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#1
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340 Duster in the 12s?
I'm going to put a 340 in my 71 Duster. What will I need to do to the engine make this car go in the mid to high 12s? The Duster will have a 727 auto. Also what gears? I want this to be streetable too, or is that asking too much? Thanks.
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#2
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That depends on your budget.
Technically, you could slap a 150 horse nitrous sytem on your stock 340 and go easy 12s..... Mildly ported iron heads, factory compression ratio will work fine, Performer Cam or Comp Cams 270H, and Performer RPM intake should get you there too. 3.55 to 3.91 gears depending on how much and what type of driving you will be doing. Don't forget chassis mods to handle the extra torque. A good converter will help too 2000-2200 RPM for what I mentioned above. My 1 cent. |
#3
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For what's it's worth....3.73 gears with as 24-25 inch tire. 1 3/4 headers (Hooker # 5204) 650-700 Holley and a 3000 converter. Oh yeah, the .474 lift purple cam wll do 12.80's all day long. Even on the stock (junk) 340 intake manifold.
Have fun |
#4
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What kind of headers are best for a 340 Duster with p/s and p/b?
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#5
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i would go with 3.91s and a taller tire, 28-27 inch.
the 474 cam is a good grind, good power to 6000 and up in the 340. however, more power could be had with a newer cam, look for about 500 lift and 225/235 @ 0.050", bigger will make more power while trading off streetability. i am running the crane 238/248 solid in my car and it makes good streetable power and idles quite nicely. j heads with good exhaust work and a good valve job will do it, nailhead high flow valves don't hurt either. look for compression to be around 9- 9.5 . the stock 340 intake manifold works and is kind of a high rise but there are gains to be made with a street oriented single plane or something like an airgap. 2500 stall should be all you need. slap it together with a set of cheap headers, dual 2.5 inch exhaust with h-pipe or x-pipe depending on wallet size and go buy a 650 speed demon and run mid 12's all day long. you might want a set of electric fans from a newer vehicle, maintain the same temperature throughout the day for more consistency. |
#6
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Do 4.10's and a 26 - 27 inch tire.
Engine mods, look below at my sig. You can do a 9.0-1 comp. engine with a Purple 284 cam and get there. TTI makes the best headers for this. I have not run an "A" body car in years. (Time to find a Duster) Other than the tti headers, I can not recomend a header. A small tube header will do the trick, but the under the front end linkage path it takes just plain sucks! Contact Frank Lupo for a converter. He's da man. |
#7
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Streetable in Nebraska...that means about 200 miles between traffic lights
I'd run a 3.91 and a Dynamic 3000 street strip convertor, RB cam, with 240 + duration at 50 and use a 650 Mighty Demon, Air Gap manifold, small tube headers, work on the weight transfer and traction, that's going to be the weak link, you gotta get it to hook up. You'll need a 60' of about 1.8 or better to get you into the 12's. |
#8
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I have looked at parts and everyones suggestions. I will probably do something along these lines with my 340 Duster I am building.
727 auto 3.55 gears biggest tires i can fit w/o being tubbed 340 bored .020 x heads mp purple cam .474 Edlebrock RPM Performer or Edlebrock Performer headers 2500 converter full interior 650 carb Will this setup be streetable and still be around 13 or under in the 1/4 mile? I plan on driving the car and occasionally doing some drag racing with it. |
#9
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Get a better, higher stall convertor. Dont order that purple shaft cam. That thing was designed 25 years ago. It will hurt you compared to newer technology. Just cuz its a mopar doenst mean everything in it has to be Mopar Performance.
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#10
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Oh, boy.....
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#11
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-----dartman- That's FUNNY. That setup SHOULD be able to pull a 13.99 on a crisp Saskatchewan winter evening. Pick any cam you want as long as it isn't a crane or comp or RB or mopar or hughes or lunati or erson or isky or camdynamics or ultradyne. They all seem to be the shits.
