1970 Dodge Dart 318 upgrades

[toolmanmike]

Once upon a time I ran a bunch of different cams on the D dyno. Here's the 318 build:
Stock bore Teen, 9.5/1, 1.80/1.60 valves, LD4B/600, 340 manifolds and dual exhaust.
I chose cams with duration 220° or less and all were hydraulics.
The winner (as far as what I can see) was the Howards 711381-10
322 hp@5000 and 399 lb/ft@3000
Specs: 208°/214° @ .050
255°/261° advertised
.479/.494 110°

 

[nm9stheham]

Tnx, TMM. That is a very interesting result. Can you tell us what the criteria was for being the best? (Not being critical, just curious.)

And a 9.5 SCR 318 is not stock, as I am sure you well know (but others might not) .... it'd be curious to see the results with a more typical 7.9:1 SCR.

 

[nm9stheham]

Does anyone really know how big the chambers are on 302's compared to other 318 heads? I know different years are different. All my engine books list 302's @ 56-65cc where as standard 318 heads are 60-69cc depending on what year.

I really dunno where 60 would come from for a factory (earlier) 318 chamber, like a 675 head... 68 would be a good nominal to use. The 60 may just the NHRA minimum.... not what one would find from the factory. I'd use 62-63 for the 302's but it would be nice to hear your actual numbers.

 

[Johnny Dart]

I strongly disagree.
Firstly you mightta missed the part about limited budget, but more importantly;
A high compression street SBM even with a 2bbl and most especially with the factory 2bbl cam, is, or rather, can be a dynomite combo when supporting mods are thrown in..... especially with hi-way gears.
The stock cam only pulls to about 4500.Altho it will willingly rev MUCH higher with supporting mods. And the 2bbl is just running out of capacity at about that time. The 2bbl does not prevent the engine from reving any higher, it just won't make optimum power up there is all. With 2.76s hitting 4500 at about 50 mph, this is no big deal. And guess what, at peak torque she will be sitting at right about 26mph. Tm is; 2.45(first gear) x 2.76=6.76. This is almost exactly like 1.45(second gear) x 4.56=6.61. The engine doesn't care how it gets TM. Light 'em up OP!
I have build combos like this. The key is in the compression and in the hiway gears. And so is the fuel-economy. Even a 340 running all the 318 stuff, is pretty impressive, with hiway gears keeping the revs down.
AJ's opinion
No you won't win any races, but that is not on OPs to-do list.

BTW
A 318 with the stock cam at 9.2 Scr is about 162 psi@137VP ( about the max you can run with that cam), compared to a fresh 360 at 8.0 with it's stock cam, making 130psi@118VP, both at 1000 ft...... I know which one I would want, hands down!

You can disagree all you want, thats fine. And I did see the part about budget.
Thats why I suggested a 4bbl intake and carb to complete the package.
If you look, the Ede Performer and Ede 600 can be had for around $300.
If you cant afford $300, you should get out of the hobby while your alive.

 

[rumblefish360]

IMO Johnny Dart makes sense. Good us d parts with a minor run of love on top is as inexpensive as it gets unless it is given to you.

But! What ever the OP wants.......
Just a cam change? Have at it.

 

[toolmanmike]

Tnx, TMM. That is a very interesting result. Can you tell us what the criteria was for being the best? (Not being critical, just curious.)

And a 9.5 SCR 318 is not stock, as I am sure you well know (but others might not) .... it'd be curious to see the results with a more typical 7.9:1 SCR.

I can change the compression and a few other parameters to make it stock. Then we can see what happens. There are way too many combinations that can change the outcome.

 

[Wyrmrider]

I would not use the old 340 cam even if it was free
closing ramps are way too long for any dynamic compression
SAE timing is 20 79 79 30 with 50 degrees of overlap (at .004 which you can compare with that Summit cam or CRANE) that's a 279-289 seat timing cam
Chrysler timing is more like .008
Howard or Lunati are good places to start looking comp has nothing in this range and others are custom except Hughes

 

[rumblefish360]

I was thinking the same cam companies, Howard’s, Lunati and Hughes. Just watch your lift with what ever slugs your running.

