bgd73 Posted January 7, 2007 Share Posted January 7, 2007 Before the obvious replies, the throttle valves are functioning as they should on lubed return springs. 1987 GL. I have removed ASV, EGR, ABF, restricted evaporator to 50% (still huge opening). It began the same time my other 87 did this after tightening the base of the carb due to very loose.At 3000 rpm or so there is a hanging of throttle open and very slow to come down. Bizarre- as throttle valves are closed. How is it doing this? My last 87 did this in an ice storm (bad time for that) and I even got pulled over by the police due to the screaming sube going by. I do not want a scenario like that again.. I am assuming lack of 10000 degree egr to melt things into moving and the pulsating wierdness of the ASV has got the carb a bit cool and sticky. I did trick the asv ports on the plenum back at itself and it strangely stopped. I am not completely trusting that however.Upon taking apart one already, I am certain this one doesn't need that either. Still good on gas, idles, etc.It was happening above 3000 and something was hanging it open regardless of throttle valve position. Less likely to do it at all when engine is warm. Any quick ideas? Should I add heat somehow? Link to comment Share on other sites More sharing options...
TomRhere Posted January 7, 2007 Share Posted January 7, 2007 Over-tightening the mount studs/bolts can and will warp base of carb. Could be your issue.... Also, gasket squished out into bore, causing plates to bind on it, throttle cable worn, throttle shaft slightly worn, weak return spring, any, or all, of the above................ Link to comment Share on other sites More sharing options...
bgd73 Posted January 7, 2007 Author Share Posted January 7, 2007 I am in the green right now, I did tighten about half a tough turn on all 4 studs. There is no sign of problem yet after making the asv port loop back at itself on the plenum (it is not on the engine anymore due to leak at head). A ride has proven increased fuel mileage, maybe the gasket was squashed out into bore as you stated. I also welded some 2 inch pipe at the end of y-pipe, that also helps the very precise hitachi. I am headed for mythical fuel mileage again, the one reason I do not get a holley 5200 or weber 32/36. Will post again if it does it. Runs very good btw, the throttle increasing with valves closed at idle left me targeting another air source: The pcv. The loopback I made (I will get a photo) no doubt interfered with a possible super gas/flow in through pcv as the problem instantly stopped afterward. Below freezing in high humidity was the worst in my other 87, tomorrow we are do for the same kind of crappy 32 degree ice/rain/freeze crud and will test it out. The throttle cable is lubed as well as springs very smooth no troubles. Thanks for input. Link to comment Share on other sites More sharing options...
WoodsWagon Posted January 7, 2007 Share Posted January 7, 2007 Spfi. Link to comment Share on other sites More sharing options...
bgd73 Posted January 8, 2007 Author Share Posted January 8, 2007 Spfi. I have a 93 spfi sitting here, ecu all the gadgets, intake etc. No wiring diagram seems to be normal for it. The carb being a rock head isn't all that bad- It has its supremely benefits. It is indeed fixed. The pcv is my only explanation- perfectly turned itself into a carb. Pressure above and below carb, then pressure difference between inside of air filter to outside. I equalized one and it stopped the whole snowball down the mountain from getting big like an avalanche ... how precise. Scares people to fuel injection and taxi cabs. Link to comment Share on other sites More sharing options...
bgd73 Posted January 8, 2007 Author Share Posted January 8, 2007 I took car into the willywags, 4-6 inches of slush, rain and fog in northern maine. I wanted to cut through the wilderness ("golden road") but was informed road was closed and I had to turn back. There couldn't possibly be anymore moisture in the air with the fog layer. Problem with throttle sticking returned, the fix: base was way too tight, and I took visegrips off of coolant line at base of carb. One more tight stud to go that will be normal. The new problem I had forgotten with my other carb- this type of weather can get water in throught the outside duct. It somehow kept sucking in steady streams of water, I had to pull over on the highway to hook up the heat riser vacuum switch to hget air breathing from inside the engine bay.. It worked for the most part, but *still* got perfect shots of water enough to bother engine... as if I were in a river. What has some folks got going for the carbs intake besides the aqua duct sticking out of the fender? I am thinking of a tube going behind the carb someplace, as that was a small area that stayed perfectly dry. I would only be putting hose there for this one type of storm such as today but will keep it there. Link to comment Share on other sites More sharing options...
