How to build a 13 second 340 Duster

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Moper: I hear ya. I'm not perceiving any bashing or criticism. I'll be talking
with the local machinists before deciding about building to better than
factory specs.

Demon seed: makes sense to me. It'll be fun to tear it apart. I plan to have
all the details worked out with a local expert before I dive into it.

Dustpan: this agrees with the comments of others. I don't know how much
difference drag radials make but I'm guessing it might be enough
that an engine done to factory specs might be close to my goal.

My idea right now is that it might make sense to put my head money into new aluminum heads. I particularly like the idea of being able to build to factory compression without being close to detonation with pump gas. I would of course have them "checked out" based on the advice given as this would not add greatly to the price.

Arlie
 
My son has Eddy RPM heads on his 9.5:1 comp. 360 in his 70 Dart. He's running a 780dp Holley on a RPM intake, not sure of cam specs. The subframes are tied and the rear springs are moved inboard with 3.55, 8 3/4 and a 4-speed. With 255 BFG TA's his best 1/4 is an extremely traction limited 12.90 at 112. Personally, I think the aluminum heads would be the way to go.
 
Here is a pic of my sons motor with the Eddy RPM heads.
dart_motor_small.jpg
 
Dustpan: thanks for the input. I see he also upgraded the valvetrain. Looks very cool, almost worthy of some transparent valvecovers!. :happy4:
Arlie
 
I'm guessing 10:1 is around the upper limit for todays's pump gas? Chamber size would be per factory J head.QUOTE]

On the comp I would shoot for no more then 10.0 on iron heads. If it is a good quench eng then you might get away up to 10.5 and still use 93 pump
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Been watching this with interest from afar

I know I have probaly said this before but what is the high rated fuel generally
available in the States?
The reason for this in Australia when we plan a decent build of street engine
we allow for 98 octane as this is available everywhere and it is surprising that you guys build for 93 at the most.
Just thought in the home of performance there would be good fuel.

Cheers

Benton
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93 is the highest that is easily available. Theres a few places around me that have Sunoco brand 100 octane unleaded though.
 
i think there may bee diferences in how the octane is measured, cant remember the names of the diferent measuring but from what i can remeber our europen 99octane pumpgas is equal to american 94octane, dont know for sure on the australian way of measuring, gues someone else may know!

Adam i would love some of that 100octane measured the american way at my local gasstation ;)
 
More than octane around us in CT is the ethanol mix they run. It's currently 10% for the entire year, but in addition to that, between November and February, we also have other additives so the moose in Maine can breathe easier. There's too much involved witht he engine package IMO to base a buildup soley on static compression. I have 10.8:1 iron head engines out there running fine all year, and I have 9:1 iron head engines that tuning for this fuel is a headache. All depends on the assembly as a whole, not just piston and head material.
 
I had a 440 with low compression TRWs .080" in the holes) L2266s ? and a set a very milled heads that would not run on pump gas. I never measure the compression on it but thosepistons are rated at 8.5:1. With my milled heads and .022" gaskets I fiigured around 9.5:1 but it could have been higher. As soon as the motor got warm it would ping like there no tomorrow.
 
There's too much involved witht he engine package IMO to base a buildup soley on static compression. I have 10.8:1 iron head engines out there running fine all year, and I have 9:1 iron head engines that tuning for this fuel is a headache. All depends on the assembly as a whole, not just piston and head material.
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This is an important issue for anyone planning an engine buildup which will involve compression in a range where detonation on pump gas could be an issue. If static compression does not provide a reliable guideline then it would be nice if someone could lay down the fundamental principles involved. Examples of a combo that works are nice, but understanding why is better.

Unless this has been well covered elsewhere on the forum, this would be a nice opportunity for those with the expertise to provide some clarification.

Arlie
 
I think it's been touched in a bunch of forums...lol. It's an evolving technology. Designing for high power on hot and fast burning (read as low octane) fuel. As far as my experience goes..designing an engine for pump gas isnt htat hard. designing a package that runs on the hairy edge of detonation while providing maximum power, when depending on the quality of "in the ground" fuel sources is. Basically, the smaller the space for combustion, and the more turbulence you can build in will yeild the most detonation resistance, regardless of octane. Factors that affect pinging and detonation are: head material, chamber design, finish, and size, piston dome design and finish, top ring placement on piston, valve type, finish, and size, spark plug type and heat range, valve seal quality, guide clearance, cylinder finish hone quality, camshaft's intake valve closing event timing, and intake type, design, and finish, and ignition type and curve setup. Alter any of those, and you can encourage, or discourage detonation and ping. In the perfect engine, you would see no deposits on the valves, chamber, or piston tops. If you see that in any form, you are giving up efficiency and power. But there are only so many ways to "fix" a design that is 50-60 years old. Over head 2 valve engines have been around that long. Look at a modern LS1 style chamber. it's very compact, wiht the spark plug pointed at the exh valve, and the exh valve area clearly defined next to the intake valve. On a Mopar, look a tthe MP Stage heads, or the Indy offerings. Those are newer designs. Still not "modern" IMO, but way beyond a set of 906s...lol. For best results, a dished piston, with the dish under the chamber which is also small and tight, will give the best resistance to detonation and power focussed on where it should be. Flat top thinking works, but you give up some efficiency again, for the benefit of better flame propogation. It's better than any raised dome design, but really, you dont want to have the flame have to travel all across the piston. You want it to burn very fast, in a small area, building maximum cylinder pressure just as the crank angle is at it's most vulnerable. It's a huge deal right now..How to keep high performance engines alive on pump fuel. And it's still under development. That's because regardless of fuel type, the physics and power production gains happen. That's why I say it's all about the complete design, and should be a huge consideration from the beginning of any buildup.
 
