right carb for this set up?

[djais1801]

I have a 71 Satellite with a 383ci, 727w/ 3500 stall converter, 509 cam, torker2 intake w/ 750 holley carb, H-pipe w/ flowmasters, 83/4 posi -391gears

It has a vacuum advance on the distributor, but the timing is off, and the car is running real rich.. and a slug in 1st gear (timing)

The 750 is no choke...

I think this was set up as a 1/4 mi car...but I want to use it as a street friendly, lay tires...go to cruise nights,etc.

ALSO, I am going to put a 4 spd in her in the summer.

Is the 750 appropriate..not sure what jets were used..should I wait until I change it over to a 4spd to worry about the carb?

Thanks,
Ivan

 

[FridayGt]

I have a 71 Satellite with a 383ci, 727w/ 3500 stall converter, 509 cam, torker2 intake w/ 750 holley carb, H-pipe w/ flowmasters, 83/4 posi -391gears

It has a vacuum advance on the distributor, but the timing is off, and the car is running real rich.. and a slug in 1st gear (timing)

The 750 is no choke...

I think this was set up as a 1/4 mi car...but I want to use it as a street friendly, lay tires...go to cruise nights,etc.

ALSO, I am going to put a 4 spd in her in the summer.

Is the 750 appropriate..not sure what jets were used..should I wait until I change it over to a 4spd to worry about the carb?

Thanks,
Ivan

Hmmm, well, I've got an Eddy 750 on my 440 that's defenitely not enough in stock configuration that I'll be richening up, but not certain about your 383 built like that. My suggestion would be to get your timing set right first, then focus on adjusting your carb based on how your plugs are pulling.

 

[Moparmatt72]

I would check timing, and you can always plug plugs and read the color to see if you too rich or lean, but a 750 should be a good size for a 383

 

[PoppaSmurf]

a 750 should be absolutley fine.. sounds as if you have not only a timing issue but a primary jet issue as well....what type of carb are you running..???

 

[djais1801]

it's a holley 750, not sure the specific model..but i know there's no choke.

 

[lewtot184]

too much cam. power valves may be leaking thru. that 383 will need some serious ignition curve mods.

 

[67 B-body]

Fix the timing,,,, Make sure the float level is set correctly,,,,, then adj idle mixture screws to provide a NON rich condition at idle,,,, then drive it and read the plugs. In that order too....
To optimize things, check MANIFOLD vacuum with a guage at idle, and compare the power valve to that reading. You should see a number stamped into the side of it on a flat "wrench flat", this is the valves rated opening point. You want it to be a couple inches less than manifold vacuum at idle for it to operate correctly. They are available for purchase in different increments to fit your application.

 

[djais1801]

too much cam. power valves may be leaking thru. that 383 will need some serious ignition curve mods.

like what?

 

[lewtot184]

like what?

like too much cam, simple.

 

[Meep-Meep]

A slug in first gear (no low end?) I'll bet is caused by not enough compression for that cam. A .509 is a pretty serious cam and if you want a street cruiser go smaller. Here are some tips to diagnose your issue.

First do a compression check. A proper street setup should be 150-160 in every cylinder with little variation. If you have something barely over 100 in all cylinders stop what you are doing and swap the cam or otherwise find out what's causing the low cyl pressure readings. If it's over cammed (as I suspect) then properly match the replacement cam to the existing compression ratio then sort the timing out. I'd dump the Holley 750 and put on a 650 Eddy or some other street calibrated carb. I'm thinking you have a 4779 Holley now and that is not a street carb. The idle and low speed circuit are not very street friendly and will tend to run rich.

 

[67 B-body]

A slug in first gear (no low end?) I'll bet is caused by not enough compression for that cam. A .509 is a pretty serious cam and if you want a street cruiser go smaller. Here are some tips to diagnose your issue.

First do a compression check. A proper street setup should be 150-160 in every cylinder with little variation. If you have something barely over 100 in all cylinders stop what you are doing and swap the cam or otherwise find out what's causing the low cyl pressure readings. If it's over cammed (as I suspect) then properly match the replacement cam to the existing compression ratio then sort the timing out. I'd dump the Holley 750 and put on a 650 Eddy or some other street calibrated carb. I'm thinking you have a 4779 Holley now and that is not a street carb. The idle and low speed circuit are not very street friendly and will tend to run rich.

I'm not sure what comp is best for the 509 cam..... I ran it with a 10.5:1 engine years ago, and it too lacked bottom end unless you dialed in a bunch of initial advance! I upgraded to a 3500 - 3800 rpm conv, and it made a ton of differance! I left the initial timing advanced even with the new added stall. I had 4:10 rear gears in the 8 3/4 housing too....
And IMHO that carb should be fine..... I use them on mine engines and you can lean the idle down far enough to stall the engine! I even get to the point to where I have water flickering out of the pipes at idle.... Good burn!
Correct power valve sizing goes a long way too...... when the carb measures the load "drop in vacuum" it does give a bit more fuel to get you through the acceleration,,,, I dont know, I guess I must be a lucky guy! :icon_joker:

 

[Meep-Meep]

I'm not sure what comp is best for the 509 cam..... I ran it with a 10.5:1 engine years ago, and it too lacked bottom end unless you dialed in a bunch of initial advance! I upgraded to a 3500 - 3800 rpm conv, and it made a ton of differance! I left the initial timing advanced even with the new added stall. I had 4:10 rear gears in the 8 3/4 housing too....
And IMHO that carb should be fine..... I use them on mine engines and you can lean the idle down far enough to stall the engine! I even get to the point to where I have water flickering out of the pipes at idle.... Good burn!
Correct power valve sizing goes a long way too...... when the carb measures the load "drop in vacuum" it does give a bit more fuel to get you through the acceleration,,,, I dont know, I guess I must be a lucky guy! :icon_joker:

I used to run around with a 700 DP on a hot cammed 383 and it was fine but it would foul a plug every now and then. Could have been the lack of an MSD. Anyway, I'm just saying there are better carbs for street driving.

