Dies when Secondaries Open (Fuel Shortage?)

[RhapidFyre]

I'm looking into going to Pick n Pull to rip a carb out of a 350, see if it makes any difference. Maybe I can even score and get a halfway decent quadrajet or something.

[jeffahart]

Originally Posted by RhapidFyre

I'm looking into going to Pick n Pull to rip a carb out of a 350, see if it makes any difference. Maybe I can even score and get a halfway decent quadrajet or something.

I'm not a big fan of this idea. But, if you do it, make sure to pull the carb off a vehicle where the carb looks to have been functioning for quite awhile and not something that is just sitting on the manifold.

Do not: get a used carb off ebay, or junkyard from a crate of carbs, or a anywhere it has just been sitting around with no known history. Those carbs were likely pulled for a reason. These carbs will need to be dissembled and rebuilt... period!

Where a junkyard vehicle with a carb that has been on for a while was junked because the vehicle was junk an not necessarily the carb. Your mechanic father in-law will need to inspect the carb good.

Again, better to borrow a known quantity. There will be no question after that.

I only suggested a carb swap as a method of expediency and it's free. But if you cannot find someone with a carb, then you just need to suck up the time and bucks for a rebuild. If you were near me you could borrow my carb for a few hours.

Again, I'm not big on the idea of a Junkyard carb for a test unit, unless it's being rebuilt(by an experienced hand).

I feel you should scrap this idea, unless you intend to go through the carb.

Research the Qjet numbers.





Good luck!


j

[RhapidFyre]

I had the impression that it was not likely the carb if the vehicle got junked, but you're right - Don't use junkyards for parts with an unknown issue. The impression I get is to use them more for the chance part that's better than what you have... Not troubleshooting.

I'm just trying to avoid buying another carburetor. I don't know anyone with one to borrow.

[geezer#99]

If you’re gonna try a quadrajet, what are you gonna use for an adaptor to bolt it onto your square bore intake?

[jeffahart]

Junkyard is great for lots of stuff. I'm running a Junkyard hydoboost and master. But for a carb it's kind of scary. You only want fuel being sucked into your engine.

I would retrace Geezers regimen. And like he said you need an adapter if you go Qjet(which would be in my future were I you). Do the easy stuff first.

Process of elimination, new part same behavior, return part. Onto the next component. It's simple, just a little time and sometimes money.

Not sure the return policy on a carb though. But I'd be tempted if I were you.


j

[PTC002]

For one you have the accelerator pump in the closest hole. I would move it back to the farthest out hole as just an easy "try". A lot easier to try than some of the others....seems like it is flooding as you advance the throttle.

Also, as previously mentioned....90% is electrical.....I would try a different HEI just for kicks.....a lot cheaper than a new carb.

[Mike_The_Grad]

Geezer would probably agree with this statement. Being as he has helped me in the past with a similar issue. Vacuum Advance Source. There are 2 locations on almost every 4 barrel carb out there. "Timed or Ported" vacuum and "Manifold or Full" Vacuum. Full Manifold Vacuum is always there as soon as the engine fires. Timed or ported manifold vacuum has none or very near none manifold vacuum at idle. It does provide manifold vacuum as soon as the throttle blades are opened enough to expose the vacuum passage to manifold vacuum. If you have a bigger than stock camshaft (lumpy choppy sounding) you could have issues with achieving enough vacuum. Also, if you have an aftermarket HEI with an adjustable vacuum canister, it could be adjusted to its max and pulling in to much timing to soon. My buddy is having real similar issues right now literally today with his 71 c10. New manifold, new carb, new hei, new wires, new plugs, new filter. His timing was way down at 0 BTDC. We pulled number one spark plug and ignition primary wire then bumped the motor over with the starter until I felt pressure on the park plug hole while checking his balancer timing mark. At first I thought we had it but it was the exhaust stroke because the timing mark was nowhere near the timing tab. Then I felt it and the mark was in the timing tab area, so we called it good and hit it with my adjustable timing light. Set it at 10° BTDC with the vacuum advance line disconnected and both of the vacuum ports plugged on his 1406 edelbrock carb. Then tightened the distributor hold down. Before he turned of the engine I plugged the vacuum advance into "Full Manifold" vacuum and checked it with my adjustable timing light. It jumped straight to 30° BTDC. So I slapped it to ported vacuum and plugged the other source off. He doesnt have a tach installed and I'm sure everyone will agree it's pretty much a necessity to get the whole thing dialed in correctly. His truck starts up just fine, will take any flip of the throttle no problem and sounds great doing it. But, as we pulled out of the driveway and hit 2nd it hesitated then backfired. And it only got worse the more he pushed it. To the point of a huge backfire and stalling the engine. He started to pump the gas and I told him not to because I could smell raw fuel. We limped it the 2 blocks home and it wreaked of gas. Its flooding pretty good. The plugs are wet with fuel.
Now, his carb has been sitting out and with fuel in it being started once a month. I'm suspecting the float in the carb is saturated. And possibly not set correctly. I dont know how many other hands have touched it or if it was straight out of the box and bolted on. But it did run for at least the 100 mile trip home he said about 2 years ago. Which come to find out was with the wrong spark plugs( the guy who sold it to him was a real piece of work,he had tapered seat plugs in the gasket seat cylinder heads.) Some more time is needed with a vacuum gauge, timing light, tachometer, and some patience. And I'll tell you the same as I told him. "At least it fires up, and at least it runs. It may not run well, but that's only a matter of adjusting and tuning."

