Right Carb for my 340

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buddyralf

buddyralf

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Hello all. I was wondering what the A body group would suggest for my 340.
spec:
10.5:1 comp
509 lift 292 dur (purple shaft)
Eddy heads
M1 dual plane
4 spd
3.73 or 3.23 gears (depends where I am going)

I now have a 700 double pump and its going through fuel like nothing. I think like a lot of you men and women, I just want to be able to drive the car and get some sort of distance to a tank. What can I do? I figure I will start with the carb, the calculator on the web sits says 570-600 cfm for a 340.
What do you guys say?
If a small carb like a 600 cfm, what size jets so that I don't have a fuel problem?
Any suggestions will be appreciated, I thank you all in advance.

104_0412.jpg
 
The cam is a bigger fuel eater then the carb is but a vacuum secondary or Eddy carb would likely be better on gas then the double pumper.
 
Holley 670 Street Avenger - and get rid of the 509 cam - go for something like a CCams 268 - way better street performance - and less gas gussling - little work for a big pay-off.
 
I think the cam is what is sucking the gas not the carb.

I have a 10.7 comp, 360 .030 over with a 474/474 Purple shaft and it has a good lope to it. I can imagine what the 509 would sound like!
 
On my 408 stroker with edel heads, M1, hooker comp, 3000 stall converter with a manual reverse valvebody.

I have a holley DP 750 with a Proform body, got 8 mpg on hwy at 55 with 4.10 gears.

With my Edelbrock 600 (4106) I get 14 mpg, everything else the same!

I use the Edel for the street, and the holley at the strip, good for at least 6/10's, probably more when I finally can hook it up!

My advice - run an Edel on the street, or maybe one of the old holley spreadbores.
 
I am running the original Thermoquad on my 73 with the .508. Tiny primaries for decent mileage and huge secondaries for pesky ricers.
 
Thanks a bunch. I see most of you agree the cam is the problem. I took a look at Hughes and found a sweet cam that give the sound of a big lumpy cam but not the draw backs of a big cam, like fuel comsumption.
http://www.hughesengines.com/partDetail.asp?partID=11613&eTypeID=1

will this cam and a smaller carb (600 cfm) give me a more steet friendly car?
What do you all think of the eddy heads with this cam? Will it kill the torque?

What do you all think?
 
buddyralf said:
Thanks a bunch. I see most of you agree the cam is the problem. I took a look at Hughes and found a sweet cam that give the sound of a big lumpy cam but not the draw backs of a big cam, like fuel comsumption.
http://www.hughesengines.com/partDetail.asp?partID=11613&eTypeID=1

will this cam and a smaller carb (600 cfm) give me a more steet friendly car?
What do you all think of the eddy heads with this cam? Will it kill the torque?

What do you all think?
Click to expand...


I couldn't get the Hughes link to work. Any smaller cam would work heck you might gain torque if anything.
 
I would look for a cam with around 225* intake and 235* exhaust duration @ .050"
 
buddyralf said:
Thanks a bunch. I see most of you agree the cam is the problem. I took a look at Hughes and found a sweet cam that give the sound of a big lumpy cam but not the draw backs of a big cam, like fuel comsumption.
http://www.hughesengines.com/partDetail.asp?partID=11613&eTypeID=1

will this cam and a smaller carb (600 cfm) give me a more steet friendly car?
What do you all think of the eddy heads with this cam? Will it kill the torque?

What do you all think?
Click to expand...

The Hughes musclecar cams are designed w/ less total lift and a less agressive ramp rate than their traditional line- but still specifically designed for our small blocks and give the rumpity rump sound and great low end torque. Still a WAY better choice than the old 292 shaft. Eddy heads should compliment nicely, but I would go with a 650cfm range carb...600 may be a little too small. It would probably work and be tame on the street but a little small.650 Demon would be my choice.

I'm running the same cam and I would love to switch to one of those cams. I think you cant go wrong. Great sound/performance and street manners.
 
72's are a good place to start on a Holley with a 225 degree cam or less on a LA engine with headers.
 
I agree with Adam on the cam with use on a 3.73 gear.

With a 3.23 gear, I'd look at a 216 intake (2* ethier way) and a 228 exhaust (2* ethier way, but same way on both sides.) duration cam and a 600 cfm carb.

For mileage and OK power, with the M-1 dual plane intake, I'd use the smaller cam and carb.
 
You can all ways swap the 4 speed for a later 4 speed over drive tranny.
 
