid combo and it's cheap as chips. i'll say it till i'm blue in the face

everybody is really over thinking it. it doens't need to be perfectly optimized, it just has to be a decent cruiser.

 

[hotrod swinger]

What's this comment suppose to mean?

I’m surprised you have to ask.

 

[Dan the man]

I’m surprised you have to ask.

I forgot, there is a lot of silly stuff that goes on here that's for sure.

 

[rumblefish360]

318WR hit the nail on the head: if you're starting with dog ****, no amount of sugar is gonna make it ice cream. comprehensive diagnostic to start. always.

I have to agree here for sure but then again in general I think the question was beyond that point in an assumption the engine and car are good to go.

from there, i personally think that a dual plane with a reasonable 4bbl carb and headers is a viable path-- despite some naysayers. is it a world beater with the 2bbl cam? no. but it's a reasonably priced path to something that's decent and all of that will directly attribute to any build going forward.

if you're going small cam, get the 340 repop. you're not building a race motor, it won't suck out too much compression, it doesn't have enough lift to need special springs or machine work, it doesn't have enough duration to need a converter or gears.

FWIW - The 340 cam is a good bit bigger and any compression loose is only going to make the already (possible) 7.9-1 ratio seem even worse. The 340 cam also uses “340” cam” valve springs. I think it to insure more rpm. Personally I think the factory did well to equip the 340 engine with the minimum of 3.23 gears.

even with a 2bbl it makes for a ripper. 340 repop cam in a 318 is a solid combo and it's cheap as chips. i'll say it till i'm blue in the face

Cheap as chips! I love it!

everybody is really over thinking it. it doens't need to be perfectly optimized, it just has to be a decent cruiser.

100% dead nuts ball crackin on.

 

[junkyardhero]

FWIW - The 340 cam is a good bit bigger and any compression loose is only going to make the already (possible) 7.9-1 ratio seem even worse. The 340 cam also uses “340” cam” valve springs. I think it to insure more rpm. Personally I think the factory did well to equip the 340 engine with the minimum of 3.23 gears.

yeah i should've made the caveat of maybe not a smogger, but a early 318 would be fine. but the reasonable assumption of running a 340 cam with stock springs is that either you're not revving the **** out of it, the valve's will float, or it just won't get there because it doesn't have enough carb or head. but more along the lines of you don't need anything out of the ordinary to run it.

i built a 318 with 360 2bbl heads and a 340 cam topped off with a factory 2bbl set up and a stock single exhaust, backed up by a 904 and 3.23's. it's in my buddy's 67 barracuda and it is an absolute gas to drive around town. i'm not saying it'll slay dragons in the 1/4 but it damn sure surprises people when playing stop light eliminator. best of all is it's well mannered and cruises the highway with ease.