today the strangest thing happend while driveing my car to work. in the stop and go traffic, my rpms would drop by like 100 or more almost stalling the car, every few seconds. eventualy it got so bad i had to "two foot" it the rest of the way home. 1000 rpm or more its fine, drives perfect. when i got to work, i cracked the hood, cranked up the rpm to about 800 idle speed (was 600 and falling every now and then) reved it a few times and it seemed alright. i shut it off and it freaking kept running for a few seconds. this is a newly rebuilt engine that has been running perfect for almost a month now, every thing is basicaly new(carb, ignition system, fuel lines,intake manifold, plug wires). its not blowing any smoke, and the timeing is set to 8 degrees(no vaccume advance). could a minor vaccume leak cause this? the fixture that goes out the back of the carb to the brake booster was a little loose and i could turn it with my fingers but it was still in there pretty good. i also sprayed some carb cleaner into it because it was "possible" a peice of rtv sealant fell off my hands and into the carb. it seems to be running ok now in my garage, but i havent tested it on the road yet. the streets are really busy here and i dont feel like dieing in full blown traffic. this car is my daily driver/ only car, so if i dont get this fixed soon im in big trouble. either way tomorow, im going to find out if i fixed it or not. but if anyone here has some light they could shed on this i would really appreciate it.

 

could be your timing, if its a fresh motor maybe a loose ground or connection somewhere, check there

 

ok, i checked everything i can think of, and its getting worse. today it was doing it while driveing around and at idle. apparently i didnt fix anything. nothing is grounded, everything should be normal. the timeing is advanced by 8 degrees and its stedy. most of the time it will run totaly fine, this is a random occurance that only gets more frequent the longer i drive for during the day. i checked all the carb bolts and they are tight, everything is tight. could it be bad gas? i filled up at this gas station that im sure doesnt get used alot and has really high prices (i was desperate). how about the spark plugs? i have bosch platinum +4's in my engine and ive heard a few bad things about them. but they costed me almost 100 dollars (canadian) im not about to just toss them in the garbage on a hunch. could a leak in the intake manifold seal cause this? also, for some odd reason it wont do this in my garage, wich makes it really hard to track down. the last two days it has been raining, could this be a factor?

 

I had that problem too I couldnt find any visible or detectable vac leaks but I changed the intake gaskets anyway when I rebuilt the carb not problem since. My guess would be a vac leak loose vac hose check the base plate of the carb with some carb cleaner when running and listen for change in idle if you hear a change there is your leak. Good luck

 

Sounds like maybe you had a float sinking in the fuel, letting more in or a stuck needle valve, same result, stalling and running on.

 

lately ive been noticeing a small pool of oil right under the throttle arm of the carb on the intake manifold. this guy i talked to said the oil works its way up through the bolt threads every now and then. he also said its normal and its a "chevy" thing. some how i just dont buy this though.... if oil can get through cant air aswell? i mean, it would have to get through the gasket before it reached the bolts anyway right? im starting to think mabey my torque wrench has bit the dust (from being used as a breaker bar too many times) and isnt giveing me accurate torque. im thinking about re-doing the intake manifold seal today just to be safe. plus, i honestly dont rerember if i used loc tite on all the bolts or not. this guy knows alot about engines and has taken several mechanics courses, so before i blow a whole day on this job, what do you guys think i should do?

 

The intake manifold bolts, all except the 2 end ones which are blind, are drilled all the way through the surface of the head, and the bolts stick right into the crankcase (lifter valley). Your friend is right, that leak is a very common SBC thing. The cure is Teflon tape on the intake bolts, being EXTREMELY CAREFUL not to ever let any of it fall down into the motor, as it will plug oil pickup screens and remain there for all time. It does not break down in oil, ever. You don't have to take off the intake, just take the bolts out one at a time, and put about 6 wraps of tape on them. You'll also find it's alot easier to torque them down with that on them, it is a fantastic lubricant.

 

ok, glad thats cleared up. also, will i have to buy new carb gaskets or can i use the same ones? i used that carb spacer/adapter plate so i have the carb, a gasket, the plate, another gasket and the intake manifold. i rerember posting on here a while back about this plate, and a couple people said it will stop it from leaking and warping the carb. my friend said differently though. he said just use 1 gasket. oh one more thing, you said the two end bolts are drilled right though? only one bolt seems to be leaking and its right in the dead center of the manifold on the drivers side under the throttle arm.

