Possible timing chain stretch???

[78longbed4x4]

Ok so I have an 83 Chevy shortbed I just put a 355 in it with a 4 speed manual trans, 208 transfer case, Dana 44 up front and Dana 60 out back. I put the motor in from another truck and it won't run right. It definitely has a rocker arm stud pulling out of the head, but when you shut it off it wants to spit and sputter and then it revs up and blows smoke out the tail pipes and back through the carb. If I retard the timing a little it's not so bad but it won't hardly run, barely any throttle response at all. When I advance it, it wants to backfire through the carb when you give it gas and then it sputters and smokes and backfires when you shut it off. Could my timing chain be stretched? I had this same motor in a 78 Chevy and it ran ok, not great but ok, I always seemed to have to adjust the timing once a week or so to get it to run right. It's got a new distributor cap and rotor, new coil, new plugs and wires. I'm lost as of now, I'm a diesel truck mechanic, but I'm just now getting into these small blocks and I don't know a whole lot about them. Any ideas? I don't have a timing light so I couldn't tell ya exactly where it's set but it's pretty close cuz it ran ok in the other truck.

[bd]

You could have a stretched chain, a spun harmonic balancer, a vacuum leak, excessive idle speed, or any combination, thereof.

See:  86 C10 Loping and Not 100% what's wrong here.

[thefarmboy21]

My buddy just went through a similar situation with a 355....they rebuilt the motor that spun a bearing and put everything from the .060 over block that ran awesome, to a .030 over block and ran like dog crap. Popping and cracking and everything....turns out they wiped the cam and 5 of the lifters ground down about 1/4" shorter than they were supposed to be, and one about 1/2" short and had a hole worn through it.

[roundhouse]

Dissconnect the  coil  Hold a dollar bill over the exhaust pipe and have a helper crank the engine.    If it tries to suck the dollar bill up the pipe. You have a skipped timing chain   Although usually they won't run at all

[78longbed4x4]

Ok I'll give the dollar bill thing a shot, but I'm thinking my cam has gone flat. I had it runnin again tonight after work and I noticed if you stand behind the tailpipe on the drivers side, you can definitely hear a miss but if you stand behind the pass side it sounds ok. So I had the drivers side valve cover off and had it runnin and a couple of the valves were hardly opening at all. But that still doesn't explain why it wants to sputter and smoke when you shut it off. Either way, it looks like I'm gonna have to replace the cam so I'll take a look at the timing chain and replace it too when I get her all tore apart.

[bd]

Ok I'll give the dollar bill thing a shot, but I'm thinking my cam has gone flat. I had it runnin again tonight after work and I noticed if you stand behind the tailpipe on the drivers side, you can definitely hear a miss but if you stand behind the pass side it sounds ok. So I had the drivers side valve cover off and had it runnin and a couple of the valves were hardly opening at all. But that still doesn't explain why it wants to sputter and smoke when you shut it off. Either way, it looks like I'm gonna have to replace the cam so I'll take a look at the timing chain and replace it too when I get her all tore apart.

The camshaft is flat:  355 with a new issue.  And, it's passing too much air into the engine at idle. 

Verifying the balancer timing marks before you tear it apart will save you some time and frustration.  If the studs are in fact pulling from the head, take the heads to a machinist.

[78longbed4x4]

Is it possible the studs just backed themselves out?  I'd so couldn't I just put some loctite on them and snug them up? I didn't look at them real well but the one I noticed was loose didn't look like the threads were pulled. I didn't pull it all the way out of the head cuz I didn't wanna lose all my coolant but that's what it looked like to me

[bd]

Factory small block studs press in.  Are you sure the studs thread into the head?  It is possible, if the heads have been reworked or are aftermarket castings.

Candidly, you need to stop the guesswork about what is wrong and begin making some careful observations.  There are plenty of people here to help guide you if you get stuck or need assistance.

[78longbed4x4]

They're dart sportsman heads on there

[bd]

They're dart sportsman heads on there

Align the pushrod guideplates and torque the rocker studs to 45 lbs-ft.  Apply Loctite to the threads of the studs only if they penetrate the intake runners, otherwise use 30 wt motor oil.  Check guideplate alignment and torque on all of the studs - not just those that are backed off.

[78longbed4x4]

Will do

[jaredts]

You should probably adjust your valves after doing that and then watch for proper valve movement again if it still runs poorly.

[78longbed4x4]

I think I'm gonna go ahead and go with a new cam and lifter kit and some heavier springs and maybe go to roller rockers while I'm at it along with a double roller timing set

[VileZambonie]

Why not verify what the problem is before you start slapping more problems at it? If it's a wiped cam lobe you can easily identify that with the valve cover off by checking the lift. Have you ensured your firing order is correct,  good spark etc? Pinpoint the cylinder that's having an issue by doing a power balance test.

[78longbed4x4]

#5 cylinder is the problem. Hardly any lift at all on the intake valve and I checked the header pipe on that cylinder with a temp gun and it's way hotter then any of the other cylinders. It's got all new plugs and wires, new cap and rotor, new coil. The push tube isn't bent or mushroomed and I re adjusted the rockers and it still runs bad and that valve still has no lift