Thanks moper.

I did a little reading about this and posted some info but somehow it didn't get onto the forum.

Basically just some principles regarding actual operating compression. One significant one being the fact that less than atmospheric pressure is delivered to the intake valve, with everything between the atmosphere and the cylinder (air cleaner, carb, intake, valve train, valve train timing etc) playing a part in how much less than atmospheric pressure is delivered. Then there's the flow characteristics, such a swirl. Exhaust resistance will also effect overall flow so there's much more than the static compression ratio, piston and chamber design involved, as you have pointed out.

It seems actual operating compression is a hard thing to pin down. It also seems to me that it is the fundamental parameter determining power output through which essentially all performance enhancements have their effect.

Hmmm... lots to think about. I'm still thinking the aluminum head upgrade makes sense, assuming Edelbrock incorporates newer/better design.



A360: Here's the answer to the octane question:
(from this website: http://en.wikipedia.org/wiki/Octane_rating)

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe.
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Arlie
 
Idaho said:
It seems actual operating compression is a hard thing to pin down. It also seems to me that it is the fundamental parameter determining power output through which essentially all performance enhancements have their effect.




The problem that I see is, what most people have to measure the variables involved cannot do it accurately. Kind of like flowing a single port on a set of heads, instead all of them. And even flowing it without the intake and carb, and without the exh header. And even doing that, you still cannot duplicate the entire true environmet in an operating engine. You cant get the pulsing an engine creates, or the momentum the temperature of the gasses creates. The best one can do is come close by "assuming" certain "average" numbers. Like the .6 mach number, and assuming airflow behaves exactly like a fluid in a shaped conduit. The results confirm the ideas are on the right track. But you can't really (at least in my opinion) point a finger at tthe result and say the positive end is only because of the theory. There's too many things that have come about by some person just rolling the dice and finding a new solution.
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Well said. I suppose the engine dyno before and after individual changes might allow one to indirectly infer operating compression effects. I guess manufacturers doing research might have some interesting data.

I'm hoping the mopar performance secrets book might give a little insight.

For me it's mainly satisfying curiosity as I don't plan to do much beyond a stock configuration, but learning a bit along the way is part of the fun.

Arlie
 
all this 340 and 13sec, is making me happy im getting a 340, bump for all the good info, o and btw i looked at the flow chart.....(im dumb) what am i looking at, what is good, what is bad, im confused. Are there any beginner flow chart how to's and cam selection sites?
 
The biggest detail is..read it all, and try to understand it all. Then we can apply it to your situation. If you have an engine that turns and the bores are good, you can do a quicky on it. A quickie for me these days is a crank kit (crank with bearings), a set of rings, and most other wear parts replaced. The fact is, iron heads will cost you $600-$100+ to get "right" and setup for performance work. So that's where the debate about Edelbrocks or others or factory iron comes in. Is the extra performance worth the extra $$ to you. If it's a real 340 car, there are some who will not like seeing eddys on it. In terms of power, it's fairly easy to make 350-375hp with nothing more than a valve job done on the right equipment and using decent parts. If that's what you want, it's cheaper. My biggest peice of advice is plan the engine as a whole, once. There are tons of good ideas here and elswhere. So it can get dizzying...lol. But if you formulate a plan that fits the budget, execute that plan properly..And the result will keep you happy. There's always room for more $$. You can cut costs with things like re-using the balancer, redoing the rods and crank, reusing main bolts if the main bores are OK, re-using rockers and shafts and tin work(oil pan, valve covers, etc)...those savings (providing the parts are good to begin with) will save a bundle. So keep reading..and keep asking.
 
Longgone said:
I`m with Adam on this one, just build the engine to 68-71 340 specs, perhaps a 3.55 gear, and cram as much slick as you can get in the wheelwell. If you can get it to hook up ,then 13.00 should be simple. My stock 68 Dart 340 A/T ran 13.80`s with street tires.
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73 Duster weighs more than a 68 Dart. Difference of maybe 200-300 lbs? Strip some of the weight out too.
 
I have a 73 340 Duster. I am using a 360 with Eddy heads, hughes 230/236 hydraulic cam, eddy air gap, holley 750 dp, TTi headers. Has stock converter and 3.23 gears. Rear tires are only 225/60-14.

I have to roll into throttle to keep from spinning tires. Ran 14.011 @ 101.26 in Las Vegas. My MPH says the Duster should run low 13's or faster if the car was geared/tires.
 
73 340 block and cast crank, j heads (clean up the bowls) 2.02 valves, 484 cam , 273 rockers , LD340 intake , hipo ex manifolds , cheapo Kieth black pistons 10:1 (polish cumb. chambers-no hot spots) ,stock ign. (recurve dist.) , holley 650 DP (I think a good TQ would have been better) ,good machine work , 833 O.D w/ 4.10's , battery in trunk , Drive to minnesota from Idaho , run 12.90's and drive back!


My Previous Motor - nothing fancy , just attention to detail and a good tune
 
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