Fire Breathing CARB

[Stingray74CC]

AAAAAAAGGGGGHHHHHHH!!! I installed the refurbished carb from Recarbco, changed the wires over to the Taylor 409s and.............

The car won't run. It'll turn over and start for just a second or two then stop. Most of the time when it quits the carbs (all three) will hiccup with a flame or just shoot fire. Once it backfired very loud. Does anyone know what's going on? I triple checked the wires...they are right.

I'm open to any and all suggestions.

 

[AKRAY4PLAY]

hoping that the carbs are right, you may want to look at the timing. it may have gotten bumped off. try backing the timing off a few degrees, somewhere between 30-36 total. first i would look at the carbs with someone else trying to start it. if you are dumping massive fuel quantities, it will cause the problems you described. good luck, brian

 

[Stingray74CC]

I'm gonna start over tomorrow...recheck the wires and timing. How do I check the timing if the engine won't even run? The carb is it same one; they didn't have any in stock so they refurbished mine. The problem seems timing related...like the wires are mixed up. Huh, dumbfounded. :confused

 

[cntrhub]

I would check the wires again. Seems you get gas to light off the engine. Once the engine tries to chase the next sequential cylinder, it lights off a cylinder with an open intake valve. Thus the spark lights the fuel and out she comes in a flame of fire through the carb.
V8 firing sequence is: 1-8-4-3-6-5-7-2. Remove the dist cap. Crank the engine over by hand. This may take a few revolutions before you time in the rotor postion with the timing mark on the harmonic balancer. The #1 cylinder's (TDC compression) rotor should be facing at 11:00 o'clock. I rather you get #1 compression for a start. I don't want to confuse you doing it another way that will have the same results. Lets keep it simple. Meaning, if you were sitting in the driver's seat, and you looked directly over the rotor (with the cap off), the rotor would face 11:00 o'clock. The rotor's metal tip should be even with the cap's metal tip also. If they don't line up, move the dist shaft until they line up. Lightly tighten the bolt. You'll need to move the whole shaft again, when timing the engine with a storbe light. We will begin with this, as our #1 cylinder postion. This should light up the engine (at least), after we are done with this. Worry about timing with a light later. Now turn the crank a few degrees until the rotor hits the next plug postion under the cap's metal tip. You're going to have to do the old "eye ball" guess doing this. The easy way is to lift (the cap) straight up to guage positions. This should be cylinder #8. Move the crank to the next wire cap postion. This will be cylinder #4....so on,and so on. This is the best way to double check your wire routing to each cylinder.
Sit in the driver's seat again. Left hand bank = odd cylinders. #1 being farthest away from your seat. Cylinder #7 being closest to your seat. Even cylinders = right hand bank. Cylinder #2 at the radiator. Cylinder #8, back at the fire wall.
Is the engine doing the same thing? Did you remove the distributor shaft and not time in the rotor at TDC #1 (11:00 o'clock)? Is the engine still doing the same thing? Did you adjust the push rods with this engine? There might be a tight valve sticking open. Let me know, I'll walk you through a valve adjustment.
Get all this out of the way before you chase a fuel problem.

 

[AKRAY4PLAY]

Anothony,
timing without running is not going to perfect. what you have to do is fairly easy and will get the motor running good enough to check timing. take a magic marker and mark your distributor housing were the number one plug wire post is. then pull your distributor cap and roll the motor over to top dead center (compression stroke) for the #1 cylinder. assuming that your balancer has marks, roll the motor (back a little) until the pointer is at 4 degrees before top dead center. then you can align the rotor with the mark on the housing by turning the distributor. this should get you in the ball park far enough to lite that bad boy off. then you can adjust the timing with the vacuum advance disconnected and plugged (if you have vac advance).
i know this isn't the case, but just to be thorough. some ford friends of mine often make the mistake of confusing the cylinder numbers and firing order. so double check that you have them right, i have even been guilty of that mistake before.
one last thing, old breaker point ignitions had the number one hole on the dist cap in a different place than the hei #1. the firing order is the same, but the point system rotated the placing on the cap one spot clockwise compared to the hei. if your plugs are off one post all the way around, it will add 90 degees of advance that you don't need. hopefully this helps and not confuses you farther. best of luck, brian

 

[AKRAY4PLAY]

cntrhub beat me to it, nice job. and excellent description as well.

 

[AKRAY4PLAY]

Anthony,
one last thing, i though i read on another post that you upgraded the ignition from points to hei syle aftermarket stuff. has the motor run since that mod??

 

[Stingray74CC]

I'm about to head out to do the checks. I don't feel as stumped this morning...I'll get it to work. I have upgraded to the Pertronix electronic ignition inside the distributor. The car has run great since that upgrade. I'll let ya'll know how this mornings efforts go. Thanks for the help.

 

[Stingray74CC]

Checked the wires...even put the old wires back on....Same thing. I'm pretty familiar with the routing of the wires. I've taken them off before. I lined the harmonic balancer up 4 degrees BDTC....the rotor was exactly where I expected it to be...on the #1. The problem does seem to be timing related (like the wires are crossed) but I don't see how. Stumped. I'm going to try to have a buddy come check out what I've done....see if he sees anything differenct than I do.

Possibly anything else to check????

