HELP - 383 W/ Edelbrock RPM Power Package 800CFM - Problems

[Gold70SportSatellite]

During the restoration of my car i decided to add some power to it as well. I have a 383 with adding the power package from edelbrock. With a Thunder series 800CFM Carb.... all brand new.! Car starts up fine and idles fine in park. Automatic transmission. Once i put it in gear it bounces around. At higher RPMS it seems to be very responsive. If i was to punch it out of the whole it wants to fall on its face before it goes. I and several other mechanics have made several adjustments to carb with barely any results. To narrow it down its a rough idle in drive and have to ease into it to get it going. can anyone help me with any sugestions? anyone local to me that would like to look at it? Before the upgrade i could slam the pedal as fast as i wanted to and it would jump and go. I miss that!

 

[Cranky]

What carb were you running before the upgrade?

 

[moparbob75]

make sure you dont have a vacuum leak around the intake, i had this problem before. you can spray starting fluid around intake and see if RPM changes if does thats the prob

 

[Gold70SportSatellite]

What carb were you running before the upgrade?

I believe it was an edelbrock performer series 600 or 650. I gave it to my son and he put it on a GM Crate 350. 290hp and it runs great on there. no problems at all. The power package reccomended going with a 750-800. i was thinking about putting a 650 back on today.

 

[70rr-brian]

800 cfm for just a stock 383 regardless of the manifold just seems like too much. What condition are the plugs in? Probably running too rich.

 

[Gold70SportSatellite]

800 cfm for just a stock 383 regardless of the manifold just seems like too much. What condition are the plugs in? Probably running too rich.

it has performer rpm power package which includes heads, cam, high rise intake. and when the lower end was rebuilt years ago it was machined .10 over. plugs are brand new with new mopar performance electronic ignition and orange E.C.U. Like i mentioned Edelbrock reccomends using the 800cfm carb using that power package on a stock 383 block.


HEAD SPECS
Combustion chamber volume84cc Intake runner volume210ccExhaust runner volume70ccIntake valve diameter2.140"Exhaust valve diameter1.81"


cam specs
DURATION AS ADVERTISEDINTAKE: 300°EXHAUST: 308°DURATION @ .050INTAKE: 238°EXHAUST: 246°LIFT @ CAM (Lobe)INTAKE: 0.32"EXHAUST: 0.33"LIFT @ VALVEINTAKE: 0.48"EXHAUST: 0.495"LOBE SEPERATION: 110°INTAKE CENTERLINE: 105°IDLE VACUUM @ 1000 RPM: 10"

 

[moperformance]

make sure you dont have a vacuum leak around the intake, i had this problem before. you can spray starting fluid around intake and see if RPM changes if does thats the prob

Do this first! Use carb cleaner if you don't have starting fluid, but verify there are no vac leaks. Did you rotate the engine around after the cam install to verify the timing marks lined back up? Go back to the basics.Try and rule as much out as you can
Good luck!

 

[lewtot184]

my opinion; too much cam for a 383 and too large of a primary venturi size for low rpm use. do a compression check. the engine will probably need at least 150lbs for that cam. do a vacuum test. the ignition curve will definetly need work with that cam. cast iron exhaust manifolds or headers? whats the true compression ratio? stamped steel rockers or adjustable? there are some accellerator pump adjustments that can be made to that carb. every time i see a post of a big hydraulic cam in a 383 i remember the time i tried it. a small solid is a better way to go if you're going to drive it.

 

[cr8crshr]

I agree...Too much carb for a 383. I am using a Holly 750 dual feed vacuum secondary in place of a CarterBrock. Also get a kit for adjusting your Edlebrock by swapping springs and metering rods. That might help also. But you gots way too much carb there

 

[lewtot184]

my favorite high performance 383 4bbl carb was a 780cfm vacuum secondary, like the hipo chevys used to run. my old road runner ran identical times with a 780 or a big 440 avs, but the 780 drove nicer. quick fuel is making this carb again. a dp6b with corvette carbs is a very nice set-up, but expensive to do right.

 

[Gold70SportSatellite]

update: put a brand new 600 on last night and checked timing again.... the vacuum advance wasnt working. i adjusted the tension and now it works great. seems to be running fine. thanks for all the advice. Not sure if i am going to keep the 600 on or put the 800 back on. I already put new springs in the 800. I am running 3" exhaust which was a bolt on kit from flowmaster. Not to happy with it. Today its at the exhaust shop getting a custom one. Any suggestions? is 3" too much? was thinking going with 2.5".... straight pipes? h-pipe?... trying to get ready to take to garlits on sunday. anyone going?

 

[70rr-brian]

I ran 2.25 exhaust and 3 inch exhaust on mine (555hp, 611tq) and honestly couldnt tell a difference.

 

[rumblefish360]

it has performer rpm power package which includes heads, cam, high rise intake. and when the lower end was rebuilt years ago it was machined .10 over. plugs are brand new with new mopar performance electronic ignition and orange E.C.U. Like i mentioned Edelbrock reccomends using the 800cfm carb using that power package on a stock 383 block.


HEAD SPECS
Combustion chamber volume84cc Intake runner volume210ccExhaust runner volume70ccIntake valve diameter2.140"Exhaust valve diameter1.81"


cam specs
DURATION AS ADVERTISEDINTAKE: 300°EXHAUST: 308°DURATION @ .050INTAKE: 238°EXHAUST: 246°LIFT @ CAM (Lobe)INTAKE: 0.32"EXHAUST: 0.33"LIFT @ VALVEINTAKE: 0.48"EXHAUST: 0.495"LOBE SEPERATION: 110°INTAKE CENTERLINE: 105°IDLE VACUUM @ 1000 RPM: 10"

The bigger carb is going to be a pain in the backside if the compression is low, gear ratio &/or the stall converter are low. (AKA lower than a 3.23 gear and stock stall. Bigger tires hurt the combo even further.)

 

[poly3521]

I would run 2.5" exhaust for the street. You shouldn't have to worry about adding the h-pipe unless you really want to. My 440 has headers, 2.5" with glass packs. Has a very nice classic sound, might be too loud for some.

 

[moperformance]

Glad you getting it straightened out

 

[dangina]

2.5" x pipe - you'll be fine...800 does seem like overkill