Dyno'ed My 360..it's a pig..what next?

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superdart

superdart

Shade Tree Tinker Gnome.....
Joined
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First, here is what I have.

1977 360 block, bored .030 over
Flat top pistons (supposedly 9:1 cr)
Factory crank, ground .010 on all the surfaces
625 Carter AFB
Eddy Airgap intake
Doug Herbert E3N cam (455/475)
576 heads "cleaned up" stock valves, chrome MP rocker shafts, adj roller rockers.
comp headers (brand unknown) 1-5/8 primaries, 3" collectors
2-1/2 duals, crossover, Edelbrock mufflers
FBO ignition curved for my setup
19 degrees advance at idle, 34 degrees total at 3400
Holley street/strip 72gph E-fuel pump, 3/8 aluminum line, regulated to 5.5psi at the carb.

Power goes through an A-518 and 8.25 rear end with a sure grip and 3.55 gears.

I did not do the actual build. I bought the parts, and a very respect member from our Mopar club built it. Mind you, it was built 15 years ago, and been driven several thousand miles. I only now got around to putting it on a dyno at a club event.....and was thoroughly disappointed. I always new it lacked power, and figured it needed tuning, but damn........

181 hp and 251 ft-lbs ??????

:protest: :violent1: #-o

Dyno%20Dart_zpsnlz03yvo.jpeg


Obviously it's running lean, and I need to address that first off. But lack of fuel isn't going to make up for what I was hoping to see at the wheels. Everyone was kinda thinking 240 was a realistic goal (assuming good tuning).

I'm looking for some input/opinions on where I should go. Is it just getting choked by the heads? Too Are there larger issues?

Ultimately it's a cruiser, weekend toy.....not any kind of race car and "absolute numbers" don't matter....but it's the biggest engine I have, and it makes the least power. :wack:
 
Well there's nothing to exotic on it, your actual compression is probably closer to 8.1 . You might want to try a 750 VS. Holley other than that start checking for leaky valves or low cyl psi.
 
Carb is too small and it starts leaning out right before the HP peak RPM. Throw a 750 cfm carb on there (Holley for max HP IMO), get the A/F dialed in and it should pick up 30-50 horses. You might be able to put in a couple more degrees of timing advance as well.

Also how long ago was it tuned up? Cap, rotor, plugs, check plug wires etc... what kind of "flat-top pistons" you said you bought the parts do you happen to remember or have a receipt? And how tall are they (zero-deck or below-deck)? What about duration specs on the cam? Sorry for all the questions but all these things come into play.

EDIT: nvm about the cam I looked up the specs but the E3N cam says it only has .440/.465" lift with 1.5 rockers and 215/225* duration at .050" lift... rated for 1500-6000 RPM yeah I think your carb is much too small. I run the same 625 AFB on mine for the street but I know for sure it's choking down the power above 4000 RPM, and my cam is about 1 step smaller than yours in duration but with more lift and 1.6 rockers (Lunati Voodoo 256/262), also mine has true 10.5:1 comp.
 
This^^^^and i would look at the cam to see if it's degreed in properly.
 
It drops power after 4750 rpm there is no rpm in this engine it will never make power with this setup. you need to address heads and cam and carb
First thing to go would be the valves. invest in good high performance valves (2.02/1.60)and a really good valve job not a std 3 angle but a good 5 angle. next would be the cam I would pick a voodoo 703 for this build. A inexpensive QF Slayer carb 750 will work very well.
 
"Ultimately it's a cruiser, weekend toy.....not any kind of race car"...... Ok, I'm going to go out on a limb here and say the "return on investment" of changing to a 2.02 valve at this level just isn't there.
 
It needs fuel!

There is a restriction in delivering the fuel. Get the fuel curve right and the power will be there, From about 4K up it's leaning out. Whether it's pump, jetting or something else, you need to find it. Something as simple as the float level being messed up can cause this.

Simple deal, step up the jetting at all 4 corners, if it lowers the numbers at the end to the 13's you are headed the right direction.

Try a different carb if you have access. A known good 750 VS carb would be a good rest piece. The current carb size is NOT the issue.
 
I agree with all on that its a fuel/timing, but I don't think you need a 750 cfm carb to make 240 HP. I have a very similar 360 with a 570 cfm Holley Street Avenger. I got my carb from Holleys refurbished shop on EBay for less than $250 and it was night and day compared to the AFB I replaced. Then get it to a Dyno shop that knows Carb tuning, can adjust your advance, and work the timing. I don't have the sheet in front of me, but my rear wheel HP went from 195 with the AFB to 247 HP (and 320 TQ) with the new carb and Dyno tune.
 
