360 build advice for my '70 dart swinger

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schultec14

schultec14

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Ok, I have a 1970 dodge dart swinger I would like to build a 360 engine for. Its a 318 right now with a 904 automatic w/ stock converter, and has a 2.76 rear. I have a early 70's 360 engine, I think its a '71, for this car. I want to know how to get some HP's out of this engine. I have a set of stock 1971 "J" Heads, and I also have a set of original 1968 340 "X" heads for this engine...I would like to know which ones to use, and which set of heads I would benefit from a porting job, a port matching, and etc.. the most. I would like to know what to use as far as pistons goes, and what compression I should keep it at to run 91-93 octane pump gas. I would like to know what camshaft setup to use considering I would like to keep it hydraulic flat tappet, unless I could see a major difference in power from roller lifters and roller rockers...overall I would like some lope and useable agressive power from this engine. I was always interested in using a low rise dual quad manifold for this build and I would like to know what carb's to use if this is a good idea to get some wot and high rpm power, I want to be able to keep it all under the hood though with out having to use any hood scoop. I have a set of nice full length headman headers for this car and it currently has dual 2 1/4" exhausts with nice flow masters and I would like to add electric cutouts behind the headers too...lol... I want to know if some one can help me address all of these areas for the 360 engine, and how much power I should expect, considering this would be a street car and would would almost never see the strip...I would still like to keep this as a nice quick rumblin around town car, but on the other hand keep it able to go on the highway, so I would like to keep the gears that are in it for now. But I am debating about the torque converter though...should I keep it stock? or can I get away with a little more stall speed so I could fit a little heftier cam in to match? Could I go with a 904 lock up converter transmission so I can keep the rpms down a little more on the highway, while using the advantage of a little lower first and second gear ratio's?...and would I even be able to find a higher stall lock up converter?? by the way, what is the stock stall speed on the converter in this car?
I need a good amount of advice for this build...PLEASE ADVISE!!
Thank you,
-ANTHONY
 
pistons use kb 107....

comp cam xe268h

intake eddy air gap
 
ANTHONY , you strike me as brand spanking new to this. Your asking for the best of both worlds and have a few misconceptions going on.

Lets start at the top.

An excellent starting point to a powerful 360 (IMO) would be the KB 107 piston that will put you at or near a zero deck height. If at a zero deck height, the compresion ratio will be 9.8-1 with ethier head you have. In which I'd go with the "X" head, an RPM or RPM Air-Gap and a 750 carb. Ethier Holley or Carte/Edelbrock and use 2-1/2 exhaust.

The 904 lock up tranny will not show a big, but a very minor gain in mileage which will all be thrown out the window once you start messing around with the engine. The RPM drop is also very very minor. Torque converters for a lock up trans are harder to come by and more expensive with not as many choices unless custom built for more money.

The 276 gears may be great for the Hwy. but will EXTREMELY limit any performance and on top of it all, will absoultely kill any bottom end with even the slightest cam change you make. Move up to 3.55's with the above cam or don't bother.

As far as dual quads go, no one makes a new intake for the engine family. You'll have to find ethier a Edelbrock D66 or a Weiand dualquad intake. The low rise version will fit under the hood.

A pair od 500 Edelbrcoks will work for this intake.
IF a Holley can be bolted on these intakes, a pair of Holley 390cfm sized carb will do great.
 
Thank you for the advice! Sorry, I did not mention it, but I am keeping the 2.76 gears in it, so I can drive it to north carolina at the end of august, but then I will replace them with a lower set of gears as soon as I get there. I am positive though that I would like to keep this engine on pump gas (preferrably 92-93 octane side) with no additives. I looked up the KB 107 pistons, and they look like the best bang for your buck, so I will be going with those. Should I keep the stock rods, and what rpm do they limit me to? Will they limit out, say for example, before the camshaft can not possibly make any more power? (the comp cam xe268h camshaft)...Could I even go with anything the next step more aggressive as far as camshafts go, but still keep it flat tappet hydraulic?... I am throwing out the idea of the lock-up tranny then. I do have 5 pre-1978 904 non lock-up transmissions and one 1976 727 transmission here in the garage that I could rebuild for this car...I also have the transgo TF2 shift kit for these transmissions too. Would you recommend keeping the stock torque converter? Or could I get away with a little more streetable stall speed, and If so, which torque converter would you recommend and what stall speed? My other performance related question is: Will the aluminum dual quad style manifold with two edelbrocks, or two holleys give me more horsepower than a single 4 barrel carburetor on top of a performance aluminum dual plane intake?
Thank you for the advice again!
-ANTHONY
 
