A idle problem

[f_inscreenname]

I have been fighting a idle issue for awhile now. I have a pretty hopped up 360 Chrysler with a decent cam and I never expected it to idle like my new truck but ….. It seems like it takes a long time for it come back to 800 rpm’s after a run at speed or a couple reves of the motor in the driveway. After a run and bringing it to a stop , take it out of gear and it will idle at 1000 to 1100 rpm’s and slowly (like over a minute) comes back to 800rpm’s. Now if I putt around and not go over a couple MPH when you take it out of gear it stays at 800 rpm’s. Now over some time I have done 2 carburetor rebuilds (Edelbrock’s are very easy to do) just to make sure there was no problem. The choke is completely open the whole time. I put new springs in the distributor, cleaned it out and lubed the weights up and added a Pertronix kit.<br /> Now I am still thinking the distributor is the bad guy here. A carb issue would not act like that would it?

 

[Don S]

Re: A idle problem

Disconnect the throttle cable from the carb and see if it still does it.<br />Could be the cable isn't allowing it all the way back to idle. It should have a slight amount of preload on the idle speed adjusting screw on the carb.

 

[f_inscreenname]

Re: A idle problem

Done that Don. Cable is free and clear. <br />"It should have a slight amount of preload on the idle speed adjusting screw on the carb."<br /> There is also. I have been all over the carb a hundred times with no change. With this problem its a real pain getting the idle set to a workable number. I don't want it to high. To much stress shifting into gear on the drive. To low and well... you know. I find myself sitting until the idle comes down before I shift. <br /> I need to figure this out before the end of the season or it is going to cost me a ton of money over the winter. Thats when I buy my elective parts for the boat. If I could buy the same (new) distributor for less then a arm and a leg that fit my pertronix kit I may give it a try if anyone thought it my be the culprit.

 

[Sagabu]

Re: A idle problem

I would suspect that the accelorator pump is sticking or a possible vacume/carb gasket leak if it races.<br /> Ive seen new pumps stick before and new gaskets leak. <br /> Are the secondaries hanging up? I have seen square flange gaskets (4 butterfly holes)rub the butterflies causing a slight hangup.<br /> Did you swap out the fast idle cam or accelorator cam on the carb?<br /> Timing can cause an engine to race as well. The irratic vacume can cause the advance (if vacume) to do funkie things. <br /> When I suspect a vacume/gasket leak, I use a small propain tank w/2' fuel line attatched running it around the base of the carb and intake gaskets as well as all vacume lines and connections. If the engine races, you have found the culprit.<br /> When I time an engine/carb, I use a vacume gauge and sett all to max vac.<br /> Doubt its the disributor. IMHO .

 

[gmcjohnny]

Re: A idle problem

if your going to use something for a vacume leak dont use propane us carb cleaner or water propane will ignite with us heat its not safe

 

[steve n carol]

Re: A idle problem

Hello Screamname, Went through your web site awhile back, soon after you posted about it, COOL his-story. <br /><br />About your idle condition...Been there, many times. All of my experiences have been that it WAS with the fuel delivery systems. Some were as simple as the idle-air adjusting screws, (not being pointed). Other times it was the casting or bushing being worn, where the shaft (or the shaft, that passes through the carb casting with the butterflies), causing a vac leak or causing the butterflies to bind, like sagame stated. On my first boat, it was the "rust band connector" (where the steam passed thorugh) that needed adjustment. Just kidding, it was a 'combination' of,<br />shift cable bind, (DON S), <br />throttle cable mounting bracket bind, (causing the new throttle cable to pinch). <br />Bind at the point of connection where the old throttle cable attached to the carb, (worn bushing). <br />And on another boat the shift/throttle cable/s assembly in the control box were hanging up on account of lack on maintaiance, from the previous owner... of course. <br />Then there was the time that the vaccume servo on the secondaries was shot. <br />Last but not least are a bad 'dashpot' (which ou don't have). <br />Old fuel injection has it's own share of problems, buts thats another post.<br /><br />Regarding the aftermarket cam...I don't know how a vaccume gauge would respond, but I would hook one up just to see an maybe test for vaccume leaks in all the areas prone to leaking.....sl

 

[f_inscreenname]

Re: A idle problem

I am getting the impression that most of you think that the carb would be the only thing that would do this? No one thinks the distributor’s mechanical advance would hang up? <br /> Sagabu;<br /> The acc pump has been changed a coupe times now with no change. Everything inside the carb is free and clear. No hang ups. The distributor is mechanical so vacuum is not a issue. I have tried carb cleaner around the butterfly shafts (and everywhere else) with no change. As for timing with a vac gage. The timing is in at all rpm’s and after it settles down the air/fuel mix is fine. So setting that stuff really is not a issue. Its just after the motor has been run at around 1/3 throttle or more for more then just revving the motor. Hell I don’t think the secondary even have to open at all for it to do it. <br />GMC; like I said I use carb cleaner. Thanks for the tip. Anyway if the wife saw me unhook the grills bottle and then take it out to the boat and open the motor cover. I don’t think I would have a place to keep the boat anymore. She already thinks I am performance crazy as it is and that would be the last straw. <br />S&C;<br />Thanks! There has been a lot of updates and there is also a link (the flashing one) to where all of the original Nova owners hang at. Stop by and check out the few that we have found.<br /> You think it is fuel (carb) too? I know it is not the linkage or cable. I have had everything disconnected and use a return spring from old car motor I had and I get the same results by running the motor over 2000 rpm’s for a few (15) seconds in the driveway (I don’t like doing that to often). <br /> I am thinking a carburetor is in my winter time future. I can live with it for a couple months but it will be definitely be on my list.