[jeffahart]

Here's a line by Ray T. Bohacz

To many hobbyists and professional mechanics alike, the word "replace" is a synonym for "diagnose"--they fix cars by throwing parts at them. The logic behind it all is, if enough components are changed, eventually you will stumble across whatever is wrong, albeit by default.

I agree, but like I said before, at some point you have to bust a move. I advocate a part swap as a diagnostic tool(not necessarily the purchase, but you can return parts) as a way to rule out a problem.

What about just coming up with a plan to get back to a stock configuration so you have a working baseline. Then you'll know what's up with your enhancements going forward. You start with stock properly matched components, and that's a good thing. Then you can enhance and build on your experience.

Tinkering is fun but..... Finicky engines get boring real quick.


j

[RhapidFyre]

Originally Posted by Mike_The_Grad

-trimmed-

That sounds super similar to what is happening. For now, I've ordered a smaller Eddy, to see what difference it makes. Then we're moving forward with everything else. This will be in the next steps to come for sure!

[geezer#99]

What intake manifold do you have?

[Mike_The_Grad]

Originally Posted by geezer#99

What intake manifold do you have?

What he said^

I replaced the stock iron intake on my 350 a few years ago with an Edelbrock Performer aluminum intake. I still run the original 4mv Quadrajet. I made sure to get the spreadbore Performer intake to fit my spreadbore Qjet. Unbeknownst to me (I hardly get to use that word.lol) The spreadbore edelbrock Performer intake manifold requires an adapter plate for my factory qjet. Yes, an adapter to mount my spreadbore carb on my spreadbore intake. Because the factory Qjet's have what edelbrock calls an "irregular mounting flange". Without that adapter plate(cost me $20) I had a massive vacuum leak that was irritating the you-know-what outta me. It took me about a week to find out that this adapter plate even existed. I created a thread as a "FYI" for those facing the same issue as me. I dont have the link saved but you can visit my profile page and use the "Find all threads started by this member" function or something like that.
Some pictures of you're setup could prove useful and may even save you some trouble by having an outside "NON-tunnelvision" perspective from some helpful members interested in your issue.

[rpmerf]

http://67-72chevytrucks.com/vboard/s...d.php?t=725070

Good information. I've been looking at the 2101.

[Mike_The_Grad]

My buddy called me about an hour ago(hes the one facing similar issues as the OP.) He told me another friend of his, which I have my own opinions about his so called "knowledge", stopped by yesterday and talked him into letting him rebuild the carb. My buddy said the needle and seat had a bunch of crap stuck in there. So he cleaned it all up and stuck it back on the motor. Then he begins telling my friend that the secondary butterflys are hanging up on the intake plenum. This is a 1406 edelbrock on a brand new Performer EPS intake on his 350. So the guy starts to try and convince my buddy that he needs to replace the intake manifold because the linkage is binding. I guess this guy had setup his linkage while he still had his old Holley Dominator intake on the motor. And because he swapped intakes he is having problems. Then he even tries talking him into a new Demon carb, and on and on and on. I dont buy it. And I told my friend that guy is not doing you any favors other than the carb overhaul.(which I'm not sure was even done correctly.)
Well, the point in all this is exactly what the title of this thread is. So, RhapidFyre please continue with this thread as much as you can endure and if you dont mind, I'll post here what me and my buddy do to figure this thing out. One of us has go to eventually figure it out.
What i suggested to my buddy is that if it is in fact binding or interfering with the carb linkage or butterflys is to try a carb spacer. My friend was leaning towards that idea as well. But he also said he was just about done with the whole issue and about to go Fuel Injection instead. Lol. I said let's start with the cheap easy fixes before you go dropping a $1,000 on Fuel injection.

