68 chevy truck problems

[homersipes]

it has an edelbrock 600 carb on it.  I dont know about the jets or anything he had to work before I got home

[CAP1]

it has an edelbrock 600 carb on it.  I dont know about the jets or anything he had to work before I got home

 edelbrocks are just re-labeled carter afb's. very good carbs, although i've not seen many on gm's.

[WWhiskey]

Cheap version of a cool can is a coffee can with an oversized filter inside,, for racing I'd fill it with ice ,, rubber hose in and out,,I always put the fuel  into the top and out of the bottom that way even if it gets air in it, the pressure still forces fuel down and out to the carb.   I had a 1967 el camino that did the same thing, a new radiator  and thermostat fixed it!  I know it might sound strange but that is what it took,  as the radiator got old and less
Effective, the engine bay heat got higher and higher, at first it had to be 100  or so outside for it to act up, but as the summer set along, pretty soon it was doing it  at 75  but once the car got hot, in my case it was an engine tempature thing, solid fan with no clutch and super hot air blowing out of the radiator, shielding can help but only for so long!

Just my 2 cents!

[morfiend]

edelbrocks are just re-labeled carter afb's. very good carbs, although i've not seen many on gm's.

 Floats ever get sticky on those Cap?  Thinking maybe the floats are bad and the bowls arent filling causing or adding to the problem.


   

[Dago]

Change the fuel filter, if that doesn't fix it, install an electric fuel pump near the tank.

[CAP1]

 Floats ever get sticky on those Cap?  Thinking maybe the floats are bad and the bowls arent filling causing or adding to the problem.


   

 i've not had many problems with those to be honest. holleys, i used to have the needle/seat assembly stick sometimes, regardless of the floats position though.

[morfiend]

i've not had many problems with those to be honest. holleys, i used to have the needle/seat assembly stick sometimes, regardless of the floats position though.

 Ya not too familar with the carters, wonder if the floats are bad/waterlogged and it's not filling the bowls and causing the vapour lock,if it's even a vapour lock issue to begin with?



     

[CAP1]

Ya not too familar with the carters, wonder if the floats are bad/waterlogged and it's not filling the bowls and causing the vapour lock,if it's even a vapour lock issue to begin with?



     

 generally, if floats lose their buoyancy, the carb will flood, as they'll never close the needle valve.

[homersipes]

not knowing much about carbs, if its set toward the lean side, it would run ok in the cooler weather and when it gets hot it would lean right out?? or would it richen dont remember been a while since I messed with old snowmobiles.

[Dago]

If it runs ok for a few minutes, it is probably not a bad float in my opinion.  Vapor lock, while less common can happen, but typically only on hot days or if someone runs an exhaust system pretty close to a fuel line.  If, and I repeat, if this were the case, moving the exhaust away should help, otherwise, an electric pump near the tank keeping the line with some pressure in it should fix the problem.

Sounds more likely a dirty fuel filter, which is usually cheap and easy to change, plus should be done on occasion anyway.

[CAP1]

not knowing much about carbs, if its set toward the lean side, it would run ok in the cooler weather and when it gets hot it would lean right out?? or would it richen dont remember been a while since I messed with old snowmobiles.

 you run the carb adjustment rich for cold air. cold air is more dense, needing more fuel. but if you're talking the adjustment screws at the base, those only adjust air/fuel mixture at idle.

 most likely it's not gonna be in the float area if it runs ok for a bit, and disconnecting/reconnecting the fuel line gets it started again.


 personally, what i'd try, would be an electric fuel pump. like this one......
http://www.google.com/products/catalog?hl=en&cp=20&gs_id=ca&xhr=t&q=electric+fuel+pump+for+carb&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1259&bih=907&um=1&ie=UTF-8&tbm=shop&cid=375973278125579511&sa=X&ei=Xp-mT4mFHuGD6AGJ7emlBA&sqi=2&ved=0CNABEPMCMAA

 simply mount it on the frame rail in the engine compartment, route a fuel line safely, use a clear inline filter, and try it again. if all is well, it was either the old mechanical pump, or the metal line.

 i'm a lazy bastage, and have had one of those pumps installed on my 68, 69, 70, and 74 chevy pickups......all 'cept the 70 had 350's. the 70 had a 400. all ran perfectly on them, as did my 79 f150.

[morfiend]

generally, if floats lose their buoyancy, the carb will flood, as they'll never close the needle valve.

  Ya Cap your right,I got it backwards!  It's been awhile havent done any real wrenching for about 20 years.  It seems too much like work these days and work is a four letter word I dont like!



   

[icepac]

If it's not vapor lock or something sticking to the fuel tank sock after a bit of driving, I would look at the engine running at night to check for electrical issues.

I've seen cars stop running that had started up fine when cold because a rotor was grounding to the distributor shaft through the plastic.

It only did it when warm.

[Captain Virgil Hilts]

Easy way to verify if the problem is fuel starvation. When it gets hot and quits, immediately spray some carburetor cleaner into it and see if it cranks up. If it fires up and then dies, the problem is fuel starvation.

Most of those old trucks had a vented gas cap, which can be hard to find, and they will go bad. Another problem can be a weak fuel pump (I always use a real Delco if possible, and a Holley if not, always mechanical) a cracked rubber line at the ends of the hard line, those are there to allow for movement between the engine and the frame, as well as the cab and the frame.

Finally, there could be elevated under hood temperatures, for a number of reasons, a weakened cooling system, elevated exhaust temperatures, or both.

If the timing is retarded, the exhaust will run hotter. If the engine is lean, the exhaust temperature will be higher. If engine power has been increased, the exhaust temperature will be higher. The addition of headers, new head pipes poorly routed, or bad mufflers can cause under hood temperatures to rise as well.

When a new problem arises, look at what has changed. Even back over the past year.

By the way, it is possible that the gasoline being used is a blend left over from cooler temperatures, which will have a lower Reid vapor pressure, that will make it twice as easy to create vapor lock.