From the description I'm thinking he has 8.5:1 maybe 9.0:1 compression.

 

[djais1801]

like too much cam, simple.

that's not what i meant...what ignition curve mods would you suggest?

 

[djais1801]

i got the car back today after fixing the ball joints, steering shaft coupler, harmonic balancer that fell off..alignment, and timing reset.
It definitely has Woke Up..it's still REAL ANGRY at cold start..stammering, stuttering until warm..then it was good..I am thinking that it needs at least a mechanical choke, which means i will be hunting for a new carb..forgive me if we keep going over this, but is it okay to start at the carb..see how it goes, and then move down to the cam/gears?

 

[djais1801]

had a huge backfire out of the carb, and seems like i blew the power valve out. I just ordered a Holley Street Avenger 770, electric choke. i also just talked to the previous owner who said that the car has 906 heads that had a lot of port work..not sure what that would mean for compression...

 

[onebadbee]

djais1801
I have a 68 40 over 383. I have 9.1 flat top piston with mild ports and polished 906 heads with a little cleaning in the bowl areas. I have been running a Hughes engines (old profile) 515-536 lift cam and a M1 intake for about ten years. I have used a 750 performer and a Holley 670 street avenger on it. The Holley did have an all around better performance, once I got the right vacuum spring. I have a still run hp manifold that are matched the heads.
Make sure your time is right.

 

[flypaper]

you need to start from the bottom up.

it sounds like you have too large of a camshaft and or carb going on.
meep-meep has the direction you should be heading

a stock 383 came with a 625 or 650 carb
to run a cam as big as you have right now,you do
need the ported heads you have and
you almost better have some
pistons that cost some good bucks down inside that engine
to push the compression ratio up so it will all keep up together...
(one change made can effect many things all need to be matched)
you need to know that before you can match something up that will work
best for you.

 

[FridayGt]

had a huge backfire out of the carb, and seems like i blew the power valve out. I just ordered a Holley Street Avenger 770, electric choke. i also just talked to the previous owner who said that the car has 906 heads that had a lot of port work..not sure what that would mean for compression...

Well, as they're all kind of dependent on one another, there's defenitely nothing wrong with making sure every system works correctly before verifying the other. Since you already bought another carb, you should be fine, but otherwise, I would have suggested just rebuilding for something like a power valve.

But, getting back to your previous question, are you choking it manually with the gas pedal? This is what I had to do with my last carb until I got a choke set up on it. Also, have you verified your initial timing vs. Your aftermarket cam? This could also affect your initial timing which could in turn require modification of your distributor to achieve both inital and advanced timing requirements.

 

[451Mopar]

Because the crank stroke is so short on a 383, I think of them more as a large bore 340. The crank strokes are almost the same.
If it has stock heads (open chamber) and non-domed pistons the compression will be fairly low for the 509 cam. The 3,500 stall converter and 3.91:1 gears are helping cover up the loss of low end torque. If my guess is right, you may only have about 6" of vacuum or less at idle. If the carb still has the 6.5" power valves they won't close and the carb will be rich. Also, it is likely the low vacuum requires the idle be set to where the throttle blades are into the transition circuit at idle.
I would use a smaller high rate of lift cam like those from Hughes, Launiti Voodoo, or Comp XE series with about 220 @ 0.050" duration (depending on actual compression ratio.) then use a Performer RPM dual plane intake. The 750 is a bit big, but can be made to work. A 650 carb might limit maximum high RPM power, but be more responsive on the street (and get better fuel mileage.)

 

[451Mopar]

Sorry, I did not read all the posts before the last reply.
Looking at the photo of the carb, it looks like the idle speed screw it cranked in pretty far, so I'm guessing your into the transition circuit at a fast idle? Usually the throttle blades are drilled to get more air at idle allowing you to close up the throttle blades and get out of the transition circuit, the the idle screws will have more effect. That would help idle mixture, but not the low end torque loss from having a high RPM engine combination.

had a huge backfire out of the carb, and seems like i blew the power valve out. I just ordered a Holley Street Avenger 770, electric choke. i also just talked to the previous owner who said that the car has 906 heads that had a lot of port work..not sure what that would mean for compression...

I think you should have gotten the 670 Avenger, and some 3.5 or 4.5 power valves.
Heck, I'm running a 770 on a 505" stroker street engine.
The problem of using too large a carb on the street is that at most normal crusing speeds around 30-40 MPH the throttle blades will only be slightly open and running more on the idle/transition circuit of the carb, than the main metering system.