 

[Stingray74CC]

She's Running

I took the air filter back off to look at the carbs. I noticed that I had lost some pedal travel since I put the primary back on. The linkage for the secondaries was holding them open with the accelerater in at the idle position. I disconnected that and she started right up.

Now the hard part.....adjusting the mixture/idle. It doesn't seem to want to stay steady. It'll idle high then begin to drop off then begin to die. I tried adjusting the idle screw with the mixture screws 1-1.5 turns out. I'm thinking there might be a vacuum leak that preventing me from getting a constant idle. The only vaccum lines hooked up are the vacuum advance/secondaries/ and power brakes. I'll try eliminating one at a time and see if I can get a constant idle.

 

[Stingray74CC]

Continuing the story....

Well, I found out the the gasket between the intake manifold and primary carb was the wrong one. :duh I may as well have drilled a hole in the intake. It was sucking in that much air. She's running much better. The idle is great for the most part....could probably use some fine adjustment on the idle/mixture screws.

Here's the last thing (for today...hopefully).

The linkage for the secondaries changed from when I sent it in. What should be the orientation of the secondary carbs in relation to the other? I'm thinking that they should be closed at idle yet allow the pedal to go to the floor at WOT. Any tips on how to adjust this? ;worship

 

[jim coulter]

According to my shop manual, you adjust the rear first. It says "adjust rear secondary closing rod so that it falls 1/2 rod diameter short of entering hole. Install in hole. Proceed to step 2" Step 2 says "adjust front secopndary closing rod so that it just enters hole". hope that helps

 

[Stingray74CC]

Jim,

yep, I must have the same manual. Mine says the same thing. The only thing is is that they rods will not lengthen and tighten enough to get to where they are supposed to go. Is there are way to adjust the primary throttle linkage so the center hole will rotate forward about .5-.75 inches? That's where it was before I sent it in. They had to have put it back together a little off from the way it came apart.

 

[jim coulter]

Be sure you dont have them swapped, front one looking back and vice-versa. Its easy to do when you mount the carbs

 

[Stingray74CC]

We got it all put back together...just not exactly the way it came off. On the aft part of the mechanism that hooks up the throttle cable and the secondary linkage there is a slotted area that runs almost the entire length of the mechanism vertically. We just attached the linkage to that and it works great. Now I can tell the real difference b/w the old and rebuild carb. Great, no hesitation, much better idle and much less disieling when I shut the car off(still a little timing here and a small vacuum issue I think). Oh Yeah, is the original color of the 3x2 setup the gold color or the clean aluminum look?

I think the secondary vacuum diaphrams are bad. I can blow/suck at the source of the vacuum hoses that open the secondaries and the air goes straight through to the carb. Is the diaphram solely responsible for sealing the vacuum (besides the hoses)? How does that work? If the linkage opens the flaps inside the carbs what does the vacuum do?

Sorry for my ignorance.;stupid

 

[jim coulter]

I forgot to mention before that the linkage on the center carb( the two pieces that go fore and aft) needs to sit just off the bottom, I think mine is about 1/2 the thickness of the rod. I'm not how sure how original mine is, since my car is a 71 and they didn't come with three dueces, but mine is the old gold color. I put new diapragms and springs on mine that I got from Chicago Corvette. They had two springs, one regular and one hi perf. (one is a little stiffer than the other, but I cant tell by feeling)It sounds like you need diapragms. I could suck on my vacuum line and hear air sucking and it wouldn't do nothing. After replacing them the secondaries now open. I'm not an expert( this is the first set-up I've ever had like this) but it looks like the vacuum pulls in the secondary carbs and the linkage just "allows" them to open depending on how far open the center carb is. You can suck on mine all you want with the center carb at idle and the linkage wont let the secondary carbs pull in, and if you hold the center carb wide open the secondary carbs wont do anything unless vacuum is applied to them. hope that helps

 

[JohnZ]

The diaphragms open the end carbs, and they get the vacuum signal to do that from a pickup tube in the center carb venturi (it's not manifold vacuum, its vacuum generated by increasing air velocity passing the end of the little pickup tube); the higher the air velocity, the stronger the vacuum signal is to the end carb diaphragms. The vacuum source hose at the center carb nipple leads to the little pickup tube in the venturi, and that will be open all the time. If you pull the signal hoses to the end carbs off the tee from the center carb and suck on them, the end carbs will open (center carb linkage must be wide open to do this); when you release the suction (vacuum), the spring inside the diaphragm will close them, as will the secondary linkage rods. Make sure the throttle plates move freely on both end carbs, and they'll open as designed.

 

[jim coulter]

Maybe you can help me, I've changed the way mine was originally tubed to the way it is now (since I thought they had it wrong) The way I've got it now is the tube directly under the bowl goes to a tee with a plug on one end and the other goes to the dashpot (I quess thats what its called) I've connected the vacuum line for the two carbs off the tube on the paasenger side just above the mixture screw( right in behind the dashpot and carb body) I had seen a picture of one done that way and the way mine was originally was just the opposite.

 

[Stingray74CC]

I'll post pictures of the way mine is run when I get back to my computer. I think I know the tube that you are saying that your's is connected to now. That seems like it would almost keep the secondaries open all the time. That vacuum is capped off on mine. I should have the pic up within a few hours.

 

[Stingray74CC]

sorry about the delay

here's the routing on my 3x2