 

[Wyrmrider]

he can't use a lot of lift
pocket porting increases flow at similar lift but extra lift does not help much unless pro ported
that said
Engle and Crane have some .904 lobes that have a lot of area with easy to build lifts
actually if he is the 9:1 area Jones motor home grind is outstanding
50 % more duration .275 lobe lift than the Direct connection 260 cam and it wears well - you get what you pay for
Jones Lobe is 264 and DC 260 is 284 @.004 I ran cam doc--so which builds more dynamic compression?

That SUMMIT 6901 cam is 276/288 so it's a little shorter than the 340 279/289 but both are Wide LCA you advance them any more and in and ex opens too early
cheers

 

[Johnny Dart]

This is a totally stock, matching numbers 318 that came in my 70 Dart.
I added nothing but bolt on parts. Ede performer intake, ede 600 cfm, 340 hipo manifolds, dual exhaust/40 series flowmasters, Mopar Performance elec ign. Stock cam, stock 2.76 gear.
I acquired all these parts from old fashioned horse trading. The 340 manifolds being the majority of the cost. But in car terms, very inexpensive hp. This car was a kick in the *** to drive, easily burning rubber all the way down the street. One of my favorite motors, and setups. Anyways, you got the motor out, and you want to hop it up. Might as well go the distance and add a 4bbl. You will be happy you did.

 

[toolmanmike]

Once upon a time I ran a bunch of different cams on the D dyno. Here's the 318 build:
Stock bore Teen, 9.5/1, 1.80/1.60 valves, LD4B/600, 340 manifolds and dual exhaust.
I chose cams with duration 220° or less and all were hydraulics.
The winner (as far as what I can see) was the Howards 711381-10
322 hp@5000 and 399 lb/ft@3000
Specs: 208°/214° @ .050
255°/261° advertised
.479/.494 110°

I went back in and changed things back to stock 318 with #302 heads. The HP winner is the XE262H-10.
The torque winner is the Howards cam I spoke about before.
The torque winner @ 1000 rpm is the Howards cam again.
The D dyno is a fun tool to compare as long as you don't rely on the numbers to be dead nuts accurate.
Too bad it is so much work to change cams just to get a real world test with the minimum of variables.
In conclusion, there is no magic bullet cam and stock 318's can't handle much without other mods.

Next question for you guys, for a stock Mopar like the OP has, would you rather have more HP or more torque?
I would think the torque would be more important with the low gears. Max. HP doesn't happen till 4500 rpm or so. Hard to use it just cruising around town.

 

[nm9stheham]

Tnx TMM. I'd vote for more low end torque any day for the daily driver app that the OP mentions... which directly translates into more mid-range HP. Broader torque curve = easier/funner to drive in a wide variety of situations.

That Howards 711381-10 cam has a very large amount of lift for the duration, compared to everything else out there; I was not even aware that there was any offering in that duration with that amount of lift in a hydraulic FT cam. VERY interesting; no wonder it wins on your comparison.

Though IMHO it's not suitable for the OP with the lift numbers and the stockish setup. And anyone using that Howards cam better have their valve train set up right to handle the very high ramp rates.

he can't use a lot of lift
pocket porting increases flow at similar lift but extra lift does not help much unless pro ported
that said
Engle and Crane have some .904 lobes that have a lot of area with easy to build lifts
actually if he is the 9:1 area Jones motor home grind is outstanding

FWIW, the engine in question is likely in the 7.8-8.0 SCR range.

 

[toolmanmike]

Tnx TMM. I'd vote for more low end torque any day for the daily driver app that the OP mentions... which directly translates into more mid-range HP. Broader torque curve = easier/funner to drive in a wide variety of situations.

That Howards 711381-10 cam has a very large amount of lift for the duration, compared to everything else out there; I was not even aware that there was any offering in that duration with that amount of lift in a hydraulic FT cam. VERY interesting; no wonder it wins on your comparison.

