I've got a 76 nova with a 305.

I haven't put a lot into it, I just basically wanted something to drive on weekends occasionally and make a little noise.

I did nothing to the lower end, but put a 262 /272 cam, highrise Weiand (think it's a 7546) single plane manifold and headders. I currently have a 600 Holley (vac secondarys) on it, but I also have an 800 Dual line /double pumper with mechanical secondarys that I'm considering rebuilding.
All ignition is stock but I'll probably go to a higher grade Plug Wire.

With the combo above would I be better off to stick with the 600 or jump up to the 800?

Thanks in advance.
Skynyrdcat  

I've been recommending 500cfm for 305's more than enough.      WIEDER  

A 360° manifold for a near-stock 305? Most single planes lose power below 3500-4000 rpm's compared to two plane (180° intakes). This doesn't take into consideration part-throttle! Which is important for a lowly street 305.

Stay away from the 800, it probably would create "over-carbed" symptoms.  

GibTG is right about the single plane manifold. Stick with the 600 Holley, that's plenty. You wouldn't be pleased with the MPG with the double pumper.  

I've heard that alot lately with the single plane.

It was a freebie though (well actually not, A guy gave it and the carb to me to put a water pump in his boat).

How much would I actually gain on low end with a dual plane? They're reasonably priced and I wouldn't mind the $125 to get one if I'd see a considerable difference.

What about putting a divider in the intake, is this worth doing? I've read pros and cons about it.

Let me know your thoughts (and what specific version you'd recommend), I may pick up a dual plane after I get mu paint on.  

I would condone making the switch to a true dual plane...

I say there is 25-30 ft. lbs of torque to be had slightly below or around peak torque with the performer rpm manifold. The non air-gap version could be used if you want to save a few bucks and especially if the car must be ran in a cold climate.  

Thanks GibTG  

Look at carb size this way. Since the intake valve is open only every other revolution, any normally aspirated engine can can only accept half of it's displacement each revolution. Hence, your 305 can take in a maximum of 152.5 cubic inches each revolution. Therefor, at 6000 RPM a 305 could ingest 915,000 CI. Since there are 1728 cubic inches in a cubic foot, that equals 529.5 CFM at 6000 RPM and 573.6 CFM at 6500 RPM. Stick with the 600 carb. It's the right size and you'll have better response than the 800.  

Sky,

Your question is a good one and it has a number of components.

1- The Holley 600 #1850 has a main jet of #66 which is okay but this size may be altered by you. I ran a 1850 Holley on an engine similar to yours and it slammed a lot of 350's.  

Q: We mentioned Jets: How do I know what is the correct jet for my engine?
A: After the car has run on the highway (and with minimal idling) allow the engine to cool down and pull 4-spark plugs (the four corners) Read the color of the plugs. They should be beige ~ if they are dark brown and sniff like gasoline, you need to buy new smaller ## jets at your favorite performance store. If the plugs are white, they are too lean...and you need bigger jets. When DIALING-IN the perfect jet sizes, increase jet size in steps. The 600 is close to your engine size, SO, a 64 to 66 is probably going to be right.

By the way:  Not all cylinders are created equal and they may vary in plug colors.

Q: What do I do if one side of the engine looks okay on spark plug color and the other side is dark or light?

A: In this situation, you should STAGGER JET your carb. That means that each side of the engine will be fed fuel through different size jets. In your case... you said that the Weiand manifold is a single plane (I didn't check the catalog number) but you will not have to look deeply into the flow dynamics of the two banks.

2- You haven't mentioned rear end gears; this is important. I will assume that you are running 3:08 gears (highway gears) this will play a part in the torque value that you will program into your Holley. The vacuum secondary springs will need to be set to the next weaker spring tension (available from Holley or your speed shop) and the distributor will need to be adressed; 34 degrees total advance at the crank(total timing @2350 rpm).

Note: Ensure that TDC on your harmonic balancer is REALLY TDC before you waste your time and effort on timing the engine over and over and over...

I can assure you that since that balancer has been on your engine, the TDC has retarded approx. 6-8 degrees; the outer ring moves around a little bit each time we REVV the engine and let off.  A lot of people buy lots of great parts and then never zero-out their TDC so when the Hot Rodder thinks he/she has 10 degrees advance (by the timing light) they really only have 2-4 degrees. Bummer...no power  

TIP: Put a NEW Balancer on the engine and use a NEW drift pin; Cost 56.00... Los of fun.  This 3-cases of beer, which you will win back from your buddies...

Have fun...
Roc  

Sky,

Your question is a good one and it has a number of components.

1- The Holley 600 #1850 has a main jet of #66 which is okay but this size may be altered by you. I ran a 1850 Holley on an engine similar to yours and it slammed a lot of 350's.  

Q: We mentioned Jets: How do I know what is the correct jet for my engine?
A: After the car has run on the highway (and with minimal idling) allow the engine to cool down and pull 4-spark plugs (the four corners) Read the color of the plugs. They should be beige ~ if they are dark brown and sniff like gasoline, you need to buy new smaller ## jets at your favorite performance store. If the plugs are white, they are too lean...and you need bigger jets. When DIALING-IN the perfect jet sizes, increase jet size in steps. The 600 is close to your engine size, SO, a 64 to 66 is probably going to be right.

By the way:  Not all cylinders are created equal and they may vary in plug colors.

Q: What do I do if one side of the engine looks okay on spark plug color and the other side is dark or light?

A: In this situation, you should STAGGER JET your carb. That means that each side of the engine will be fed fuel through different size jets. In your case... you said that the Weiand manifold is a single plane (I didn't check the catalog number) but you will not have to look deeply into the flow dynamics of the two banks.

2- You haven't mentioned rear end gears; this is important. I will assume that you are running 3:08 gears (highway gears) this will play a part in the torque value that you will program into your Holley. The vacuum secondary springs will need to be set to the next weaker spring tension (available from Holley or your speed shop) and the distributor will need to be adressed; 34 degrees total advance at the crank(total timing @2350 rpm).

Note: Ensure that TDC on your harmonic balancer is REALLY TDC before you waste your time and effort on timing the engine over and over and over...

I can assure you that since that balancer has been on your engine, the TDC has retarded approx. 6-8 degrees; the outer ring moves around a little bit each time we REVV the engine and let off.  A lot of people buy lots of great parts and then never zero-out their TDC so when the Hot Rodder thinks he/she has 10 degrees advance (by the timing light) they really only have 2-4 degrees. Bummer...no power  

TIP: Put a NEW Balancer on the engine and use a NEW drift pin; Cost 56.00... Lots of fun.  The cost of this balancer is probably 3-cases of beer, which you will win back from your buddies... because they are running 2-4 degrees timing and they don't know it. Hhee..

Have fun...
Roc  

Very good rocs...

Thanks to all for the great responses.