360 horsepower estimates and suggestions needed.

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71dusterdan

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Hey everybody Gonna start buying parts for my 360, just lookin for some educated guesses and maybe some suggestions or advise. The car is gonna be a near daily driver, I want decent mileage with my od trans. It needs to be mild enough to enjoy driving everyday, and I dont really want to spin it past 5500, but 6000 will be ok. Now years ago I had a .30 over Crower .509 cam,and appropriate springs, 9.25-1 comp, headers, performer intake, Holley 600(hated that carb), 3 angle valve job, on otherwise stock 1978 360 heads. Stock valvetrain, and rockers. The builder back then thought it was a solid 325-350 horse. It was fun, ran like a scalded cat in a 78 Magnum, but was a little rowdy in the idle . The power came on strong about 2200 and pulled well past 6000. So My new plan is .30 over as high as 10-1 comp, balanced, stock bottom end, RHS heads, Comp Hyd Roller cam either the 268, or 270...not much difference between them. Gross lift for either one was about .530's. My Eddy performer , and Thermoquad, with HP manifolds, whatever I need for ignition, stock , recurved should be pretty good. So what do you think it should make? Are the RHS heads a waste with this combo. The only thing I have so far, and am not willing to upgrade is the performer and TQ. Anybody think it can make more than 350 hp. I would love 400, but not at the sacrifice of driveability, or mileage. Thanks Dan
:burnout:
 
oh and just in case it is pertinent... 71 Duster, 4 spd, 3:55-1 rears and a 275/40/17 rear tire. All the glass, and no fiberglass.
 
Run the 274 hyd roller with 1.6 rockers and it will make more than 400 EASY! It will idle easy, with a mild lope, make good power to about 5600-5800 is my guess.

Get rid of the performer 318/360 intake if that's the one you have and get an Air Gap/RPM/LD340 and a 750 holley DP or Vac sec carb. HP logs will hurt you a bit.

The RHS heads will work fine with that combo and make good power.
 
Your not going to make 400 HP and keep the mileage. Buta better idle and in general, better performance can be obtained with a better cam. The idea of a roller is a good start IMO.

IF your going to keep the exhaust manifolds, you need a way different cam.

Use a MP M1 or Holley Strip Dom since there TQ friendly. If a dual plane is needed, then the Weiand Action Plus is what you want.

Oh, forgot to add, yea, I think the RHS would be a very good set of heads to run with.

FWIW, IMO, use headers into 2-1/2 pipe exhaust. You'll pick up alot of power.

Also, if you could supply cam spec, I or someone (Yourself) plug them into a desk top dyno program and see how it will work, though I take the power graph's with a grain of salt.
 
Call someone and get a cam cut on a 114 lobe separation angle as that works better with manifolds. The 110 will work well a 114 angle would be better.

I know guys like Brian at IMM can get custom cut cams for the same or less than a shelf cam in most cases.

If a 360 with RHS heads, 750 holley, headers and a std hyd XE275hl can make 430hp, a roller version with manifolds will bust out 400 pretty easy and not idle poorly. Properly tuned it could get 15-18 on the highway at a reasonable speed, 60-65 mph. Seen some hyd roller engine bust out WAY more power than most think they should, retain a real docile idle and mileage outputs.
 
I wish I could remember the size cam I had in my last 360-years ago. I had a 78 360 bored 30 over with 8.8 comp pistons, 340 intake headers with 2 1/2 out the back duals, and the tq 750 cfm. I hooked that to a 904 trans and 323 rear. Have no idea the horsepower it had, but there wasnt a stang that could get me! Any idea on the horse output I had? I know its hard without cam specs, but a decent guess? The cam was a good idle cam-not much lobe effect at all, but strong. Heads were the standard 1.88 valve.

