Im almost embarassed to ask, since they are pretty much the simplest engine in the world, but anyway...
1970 chevy pickup, with the stock engine. The cam gear for the timing chain disintegrated, bent all the valves, etc. took it apart, replaced the valves, head gaskets, valve springs, rockers, etc. Put in back together along with a rebuilt q-jet, the rest is pretty much how it was before. Tired to start it, it started right up and ran fine, but would imediatly die when you put it in gear. I drove it up and down the street and it would barely run, then it got harder and harder to restart, now it wont start at all. It is getting fuel, spark and timing appears to be correct (it ran perfect when i first started it up as long as it was just sitting there idling). I know i should check the compression again, but any other sugeestions? I also tried starting fluid and that did nothng either.
1: Check manifold vacuum 1a: When there is no vacuum replace leaking intake that blew out the rear ;)
2: Check fuel pressure. the fuel pump rod may have failed OR the lobe that pushes it.
3: Buy 6.2L Turbo LS engine and rokk that schit!
ncjay
New Reader
2/12/09 5:48 p.m.
I've built a few Q jets over the years. They are on almost every engine I own, which is several. Sometimes they work perfect right from day one, sometimes the floats refuse to work properly. Check the fuel pressure, check the oil pressure (just to be sure). Maybe some trash got into the carb somewhere. If all the valves were bent, did the bottom end sustain any damage? If it's a completely stock engine, Chevrolet uses a plastic cup on the oil pump driveshaft that can break, letting the oil pump stop turning, but it sounds like the engine still turns over well enough. Only other thought is if the spark plugs are firing and look ok, maybe the harmonic balancer slipped on the vibration damper. If that happened, you're just guessing with the timing marks. Keep us posted on what you find. The SB 350 may be the most common engine in the world, but it is far from simple. Also, maybe the pin holding the distributor gear on sheared off. I've had that happen to me. It progressively runs worse and worse until it just stops.
cwh
Dork
2/12/09 6:48 p.m.
A zillion years ago I built up a sweet 350 and dropped it into an S-10. Was driving it to the muffler shop for the exhaust system and it just got worse and worst and finally died on the side of the road. Problem? I had not tightened the distributor lockdown enough, and the engine re-timed itself to not running. 30 second fix by the guy that knew what he was doing. Sounds a lot like your problem.
yes.. I am betting on either the distributer or a vacuume leak on the intake.
or the valves are adjusted too tight, so it's marginally OK without load but won't run with load.
iirc not all SBC gaskets are created equal i.e. if you have an EGR gasket set a non EGR manifold will run like crap and vice versa.....or it could be the Trader Vic's Mai Tais talking, but its something to think about.
AngryCorvair wrote:
or the valves are adjusted too tight, so it's marginally OK without load but won't run with load.
That is the one idea I had that i still need to check.
if they're hydraulics, back off the adjuster nut until you can feel slack between the pushrod and the rocker. then hold the pushrod between thumb and index finger and spin it while you tighten down on the nut. when you can't spin it without great effort, that's all you need.
AngryCorvair wrote:
..when you can't spin it without great effort, that's all you need.
Zero lash, No preload?
(P.S. I know nothing about V8 valve adjustment)
aircooled wrote:
AngryCorvair wrote:
..when you can't spin it without great effort, that's all you need.
Zero lash, No preload?
(P.S. I know nothing about V8 valve adjustment)
i'm sure there's some preload with this method, but i always set mine up pretty loose and they always run well. i guess you could go a quarter-turn past not being able to spin the pushrod, but as long as they don't clatter when the engine's cold, i figure that's tight enough.