Talking to Tim a Hughes engines he likes the traditional stye cam they are known for.
http://www.hughesengines.com/partDetail.asp?partID=11520&eTypeID=1
Intake Valve Lift 1.5
Exhaust Valve Lift 1.5.470"
.506"
x.gif
Intake Valve Lift 1.6
Exhaust Valve Lift 1.6.501"
.539"
x.gif
Intake Duration at .050"
Exhaust Duration at .050"215°
223°
x.gif
Lobe Separation Angle112
x.gif
Intake Opening at .050"
Exhaust Opening at .050"-1.5° BTC
46.5° BBC
x.gif
Intake Closing at .050"
Exhaust Closing at .050"36.5° ABC
-3.5° ATC
x.gif
Min. Suggested Cylinder PSI155
x.gif
Sweet Spot RPM1200 - 4900
using my 3.23 gear
and a 600 cfm carb


This is the cam he thinks would be great for me. He asked me to find out my cylinder pressure and told me the smaller cam will incease cylinder pressure from whatever I have now, he hopes it to be at 185psi with the smaller cam. I will see what I get when I test it.

It seems the main reason he didnt like the other muscle car cam is because it trades off ecomomy for idle.
These cams are designed to provide a very aggressive, "Muscle Car" idle without all of the draw backs of big cams. They sound big and bad but are still tame enough for cruising and car shows. They will provide explosive power, off idle. Great for stop light to stop light cruising or just for showing off at the car shows! They sound bad to the bone just like the muscle cars of yesteryear but with awesomely quick throttle response. They will not produce the full power of our "real" Chrysler cams but they sure sound like they will. These cams have fast rate of lift, but the lower total lift will somewhat limit the rates. With the lower total lift, the valve guides will not need to be shortened so the cams can be installed without removing the heads for machine work. They can be used with stock rockers, stock length pushrods and stock torque converters.

Previously only available by custom order, these cams are now available in our three most popular hydraulic cruiser, car show type grinds. These cams are designed to be used with our 1110 spring in the Small Blocks and our 1105 spring in the Big Blocks. You can use either our 5001 or 5003 lifters.

Intake Valve Lift 1.5
Exhaust Valve Lift 1.5.470"
.470"
x.gif
Intake Valve Lift 1.6
Exhaust Valve Lift 1.6.501"
.501"
x.gif
Intake Duration at .050"
Exhaust Duration at .050"214°
214°
x.gif
Lobe Separation Angle108
x.gif
Intake Opening at .050"
Exhaust Opening at .050"2° BTC
38° BBC
x.gif
Intake Closing at .050"
Exhaust Closing at .050"32° ABC
-4° ATC
x.gif
Min. Suggested Cylinder PSI150
x.gif
Sweet Spot RPM
 
I just had my 340 rebuilt for my 69 swinger, .30 over, forged 10.5/1 slugs eagle rods arp studs finely balanced,X heads with old LD340 comp cam xtreme energy cam kit with 460/470 lift comp cam adjustable rockers with anti pump up lifters running through 727 beefed up with 323 gears I ran the original avs then builder got me a 600 holley with mechanical secondaries and changed shooters to a 31 and 35. RUNS Excellent and not bad on gas if you keep your boot out of it. Shifts into second at 6200 rpms with big bark.builder said the balanced assembly was 27 grams lighter per cylinder with the eagle rods. Im very happy, as I can drive it like a regular car and performs very well.
 
has anyone ever locked the distributor up? The reason I say this is because I am going through lots of unburt fuel and I blamed the cam and the carb, but what if the distributor was locked out. Put at one setting and left alone. I am told the car will preforme better off the line, will burn the fuel instead of dump it out the exhaust. Anyone ever try this, im sure its a practiced modification.
 
I like Holley 750 VS carbs. The old 3310's.

Get a metering block and spring kit for the secondaries and they are hard to beat on a 340. Easier on fuel as opposed to a Double pumper and will easily outperform an ede carb.
 
Well I put on a AVS from a 1969 383 motor manual trans from Calf.--I love E-bay--needed a accel pump and a bit of cleaning--looks very nice for 40 years old.

Was hoping to improve my 10 mpg 318 motor with MP 360 heads-308's. It didn't! In fact I believe I lost 1 mpg. Ran OK--it wasn't rich, ran with choke left open, could feel it was lean for the first few mins. in the morning. The secondarys I went from .091 to .095 was the best seat of the pants. It was down a little on power from my race Demon 650 dp...mid range it pulled almost if not the same as my Demon but top and bottom end was down.

Funny thou, it rev to 6200 a bit quicker--my demon hits 5800 before slowing a bit--have 3.91 gears.

I had it on for 4 days and $60 bucks worth of gas, this afternoon the Demon went back on and will stay 8)

I think my MPG is better with the Demon cause I need to push less on the gas pedal to accel as quick. I did not drive it easy, just my normal hot rodding around our muti-lane 55 and 70 mph zones.

I am keeping the AVS thou...its great if it needs to go to a repair shop--even starting the motor it make less noise and feels more like a "normal car"..not a race car :love7:

I believe the AVS was all stock too...now if I babied it, maybe then the MPG would have been better but I have a 1992 Olds that gets 21 mpg if I want good mileage.
 
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