symptoms of bad intake gasket ?

[R77K10]

alright i appreciate anything anyones got

the 400sb in the 77

when i got the truck it was a good runner, had a little roughness in the idle somewhat, but nothing bad, though maybe it was just in the crappy dual exhaust pipes it has

been driving it and everything, well about 4 days ago i went ot start it back up to leave right after i just had shut it off minutes before

it popped out the carb once, didnt start
cranked again and it started up but no idle at all, would jut die, had to keep some foot in it to get it home, a few blocks away,

replaced the fuel pump and swapped the carb off

idles but rough, crappy, but stays running and driveable without having to keep into it

bought a remanufactured Q jet, new plugs, reman distributor, readjusted rockers, they were a full turn plus a hair more loose :O

still total crap idle, seems like too much fuel but plugs are tan and dry

inside of heads looks great no carbon or water or anything, looks excellent

engine is never a smoker or anything, runs great above part throttle

but not so good now, getting worse fast

done everything short of pulling heads and intake

odds of it being crap intake gaskets ?

is a total stock untouched 400 1977 truck

tight engine it starts right up and when you shut it off it stops turning like a light switch flip, poof

still stock original iron Q jet #250 intake and #882 heads and exh manifolds and all

its baffling me,

never had such trouble with a good old chevy sb before,

never had one that i couldnt make run like brand new

gotta be something retarded that im missing out on

sounds like a tractor or diesel starving for air and the idle sounds like its got a huge lumpy cam in it

i would think that a leaking intake gasket would make it lean and run faster smoother more than anything else,

but maybe not

either way im pulling it off and putting this old edelbrock SP2P manifold on tomorrow, low RPM manifold,
the #250 intake is not one of the most desireable stock intakes they made ive learned


thanks for anything

 

[diesel4me]

sounds like...

Vacuum leak!...checked all the hoses,PVC valve,carb base gaskets,--EGR valve sticking open??..

If an intake gasket failed,it could suck oil fumes and air in thru the lifter galley,or let coolant get into the block or cylinder..also any lean running cylinders plugs would be white or blistered.not tan like a normal runner would look like..

Since it backfired,I'd look closely at all the rockers and valve springs too,and the pushrods...distributor cap,pick up coil or module could be failing too..(but you say you put a reman distributor in,so its doubtful..ignition coil good?...

 

[Leper]

What are your wires/cap/rotor/coil like? Ask some more questions before you go replacing parts. If you swap a part and the problem doesn't go away, put the old part back on and check(not replace) something else. That way you don't compound the original problem.

 

[R77K10]

everything is brand new

i pulled the original iron intake off and low and behold i found a crappy surprise

some moron RTV'd the entire gaskets both sides

was horrible mess and the gaskets were jut plain oiled badly

horrible

i put on an old edelbrock s2p2 intake and new gaskets, after meticulously cleaning all the rtv and oil off the heads(that was NO fun)

and well it runs freakin awesome now, all fixed and its running smooth and STRONG, gobs of low end torque, its great

the rocker arm adjustments helped too, noticeably, they were one full turn plus a hair more loose

:O


how could i compound a problem by swapping a part if i swapped on a brand new one ??

lol


i just have some more good used parts around here now, a couple more carbs, an HEI, and so forth

everything on it was good lol, it was the damn intake the whole time, some backyard retard screwed it up in the past



thanks

 

[mouse]

Some people just don't understand how to use RTV.