Technical SBC guys, help me get my 283 runnung right before i put a match in the gas tank

I have one more small thing; does the power valve actuator "dashpot" and rod move freely?

 

A bad coil sputters and falls on it's face under load. They are like $15. I keep a spare around for troubleshooting.

 

The hardest thing to do when you feel that you've checked everything and haven't found the problem is to approach it as if you haven't checked anything and go thru it step by step and look at it like you are troubleshooting it for the first time! If you can't do that your chances of finding the problem is not good.

 

Last year, I decided to check plugs, and even though burning clean, I installed a fresh set. Well, had some issues for a day or two, not long enough to involve the HAMB brotherhood, but getting close. First, couple plug wires fell off(I have shoulder issues and couldn't get push). Got that rectified, but running funny/rough off idle. Started playing with idle mixture, clearing out air bleeds, etc-OK. Checked firing order good. Checked again later, I was wrong, 2 plug wires on same side of engine, were confused and on the wrong plugs. SBF, on driver's side. All good!

 

That’s it right there !
And a very supportive way to say it. I’m probably going to steal it.

It’s a lot better than my usual smart ass
ok you checked everything and everything is good. Then obviously it’s running perfectly fine! Not running fine you say well then you didn’t check everything and everything isn’t good.

 

31 Vicky is going down the same road as I was thinking, after double checking valves, no improvement?, a compression test would be next,maybe cam timing is off, or new valve job isn't up to par, sealing wise. Perhaps an update will be posted.

 

One thing, Can that carb actually be reversed on that intake and not have a hidden leak or not have exhaust get into the intake if you don't plug the crossover holes. Will the throttle plates open up all the way without hanging up?

This is a collection of photos of a 62 283 intake and a crusty and a clean 62 two barrel base. I'm not positive that you can actually get away with reversing that carb on the intake and not if you don't plug the exhaust cross over holes in the intake.
Last but not least, an unplanned restriction in the fuel line, squashedhose or tube, kinked hose or tube. Gas cap that isn't venting that shuts off the air going into the tank so that it creates a vacuum in the tank that overcomes the fuelpump, The more gas in the tank the faster it acts up.

If you let up on the gas for a few seconds like doing a slow shift to second will it pick up and go for a bit before it acts up again? That would be the fuel bowl running out of gas and having to wait for the pump to fill it up again. I had that happen on my 57 panel 50 years ago and it was a brass fitting that was intended for a natural gas connection in the fuel line. That one was feeding two four barrels on a Corvette intake but the carbs ran out of gas real quick on hard acceleration but toddled along at low speeds ok.

 

Yes, i always keep a spare also.Coil was one of the first things i changed. Installed a new accel coil that tested good.I'm about to get another one just in case this new one has something weird going on.

Thanks for the comment. Let me be clear. I have no problem "starting over" as you suggest.I have done so severel times before i even posted this issue. Thats why i posted. I haven't checked things like firing order once or twice, i've checked them 10 times.Same vith vacumme leaks,grounding issues, power to the coil, points plugs, condenser , rechecking tdc over and over etc. Multiple times. Obviously i'm missing something but it's not the result of not wanting to put in the work.I'm not new at this, i'm 67 and been in this hobby since i was 14.

 

Thanks, i made an aluminum base plate that mounts the carb w/o any leaks.I don't know if there is any other reason why mounting the carb backwards but with the plate i made there isn't a leak and the hot air holes match the carb base w/o regard to the carb orientation.Throttle plates move full open.Checked fuel flow severel times and seems fine.On hard acceleration it initially dies out,just like running out of gas then i can accelerate a bit but engine is missfiring and breaking up.

 

Did you say what you have for exhaust? I had a problem similar to that once. Exhaust /mufflers were restricted.

 

At this point i only have the header pipes on the engine so no restriction.Thanks though!

 

One thing to check is that the vacuum advance plate may have flexed the wire to the points enough times that the copper in the wire has broken, when the plate moves under heavy load the copper might separate but then carry current when advance plate returns, that little wire has burn't me more than once and takes a while to figure out

Another problem that took a while to figure out was when my newer one wire alternator went bad after welding tabs on the car frame, suddenly the gages go wonky after start up and the engine would miss and backfire during high rpm after two weeks of trouble shooting still had the problem, tried disconnecting the alternator wire with no change, then finally removed the fan belt and the problem was resolved.
The alternator shorting into its metal case

 

A restriction in exhaust is diagnosed with a vacuum gauge. A quick as you can 1/2 throttle blip and the gauge drops to zero and hangs there momentarily slowly recovering to baseline. Normally that gauge moves fast as you blip the throttle never touches zero

 

Did you blow out all the passages in that carburetor. Is there a chance something is plugged. Anymore I boil my carburetors in an old deep fryer with a pinesol solution to agitate and remove encrustations. Are the gaskets correct to the carb model? Is the power valve too long or too short? Is the float sinking? Is the needle and seat machined proper? Is the fuel pressure too high or too low? Could the Mallory condenser also be bad out of the box. Could the head bolts have backed off? Are the intake gasket ports too big, ? Is the wire that goes into the distributor chaffed and shorting? Is the end clearance on the distributor excessive causing the rotor to lift and contact the cap. Is there a vacuum leak at a Rocker stud. Is the timing gear machined wrong?There is 30 years plus of my frustrations I've discovered in various engines. Good Luck. Nothing is more fun than doing everything over and over the same way and hoping for a different result.