Though IMHO it's not suitable for the OP with the lift numbers and the stockish setup. And anyone using that Howards cam better have their valve train set up right to handle the very high ramp rates.

FWIW, the engine in question is likely in the 7.8-8.0 SCR range.

Agreed. And the Howards cam might be a noisy one. There are many others that would work almost as good without issues.
The Comp 265DEH runs a close second. 211/227° 265/276° .442/.462 109°
(Much easier on valvetrain) But the exhaust duration is close to 230°.

 

[318willrun]

if it were me, i'd say....
"give me that 340 cam, cast intake and TQ" The deadliest cam, carb and intake combo available for a stock long block 318. Sorry hughes, edelbrock...…

 

[DartGTDan]

This is a totally stock, matching numbers 318 that came in my 70 Dart.
I added nothing but bolt on parts. Ede performer intake, ede 600 cfm, 340 hipo manifolds, dual exhaust/40 series flowmasters, Mopar Performance elec ign. Stock cam, stock 2.76 gear.
I acquired all these parts from old fashioned horse trading. The 340 manifolds being the majority of the cost. But in car terms, very inexpensive hp. This car was a kick in the *** to drive, easily burning rubber all the way down the street. One of my favorite motors, and setups. Anyways, you got the motor out, and you want to hop it up. Might as well go the distance and add a 4bbl. You will be happy you did.

View attachment 1715192955

I'm in the same boat as Johnny Dart with a couple of differences. I was lucky enough to find a LD4B intake, 1406 4-bbl, use the original 318 exhaust manifolds with FlowMaster 40s with 2 1/4" dual exhaust, MP Electronic Ignition, MP viscous fan, and the stock 3.23 sure-grip 8 3/4" rear end. It's a fun car that does everything I want it to do.

Here is my newest under hood addition:

 

[Wyrmrider]

comparing Hughes and Howard with comp or edelbrock or stock 340 or summit
= no contest on a 8:1 motor if you pick the right one
the first two win the torque contest
agree on the intake and TQ
340 cam on an 8:1 motor- you can make it work strip only with converter and gears but I would not want to drive it on the street
and btw the .904 Howard is just as easy on the valvetrain as a comp chevy cam- the larger lifter gives it more time to get where it's going

 

[318willrun]

comparing Hughes and Howard with comp or edelbrock or stock 340 or summit
= no contest on a 8:1 motor if you pick the right one
the first two win the torque contest
agree on the intake and TQ
340 cam on an 8:1 motor- you can make it work strip only with converter and gears but I would not want to drive it on the street
and btw the .904 Howard is just as easy on the valvetrain as a comp chevy cam- the larger lifter gives it more time to get where it's going

opinions, of course. disagree completely on the 340 cam assessment. Been there, done that.

 

[Wyrmrider]

me too compression makes a big difference worst offender was a customer that put a 340 cam i a 360 motorhome
I can see it working in an A body, still really long ramps especially on the closed side 260 DC is better
cheers

 

[nm9stheham]

and btw the .904 Howard is just as easy on the valvetrain as a comp chevy cam- the larger lifter gives it more time to get where it's going

I have been musing on this and can't quite figure this out. But I'm not sure I know the right answer so thought I should throw this out for further comment:

• Seems like more lift in a shorter number of degrees would be higher speed ramps, and put more pressure on the valvetrain during opening...? (And I am only looking at the advertised vs .050" durations, as I don't have other numbers like .200" durations.)
• Now, if the opening lift occurs sooner, and the closing ramp starts later, then maybe going 'over-the-nose' will be gentler, and less need for heavy springs to fight float?
• Then on the closing, the deceleration at the end of the ramp would be harsher and higher pressures again, so it seems.