Another thing to think about is the exhaust. Compression bent 2 1/2 " full length exhaust can cost a lot of power even on a mild motor. Might try pulling it off and adding some collector extensions and try testing it again.
 
A-518....727 with overdrive....Horse power eater....
 
Do verify that you have the secondaries fully opened at WOT.That being said go back to the basics and recheck everything tune-up related.Get the a/f ratio where it should be before you start making changes.
 
superdart said:
First, here is what I have.

1977 360 block, bored .030 over
Flat top pistons (supposedly 9:1 cr)
Factory crank, ground .010 on all the surfaces
625 Carter AFB
Eddy Airgap intake
Doug Herbert E3N cam (455/475)
576 heads "cleaned up" stock valves, chrome MP rocker shafts, adj roller rockers.
comp headers (brand unknown) 1-5/8 primaries, 3" collectors
2-1/2 duals, crossover, Edelbrock mufflers
FBO ignition curved for my setup
19 degrees advance at idle, 34 degrees total at 3400
Holley street/strip 72gph E-fuel pump, 3/8 aluminum line, regulated to 5.5psi at the carb.

Power goes through an A-518 and 8.25 rear end with a sure grip and 3.55 gears.

I did not do the actual build. I bought the parts, and a very respect member from our Mopar club built it. Mind you, it was built 15 years ago, and been driven several thousand miles. I only now got around to putting it on a dyno at a club event.....and was thoroughly disappointed. I always new it lacked power, and figured it needed tuning, but damn........

181 hp and 251 ft-lbs ??????

:protest: :violent1: #-o


Obviously it's running lean, and I need to address that first off. But lack of fuel isn't going to make up for what I was hoping to see at the wheels. Everyone was kinda thinking 240 was a realistic goal (assuming good tuning).

I'm looking for some input/opinions on where I should go. Is it just getting choked by the heads? Too Are there larger issues?

Ultimately it's a cruiser, weekend toy.....not any kind of race car and "absolute numbers" don't matter....but it's the biggest engine I have, and it makes the least power. :wack:
Click to expand...

Supposedly 9:1? It is or isn't? You should know. It needs to be at least 10:1.

But lack of fuel isn't....what? Where do you think making power comes from?

Carb is way too small. No doubt.

What size valves are in those heads? I have no idea what the stock size is.

Sounds like you have a stock build, through the chassis.... Why are you bothered by it, what were you expecting 300HP?

What are your plans either way? If you want more power you are going to have to take the motor out.

Cam is too small no doubt, needs to be in the .48- .5 range. Comp needs to be legit 10:1, real valve job and pocket port MIN, with good springs. Motor needs to rev comfortably to 6K. Carb needs to be 650-700 cfm. Headers may need to be 1-7/8 primaries and stepped.

Dynos are either the ultimate truth, or liar...depending how they are set up. Just another tuning tool.

Brian
 
I guessed you'd make 285 at the crank before looking at the graph. A 750 is probably too big, 1 7/8 headers are totally unnecessary. You need a bunch more compression, worked over or new heads, and a bigger cam to get anywhere. I bet with some carb tuning you could get a lot closer to 200 at the wheels. Not all dynos read the same. You could jump on someone else's rollers and read something way different.
 
First - if it's a cruiser then tell people it's 300hp and drive it.
Or - if you want the power... There's the potential for a ton of screwed up, power robbing issues with your setup. The vast majority can come from simply skipping some steps during machining and assembly or chosing components that are simply not that good (at least IMO). I don't think it's the carb. Obviously that carb wasn't tuned & I feel a 750 would be too much for a mild cruiser. The exhaust is more than it needs, but isn't robbing power. The heads are probably a mess and the bissgest choker. I've seen what "cleaned up" reused clapped out heads look like and they waste a lot of power. The cam is too small IMO, and I would have wanted another 10 degrees at .050 and another .030-.040 lift.
 
MRL Performance said:
It drops power after 4750 rpm there is no rpm in this engine it will never make power with this setup. you need to address heads and cam and carb
First thing to go would be the valves. invest in good high performance valves (2.02/1.60)and a really good valve job not a std 3 angle but a good 5 angle. next would be the cam I would pick a voodoo 703 for this build. A inexpensive QF Slayer carb 750 will work very well.
Click to expand...

This here ^^^^^^^ seems the best advice to me. It all comes down to how much money you want to spend though. IMO, everything you have (cam, carb, headers, and valves/heads) are too small for 360 ci. If you have to piece things together get bigger valves/or complete heads first, and then go from there, cam, carb, and headers. Also, everyone's definition of a street cruiser is different, I know people who consider mid 11 second 4spd cars with 4:30-4:56 gears street cruisers. Good luck and hope you get it ironed out.
 