 

Actyally the center bolts on the intake are exposed to oil too. I just went through this myself. I sealed mine up with liquid teflon pipe sealant, ensuring that I used it sparingly and made sure non was hanging over the end of the bolt. RB is right you dont want the stuff in the oil it doesnt break down. As far as the carb gasket goes the Victor Reinz set from NAPA has a new carb gasket in it. I wouldnt mess with using the old gasket. They are cheap enough to replace. But again I onl y paid 13 dollars for the complete intake set I bet a new carb gasket is ony a few dollars.

 

where can i get some of this liquid teflon? if i use teflon tape, wont that eventualy cause the bolt to slip out? what about if i just use ALOT of the medium (blue bottle usualy) thread locker and try to seal it that way? also, what will happen if teflon gets into the cylinder? i mean the stuff is plastic like and easy to break, so wouldnt it burn up and flow out? the oil isnt really that big of a problem, but the deiseling is. i have to lower the idle to around 700 in park, in drive it drops to about 550 - 600. like this, it takes forever to warm up and sounds like its gona die when im at the lights how can people have their idle at 1000? my e ngine will run on, guarenteed at 1000rpm, even at 800 it does it randomly. it doesnt make any sence for this to be happening because everything is brand new

 

Permatex PTS. Get it at most any automotive store, should be in the section where they keep RTV and other sealers.

 

I used teflon in a permatex bottle but any pipe sealant with teflon will work. Dont use the blue thread lock atleast i wouldnt anyway. No the teflon tape or teflon sealant will not back out if torqued properly. It is what I used and havent had a prblem with it yet. You shouldnt use the threadlock because once it cures and you decide to retorque which is a good idea anyway the threadlock would be like glue and hinder retorquein the intake. I wonder, what did you use on your head bolts?

 

i thought the idea of thred lock was so you didnt have to re-torque bolts?

 

Usually its not the bolts that are needing retorqueing its what ever the bolts are holding ie gaskets. Some gaskets require torquing after running the engine. I am not sure if intake gaskets are one of them. I always retorque mine in the same sequence as when applied you will be surprised how loos the bolts will seam. After running the engine. The blue threadlock or any thread lock in that matter will hinder retorquing. The threadlock may not afford you good lubrication for torquing like the teflon will. Remember teflon is a lubricant and threadlocking devices like threadlock typically are not. Teflon never hardens threadlock does. Some threadlocks breakdown in oil Teflon does not. Do you remember what we use for rod bolts? OIL have you ever had a problem with one them coming apart. Use the teflon, in the event you have to take it apart you wont have to worry about breaking knuckles on the bolts breaking them loose.

Ed

PS RB and Vader usually provide good advice for stuff like this. I believe RB gave you the same advice as I did. If you use teflon tape remember to wrap it on in a clockwise fasion

 

alright, teflon good, threadlock bad. got it

 

1 more thing though, im new to teflon.... is teflon tape universal? or do i need some special automotive teflon tape? i have a roll that i bought from home depot in a yellow plastic case. its really thin, about half an inch wide and white. is this the right stuff? how tight should i put it on the bolt? to the breaking point, or just gently rap it around? i appologize for my lack of knowledge :hail:

 

That tape should be fine between 3 and 4 wraps should be fine put it on the bolt the same way as a nut would tighten the one thing to make sure is the tape lays nice and flat with no folds this tape folds easily. Do wrap it tight and work from the distal end toward the head overlapping your wraps 4 wraps should do just fine for course threads I see you have 1/2 tape I would look for something a little wider but that tape you have should work. It is the same stuff the automotive suppliers have except they charge 2 times what it would cost at the hardware store simply cause it says automotive. Good Luck
Ed

 

Carb may need a rebuild... a rebuild on my 4 barrel did wonders for it.

As for the dieseling... how hot is it running? This usually only happens when its way too hot when you shut it off (my experience anyway).

 

Whoops... never mind about the carb rebuild (assuming its a new carb) cuz if its new, it better not need a rebuild

 

actualy its running way too cold. the needle rarely passes 1/4 on the guage. and its in celcuis, not ferenheight or how ever they are spelled

 

Mine too is in *C and not *F.... running temp should be around 105*C.

I dunno why it would diesel if its too cold... maybe your carb stays open too much?