Nick's 1971 Mark III

[1Bad55Chevy]

Hmm. Do the screws control fuel flow or air bleed?

Air bleed per that edelbrock diagram.

I was talking vacuum leaks if the vacuum levels were not changing with the rpm variations from the idle mixture screws. Lee is right about vacuum leaks causing an extremely lean condition that would require a rich carb state.

Here is a good question... if the idle mixture screws are closed there would be no air flowing through the air bleed. Would no air flow through the air bleed cause increased suction on the idle jet? If that was the case and there was a vacuum leak would the engine still run since the idle jet would be supplying more fuel?

I am not good with edelbrock carbs mosty because they work out of the box.. I am more of a 4150 guy..

[Lee]

It's conventional...turn mixture screws clockwise, and it goes lean. Air is added by opening the throttle plates with the idle speed screw.

[1Bad55Chevy]

Thats how the circuit functions. That should be in the book for your carb.

Based on that your issue is elsewhere and the reason it is running with screws turned in is because the idle speed screw is turned to far in.

[LithiumCobalt]

Thanks guys. Sounds like my idle position is set too high. Next time I am up to the car I will get that addressed. Barring any other surprises, I will finally get to drive the car after almost a year and get some fresh gas in it.

If anyone is wondering what the issue that I had with getting the car to run, it’s quite embarrassing, but I will admit it anyways. Had everything setup just perfectly except for one critical item. I wasn’t aware this could even happen ahead of time and it’s why I wasn’t watching for it…..

Apparently on the 460, it is possible to dislodge the oil pump driveshaft enough to misalign the position but without dropping it into the oil pan and still be able to insert the distributor fully without interference. I have no idea how this is physically possible, but it happened. Before I started the car for the first time after all the engine work, I primed the system fully as expected. Dropped the distributor in without any trouble and started the car. Engine would start and run, but would get progressively noisy and run worse and worse. Couldn’t figure out what was going on. It never occurred to me it was not getting oil. Apparently when I pulled the priming tool out it must have pulled the driveshaft just enough that it was no longer lined up. Unfortunately I did not check before I inserted the distributor.

Had a couple mechanically inclined friends stop by to check my work. Pulled the valve cover on the left side to check position of distributor rotor was correct in conjunction with valve position. It was, but it was also dry under there. Immediately pulled the distributor and noticed the end of the pump driveshaft was barely visible through the hole. It was off-center dramatically and obviously not engaged with the distributor. This was the source of my problem. After spending an hour or so trying to get the shaft reinserted and aligned properly, I dropped the distributor back in and started the car. It runs beautifully. Oddly enough the driveshaft did not have a locking washer on it as expected. I was able to pull it right out with an extendable magnet.

Apparently this is a common problem on the 460 as I did a quick internet search and saw MANY accounts of the exact problem. Luckily I did not run the car long in this state, but who knows how much damage was done in the meantime. I will drive the car and monitor oil pressure and condition. If something ends ups being seriously wrong, it will be time to yank the block and do a real rebuild.

Thankful that I got it running. Hopefully this helps someone else not to make the same mistake.

All I have left to do now is seal up the valve covers, fine tune the timing and carb and off we go.

[Lee]

Hope it turns out well, Nick. You hardly have the “dumb move” category to yourself. This is one advantage of having an idiot light over a gauge.
Don’t know how long it ran that way, but you might consider changing the oil and filter.

[LithiumCobalt]

Probably a good idea on the oil change. I will do that.

[1Bad55Chevy]

Was the distributor sitting all the way down and flat to the block?

I agree with the oil change but I would add cutting the filter open for inspection.

[LithiumCobalt]

Yep, distributor was down all the way. In fact I had the retention bracket and bolt almost all the way in. Just loose enough to move the distributor from side to side.

[Lee]

Was the distributor sitting all the way down and flat to the block?

I agree with the oil change but I would add cutting the filter open for inspection.

That's a great idea on cutting open the filter. It may be ugly, but at least you'll know.

[1Bad55Chevy]

https://amzn.to/46e1RH3

I have something like that but it is a lot older. I stole it out of my father's tool box 20 years ago so I have no idea how old it is. They work like a can opener and if you drain the filter first it won't make a mess.

[Lee]

You know, you might even throw in a quart of “Motor Flush” (basically kerosene) and run that in with the warm oil for the last 5 - 10 minutes or so before you drain it. That way you’re more likely to remove all the wear particles before you put in fresh oil. I’ve done that before with old engines new to me, where I didn’t know the history.
https://www.amazon.com/Gunk-Motor-Flush ... 192&sr=8-8

[LithiumCobalt]

Great advice guys. I’ll add to my list and report back what I find. As for the oil filter, wouldn’t a recip saw do the trick rather than buying this tool I’ll probably never use again?

[frasern]

Motor flush will dislodge years of sediment, if you want to know what has happened in the last few weeks, maybe hold off on that till next oil change. Anything that will cut metal will cut the filter, I would punch a hole in the top and let that drain overnight (it wont drain as well from the flange), then cut it from that point with tin snips, so as not to create filings.

That's a weird one, the shaft coming out of place. I have never seen that retainer break off, but it could have happened to anyone, they are pretty flimsy.

[LithiumCobalt]

Anyone have a recommendation on a tool that can properly measure the tension on the v-belts for our cars? I want to make sure that I have them perfectly adjusted

[Lee]

Nick, I have to admit that I've never owned one, but I can tell you that I've seen this handheld style illustrated in the factory manuals
https://www.hemmings.com/stories/2015/1 ... sion-gauge
Looks like they are still being made new, but the price is pretty steep. I see a few used ones on eBay for maybe half that.