schultec14 said:
Thank you for the advice! Sorry, I did not mention it, but I am keeping the 2.76 gears in it, so I can drive it to north carolina at the end of august, but then I will replace them with a lower set of gears as soon as I get there. I am positive though that I would like to keep this engine on pump gas (preferrably 92-93 octane side) with no additives. I looked up the KB 107 pistons, and they look like the best bang for your buck, so I will be going with those. Should I keep the stock rods, and what rpm do they limit me to? Will they limit out, say for example, before the camshaft can not possibly make any more power? (the comp cam xe268h camshaft)...Could I even go with anything the next step more aggressive as far as camshafts go, but still keep it flat tappet hydraulic?... I am throwing out the idea of the lock-up tranny then. I do have 5 pre-1978 904 non lock-up transmissions and one 1976 727 transmission here in the garage that I could rebuild for this car...I also have the transgo TF2 shift kit for these transmissions too. Would you recommend keeping the stock torque converter? Or could I get away with a little more streetable stall speed, and If so, which torque converter would you recommend and what stall speed? My other performance related question is: Will the aluminum dual quad style manifold with two edelbrocks, or two holleys give me more horsepower than a single 4 barrel carburetor on top of a performance aluminum dual plane intake?
Thank you for the advice again!
-ANTHONY
Click to expand...

If you really intend on keeping the 2.76 gears, then i'd stay conservative on the cam/carb/intake, even on the stall, i'd say the 258 or 262 might be a better cam choice, but i will tell you, the car will cruise down the highway just fine with 3.23s & a 27" tire, even a set of 3.55s would work, now with these gears, you open up a whole new window for a cam & converter choice, the car will still be a nice cruiser but it'll run a "whole" lot better, i'd say bare minimum 3.23 gears, then you can run the 268 cam & a 275.00 2600 stall, stay with a smaller carb though like a 600/650 cfm. You want to stay conservative, but not "TOO" conservative, because you won't be happy for long i'll garuantee, if your going to do that, then just drop in a stock 360 & be done 8).
 
Ok, cool, I would definitely like to change the gears to a lower ratio for sure once im there after a 500 mile trip, and I could pt the 3.23 gears in it that I have laying in the back for the trip down if I had to...Once I'm in town, I'd like to stay with 3.55's for sure. Which specific torque converter would you recommend for this build? Also back to this dual quad, dual plane intake setup...would that give me more power all around, and give me better high rpm flow compared to the single 4 barrel carb setup? I have a friend who has a 327 chevy motor thats on pump gas...that thing has dual quads, not on a high-rise intake, and it is fast! By the way, whats the specs on your 71 swinger JoeDust451? Just wondering..
Thank you,
-ANTHONY
 
schultec14 said:
Ok, cool, I would definitely like to change the gears to a lower ratio for sure once im there after a 500 mile trip, and I could pt the 3.23 gears in it that I have laying in the back for the trip down if I had to...Once I'm in town, I'd like to stay with 3.55's for sure. Which specific torque converter would you recommend for this build? Also back to this dual quad, dual plane intake setup...would that give me more power all around, and give me better high rpm flow compared to the single 4 barrel carb setup? I have a friend who has a 327 chevy motor thats on pump gas...that thing has dual quads, not on a high-rise intake, and it is fast! By the way, whats the specs on your 71 swinger JoeDust451? Just wondering..
Thank you,
-ANTHONY
Click to expand...

Its a very mild 360 magnum out of a 95 truck, I love the magnums, our DA is at 3000ft. right now, i'm running an 11" 2800 PTC converter & 3.73 gears, 650dp & summit headers & mufflers, RHS heads, cam is small, .477,.477-.218,.218 @50 112 lsa. I drive too & from the track (100 miles round trip) & clean house on many stangs & LS1 camaros, my 60fts are dead consistant at 1.82 every pass in this heat, best was a 1.79 last month, I run between 12.63 & 12.67 at 104-105 through the exhaust shifting at 51-5200. Best run was a 12.58.

On something like yours, i'd stay with a single carb, a 600 eddy will work good, but i like holleys, i'd either run a 650 square bore vacuum sec. or a 650dp.
 
It won't be easy to find a happy compromise between performance and mileage. Dual 4 barrels migh look neat and can be fast, they are not easy to tune. In many cases, a properly tuned 4 barrel on a good aluminum hi-rise intake will outperform a low-rise dual quad set up. Having too much airflow is just like too much cam or big ported heads, it will hurt low end and midrange performance, which is where the engine will spend most of its time, not to mention fuel mileage.
 
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