Re: Best Carburator for 5.0LX
Is the hiccup on any takeoff or just a quick throttle-opening holeshot? And is your 2500 rpm hiccup when you go past 3/4 throttle with your stick? Or is it absolutely connected to RPM?
If your hesitation is from quickly moving the stick a long way, make sure you get two good shots of fuel from your accelerator pump when the throttle is moved fast. Just check with the motor off and looking down the carb.
If you haven't unscrewed the main jets and cleaned them up that could have something to do with your holeshot hesitation. The tubes they are in need to be clean too, they supply the main venturies. The jets can be removed and reinstalled with a screwdriver, no issue. Clean the tubes by blowing compressed air backward through the main venturies. If you do open the carb make sure to carefully set the float height. Those little machinist's rulers with a t shaped depth finder are great for checking float height. They sell amateur ones at Harbor Freight for cheap money.
If all that stuff is good make sure you have a nice smooth idle with no smoke, if it's smoky check your idle mix, the adjustments could be rich. If the idle is too rich the plugs get a little bit fouled at idle and they might clean up after a cough once you get off the idle circuit and onto the primary fuel.
Timing needs to be at spec or a degree advanced.
Ignition wires need to be good. When my wires got old I would get a pop back through my carb when accelerating from engine speeds above maybe 2000 RPM.
Shoot some carb cleaner around the base of the carb and the edges of the intake manifold and any possible air leak spots in the carb. Spray at the choke pivot, secondary flap pivot and throttle pivots. If the idle picks up from any of that stuff it's an air or vacuum leak.
You can check the function of the vacuum break by removing the vac line from the back of it, compress the link with your hand, put a finger over the vac hole and see if the link stays in. If it does it's good. If it leaks that will make your boat run wrong.
If that stuff is OK, or if you are interested in finding every little bit of performance, you can try different settings for the tension on the secondary air valve flap.
Spec is 1/2 to 3/4 turn from contact, but I go a little looser. Like maybe 1/4 to 1/3 turn from initial spring contact. It's easy to screw up though, you have to keep at least some tension on the spring when you release the set screw. If you allow it to go slack and lose the spring contact you will probably have to remove the carb and tip it over to reengage the spring. I put a little technician's screwdriver in the spring tensioner slot and hold it while I release the tension on the upward facing torx screw. Set the tension where you like and retighten the torx. The torx is a #10 and the space to reach it is limited, the best way is with a very short screwdriver bit holder and the #10 bit.
That's all I got, there's more but it's unusual to need in a boat carb. Good luck.
If you decide to get the Edelbrock, and are getting done with the OE carb I'd like to have it if you are not keeping it. I have a buddy who goes to Burlington every so often. Maybe he could pick it up if you are any where around there.