I am just trying to understand how this higher lift, short duration cam would be as easy as a low ramp, and the only place I can see is 'over-the-nose'

 

[rumblefish360]

I have been musing on this and can't quite figure this out. But I'm not sure I know the right answer so thought I should throw this out for further comment:

• Seems like more lift in a shorter number of degrees would be higher speed ramps, and put more pressure on the valvetrain during opening...? (And I am only looking at the advertised vs .050" durations, as I don't have other numbers like .200" durations.)
• Now, if the opening lift occurs sooner, and the closing ramp starts later, then maybe going 'over-the-nose' will be gentler, and less need for heavy springs to fight float?
• Then on the closing, the deceleration at the end of the ramp would be harsher and higher pressures again, so it seems.

I am just trying to understand how this higher lift, short duration cam would be as easy as a low ramp, and the only place I can see is 'over-the-nose'

Looks like you got it right to me.
The need for valve springs to exacting cam specs should have been handled by the grinder. However a heavier spring, needed or not, not only helps control the valve better but also for more rpm.

Going deeper than this becomes a scientific chat.
You can do better by reading up from the original cam greats. Start with Mr. Crane and finish up with Harold Brookshire.

If you get what there talking about, your in awesome shape. I just don’t think I can regurgitate what they say simply. It’s just a bit complex for me to break down. They do a good job in explaining things anyway.

 

[Jim Kueneman]

Several have said this and I have a 318 in my Coronet and am currently building one for a Duster. I have spent hours with the Performance Trends program on the 318 and have come to a few conclusions based on how I drive and what I want out of the motor. The first thing is how do you plan on driving this? My Coronet is a cruiser with high gears for the road. My opinion today is similar to a previous post.... step 1 is get the compression up to what the stock first years of the LA 318 were, around 9.2:1. If this is a cruiser and you never take it above 3000-4000 RPM (and then only on a rare occasion) I don't think the cam is worth the effort. You won't get much (if any) out of it in the less than 3000 RPM range with a cam. You WILL get a LOT more out of it down low with compression. My next 318 (will likely pull the Coronets engine someday) the first thing will be a 390 stroker kit. That is the only way to really make much difference in the <3000 RPM range on the 318.

 

[nm9stheham]

I agree with the post above, and the importance of the question of 'what is the use for the engine/car'; different uses result in different solutions.

FWIW, the production 318's were NEVER 9.2:1, early or late. The only ones that got into the mid 8's actual static CR were the Magnums. Even the early LA's were high 7's or low 8's. It is a 'theme' all across the board at the time: use some theoretical minimum chamber volume to compute and advertise CR. All the numbers I have run through say that Mopar exaggerated CR by .75 to 1 full point into the early to mid 80's.

 

[Jim Kueneman]

I agree with the post above, and the importance of the question of 'what is the use for the engine/car'; different uses result in different solutions.

FWIW, the production 318's were NEVER 9.2:1, early or late. The only ones that got into the mid 8's actual static CR were the Magnums. Even the early LA's were high 7's or low 8's. It is a 'theme' all across the board at the time: use some theoretical minimum chamber volume to compute and advertise CR. All the numbers I have run through say that Mopar exaggerated CR by .75 to 1 full point into the early to mid 80's.

1968 Service Manual states 9.2:1 compression for my Coronet and I measured how far down in the hole they were (100% original car) and they were just about 0.028"/0.030" with a steel gasket. I think that would get you very close to 9.2. The Sealed Power Pistons put you a disgusting 0.090" in the hole.

 

[318willrun]

1968 Service Manual states 9.2:1 compression for my Coronet.

they list it as that, but cc'd and all I doubt you'd get it.

 

[Jim Kueneman]

So I am going to back peddle since I never really looked at the cam without some of the other changes I have made. That is the same cam that is going in the Duster so I was interested..... Again this is a model but it is telling. The cam will make the biggest difference for low end torque outside of a stroker (did not include that data). All other items effect 3000 and up..

Next I looked at the difference between Stock/Stock with the Cam/My 318 build for the Duster. Notice in "cruise" RPM the extra $2500 I have in mine did almost nothing to where your stock with a cam is.

Then I added the 4 Barrel..... Unclear if it is worth the trouble if this is a cruiser but remember this is with a stock restrictive exhaust/small valves so the top end likely has more than these plots show if you let it breath better. The carb in itself would not be much help.