Is the spring on the left or right side?
You need to pull your tanks out and completely flush. You can use tide soap to flush tanks. Replace all your fuel lines, filters, etc. I know you said you have new filters youll need new one's again. Also you should replace the fuel pump also just a stock mech. If you don't do all these things these problems will plague you for every. I know because I bought a boat that had sat for years with gas in it. The gas turns to cystals in your tanks.
Hey ZGOO. The secondary return spring on a vacuum secondary carb is in the vacuum can. If your'e gas is clean in the filter, or sight glass most likely your'e filters are doing the job. NOW if the secondary butter-fly shaft needed to be pushed down to get fully closed you found the problem. If at all possible do not remove the butter-flies, as realignment to proper closure is a bitch. I would advise lube and move till it seats automatically on its own. And if you pull the vacuum can on the right side of the carb look at the color of the spring, this identifies the amount of vacuum it takes to open the secondaries. A silver spring will open long before a purple or green will. NOW carb tuning trick. At W.O.T. {wide open throttle } manifold is at zero vacuum and as the motor comes to grips with the amount of feul absorbed vacuum will again incress thus again creating vacuum and at this point the spring comes into play. It will then open secondary floww to feed the starving bitch. And by the way a 650CFM carb is aliitle small for a 460 ford.
Well taking out the tank to clean is not going to happen due to it being under the floor with no way of removing it. I did look in side of it and it looks pretty clean, so I will have to take my chances. The plugged elbow had the crude in the tight turn as it went into the check valve and it was rough water when it happened and some of the crude came loose and drop about and 1" down the pickup tube into the little cup screen sitting in the top of the tube, so the crude was swirling around in this little area until it cut the fuel flow down. So that should fix that. Now the carb.....
I will remove the vac. can and check it. I do know the when I had the carb apart that the shafts turn free with no sticking. The boat is such low hours that the carb is like new. But I did push up on the vac. can rod and the sec. did not close all the way. Could the spring be weak in the vac. can? Also, the linkage on the primary side that has a rod from the primary to the secondary is a short bent rod, with the primary closed how louse should that rod be?
The 650 Holley is the stock carb that came with the boat, if you guys could see this boat, the condition would blow you away. For a nearly 30 year old boat it is amazing to see how many people commnet on it. I was docked next to a new 38' Fountain and and more people were commenting about the Glastron. I even had people in other boats and skis come over to where I was floating down the river to say that was a cool boat!That never happened in my Chaparral. What would a bigger carb do for this engine?
The spring in the vac can should be very light to ease the opening of your'e secondaries and reseat the secondary butterflies when you come off throttle. But this not going to happen if the baseplate shafts are hanging up. When a boat sits for awhile all may seem clean on the outside but you never know what monsters are growing in tight spaces. Just work with them with some carb sray and then wd40 and they will operate smooth once again. The linkage on primary to secondary should wiggle when both are closed. 650 okay but 750 vacuum secondary like an old 3310 would bump the topend rpm on a jet boat assuming water jacket exhaust and stock motor.
What would a bigger carb do for this engine?
I looked at other CFM selection charts, but this might help you. It is for automobiles.
http://www.buicks.net/shop/reference/carb_cfm.htm
Could be as simple as a backwards gasket. Did ya check?
Hey ZGOO. The secondary return spring on a vacuum secondary carb is in the vacuum can.
dammit I hate getting old. Yes, the spring is only on mech secondary carbs. I coulda swore it was on both, but a quick check of my inventory says no. Only mech secondary carbs have the spring. Seeing as how the vac canister has a big freeking (and tunable!) spring inside, it makes sense. Duh.
I've only been doing this for 25 years. I feel smart at the moment.
I would say you need at *least* 750 CFM with a single plane, 800 CFM with a dual plane to get max RPM.
Here is an update on this problem.
I replaced the rubber vac. part and check it to make sure that it will hold vacuum. The check ball is in the right hole and the spring was marked with a yellow paint. I checked the sec. shaft and it is free and smooth. I then took the boat out and it ran fine but did the same thing after a full rpm run to get the sec. open, it will still not idle below 2,000. The primaries are closed and on the idle stop but the sec. are open enough to keep the idle up at 2,000. So I removed the sec. vac. can and check to make sure that the vacuum ports to both the sec. and primary sides were clear, and they were clear. It's acting like there is too much vac at idle and keeps the shaft open, but that's impossible.
One thing that someone might be able to answer is the base gasket on the manifold to carb mount. there is a thick gasket that is all open between the sec. and primary sides, is this normal or is the carb suppose to have the sec. and primaries seperated from the carb to the manifold?
I rebent the linkage rod on the primary side that goes to the sec. shaft and made it tighter so that when the primary closes it will pull the sec. closed as well, is this a good ideal?
Guys, I'm totally stumped on this one.......
Dan
does it have a choke? if so, have you checked to make sure it's not sticking a little?
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