383 runs like a giant turd WTF

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440dart123

440dart123

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So i have a 383 built to stock 70 specs with a mopar 509 cam and edle tourqer intake. I cannot for the life of me get this car to run good it idles great no burbles nothing smooth as can be crisp response running 750 dp. I checked the cam timeing its good, checked comp it was 140psi across the board. I even tried a 2 differnt carbs and same thing.

I talked to one guy and he said that the 509 sucks in a 383 now i could see it not working as well as some other cams but i not jokeing, a good running caravan could give this car a run for its $$$

car is around 3300lbs
4speed
3.55 gears
 
1. What is your elevation?
2. What is the actual static compression ratio?
3. What is the initial timing?
4. What is the total mechanical timing and all in by what RPM?
5. What are the exhaust components?

This is a place to START...
 
More info is needed. Who built this motor? Did they know what they were doing? what is the compression ratio? Was the block machined properly?
A 509 cam and 750 DP is not 1970 "stock specs".
 
roadrunnerh said:
More info is needed. Who built this motor? Did they know what they were doing? what is the compression ratio? Was the block machined properly?
A 509 cam and 750 DP is not 1970 "stock specs".
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That is because everything else is except the cam and carb. Which the pair are well known to make stock engines into turds.

383 runs like a giant turd WTF
So i have a 383 built to stock 70 specs with a mopar 509 cam and edle tourqer intake. I cannot for the life of me get this car to run good it idles great no burbles nothing smooth as can be crisp response running 750 dp. I checked the cam timeing its good, checked comp it was 140psi across the board. I even tried a 2 differnt carbs and same thing.

I talked to one guy and he said that the 509 sucks in a 383 now i could see it not working as well as some other cams but i not jokeing, a good running caravan could give this car a run for its $$$

car is around 3300lbs
4speed
3.55 gears
Click to expand...
Which 70's 383 spec slug is in there. The HP 383 had a high compression slug. The "509" cam should see a honest 10-1 at a min. The torquer intake is killing all bottom end. Your idle issue's are caused by 2 things I can see up front. Single plane and big overlapping cam.

MoPar put out a second series of cams on a wider centerline in order to smooth idle and increase the street friendly-ness of the cam. The C-lines are 110 and recommended to be moved down (Installed) @ 108. The newer one is a 112. Big difference.

What size tire with the 3.55's?

An old buddy of mine had a dead stock except headers 383 RR (1970) and IMO, it was slow.
 
Jim Lusk said:
1. What is your elevation?
2. What is the actual static compression ratio?
3. What is the initial timing?
4. What is the total mechanical timing and all in by what RPM?
5. What are the exhaust components?

This is a place to START...
Click to expand...

A big HELLO to Jim and a great idea to boot.

Also, did you centerline the cam as per MoPar instructions?
 
I tried a single plane on a 10:1 comp 383 with a 484 mopar cam and it was lame. I changed to a performer intake and it spiced things up. The engine was in a 68 charger. I installed 4:10 gears with 275/60/15s and a 2800 stall converter. That car was fun!
 
That combo,I would consider adding a good dual plane,and possible some Rhoades lifters.If setting the distributor curve doesn't work.Had a similar situation in a 396 chebby.Idle vac was 5 to 7".Curved the distributor,threw Rhoades lifters at it.Idle vacuum,(and low end torque!) went through the roof.Idle vac went to 12,and rock steady.That helps low end drivability,with a steady vacuum signal.
 
Never had any luck with a 509 without a lot of stall.That cam dont start pulling till at least 2500 r,s
 
I was told my MP 284/484 was "way too much cam" for my 9.5:1 70 HP 383.

I had the same torker intake as well.

Mine ran great, but... I spent time understanding and degreeing the cam.

I believe that 509 may actually be "too much cam", especially if you haven't degreed it.

I also had lots of stumbling issues, until I concocted "frankencarb", which was a 600 Holley with a seconday metering block added from a DP Holley (650, I think), and a whole bunch of pump, cam and jet swapping around. The 650, and 750 I tried must have been too much off idle, but not enough "shot". Was a nightmare to tune, but once it was in, it rocked!

I also ran a ****-load of advance, like 38* or so, but it did fine on 89 octane with a 1/2 tank of 93 on Friday night
 
rumblefish360 said:
That is because everything else is except the cam and carb. Which the pair are well known to make stock engines into turds.

The "509" cam should see a honest 10-1 at a min. The torquer intake is killing all bottom end. What size tire with the 3.55's?

An old buddy of mine had a dead stock except headers 383 RR (1970) and IMO, it was slow.
Click to expand...

mullinax95 said:
I tried a single plane on a 10:1 comp 383 with a 484 mopar cam and it was lame.

Abodybomber said:
That combo,I would consider adding a good dual plane,and possible some Rhoades lifters.

daredevil said:
Never had any luck with a 509 without a lot of stall.That cam dont start pulling till at least 2500 r,s
Click to expand...

Now that you know that combo doesn't have much low end, what kind of rpm's are you running it to. Once you get it up in the 4k-6k range it should still pull pretty decent. Is your tach accurate? I had a guy come to me once with a similar complaint. Had a big single plane and a cam in the [email protected] range. I told him to take me for a ride and he was shifting the 4spd. at 4800 to 5k. I got in it and went from a 3000 rpm roll in first and ran it 6500 thru 3rd gear and he looks at me and says...Damn:D.