Im looking to do the same thing again. This time maybe 9.o comp pistons-keep midgrade fuel, 2.02 valves, maybe shave the heads. I dont want to go all out- basically looking for a fun weekend car and good go to work car with some gas mileage.
Any ideas?
 
crackedback said:
Call someone and get a cam cut on a 114 lobe separation angle as that works better with manifolds. The 110 will work well a 114 angle would be better.
Click to expand...

LSA isn't the key here, but a the idea is good. I understand where your going with it. The real big issue is the restrictive exhaust manifolds that will need about 10 or more degrees of exhaust duration in order to get it to perform well.

The actual timing events will determine drivabilty.
 
TXDart said:
Here is a good read and link :
http://www.buschis-place.de/mopar_360cui_performance.htm
Click to expand...

Very useful info there.

I have a 1973 340 for my Demon 4 speed clone project that will need a rebuild. Like many I was enamored with the 340, partly due to recollection of a friends 340 Duster in my teens. The one I have did not cost me a lot. All I know is it turns over. It came with a TQ carb I'd like to make use of (if I can figure out how to tune it).

I envision a build much like package 3. Possibly aftermarket heads (not sure which). I'd like to assemble it myself.

From reading on FABO, I understand now that a 360, similarly built should have some advantage over the 340 in a street car for weekend cruising with the longer stroke giving better low RPM torque and a few extra cubes for total horsepower. I want enough power to do this :burnout: with tires that fill the wheelwell.
Pump gas. Don't care about fuel economy.

I don't care much about keeping things original and am wondering if the difference would make it worth building a 360 instead. I'm sure a 360 would be cheap at the junkyard. How much difference would there be? What would you guys do?
 
Plug in a Crower ultra street beast,(269/282 adv/112 l/c) some bowl work,on J or X castings. Most important thing is the valve job.Run out radius gauge,or serdi.Stick with the intake you and carb you have. Headers make it pop,if you can.Last combo, I had went [email protected] yeah,it got 22 mpg.
 
Idaho;

There's several threads on this, try a search. It is a subject half beaten dead, but, to answer your question;

A 360 is a better engine to build for these reasons;

A longer stroke for more torque to get the car moving sooner and quicker. Being the engine has a longer stroke, this will have the engine producing peak torque and HP numbers a few hundred RPM's sooner than a 340.
The 360 wins on torque and has a slight disadvantage in total HP. Both of these (TQ & HP) differences are small in a apples to apples comparo between the 2 engines built as close as possible between them.

The 360 has a little bit of a cost advantage over the 340. IF you had neither of these engines, the 360 comes cheaper to start with. Sometimes, you can get a full 360 out of a junkyard for as little as $200 while sometimes, a 340 block has been seen being sold for more than $700. IMO, $500 for machine work is a good jump start.

Besides crank, oil pan, pistons and balance-rs, everything else swaps over and between them.
In an example of parts being a little bit cheaper than a 340, only some parts are while others are not. The biggest savings I can think of off the top of my head is pistons. Zero deck height slugs from KB cost under $200 while the 340 units are a bit more at $260+.
 
As far as builds go, your description is broad and opinions will vary a lot. To this end, there is a nice page running around the net for about 10+ years now (LOL) that has some interesting set ups. The author lists parts and dyno results.

I have contacted the author before and he was most willing to help. (IMO I would not be surprised if he is on line helping now) A very nice guy about matters.
This should help a good bit.
Click his page here; ---> http://www.mopar1.us/dyno.html
 
Mr Rumble, thanks for responding on a beat up topic. I've done some reading but not great depth yet as I'm chopping on the body before engine work. This topic just kinda got me going as the engine to me will be the most juicy part as in interesting and fun. I'm saving it for desert.

The link is almost identical to the one given by TXDart. I think it's awesome information.

Abodybomber: "Run out radius gauge,or serdi"

What does this mean? I'm interested to hear more about valve work and its importance. I'm thinking about what a good valve job costs and the idea that a few bucks more would get new modern design heads. I know I should not ask too many questions that have been answered so I don't mind if you say "do a search".

71Dusterdan: sorry I'm kinda hijacking here.
 
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