Few Problems

[ripped_78]

I have a 1986 Fourwinns 19 footer with a 4.3l mercruiser alpha one. I recentley put on a new holley carb (rebuilt) and 19 Pitch prop and new pcv valves. I can not get the boat to plane and the RPMS will only go up to 3,000 should I try a new prop or should be worried about the rebuilt carb not working It runs fine but it stumbles relly bad at idle almost like a vacum leak. I replaced the PCV valves and hooked both of them up to the flame arrestor and now there is oil coming out of the dipstick. Any help would be appreciated.

 

[ripped_78]

Re: Few Problems

Should one of the pcv valves be hooked up to the Carb? If so where

 

[tommays]

Re: Few Problems

Both valve cover hoses hook up to the flame arrestor so the fumes are drawn into the motor <br /><br />I might be worng BUT is there supposed to be a PVC valve or just a dirrect hose ? <br /><br /><br />

<br /><br /> VENT HOSE (CORRUGATED)<br /> ELBOW, VENT HOSE TO ROCKER COVER<br /><br />tommays

 

[Reel Poor]

Re: Few Problems

The PCV valves you removed from you engine are not PCV valves. Yhey are merely hose connectors. You need to put the origionals back in (if you still have them). If you dont you will need to buy new from Mercruiser.<br /><br />Basically by installing PCV valves you have stopped the ventelation capabilities of you engine. With no ventalation pressure is created in the engine, therefore the dipstick blows out, seals start leaking, gaskets blow out, and performance can be affected.

 

[ripped_78]

Re: Few Problems

I will yank those out and get some oem ones do you guys think that is what was the reason it wouldn't plane?

 

[Don S]

Re: Few Problems

Just pull them out and go for a test run. That will end any questions of will it or not. Then get the proper parts.

 

[ron7000]

Re: Few Problems

Originally posted by ripped_78:<br />It runs fine but it stumbles relly bad at idle almost like a vacum leak.

fix the crankcase vent first like was said,<br /><br />I have a holley 4-barrel on a 351w ford engine. That carb is setup to have a pcv valve with a hose going from that to an adapter plate beneath the carb. So when the engine is running, there is constant suction of unmetered air. The carb is set up for this and will run the proper air fuel ratio as long as the pcv valve is letting in the proper amount of air. At idle right down to 500 rpms mine runs smooth but if I plug this air source then the engine will get lopey and need to either idle higher to be smooth or it will stall out due to the air-fuel ratio being too rich (not enough air). I am guessing (key word guessing) is that this might be what you're experiencing. If this is the case, you may need to do some adjustments on the carb to get it to idle well. If you have trouble after correcting the crancase vents, give Holley tech service a call at their 800 number, have your carb list number handy. Also, since it's a rebuilt are you sure it's for a 4.3L mercruiser?<br /><br />You mentioned it stumbled really bad at idle like a vacuum leak- if it was a vacuum leak that usually gives you a fast idle which you can't lower.

 

[Bondo]

Re: Few Problems

Which Holley Carb was Ever mounted on a Mercruiser 4.3l,..???....<br /><br />Is this the Right Carb,.??..<br />Is it a Marine Carb,..???.....

 

[ripped_78]

Re: Few Problems

It is the right carb and it is also a marine one I am going to take the boat out tonight with the pvc valves off and see if that helps I don't think it is the carb it fired right up and never bogged down when I hammered it. I have never heard of losing poer because of the pvc valves being incorrect but I'll try it out tonight, and see what happens.

 

[ripped_78]

Re: Few Problems

I took out the pcv valve and put in some blank ones and there is no oil coming out of the dipstick anymore. I figured out why it wouldn't plane, the back throttle plates were not opening up so I had to hook it up manual they are supposed to be hooked up to a vacum but there are no vacum lines coming from the engine at all. Am I missing something?

 

[ron7000]

Re: Few Problems

post the list number of the carb if you can.<br /><br />the secondaries can be controlled by mechanical linkage or by vacuum. In the case of mechanical linkage they will always open fully when you push the throttle wide open with the engine not running. If they don't then something is wrong or not adjusted right with the linkage.<br />Most all holleys are vacuum secondaries, so I doubt you happen to have one with mechanical linkage. The secondaries are controlled by a diaphram, when enough vacuum builds up in the throat of the carb it overcomes the spring in the diaphram and the force of vacuum pulls the diaphram to open the secondaries the proper amount. The diapram prabably has a whole in it which is common. It's replaceable for $10.<br />The diaphram is located just to the right of the wording "Marine j-style vent tubes" in the pic, you can see 3 screw holding the cover to the diaprham.<br />

 

[ron7000]

Re: Few Problems

also see http://69camaro.20m.com/photo4.html <br />"vacuum secondary diaphram and choke assembly"<br /><br />the diapram assembly is off the carb with a diaphram still in it- you can see the rod sticking out. Another diaphram is laying to the left, it's black. You can buy them at most decent part stores. places like vatozone can order them, but make sure they order the correct one. The arm length to them vary for different carbs, you get the incorrect one it will either not fit the linkage or will fit (with too short an arm) but not allow the seconaries to close at idle causing an idle that you'll never be able to lower.<br /><br />

<br /><br />Also, on the diaphram assembly you can see a little black o-ring among the 3 holes that make up an L shape. That gasket needs to be there and seal properly otherwise the diaphram won't work properly. That gasket is often a stick on piece of cork.

 

[ripped_78]

Re: Few Problems

Here is the carb I bought It was a rebuilt one I was told it does have a linkage on the other side where I can hook it up to the throttle cable so when the cable goes 3/4 the back two valves start opening up. Is it ok to hook it up manual and just leave it?

 

[ripped_78]

Re: Few Problems

http://www.holley.com/0-80492.asp <br />Here it is

 

[Bondo]

Re: Few Problems

It is the right carb

I Didn't Think Merc. ever used the Holley on their motors,.......<br /><br />What Happened to the Merc/Weber that Was on it,.???....If it was a 4bbl. Before you started working on it,.???

 

[ripped_78]

Re: Few Problems

yeah it was a fourbarrel but it was a auto carb I bought an adapter plate for it and it bolted right up all the vacum lines were plugged I did hook the second plates up manual last night and it ran great I will take the diaphram off tonight and see if it is tore if so I'll replace it but as for now I'll just leave it hooked up manual.

 

[ripped_78]

Re: Few Problems

Ron thanks for the help with the diaphram thats what is was is wasn't making any kind of seal i tore apart and put it back together now it runs great I appreciate all the help you guys have given me. I have learned alot from this forum.