I have a 77 Chev C-10 with a smogged 350. It's started sputtering out
and dieing and then being hard to start. Is that simply a dirty carb,
or is a vacuum component not working? I notice that the inlet from
the PVC valve had some motor oil on it. Could it be the carb?
Any help would be appreciated.
Could it be the throttle valve? This is a two opening valve that
bolts to the front of the intake manifold. There does seem to be any
available replacemnent part for it anywhere.
Pallister wrote: " I have a 77 Chev C-10 with a smogged 350. It's
started sputtering out and dieing and then being hard to start. Is that
simply a dirty carb, or is a vacuum component not working? I notice that
the inlet from the PVC valve had some motor oil on it. Could it be the
Any help would be appreciated.
Could it be the throttle valve? This is a two opening valve that bolts
to the front of the intake manifold. There does seem to be any available
replacemnent part for it anywhere. "
Really it could be lots of things but if it was my truck,which is
very similar to yours,I would check and replace as necessary the fuel
filter,air filter,cap+rotor,etc.Then I'd try to determine if I had a
fuel,electrical,or mechanical problem.Does it idle smoothly,have good
power,spark is good,smog stuff functioning properly? ETC.
But first do the easy stuff,the filters etc.
And yes,it could be the carb,but it could also be the fuel pump or the
EGR valve or a lot of things.Do the maintenance and get a repair manual
and approach it systematically instead of throwing parts at it. Best
It sounds like heated fuel. Check your spark plugs for discoloration
(gray or white.) I'm assuming your timing is set in the BTC zone. Is the
truck running hotter than normal? If so you may want to cool it down
with a 160 thermostat. Also try one heat range colder plug. Gap it to
.045. This will give you better gas mileage.
Check your fuel lines to make sure that they are not up against
something hot like your exhaust or intake manifolds. Also make sure that
the fuel filter is clean. If a PCV is bad this will cause rough running
at idle or slow speed. At $3.00 they are worth replacing. Check all your
vacuum lines for leaks. An air leak (vacuum leak) can also cause a lean
mixture and heat. Also check your power brake booster and hose. A good
way to find leaks is to spray hair spray or starting fluid around
suspected leaks. The will change your idle if leaking. If you have a
leak this will indicate where. Another possibility is the vacuum
(temprature) switch in line with your distributor. It should be on the
thermostat housing. If this is bad it will not allow vacuum through to
your distributer causing it to not advance. This will cause a hotter
engine, harder starting, pinging, and diesling. You can put a vacuum
gauge on it at the distributer port stem or put your finger over the
port stem to feel if vacuum is there. This is after the motor is in
operating temp. Instead of rebuiling the carb you may just want to run 2
cans of berryman's carb cleaner in your gas tank. Do it about every 6
months or so. Your truck may run rough until it burns it out of the
system. Not to worry, this is normal. If you decide to rebuild the carb
make sure that the jets are tightly in place, float level adjustment is
right, check for float binding, and most importantly use compressed air
to blow out the ports completely. When setting your idle speed turn the
screw out one and a half turns from seated. Start the truck and let it
warm up. Turn the screw out 1/4 turn every 30 seconds. Your idle speed
should increase with every 1/4 turn. You may find out that it might
increase by closing the screw a 1/4 at a time also. This is not likely.
What you are looking for is the best clean idle. Turn the screw until
the engine speeds to it's maximum idle speed. If you turn it and it
doesn't change or slows down turn the screw back a 1/4 of a turn. Your
finished. I hope this solves your problem. Good luck.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.