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#12
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That's one of the big arguments alright..... |
#13
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A 12.65 1/4 mile duster
Here is what I have. 340 30 over with m-1 single plane the mp 292- 509 cam. 2.02 1.60 x heads no porting done, headman headers, double pumper, I run the jacobs omni pack, carter mech fuel pump, 4.10 gear with old style posi, with 29x15.50 micky thompsom sportsman pros, 904 with a cheetah man. valve body with a GER 3500 stall converter. That was a 650 double pumper and 2 1/2 exhaust into flow masters.
Ran last weekend at Norwalk Raceway Park the car ran a 12.65 at 106 mph. I drove the car about 50miles to the track took off the air cleaner and went that time. Put the air cleaner back on and head for home. Good luck |
#14
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I had the Mopar 280/.474 cam in my 340, didn't like it and it didn't perform very well. I would suggest that you don't use it. I would call up Racer Brown and get a custom grind cam. Thats what I would do if I did it all over again. I can only do a 14.1 in the 1/4 with street radials. On the NOS with a 125 H.P. shot I can do a 13.2. See my sig. for what I am running. Our elevation is @ 2200 ft. I know I should be doing better but I got my heads done at the local "we do all kinds of head work for all kinds of cars" shop. Don't think I got my moneys worth and I think there is a lot more that can be got out of the J heads.
Yes, cuda, I know, should have researched a little more. Now you can give me the lecture (bowing my head in shame). |
#15
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Mr. Mopar,
Have you tried any other intakes beside that LD340? An Edelbrock RPM and some 3:55 gears ought to shave some tenths off of that E.T. With that converter and those gears, you are probably leaving the line with the converter slipping. |
#16
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I did have 3.91's and a TQ in it before. With slicks and the NOS I was able to pull a 12.35 @ 110. Without the Nos I was always in the 14 - 14.1 range. I didn't try it at the track with the Holley and the 3.91's. I noticed that the Holley and the MSD made a big difference because I am doing the 14.1's now with the 3.21 gears whereas before I had the same timeslip with the 3.91 and TQ. I am quite surprised because I always thought the TQ was the better carb. Now I think differently about that, although many will disagree. I won't go back to the higher gears because the highway rpm's are too high for cruising and I like it this way now. If I bolted on the slicks I am sure I would be in the high 13's without the juice. The convertor is probably slipping, but maybe at the higher speeds, not at the launch. A set of Edelbrock aluminum heads wouldn't hurt either. Why would you suggest an Edel. RPM? Isn't that intake about the same as the LD340? I tried a Edelbrock Torquer 340 single plane and took it off faster than it went on, now thats a piece of junk!
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#17
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Mr. Mopar
What RPMs were you at going thru the lights with the 3.91s? and what dia. of tire? We have similiar setups and I'm convinced we both need more convertor (at least I do) as mine stalls @ ±2200 at 3800ft elevation so the lauch is just not there - 2.2@60'. for a best of 13.6 with no wheel spin and 26" street tires |
#18
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Quote:
"I am quite surprised because I always thought the TQ was the better carb." Reallllyyy....suprize suprize suprize....well Gollyyyy. |
#19
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Well 345dart, you are doing way better than me. I was going through the trap at about 5900 rpm and I am running a 25.57" radial tire. I am suspect of the convertor. Don, I'm learnin'. more about all of this stuff every day. Some of the guys out there are really die hard TQ lovers. I will have to admit, I did think they were superior. Maybe if I ran one that was set up right on the mark, things could be different. I like the Holley right now and I bet if I had a Demon, I would like that even better. How about giving me one just to try, I promise I'll give it back.LOL
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#20
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408 stroker 69 valiant full steel full exhaust street tires 2800 ft elevation 11.07 @ 120 mph using a thermoquad!
its all in the setup. |
#21
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That's dam good, ever tried a modular carb for comparison?
The TQ is a decent carb, especially when compared to a Eddy. If you've got one and your happy then stay happy, if you want to go faster and more consistant then try a Demon, you will go faster and you will be more consistant. |
#22
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Mr Mopar, what T.Q. were you using? It makes a great deal of difference as does the right BG, Holley or AFB/AVS. The carb is as important as the cam selection.