 

Open headers don't help when trying to listen for clues to diagnose a problem, everyone's added their ideas, and then some. The man has abilities, he'll figure it out, reminds me of the 54 New Yorker guy a couple months ago, he fixed it, it's hard to diagnose over the internet, unless you're over his shoulder with a second set of eyes.

 

I remember this one time I was working on an old Harley that wouldn’t run right all the time. imagine that !!??!!
It was obvious electric issues. I chased the entire system all the way around thru the headlight bucket, back thru the engine, thru the ignition switch and eventually ending up at the taillight. Everything checked out good, couldn’t find an issue but it was still running like shit only sometimes.
I ran thru the valve adjustment, fuel delivery, points went away and got electronic ignition, put new coils plugs and wires. Still the same thing. Kinda pissing me off now.
Ran this situation over with my dad and his first question was how’s the battery? I said it’s good, checked out fine. He said it runs fine then it doesn’t then it does then it don’t. How’s the battery check out when it’s not running fine? IDK? How can I tell? Try a new battery, something is “there” when you test good and “something” goes away when it runs like shit.
Swapped the battery that’s tested absolutely fine with everything I had to test with. Of course that fixed the issue. Something internal didn’t like all the vibrations and would intermittently drop voltage.

Some place on the HAMB is the entire story I told of how a routine tune up turned into a complete rebuild because of a set of spark plug wires.

 

I made my living diagnosing car problems. 47 years, the hardest to find was on my own vehicle.
Secondary coil wire had a gap inside. Run it long enough and the coil overheated, usually in the middle of nowhere and I was alone.
Cool down and it would fire up and go a week without a problem.
The answer will be simple when you find it.

 

At last count you have received over 100 replies of thoughts...it took Thomas Edison over 200
trys before he got the right filament for his light bulb. When asked if he got frustrated after so
many failures, he replied, "No, because each time I still learned what did not work." Go down
your list and then sit back and go through it again in your mind. You will get it. And when you do,
it will be one of those "ah-ha" moments.

 

Last winter I had a brand new NGK in my yard tractor that would sometimes spark across the ground strap and sometimes ground into the threads. That was difficult to find.

 

The only thing that isn't "NORMAL"...is the backward carb set-up.
You seem pretty sure it will work but.........
I'd go through the trouble to PROVE to yourself the backward set-up does indeed work well.
6sally6

 

Yep. Recently went through that with mine. Turn on the switch, electric pump cycles. Turn ANY light on, and pump cycles again!! Checked EVERYTHING! I thought. I had just installed a new battery when problem first showed it's ugly head. Finally, changed the pos battery cable. All is well. Unseen corrosion inside the cable allowed momentarily low voltage, I guess. causing the pump controls to recycle. I hate gremlins.

Ben

 

Since the thoughts keep coming, here's another, if the diode rectifier in the alternator starts to fail, it will introduce AC voltage into the electrical system, on new cars any more than .250 -.500vac. causes problems with computer. On points system maybe could tolerate a bit more but definitely affects battery life. Set a DVOM to ac and check across battery terminals while running at 1500 rpm.

 

^^^^ This, on my O.T. '91 M-B 300SLR.
Shortly after replacing alternator AND battery ($$$$) a miss was detected, under load. It was at night, but I raised the hood after driving into my car port: Raised the hood, and noticed a fast spark unloading onto inner fender 'shelf', from bottom of defective coil! Only at night... LOL "Darkness, darkness..."
Expensive weekend...

 

I'd imagine someone else has suggested this , get away from it for at east a couple weeks , do other things ,a new perspective can work wonders , the more you fight it the worse it becomes !

 

Shoot Mike.......I pulled the bed off my truck and replaced the fuel pump when the miss was......
bad spark plug wire !
Must be the name Mike ???!
6sally6

 

Can you put a wideband O2 sensor and gauge on? That’d let you read the A/F mixture without trying to read the plugs. Might also help show why it’s ok at idle, but not under load.

 

Those things are pretty nifty, hard to watch and drive through, so you need a co pilot or a data logger. I could be wrong, but im gathering from the post there is not even been a fuel pressure gauge in the trouble shooting process.

 

My first thing would be to turn the carb around I try to elimate the low cost first even if you run it by pulling the throttle with a wire to test. One less thing to cross off the list instead of throwing parts at it.

 

A simple bell crank can reverse throttle direction easily .

 

Shut it down, spend an evening with a bottle of The McCallan 15