[Mike_The_Grad]

Rpmerf, in my opinion, Do it! It's a better design, shaves off a hefty amount of weight. I'm super happy I made the swap and wish I had done it years ago. One other piece of useful information is: make sure you get the correct gaskets. The aluminum intakes take a different intake gasket than the iron intakes. I think the correct part number for the felpro gasket is 1205. And dont use the cork block end rails. Just a nice size bead of that black RTV. About the same size as you put on your tooth brush across the front and back of the block and a little extra in the corners and your good to go. You'll be happy with it if you decide to go that route.

[RhapidFyre]

Hey guys -

Thanks again for all the advice. Today, my mother in law passed away and it has devestated the entire family. It was unexpected and sudden, and she was only 43. My father in law is the man who has been helping me through this restoration.

Needless to say, nor he or I will have time to work on this for a few weeks.

I will be sure to respond as soon as we have the time and willingness to work through all your suggestions.

Thank you so much once again.

[Chris_oz]

Sorry to hear about your loss.
Thoughts and prayers to you and your family.
Stay strong.
Look after the family first.

[Mike_The_Grad]

Family first is what I have learned in life.
Thank You for starting this thread, it helps to know that you're not the only one going through something,Regardless of whatever that may be.

[Rich69shortfleet]

Originally Posted by Mike_The_Grad

What he said^

I replaced the stock iron intake on my 350 a few years ago with an Edelbrock Performer aluminum intake. I still run the original 4mv Quadrajet. I made sure to get the spreadbore Performer intake to fit my spreadbore Qjet. Unbeknownst to me (I hardly get to use that word.lol) The spreadbore edelbrock Performer intake manifold requires an adapter plate for my factory qjet. Yes, an adapter to mount my spreadbore carb on my spreadbore intake. Because the factory Qjet's have what edelbrock calls an "irregular mounting flange". Without that adapter plate(cost me $20) I had a massive vacuum leak that was irritating the you-know-what outta me. It took me about a week to find out that this adapter plate even existed. I created a thread as a "FYI" for those facing the same issue as me. I dont have the link saved but you can visit my profile page and use the "Find all threads started by this member" function or something like that.
Some pictures of you're setup could prove useful and may even save you some trouble by having an outside "NON-tunnelvision" perspective from some helpful members interested in your issue.

Originally Posted by rpmerf

http://67-72chevytrucks.com/vboard/s...d.php?t=725070

Good information. I've been looking at the 2101.

First of all, condolences to the OP for your family's recent loss. Our thoughts will be with you and your family.

Concerning a good intake for a Quadrajet, I'd suggest looking for the old Edelbrock Peformer RPM Q-Jet manifold. They don't make it anymore, but you can find them at swap meets or on ebay. I got a very nice one for a little over $100. They take a Quadrajet as a direct bolt on, no adapter needed, exactly what they were designed for. You can tell the difference by the manifold type cast right into the left front runner. With this older manifold you also don't have to mess with the EGR (there is none cast into this manifold) and it takes a nice simple divorced choke stove. You do have to buy or make a choke rod unless you have one lying around. It is longer than the one use on the stock intake.

This manifold made a world of difference on the sb400 in my truck when I swapped up from a stock cast iron Quadrajet manifold.

[RhapidFyre]

Hey all - Semifinal update. While the family was going through celebration of life plans today, my new Edelbrock showed up. This one is a 600cfm versus the 750. I swapped them out and it screams like the day it was first bought.

Due to the circumstances and a flat tire I don't have time to drive test it. However it SCREAMS at idle and has NO drop off or dying issues.

When we took the other carb off, the throttle plates were covered in brownish black goop. Like really old fuel. Probably from before we replaced the fuel supply.

[Mike_The_Grad]

Glad to hear you have somewhat of a resolution to the carb issue. My buddy actually did the same thing. He bought another 1406 carb to replace the one he had on there. And he installed a 1" carb spacer. I'm heading over there later today to help with the tuning. I'll report back the results.

[Chris_oz]

Originally Posted by RhapidFyre

Hey all - Semifinal update. While the family was going through celebration of life plans today, my new Edelbrock showed up. This one is a 600cfm versus the 750. I swapped them out and it screams like the day it was first bought.