Don't feel bad. Back in the 70's in my hood the 383's had a pretty bad rep. The only one's that really ran strong had 4.56/4.57 gears. With that said i know your around 3,200 ft. and that doesn't help, but with a focus on bottom end power via timing, maybe a dual plane and possibly a little more gear that Caravan wont stand a chance.....lol.
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Click to expand...
 
Yea, a good bit of gear and tire to hold it to the floor would fix it up a good bit. I'm wondering about the C-ratio and head chamber cc. Is this a true 10-1? As you measured it? Or as advertised by the slug maker?
 
Sage advice.I saw a wildcat of a 383 in the late 80's.70 Challengethe nasty Turbo Action 4200 stall, 4 .30s out back. 284/.484 D/C cam,healthy 906s (worked hard). 11.70s ,with a ct piston rebuilder's short block.
 
Rob, wern't the 2bbl 383's rated 9 to 1 back then? I can remember the most minute specs on some things and others i have to question myself and actully research it. Although it was 40 yrs. ago....lol.
 
Yes,as rumble posted.Heads,the same.Comp jumped,with increase of the Magnum cam(a la 68 Road Runner).
 
OldmanRick said:
Rob, wern't the 2bbl 383's rated 9 to 1 back then? I can remember the most minute specs on some things and others i have to question myself and actully research it. Although it was 40 yrs. ago....lol.
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I do *think* so. I forget myself. I'm not so engrossed in the car world as I used to be. This is why I questioned the C-ratio. The 383's are finiky (sp?) much like the 318. They lack bottom end torque. A cam of the 292's size, which is a sizeable cam, can kill it dead quick. Installed wrong, just 2*& retarded will mess things up.

The 383 is a capable mill. Something is off with this build. More info is needed. We could be over looking something simple as well. Remind's me of a 360 I built once. Similar deal. Poor runner. Could have gotten spank by a moped. Between the carb secondaries not fully opening, damper being off, (Stock one that moved, which also throws distributor timing off) and installed in the wrong key way on the timing chain...well, like I said, a moped could have taken me out. :violent1:
 
rumblefish360 said:
Remind's me of a 360 I built once. Similar deal. Poor runner. Could have gotten spank by a moped. Between the carb secondaries not fully opening, damper being off, (Stock one that moved, which also throws distributor timing off) and installed in the wrong key way on the timing chain...well, like I said, a moped could have taken me out. :violent1:
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LOL, i've been there too, with a few different brands also...lol. Wasn't near the products or info. we have today. Was more of a learning experience. This particular engine looks old school to me so i'm looking forward to what the OP responds.
 
I had a similar set up in my Barracuda and it had NO bottom end, I switched to the smaller mp 484 and an m1 dual plain and it was a different car, It became a frigging beast.

I forgot to mention I also changed out the original carter avs for a 700 Holly DP at the same time. Yeah it was my first build and I had the setup all screwed at first but after I got it figured out it was on.
 
rumblefish360 said:
I do *think* so. I forget myself. I'm not so engrossed in the car world as I used to be. This is why I questioned the C-ratio. The 383's are finiky (sp?) much like the 318. They lack bottom end torque. A cam of the 292's size, which is a sizeable cam, can kill it dead quick. Installed wrong, just 2*& retarded will mess things up.
Click to expand...

The 383 has only 0.065" more stroke than a 318 or 340, basically the same for all intents and purposes. Thus it has to be built like a small block; that cam is way too big unless you bump the compression up and/or put some really short gears in the back. Or throw in a stroker crank...:D
 
No,different animal.When you go big block,whole another world.Bigger bores,bigger intake valves.Way different response.
 
My 68 Coronet had a 383/4 spd Magnum. A 383 will rev almost like a 340 but produce Big Block Power. They are not a joke. It was stock before I rebuilt it, then added headers, tunnel ram, MP electronic ing, MP street hemi cam, hi vol oil pump, fully grooved mains, file fit rings, MP rod bolts, baffled pan w/ windage tray, heads were done by ED Garlits, 750 Holley, double roller chain, and a few other things I forget.... I ran it over 7000 rpm w/ stock rods and pistons.....Almost got one out of a 66 C body the other week but the ford boy thinks he has a gold mine (rotted up, needs total resto...)
 
MOPEkidD-3 said:
The 383 has only 0.065" more stroke than a 318 or 340, basically the same for all intents and purposes. Thus it has to be built like a small block; that cam is way too big unless you bump the compression up and/or put some really short gears in the back. Or throw in a stroker crank...:D
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Agreed!

Abodybomber said:
No,different animal.When you go big block,whole another world.Bigger bores,bigger intake valves.Way different response.
Click to expand...

Disagree!!!!!!

While the power output is a big jump up, the way you go about building one is truly No different than a 318 for the 383, like a 340 for the 400. All for engines listed above are
Short stroke engines and should be built likewise In the same manor.
 
depending on the year of your motor if i recall correctly i think you said it's a '70. some of those motors will not accept the '509 cam because there is valve to piston issues when there is no valve reliefs. you might want to do a leakdown test.
 
I have the same cam with TRW forged flattops,906 heads, edy tm-6, hemi battleship springs, 750 DP, gold ecu 36 total timing. 3800 9 inch convertor with 4.56 8.75. Barracuda was a dog after swap from 284/484. Degreed the 509 + 2 or maybe 4 (been 26 years ago)and she came alive. This cam needs a free converter and gears. Before I advanced the cam from the recommened centerline of 108 if my memory is right, she would not even break traction on the 275-60-15s.
 
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