383 build no power

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I ran the same cam in a 70 340 4 speed Duster with 4.30 gears and it ran like a raped ape. I did advance it 4 degrees. If I recall installed @104. I think the weight, gear and stall is holding you back. I think you have a prime example of over cammed.
 
.....I've been there b4 with the 383.......too much cam, too little converter, wrong timin curve............kim............
 
I had a similar problem with a 440 years ago. Turned out the valves weren't closing all the way. I had to shim up the rocker shaft. Trial and error a few times. Ran strong after valves set right... Do the compression check.
 
Well something's not right.
If the compression really is 10.7 and the cam is a 284/108 in at 104, then the ICA (Intake closing Angle) should be 66*. with those inputs, in a stock bore/stroke 383, the cylinder pressure should be closer to 170psi.And more importantly the Dcr should come in around 8.36, and that should make plenty enough torque to lite up 215s right off idle.
Because the pressure is down, and because it does not lite them up, I have to think that the C/R is not 10.7, or the cam is not in right, or the pressure is leaking away.
But moving the ICA to 70 * would still only drop the pressure about 8psi, to 162.

Now if the C/R is actually closer to 9.7, and with the ICA at 66*(cam in at 104*), then the cylinder pressure would be right around what you currently have.Now if that reflects reality then the Dcr would be down around 7.6, and that would be some lazy at low rpm.

So at this point I would be doing a Leakdown Test to prove the valves and rings are sealing.If they are sealing, then I see no way past this except a higher stall TC, to get the rpm up to where the torque is.

Or, as I would probably do, toss that bad-boy cam.
 
Brother-in-law had that cam in his 73 charger with an 8.5to1 383 400 tq intake and carb it ran best with 40 total timing. Car had 3.23s and stock converter. Car was down on torque but not near as bad as you described. You could still fry the 235 60 15s. Don't get me wrong, the car was no killer. Ran better with the stock hp cam. We were young and thought the cam would make this thing scream. Lesson learned.
 
72golddustermike said:
as told compression was 9.7 by original owner
Click to expand...

OOps, I screwed up! I had it in my head that post #1 stated 10.7. Sorry about that. And that then explains the problem.
As previously stated, too much cam for 9.7Scr, and the low-stall TC. The cylinder pressure is just not there at the 2000 stall-speed.
Stated another way tho; not enough stall for that 284 cam.

So to recap; you have two choices. A cam with an earlier closing intake, or a higher stall TC. Easy-peasy solution. And either solution is close to the same money.
A 3500TC will turn that 383 into a hi-rpm screamer;perfect for that short-stroke,big-bore engine.With this TC you can put some more serious rubber in those wells.
And a 262/110 cam,in at 107,( or that Lunati 256/262/112 in at 110) will turn it into a tire-frying,smile-inducing,tow-anything,torquer.This will get you a 58*ICA, and might bring the Dcr up to about 8.1 and the cylinder pressure to over 160psi. But I think the TC would still need to be bumped, just not to 3500.Probably 2800 would do it.Maybe even a tad less.This would make a nice cruiser engine.

Since the TC has to go in either case, Hmmmmm;decision,decisions........Lots of good advice in this thread; I counted at least 8 right-on posts,not including my junk.
 
Replace the Auto for a 4 speed and your fun factor will go through the roof!!!!

We will not be able to wipe the smile off your face!
 
Compression readings are low. I'm guessing the static compression is lower - he used "9.7:1 pistons" with a typical taller-than-blueprint block and it's closer to 9 or less depending on the heads and gasket. Then the .484 is not in advanced enough anyway. Best plan IMO is replace the cam, then you can either have FBO try again or get back to a better ignition setup.
 
checked vacumm readings again idle 9.5 out of gear 4.5 in gear. out of gear I can turn idle adjust in and engine will die like it supposed to,but I have to turn 3 turns for highest vacumm readings
 
72golddustermike said:
checked vacumm readings again idle 9.5 out of gear 4.5 in gear. out of gear I can turn idle adjust in and engine will die like it supposed to,but I have to turn 3 turns for highest vacumm readings
Click to expand...

A) Somethings not right with that. What idle rpm goes with that in-gear 4.5 inches? I've seen smaller engines with bigger cams have more Neutral vacuum, and more in-gear vacuum.
B) And is the idle timing still 30 degrees? And where does the timing drop to, at 4.5 inches? See, with the Vcan hooked to manifold vacuum, the timing at 4.5 will likely drop right out, leaving you with 12 less degrees. IIRC that would be 18*.If that happens, that's another nail in the coffin for running full-time vacuum to the Vcan.And if the power valve is opening at 4.5, the boosters may be dripping.But at 3 turns out on the mixture screws, that's likely not happening.
C) Ima thinking the butterflies are not open far enough.The transfers are not supplying quite enough fuel. That means the speed-screw needs to be cranked up a bit. Then To get the speed back down,either the secondarys need to be closed up, or the idle timing reduced, or you need to go hunting for air that is getting into the engine from some other uncontrolled source; such as a faulty brake booster, a faulty PCV system, a carb base gasket, a leaking intake manifold, a falling apart carb, or any other vacuum device, and finally a too-tight valve lash/faulty geometry (which takes us back to the leakdown test,per post #29).
 