Due to the circumstances and a flat tire I don't have time to drive test it. However it SCREAMS at idle and has NO drop off or dying issues.

When we took the other carb off, the throttle plates were covered in brownish black goop. Like really old fuel. Probably from before we replaced the fuel supply.

Good to see you got it sorted.
Sounds like the fuel was not getting into the old carb. Or if it was getting in, the jets were full of crud and it wasn't able to get out.

[Mike_The_Grad]

I went to my buddy's place and I wired in the electric choke. We had a fuel leak where gas was puddling on the intake manifold right below the fuel inlet to the carb. When I pulled the fuel hose off the carb I tried dumping out the fuel in the clear inline fuel filter and it wouldn't come out. It was in backwards so he swapped it for the filter that came with the carb. Then when I tried to hook up my timing light to get an idea of where the timing was, I had no spark in the plug wire. I had power to the light because it connects directly to the battery but it has an inductive pickup that you clamp around the spark plug wire when it gets spark from the distributor. So I popped the dist. Cap off and checked the coil and the carbon button. They both checked out fine. I verified that the distributor was getting power. So I snugged up the screws and popped the cap back on and reconnected the plug wires. Still no spark to the plug wires. I took the distributor cap and rotor off and pulled the module so I could check and eliminate the pickup coil as the problem, when I tried to separate the module from the pickup coil leads it wouldn't budge. I had to wedge a screwdriver in between them and pry the module off. After checking the modules contacts I could see a black burn mark on the terminal that goes to the pickup coil ground wire. So I'm thinking the module got fried somehow some way. It was to late to grab another from O'Reilly's so tomorow looks like we will be able to get this thing back together and hopefully get it all ironed out once and for all.

[Rich69shortfleet]

Originally Posted by Mike_The_Grad

I went to my buddy's place and I wired in the electric choke. We had a fuel leak where gas was puddling on the intake manifold right below the fuel inlet to the carb. When I pulled the fuel hose off the carb I tried dumping out the fuel in the clear inline fuel filter and it wouldn't come out. It was in backwards so he swapped it for the filter that came with the carb. Then when I tried to hook up my timing light to get an idea of where the timing was, I had no spark in the plug wire. I had power to the light because it connects directly to the battery but it has an inductive pickup that you clamp around the spark plug wire when it gets spark from the distributor. So I popped the dist. Cap off and checked the coil and the carbon button. They both checked out fine. I verified that the distributor was getting power. So I snugged up the screws and popped the cap back on and reconnected the plug wires. Still no spark to the plug wires. I took the distributor cap and rotor off and pulled the module so I could check and eliminate the pickup coil as the problem, when I tried to separate the module from the pickup coil leads it wouldn't budge. I had to wedge a screwdriver in between them and pry the module off. After checking the modules contacts I could see a black burn mark on the terminal that goes to the pickup coil ground wire. So I'm thinking the module got fried somehow some way. It was to late to grab another from O'Reilly's so tomorow looks like we will be able to get this thing back together and hopefully get it all ironed out once and for all.

Wait, you lost me. It runs but when you check the timing you can't get the timing light to fire? Because when a module goes out, it won't run at all. If it runs but is not firing on one cylinder or more it will noticeably run poorly. Did you try your inductive clip on any other plug wires to see if you had other cylinders firing spark? A bad module would not cause one or two cylinders to not fire, it would cause no spark at all.

Also, when connecting your inductive pickup clip, are you clipping it on properly? They typically have to be clipped on the wire with a specific side of the clip pointing toward the spark plug. The top of the inductive clip is usually marked PLUG with an arrow. If you have it on backwards it won't fire the light.

[Mike_The_Grad]

I'm sorry. The engine will crank but will not fire. Yes I tried the inductive on other wires, still no spark. We pulled the number 3 plug and wire and laid them next to the frame while my buddy cranked the engine and still no spark. This engine was running two days ago. Albeit not with this new carb.

[RhapidFyre]

Success.

There was too much drama in the house about the loss we've suffered, so I got out to the truck yesterday and worked off my frustration with a few new steps....

The carb swap worked; It now has an Eddy 1406. I just took it on the road with new belts, topped off power steering and replaced the alternator for the hell of it. Jimmy Jr hit the road and had NO issue reaching 70. Pretty hard power falloff around 80 but for a classic I think that's perfectly normal. This thing wasn't built for drag racing. Shifting appropriately, absolutely no lag in the throttle and 0-70 is not a struggle for it whatsoever.

Now the real fun begins.