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View Full Version : New 4a084 carb trial and fail



Doozit20
11-16-2013, 06:09 PM
Ok after some problems with my stock carb I thought I'd give a different carb a try. After some nudging from a friend I desided to try a radical different carb that from what I can tell has never been tried and after doing all the machine work to get an adapter plate made I found out why lol. The carb I tried was a SU HS-4 carb. The reason I found that this didn't work was due to it being to large and not being able to even get it to suck the gas down the throat. Itt would fart over using starter fluid but that was it and I know it was getting gas to the carb so I know that wasnt the issue. I have an outboard carb that inwill give a try next as it has almost the same throat as the stock carb and the bolt holes to mount it are the same so it wont hurt anything to just mount it uo and spin it over a few times to see what happens. Here's a pic of the SU crb that didn't work

http://i957.photobucket.com/albums/ae54/Steven_Brouwer/Mobile%20Uploads/20131113_174433_zps084b4347.jpg (http://s957.photobucket.com/user/Steven_Brouwer/media/Mobile%20Uploads/20131113_174433_zps084b4347.jpg.html)

Papee
11-16-2013, 09:12 PM
Looks like the fuel line is hooked up wrong in that pic. That outside line is the input and it looks like it's going to the carb?

Doozit20
11-16-2013, 10:57 PM
I've always wondered the same thing but for some.reason mine runs that way which is oposite from all the others that I have seen. I know it pumps gas that way because I was running my boat like that before this switch and after many pulls with out a successful crank it will over flow the bowl so it has to pump that way. Ill pull the hose and pull it a few times tomorow or monday just to make sure it does pump that way, but I am pretty sure it does.
Steve

Doozit20
11-17-2013, 08:13 AM
Ok so I just took the gas line off the carb side of the fuel pump and pulled the rope once and gas shot out of the hose so it has to be right. I think the guy who had this before me may have switched the pump around somehow to make it work this way. It might be as simple as switching the top of the pump 180 degrees I don't know though.
Regards
Steve

Doozit20
11-18-2013, 06:52 PM
Just mounted the outboard carb to my motor and it idles good but when I try to throttle up it would try and die out. I found that if I hold my hand over the carb and partially choke the carb it would throttle up fine. I did this to simply see if it can be done. The cool thing is I didn't have to make anything to mount that carb. I just simply unbolted the stock carb and bolted it to the engine. The outboard carb could be a very viable option if someome wanted too.

Now I bought a new old stock carb and it runs great except for the fact that I only gain rpm until mayne 3/4 throttle then if I push more it would loose rpm. I found that if I partially closed the choke it would run fine and gain a little more rpms at the last 1/4 of the throttle.

Hope any of this rambling helps some. Any questions on the two carbs I tried will be answered if I can.
Steve

Papee
11-19-2013, 08:01 AM
A air cleaner with help with that situation, mine ran like that sometimes if I didn't have an air cleaner on it.

Doozit20
11-19-2013, 04:11 PM
Hi papee
I actually have an air cleaner on it with a hose from the breather go to it as well. I spoke with a friend and he suggested to put tape around half of the air cleaner and see how it runs then take and cover only 1/4 and see if it runs any better. I'm going to try that and I will also put my old tube from my other caeb in iy to see if that has any effect because those little holes are actually smaller then the new one. Not sure if it will help or harm it but there's only one way to find out right lol

Rrgards Steve

Doozit20
11-20-2013, 11:20 AM
http://i957.photobucket.com/albums/ae54/Steven_Brouwer/Mobile%20Uploads/20131118_171205_zpsf1c15590.jpg (http://s957.photobucket.com/user/Steven_Brouwer/media/Mobile%20Uploads/20131118_171205_zpsf1c15590.jpg.html)



Here's a pic of a 1987 40hp evinrude carburetor mounted right to the existing studs on the stock intake manifold. I think with a little tweaking it would run good. The pickup tube is cracked in this carb so it would loose suction on acceleration but if I were to place my hand over the intake about half way it would throttle up to 3100 rpm without trouble. Thats a 59x10 three blade prop by the way without reduction

Steve