Q: Carburetor – Converting From 2 BBl to 4BBL
I’m converting my 1968 2 BBL to a 4 BBL EDELBROCK Performer 600. I’m up to the point of making connections to the carb (linkage, fuel line, air cleaner, vacuum lines). I have the following questions (I know several of you have done this).
Note: Bare in mind that the article in the Jan.99 issue of Car Craft covers a 4bbl Qjet to 4bbl Edelbrock swap. The article is a little lean on details in any case.
1. The carb didn’t come with any linkage parts or documentation (I bought it used). The original accelerator cable doesn’t reach the throttle points on the carb using the stock bracket. Any suggestions on how to hook this up?
2. The fuel line originally bolts to the front of the stock carb. Now it “routes” to the right side of the carb. and requires an inline fuel filter. I bought a Specter glass filter. Are there any kits for hooking up to the stock line or do I need to make my own.
3. I also installed the Edelbrock Performer intake. What’s the best point for connecting the vacuum advanced and PVC valve (do I even need a PVC valve)? On the 2 BBL setup, there was vacuum point on the intake connected to a port below the throttle butterfly. Is it still needed?
4. The stock air cleaner had an air breather tube connector to the top of the right valve cover. Is this still needed, or can I cap it off.
5. What do I do with the large ports at the top of the Edelbrock carb. Do I cap them off?
A: Q1: You will need to get an aftermarket bracket. It will bring the cable closer to the throttle lever on your carb. The Edelbrock catalog shows a number of linkage accessories that might be helpful.
You may need to fabricate something for your kickdown switch. Maybe using parts from your 2bbl carb.
Q2: Edelbrock has a fuel line kit (#8135) that consists of a rubber hose, some fittings,a filter, and clamps. In addition, you will most likely need a banjo fitting (#8089) to allow clearance for a low profile air cleaner. There are no hard line kits. You will have to make your own hard lines if desired. Tube bending and flairing can be fun! If you use a rubber line, route it away from heat sources to avoid percolating you fuel, or fire danger.
Q3: If the manifold does not have a vacuum fitting, then there are three provisions on the carb for vacuum. Looking at the carb from the front, there is a large port in the center of the base. This is your PCV port. This is critical to keep crankcase pressure under control so that you don’t get oil blowby at the rings. To the right of this is a smaller fitting. This is a full time vacuum port. To the left (I think) is a ported (part time) vacuum port. Most distributors use this port but you must verify that this is the type of vacuum needed by you. Cap off the unused port so that you won’t have a vacuum leak.
Q4: 2 options. Get rid of the tube and put a breather on the valve cover opening. Or knock out the plug at the bottom of the aftermarket air cleaner, get a fitting (from any performance section of your parts store) for the hose and route it there. If you use a stock (4bbl) air cleaner, then use the hose as in stock configuration.
Q5: I can’t recall their function. I’ll check my user manual. You might also contact Edelbrock on this.
A: Any 4bbl air cleaner will work as long as the carb neck is the same (most are universal). Look for one that the intake neck is on the same side as your current cleaner. Look at a second gen firebird, should be close. be careful the one you pick isn’t too tall. Compare with the original and if taller, close hood SLOWLY to be safe. If you chose well, most people will not have a clue it’s not original. This would get you by until you can find an original.
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Content last modified: January 15, 2014 at 1:24 pm