bgd73 Posted January 9, 2007 Author Share Posted January 9, 2007 no replies again for something this complex, I resorted to ingenuity. This is summary with cause and effect: scrapped egr, asv,abf completely Effect: carb too cold, sucks in more air, good for alot more power,but problematic in bad weather by sucking in water. here is my hillbilly resolve. After looking at the size of both hitachi barrells, they are quite venturid to keep the little 1781 from being a mini monster. I spotted the open tranny cooler lines not in use, here is what I did: The temp guage dropped 2 widths of the needle at an idle. with hood shut I revved for a little while, and lo and behold it uses it for warm air is easier to move. below is photo of what I had to do in the weather scenario I was in yesterday, just to go down the road (4-6 inches slush, raining and fog- if 200% humidity were possible, I was in it) kept air sucking from within engine bay- and it still wanted water. With above photo and this one, it should stay decent after I out a round hose on the bottom round opening and have that sitting by the center of the engine behind carb. I have proven to myself cool air is not a winner for the hitachi, as it is sucking quitye a bit and compressing into super cooled even with oem heat risers. Will know for certain next storm. As it is the 2bbl is very responsive now (as much as the little hitachi can). Link to comment Share on other sites More sharing options...
robm Posted January 9, 2007 Share Posted January 9, 2007 You are probably not sucking in liquid water. In high humidity conditions, the water in the air condenses out as it goes through the carb venturi. The temperature drop can be large enough to actually cause ice to form. This is "carb icing". Putting warm air into the intake is the best solution. Making sure the carb has proper heating will help, too. This is one reason why carbs/manifolds have heating, and the main reason why they have hot air pipes to the intake. I can see you have the temperature control on the intake horn, but I don't see the hose to pick up hot air from around the hot exhaust manifold. Normally, this device mixes hot and cold air to get a constant temperature. They do get worn out, though. Some cars won't run well if this thing is fazooed. Link to comment Share on other sites More sharing options...
WoodsWagon Posted January 10, 2007 Share Posted January 10, 2007 You are probably not sucking in liquid water. In high humidity conditions, the water in the air condenses out as it goes through the carb venturi. The temperature drop can be large enough to actually cause ice to form. This is "carb icing". Putting warm air into the intake is the best solution. Making sure the carb has proper heating will help, too. This is one reason why carbs/manifolds have heating, and the main reason why they have hot air pipes to the intake. I can see you have the temperature control on the intake horn, but I don't see the hose to pick up hot air from around the hot exhaust manifold. Normally, this device mixes hot and cold air to get a constant temperature. They do get worn out, though. Some cars won't run well if this thing is fazooed. Which is why this: and I took visegrips off of coolant line at base of carb. did a lot to solve the problem. Link to comment Share on other sites More sharing options...
bgd73 Posted January 12, 2007 Author Share Posted January 12, 2007 It Worked!! Befrore fix It was truly sucking in water, car was soaked to no run as I sat on the side of the drenched slushed heavy rain on the highway. I took rubber duct off and water with road salt came out dripping. I still had to turn engine over for 30secs or more after it had a chance for dry air... I took off the rubber connector to outside duct and left it off for drier weather. again, the cause for more air is some emmission stuff removed creating the super sucker and I blocked off an opening (where I put the heat riser to radiator) making the regular main duct suck too much. Also the carbs are designed to have full air, making it a likely problem, unless another opening was safe someplace else (I did not have one at the time) to keep the flow slow via greater volume. The "hillbilly heatriser" really went to work today after I hooked the rubber connector back up to outside duct (it is dry now), the restriction the rubber duct gave the plenum made my little hose really suck in a steady shot of warm air (not hot), like I wanted. I popped the hood after a short run, sure enough it was warm and functioning. I have always wanted a top end heat riser and on the drivers side. As this is my second oem carbed soob , in some winters the frigid made carb too cold and problems arose with sticking- all this was from an oem setup, unlike now, which I have made worse due to how cool it stays. The other reason I wanted another heat rise is the warm air is easy to move,to help get car to full operating temp sooner. the carb saw too many years of the hot egr (hot is an understatement) and the parts would get sticky running too cool. Now the vacuum cleaner effect it had in the rain can no longer happen, so keeping the rubber connector to outside is A-OK. Any sign of throttle stickage (while valves were closed was even more bizarre) is not happening. I can already tell the fuel mileage is almost back to normal.I am finishing it off with a section of aluminum piping and not even going to laugh at how simple that got for me to fix. I spotted below zero or near zero F for lows here next week, will be sighing relief at a good functioning carb doubt free, and can try it for certain then. Todays run was in the 20's F and car warmed up fairly quick, throttle was normal. Link to comment Share on other sites More sharing options...
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