I have 67 352 with performer intake, and 600cfm edelbrock, both brand new. it did fine for a while but now has gotten hard to start, won't idle, idles real rough when it does and shakes the whole truck like crazy when you keep your foot on the gas to keep it running. It could be ignition but i know all plugs are getting a charge but don't know if they're sparking. I'll replace those tommorow. Tried tuning the idle mixture screws on the carb but to no avail. I'm just about stumped. it could be too much gas, too little gas, plugs fouling or not firing, who knows. But i think it's something that broke and is keeping it from running well, because it ran fine a little while back, it was even driveable (it is a garaged project till parents are ready to let me drive it). sorry so long just trying to describe it best i can. please post and help me, i'm stumped.

Thanks
Nate

 

[updated:LAST EDITED ON 24-Oct-02 AT 10:37 PM (EST)]How's your timing? I could see too much initial timing advance making it hard to start and idle rough. Make sure it idles around 12 degrees BTDC. Maybe the dizzy slipped a notch on the cam gear. Or, your timing chain may have slipped.

 

Or.... maybe the metering rods have stuck up.

Barry

 

You should be able to take the metering rods out while the engine is idling without effecting the idle, that is if the engine is producing more vacuum than the metering springs are rated for.

With that said I believe you distributor is retarded beyond 0 degrees and not advanced as previuously stated.

An over advanced ignition would make it hard to start, but should run relatively fine, but overly retarded igniton would run like dog****.

No matter what I do with my current distributor it always seems to slip -5 ATDC every 10,000 miles or so and the engine acts exactly as you are describing.

Josh

 

I guess it depnds on what you mean by "hard to start". Does it have a hard time turning over, sounds like "wump wump wump". Or, does it turn over at full speed and not fire up.

Mine does the "wump wump wump" when the timing is advanced and the engine is hot. My big cam likes very advanced timing to idle, but it it is difficult too start.

 

The timing appears to be about 11 BTC from the marks on the engine. As far as the timing chain or the cam gear slipping who knows. I know this is the original engine but don't know if it's ever been rebuilt, when i took the stock intake off it looked like it'd been there forever. How can you check if the timing gears and chain are ok externally, or do you have to get the timing cover off? Metering rods; just unhook the linkage and pull it out right? They don't appear to be stuck when i move the linkage it pumps up and down, plus it's abrand new carb so i hoipe it works. It turns over fast and doesn't start, but last time i had it out of the garage it started fine getting it out, started fine the next time, a little grief the third time, and we drained the battery trying to start it the 4th time to put it back in the garage.

Thanks
Nate

 

check the timing chain for slop by removing the dist cap, rotate the engine in the normal direction by hand until the timing marks come into view. Pick some point on the harmonic balancer marks and note where the dist rotor is pointing. Now, rotate the crank in the OPPOSITE direction until the rotor starts to turn. Note the degree marks on the crank pulley when the rotor starts to move. The difference is the amount of slop you have in the timing gears/chain. (plus the slop in the dist drive gear/cam matchup). Should be less than 10 degrees.
I betchur plugs got fouled, or a lifter has gotten stuck. Take out the plugs one at a time, and make sure that they are not covered with black stuff... soot. Make sure also that they have the correct gap between the center and side electrodes. 'Bout .032-.036 in, if I remember. Put them back and reconnect the plug wires. Take a look at the points in the dist. They should be opening about the thickness of a matchbook when the follower is on one of the lobes. If you adjust the points, you also have to adjust the timing. Make sure that the choke is open all the way so that you do not foul the plugs. DO NOT LOOK DOWN THE CARB WHILE CRANKING if you like to keep your eyebrows....
tom

 

if you have a holley carb check the power valve If your engine backfired throubh the carb at all its possible you blew it out (inverted the plunger).Those are common for doin that.I had a 68 with a 352 in it and it ran great then I took it out to check it for a rebuild and found that 0ne ring on every piston was broke yet it never lost power or burt oil. Those things are about bullet proof.any way chek that power valve holleys were bad about that but any carb can do it

 

The dude said in the very beginning he has an AFB carb and not a Holley.

What do you mean "unhook the linkage" when referrencing the metering pistons? It is a little cover you unscrew to gain access to the rods. You can unscrew the cover while the engine is running to make sure the pistons are ALL THE WAY DOWN.

But if you engine is stock and is healthy it should easily have more than 5 HG of Vacuum.

Hmmm...

Josh

 

I read most of whats said but, You would't happen
to have a manual choke would'ya? I had
a real fun time with mine a week ago
fuel pumps can be a problem too.

 

Yes it's a manual choke. We think we've figured it out to be a clogged idle jet. I'm going to disassemble it later and will post with my finding. By the way i have 2 new fuel filters on it one between tank and the metal line and one between the pump and the carb, so where could gunk come from except the open carb top? It just sits in the garage so could dust just "settle" into the carb and clog it?

Nate

 

old gas turns into a varnish kinda substance and will clog
jets,

Fe power