From reading the build, it is what I would expect. The 240HP guess is close to accurate for at the flywheel. The cam is small and about what it would do with those parts. I used a Crane Cam 216/228-,454/,480-112 cam it and was a fine driver for the 318 pumping out high 14's at her best with 3.21's on a stock tire & converter/trans.

Raise the compression if it is low and as said, cam, carb after that.
 
What is your budget?

You can't get better advice than from ABODIES only...the only trick is to figure out which one you can afford/do yourself or pay someone to do it for you. If you had $5000 -$8000 to spend and you were looking to get closer to 380-450HP, I would recommend you pull your motor, and send it to MRL performance or Indy Cylnder Head (or someone that really knows MOPARS). I really like what MRL Performance recommend (new cam, aluminum heads, valves, lifters, intake, new carb MSD ignition etc). Let them do what they do best...build awesome motors. If I had to do it all over again, I would have paid $10,000 to MRL performance to build me a 500HP motor from scratch the right way rather than let the hack job idiot that I used locally try and do it for me. (he was trying to put LA heads on a Magnum Block and couldn't figure out why he kept bending pushrods and valves). I spent $5000 on parts (block, heads, valves, cam, etc) ended up having to ship my motor to INDY Cylinder Head to have them tear it all down and start over and fix the problems. (that cost me another $5000). So I am $10,000 into my motor. I could have had one BAD A$$ motor from MRL for $10,000!

IF you dont have that kind of cash, I agree with everyone else, pull the engine, start with the cam shaft, have your iron heads tuned, new high performance v build the rest of the motor around the cam. It really is the heart of the engine.

Now I don't know everything, and again, I AM NOT A MECHANIC...most of these guys on FABO have forgotten more than I will ever know..but from a lay person (a customer who says please build me a sweet engine) I have learned the hard way...I would have been better off to have it built by a professional shop.

Good luck..send us some before and after pics..and tell us how it goes!
 
That set up with good tuning and what he has should make 300-325hp.
 
To answer some questions (I'll try to get them all):

Pistons - I don't know. They came with the lower rotating assm when I bought the car (some assembly required). In fact, all of the lower assembly, heads, etc, came with the car when I got it (I added the roller rockers and chrome shafts later). Things like the cam, intake, carb, peripherals, etc I bought to get the engine together. Yes, it's an issue, and it's one reason I'm leaning toward hitting the reset button and starting over, so I KNOW what is in the car....but that is more money that dealing with what I have.

Fuel - What I meant was I don't think I'm going to get near the 240 everyone was expecting just through fixing the A/F issue. Fuel volume and pressure and good.

Money - My card has a high limit....but I don't like running my hobbies on credit. :D Honestly, dropping $10k on a motor, for my purposes, is silly. If I was going to spend that I'd sell the Dart, the Avenger, add that money, and put it down on a 392 Scat Pack, or even "just" a Super Track Pack R/T.

Street Cruiser - They hit 5200 on the dyno...that is probably the FASTEST that motor has ever spun in 15 years. Even in it's current state it "works" as a cruiser and fun car just fine. The fact that it's "not right" will just bug me to no end.

Yes, I know the 518 OD saps power, but turning 2200 rpms at 70mph is just NICE. I figured this was going to hurt some.

Tuning - maybe 5-7k miles on the cap, plugs and wires. Trans and fuel filters get changed every few years. Fuel tank, sending unit, etc are all relatively new.

After looking at what stock 4bbl 360s were back then (220/280), versus mine (with the lean fuel condition) the numbers are probably about right. There was definitely a torque increase, even with the 518 and the lean A/F. We'll see what happens after some carb work and general tuning.

If I know it's a least "right" maybe I'll be happy. I considered a nice little 318 instead, but then I'm giving up the low end torque that's handy for daily driving.
 
You pretty much have stated the obvious,the 576 castings though a replacement head did come with more material in them and were meant for superstockers to work over and flow less than other big port Mopar heads,even the 308s they replaced.
The carb is costing you 20+ HP and what cam are you running?
If your compression is really low even some ported big valve 302 heads,with 1.88" intake valve would boost performance a lot.
Especially seat of the pants torque.
 
stock hi compression 340's were only about 280 and that would be around 190 - 200 at the rear wheels.i don't think your there with a lo comp. 360.
..i think Gumper is correct.. and that transmission is a power robber too.
..Dynos can really vary,some getting unbelievable power where it doesn't seem possible.
 
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