Question about buying Carter BBD for my 318 (unless I should look at something else)

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Between yellow lines is low area for air to pass between bores, this is in addition to air from open area center of base gasket. So there is some interaction between bores, just not in manifold. One thing that carb has no notches,later carbs did.Will need base gasket with notches
 
Bugman said:
newer carb notches line up with throttle shaft
Click to expand...
If you have the notches (as shown in the photo) then the manifold gasket is *not* supposed to have notches (and vice versa) ? Do I have that right?

And what's the deal with manifold gaskets (or maybe they're called flange gaskets) that are really thick (like 5/16 with metal sleeve inserts) vs 1/16 ? My current bbd has the thicker gasket, the repop I just bought has a couple of the thin gaskets (with notches) - no idea why they sent 2.

Since these carbs have spiral throttle return spring, do you still need to use the original long return spring also?
 
If you have the notches (as shown in the photo) then the manifold gasket is *not* supposed to have notches (and vice versa) ? Do I have that right? Yes you do, That passage draws vacuum from both sides of carb,feeds
choke pull off etc. needs to get vacuum signal, make your own notches in gasket if needed. And if need too use notched gasket with notched carb.
 
And what's the deal with manifold gaskets (or maybe they're called flange gaskets) that are really thick (like 5/16 with metal sleeve inserts) vs 1/16 ? My current bbd has the thicker gasket, the repop I just bought has a couple of the thin gaskets (with notches) - no idea why they sent 2. The 5/16 gasket with metal insert is correct one. Insert so gasket is not crushed,thickness for heat block, keeps carb cooler, and matches length of choke rod.With thin ones choke rod too long.
 
Here's a question. See the image below:

carbs+gasket.jpg


So I'm basically asking here, was the gasket in the top photo the correct one to use on the carb in the middle photo, even though it completely blocks off the ports in the red box.

My second question is - explain the difference in how the ports in the red and green boxes are arranged with regards to having an open path to the intake manifold as determined (or not) by the gasket.

The new repop carb I'm putting on does have notches on the left and right side of the channel that allows a path from the channel to the intake (the carbs above do not have the notches). The new gasket is thinner than the one in the photo but is cut exactly the same.

yea I see how the gasket thickness can affect choke thermostat rod length.

I don't think I can re-use the thick gasket on the new carb because of how the surface of the gasket is indented and not smooth.
 
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Since these carbs have spiral throttle return spring, do you still need to use the original long return spring also? Federal safety requirment,if one spring fails you have backup fail safe.
 
The older carbs only had 1 spring. So the rules changes requiring 2 springs? Doesn't that make pedal feel stiffer?
 
Green box vacuum to step up power piston, red box do not have carb to look at older carb. See were passage goes
 
I'm flipping through rock auto and the first year they show for the thicker mounting gasket is 1970. The specific gasket is Fel Pro 60188 (9/32 thick). in 1969 and all prior years they show Fel Pro 60045 (I'm guessing 1/16 thick from the photo).

Maybe the BBD's didn't come from the factory with the thicker gasket until 1970?
 
What does it mean if I can screw the idle screws all the way in, and the 318 still idles at 500 rpm, vac is 14 - 15 ?

This is with the china dromedary BBD clone.

With the screws out about 1 turn, rpm goes up, vac goes up, about 17-18 inches.

Either the screws are not completely blocking flow, or there is another path for gas at idle (that shouldn't exist?) ?
 
So how is idle better, sounds like screws make a difference, Are the venturi bigger than your old carb
 
I wanted first to see how this clone BBD worked, I think it idles better, but maybe with points I'm just not going to get a rock solid idle at the 500-550 rpm I want.

I first ran it with the thin gasket they supplied, I was getting a very loud whistle from the throttle plates when I was dialing in the idle RPM I wanted. I couldn't deal with it it was so loud. I ordered the thicker felpro gasket (same as orginal size, about 3/8 thick). It helped, can still get a whistle sometimes but it's mostly gone. I thought I was going to have to drill a small hole in the throttle plate to make the whistle go away.

Something I'm not sure about - I am plugging all unused ports on the carb, and I'm measuring vacuum from a small port coming off the back side of the throttle plate. I think the rpm's go up a little if this port is unplugged. The underside of the air cleaner has a small port, not connected to anything. Is one of the carb ports supposed to connect to this air cleaner port instead of being plugged?

That's my only question right now, is one of these ports supposed to be flowing air instead of being plugged. The distributor advance line is connected, the PCV line is connected, the choke pulloff is connected.
 
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