I used the MP .474-280 and it did make very good power. This was in my 71' Duster with 1-5/8" headers, dual plane 71' 340 intake, 850 cfm T.Q., 727 trans and 8-3/4 with 3.55 gears. At @ 4,500 rpm's the tires would break loose 'before' shifting into 2nd gear. I agree that cam designs have changed since the MP cams were first designed by Racer Brown/DC in the early 70's. Much of the success of the MP cams is a carry-over to the new designs in the quick opening/closing and true Mopar ramp/lobe designs. What I do not like about the MP cams is that these cams often do not break in correctly and you will wipe a lobe or two. I have stopped using the supplied Elco break-in lube in favor of Redline and still have wiped lobes. Comp, Engle/Hughes, Crower are all good choices. |
#23
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Hey Demon Sizzler how fast is that 71 Duster?
And you say a comp cam or hughes cam would be a good choice? |
#24
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Just be sure you request a Mopar grind cam or Comp will put you into a Chevy grind off the shelf piece...of course they charge extra for the Mopar ramp design.
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#25
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That 71' Duster was a 323 cu in .030 over 318 with Speed Pro forged pistons, 72' 340 J heads and a final comp ratio of 9.3:1
It could run 13.40's at 98 mph. The Comp Cams Extreme cams have a great reputation if the rest of the engine is correct per their guide lines. The Hughes higher lift cams with moderate duration are also given thumbs up. I have personally not used an Extreme or Engle/Hughes cam but have used the Lunati .480"-292 dur, the MP .484-284/.474-280, .509-292 I don't necessarily use split pattern cams depending on the rest of the engine build......heads/induction ect. I am currently using a Crower cam in my latest 318 and I really like it. I am going to use another Crower cam in my 365' buildup and it has a lift of .518" and a duration of 296 deg. I am also running an Engle .550" lift-296 dur hyd cam in my 440 and I can tell you that this engine with my race preped T.Q. and 11.8:1 compression, will rev faster than any engine I have ever owned and it sounds like a much larger mech cam through the open Hooker Super Comp fender well headers. The absolutely loudest engine I ever ran on open headers was the 323"/318 in my 71 Duster; it was REALLY loud! The very best Mopar cams will have the 'real' Mopar cam lobes and will therefore make the most power, DAVID. |
#26
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Demon Sizzler, the TQ I was using was the 9811 Super Quad, with .97 primary jets, .149 secondary jets, metering rods were .47 (WOT), .67 (PT). with a .040 pump shooter. It was set up like this according to the Mopar Speed Secrets manual. I really never gained much using this carb in this particular set up. I have, however, gained more with the 3310 Holley. I am not bashing the TQ, I am just stating what the results were after the swap. In all fairness, I did add the MSD 6A ignition after the Holley swap, maybe that accounted for a bit. I still think my Dart should be in the mid to high 13's, but it just won't get there and I have tried many things such as cams, timing, re-curving, intakes, etc. I still think the main problem is in the head porting and valve grind. I would like to see what a proven "good" set of heads would do to the 340.
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#27
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Mr Mopar, no offence taken; your info is very concise and useful.
You had about the optimum jetting from what I can see. The SuperQuad such as the one you had is a good carb, but when I tested the one I have VS an early stock jetted 850 TQ, the 850 turned better times. It is my opinion that your gear ratio is really hurting your ET's. I recently picked up 1.3 sec in the qtr mile with a gear change from a 2.71 to a 3.91. The car is so much more fun to drive now! |
#28
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Yes, I agree with you on the gear ratio. I could always put the 3.91's back in just to compare, but I won't until I get an OD trans put in it. I really like the slower revving highway cruising now. I know a guy in Edmonton, Alberta that has been doing OD trans swaps in A bodies and it has been working out very well. He doesn't have to cut out the tunnel like ordinary, just does minimal clearancing and welds up a new cross member, and I think he uses the A500 trans. He has an 11 sec. Valiant that uses this application and his son has a 12 sec. Dart. Guess what, they both use an 850 TQ and they both run a 360. I didn't think the A500 would stand up to the abuse but it does. With the trans swap I will put in 4:10's, that oughta wake it up!! And then I could cruise home @ 2500 rpm. I am going to keep my 9811 TQ and maybe some day someone will offer me enough cash to part with it. It is in pristene condition and is worth every penny.
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