Wow! That's some tight TC.
Get some eyeballs on the boosters as she is idling in gear.If they are dribbling, however slightly, then yes a PV swap will help. But this is not the right question, nor the right answer.
The right questions are; why the 360 rpm drop when in gear?Why are the mixture screws out 3 turns, and above all; at 950 rpm with 30 degrees of idle-timing, why is the vacuum only 9.5
inches?Solve this riddle and the PV will take care of itself.

Back to Post # 36
 
checked for vacuum leaks with propane around carb intake no change in rpm or vacuum
guy I got it from said he installed cam strait up. I have I- phone video of vacuum gauge ad rpm but don't know how to upload it
 
72golddustermike said:
Engine was rebuilt when I got it here are the specs

70 challenger
9:7 compression
Old 284 484 cam
2000 stall
3.23 gear
215/70 14 tire
Factory 600 holley
Factory intake
HP manifolds

Car will not even think about spinning a tire. it has no power at all. I have a pertronix 3 distributor that was curved by don at fbo he curved it to be all in at 3200 could this be the problem, I am almost ready to just yank the cam out and replace it with one that would suit me its a show/cruiser not looking for high rpm.
any suggestion
Click to expand...

Normally Rhodes would be a great idea. But
I'm not sure those are such a good idea for this app.
I guess the OP would have to decide if he can handle the clickity-clack.
 
72golddustermike said:
checked for vacuum leaks with propane around carb intake no change in rpm or vacuum
guy I got it from said he installed cam strait up. I have I- phone video of vacuum gauge ad rpm but don't know how to upload it
Click to expand...
You know what, at 9.5 inches, sometimes propane just won't get sucked in, especially with the fan buzzing around at 950 rpm.
Normally, straight up means "dot-to-dot" and no degreeing having been done.There is just no easy way of checking it.

Back to post #36
 
72golddustermike said:
checked for vacuum leaks with propane around carb intake no change in rpm or vacuum
guy I got it from said he installed cam strait up. I have I- phone video of vacuum gauge ad rpm but don't know how to upload it
Click to expand...

You have to post videos on youtube and then put a link here.
 
AJ/FormS said:
Normally Rhodes would be a great idea. But
I'm not sure those are such a good idea for this app.
Click to expand...

Why not?

They will bleed down .025" lift and 15° at idle and help tame his cam out... It will improve the low and mid range that he needs....

I put them in a 340 with a 484/284 cam with a stock converter and 3.91 gears and it ran like a raped ape....

I could roast the tires at will, but the guy taking this picture didn't know and snapped it too early...

View attachment Barracuda 2.jpg
 
Well, it's just my opinion.Based on the following inputs;
Firstly he's wanting just to show the car and to cruise it.
Secondly, in his first post, he linked us up with small cams
Thirdly, He states that he's not looking for a high rpm screamer.
Fourth, he has limited tuning skills.
Fifth, 284 less 15 is 269, which is still too much for his combo
Sixth, he's still stuck with that 2000(or less)TC
And the 2.93s
And then there is the clickity-clack.

So that comes to about 8 reasons, in my opinion.
 
AJ/FormS said:
Well, it's just my opinion.Based on the following inputs;
Firstly he's wanting just to show the car and to cruise it.
Secondly, in his first post, he linked us up with small cams
Thirdly, He states that he's not looking for a high rpm screamer.
Fourth, he has limited tuning skills.
Fifth, 284 less 15 is 269, which is still too much for his combo
Sixth, he's still stuck with that 2000(or less)TC
And the 2.93s
And then there is the clickity-clack.

So that comes to about 8 reasons, in my opinion.
Click to expand...

Let's address these individually:

Firstly he's wanting just to show the car and to cruise it.

Rhoades lifters won't interfere with that. I showed and cruised my Barracuda. Nobody complained about the lifters and I didn't notice it. If it's such a concern, then double up the hood insulation pad and/or tell them that you have a mechanical cam 273...


Secondly, in his first post, he linked us up with small cams

A set of lifters is cheaper than a new cam and may fix his problem...


Thirdly, He states that he's not looking for a high rpm screamer.

He's complaining that he can't spin the tires... That would require some degree of performance... Kinda negates this argument...


Fourth, he has limited tuning skills.

Rhoades lifters tame out the engine and make it easier to tune...


Fifth, 284 less 15 is 269, which is still too much for his combo

269 is between 268/276 which is the stock 340 cam specs. It's not that radical... 383 2 bbls had 260/268 cams, and 4 bbls have 268/284 cams, not far from 269... And those engines came with 8.7 compression in 71... One degree will not make that much difference...


Sixth, he's still stuck with that 2000(or less)TC

I always run stock converters. My Barracuda has a stock converter, it runs fine... I've used Rhoades with all of my builds for the past 25 years with small or slightly larger cams with no problems...

I ran Rhoades lifters in a 318 with a stock 340 cam, 2.76 gears and stock converter. It idled at 24" Hg with 318 heads and 2 bbl intake, then only dropped down to 22.5" Hg when I upgraded to a 4 bbl and 360 heads... I got 17.75 MPG with a 10.5" power valve in the carb...


And the 2.93s

May be a little low, but may also be workable with the Rhoades lifters...


And then there is the clickity-clack.

As stated earlier, tell them it's a 273 solid lifter engine or double up the hood pad for more sound insulation... Or get louder mufflers or stereo to help cover it up...
 
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