Tpx

I have a freshly rebuilt 350 sbc with hei, qjet and no computer. Blue smoke is coming out the tailpipes at 2500 rpm and above. My first thoughts were running too rich, but it was tuned correctly before it was rebuilt and this wasn't happening. Now that the engine has been taken out rebuilt and put back in this is happening. What could be the cause?

Was driving it home from the shop that just put it in when I noticed this. Shop said it was just cause it was running very rich due to the computer controlled qjet not having any computer to manage it. How can I adjust this?

383roller

holley or demon

Tpx

In my post I said it was a qjet, stock qjet if my memory serves. 1982

five7kid

iTrader: (14)

Blue smoke is oil being burnt. It is possible it's running so rich that it's diluting the oil and allowing it past the rings.

But, if you have a computer controlled q-jet, there's only one way to adjust it - with a computer.

If you took the computer out, shame on you. You just disabled the best street performance carb system available. I would normally call such an action "stupid", but if it was you, I don't mean to insult; so shall we just leave it at "ill advised"? It also happens to be illegal (doubly so in California).

Put the computer back in, get it operating correctly with all the wiring, sensors, etc. If you don't have those things anymore, it just so happens I have a complete intact '82 system waiting to rescue someone who ill advisedly removed theirs, threw it away, and now needs it again. It was taken out of the car that is receiving a 2000 LS1/T56, which has its own computer system, in case you're wondering why it was removed.

Tpx

Well I took it by a shop today for a second opinion and they said it was oil getting past the rockers? Something about a bad seal, is that likely?

This situation is bad because I need to get back up to college and the guy who built the engine (and who would fix it free thanks to warranty) is out of town for a while.

I have since ruled out too much fuel, because we hooked an a/f gauge up and it reads slightly rich but nothing drastic that cause such emissions.

About the computer, When I bought the car it had had the computer taken out, and the old qjet put back on (I believe it's because he had a very expensive carb on it and put the qjet back on to keep his carb). So that's not my fault, and I'm not sure I want a computer back in.

blue85305

if you don't wanna put the stock computer back in, then you really need an older non-cc qjet, a holley, or a edelbrock carb. you know something not for use computer controlled applications. older qjet might be best if you still have the stock intake. and just remember this when people start ragging you about no computer, cars ran without them for about 70 years or so, not really a need for them. the old school way just takes more work to get to work right, and you sacrifice a little bit of gas mileage, but the mileage sacrifice is probably negligible. do what you want and have fun with it.

Bowtiebruiser

I'd say Valve guides, were the heads rebuilt or was it just the bottom end?

five7kid

iTrader: (14)

Valve stem seals, specifically. Either not installed properly or not installed. Sloppy guides is a possibility.

As to the computer - putting it back in (assuming you still have the computer controlled distributor - oh, never mind, I still have that, too. . .) would be the least expensive, easiest way to go, and it would give you a better system than Holley, Edelbrock, or non-computer q-jet.

At any rate, more details about the engine and what was done to it would be helpful.

kmann101

Yes blue smoke is burnt oil and I have seen countless Chevy engines "burp" blue smoke because of the valve guides and seals. I have seen no harm in this other than it can **** you off because it does it. If the heads have been rebuilt I'm not sure what to say other than deal with it. But if they have not been completly rebuilt I would highly recommend it.

Bowtiebruiser

Hey now my 82 doesnt have any of the computer stuff left, MSD distributor, old school big block Holley spreadbore

Tpx

Heads were rebuilt, AFR eliminators.

This isn't some occasional burp of blue smoke, it's a HUGE billowing thing at 2500 rpm or above. So bad that at 3000 rpm on the freeway I could barely see out the rear view mirror. It's serious, I think. But like I said, engine runs very strong, no hesitation or bogging like to much fuel might do.

I will be buying a new carb that's boost referenced in preparation for a weiand 177, but for now the engine was running FINE before with this qjet computer or not. But thank you for the opinion, I appreciate superior knowledge when it's given honestly.

I will be taking it back to the builder for him to fix all this, but I would like to know what went so horribly wrong?

Another symptom arose later this evening. Engine's running very rough all a sudden, with LOUD knocking sound in unison with rpm's. Higher rpms = louder sound. This knocking's so loud that I hear the knocking CLEARLY over the 4" exhaust with 40 series 4" in 4" out flowmaster dumping behing rear bumper. Isn't that serious?

Oil pressure is above 30 always, water temp always nominal, my engine just seems to want to rip itself apart! I've never had such trouble with an egine, let alone a rebuilt engine. Everything was done to it, ending up costing $1,500 for the block work, head work, new bearings lifters, cam, oil pump, etc. Should be running like a champ don't you think?

Tpx

Yes they were rebuilt.

Tpx

Thank you for your input. I'm not sure if it's actually a computer controlled carb, I've been told it is but my car was an indy 500 special edition, it had a 400hp engine in it from the dealer and I'm not sure it was computer controlled.. I've come to find that many of my "stock" parts were special for the pace car edition and not stock for z28's only

Camaro383ci

Go drive your car somewhere its safe and no traffic staying at 2500-3000 rpm and then shift to nuetral while simultaneously shutting the car off being very careful not to turn the key all the way off causing the steering wheel to lock. When you come to a stop take a spark plug out and see if its fuel fouled or covered in oil. You may have to take out more than one. At least that would help determine which cylinders are messing up and if its fuel or oil.

383roller

Stop driving it immediately, how many miles has it been since the rebuild? i would definately take it back to the builder. If it is knocking that bad you have a very serious problem your bearings sound like they are already shot. If it was mine i would drain the oil, cut the oil filter and see if there is bearing material inside of the paper.

five7kid

iTrader: (14)

That's easy enough to tell by looking at it. Take the air cleaner off, post a couple of pictures of the carb from front and side.

liquidice

also if your car i smoking so much it could be over-honed cylinders,improperly installed piston rings. or the machineing was bad. did he hone with a torque plate? if not the cylinders could be out of round or oblong. but highly unlikely. alo if you have a knocking sound your probably f'ed get it warrentied. ive machined engines in a depot center for the army. if you have any questions just ask, and good luck.

Tpx

Well for those interested in what was at the root of the problem, it was poorly torqued rockers. Bolts loosened up after a few miles of driving, allowing too much rod play, which caused all the symptoms described here.

When it was taken apart, the rod on #3 was badly bent, and many bolts were working loose. All tightened up and good to go now. No other parts were affected, since the engine wasn't driven much more than 30-40 miles since the rebuild. Thankfully it was fixed before anything else broke. Free fix from the shop, plus a 100 refund on the cost of the work done as an apology. Not much but it's a nice gesture.

Thanks for your help in the replies, unfortunately it wasn't something any of us thought of. Until next time.