I am using a 1979 Ford Thunderbird 351W in my 1969 Ford Fastback Mustang. I am using no emissions since my car never had them. Ignition: MSD 6A, blaster 2 coil, 2 wire electric MSD distributer, 3500 TCI stall/C-6(heavy built/cevlar etc), 3.89 posi gears, Edelbrock performer intake and 4105 600CFM Edelbrock carb(plus rebuilt). I can't get the idle to work right (almost like a miss) plus it is ritch (screws almost all the way in before engine change/primarily passenger bank). I replaced the intake, so no vacuem problem now. Did MSD system checks, pass good. It will run fast and rap hard with quick starting and fast response. It is just the idle, give a bit gas it wants to go. I have messed with all this for 6 months or more, same issue. I leave the car under cover since it is too pretty to be idling bad. Can anyone give some light to the situation? Oh by the way, what is the little airports on the intake manifold plane of the heads. Do I need to do anything with the ports(they go inside the head, but I don't know where they come out. Thank you in advance!
I forgot this was originally a fully smog motor. I have never seen this to be an issue, but your inpute would be appreciated. Alot of nickles and dimes is killing the wallet.
Setting idle mixture, you are turning them in until the motor slows, or better yet the vacumm drops. When you think it is good, count the turns it takes to screw each one all the way in.
Try unhooking the accelerator pump lever, and see if anything chages at idle or your adjustments. Many times the adjustment and bouncing of the pump can add fuel.
Right after it's run for a while, turn it off and look down the carb for fuel leaking out the venturies. Setting the float level is the biggest weakness of these carbs, it can easily be too high causing it to drain out the venturies. You may want to pop it apart and lower the float level just for good measure.
Check for a regular miss, grab a good tach and watch it as you let it run and CAREFULLY pull off each plug wire one by one and note how much the RPM drops with each one. If the RPM doesn't drop with one or drops less then the others, that is a weak cylinder and we need to look into that.
Hope this helps, let me know what you find or think.
The car pulls very hard when driven. Will spin both tires at 35mph at only 3/4 throttle. I tried unhooking the excellerator pump, no change. But, I did notice something else which is making me believe it is the carburetor. When the electric choke fully opens the air flap the motor starts doing the missing sound on idle. Before it opens (1min at most) the car sounds great on idle. With the air flap fully open the passenger needle only changes the motor when it is almost all the way in, the driver side changes the motor about 1 1/2 turns out from all the way in. If I hold the air flap half way closed the idle problem quits, but doing this I can screw both screws all the way in with no motor change. The carb is freshly rebuilt, but I know how that goes. It wasn't flowing over when I shut the car off. I have also checked the adjustment on the floats. It is almost like I don't have enough vacuum with this Edelbrock performer intake or the carb is putting too much fuel on idle. Haven't hooked up tack, I can't remember which wire goes where, green, white, red. I know one goes to my MSD box, one to the batterie and one to the excessories. Again thank you in advance.
Pulling hard is good news, it tells us all the important stuff works.
On the choke, what you describe is normal, but not to be considered. ALWAYS do these idle adjustments with the engine warmed up, the choke full open (flap virticle) and if possable in gear. You want the car as close to the condition it would be in just driving around and stopping at a light. So all this needle adjustment in different choke positions, just stop that your adding a complication that doesn't need to be there.
How much vacuum you have has nothing to do with which manifold you use. It is mostly a function of the cam, and ignition timing.
How much timing at idle, is the vacuum advance hooked up and to which port?
How much vacuum at idle?
You need to hook up your tach, wire colors are standardized on aftermarket tachs. The green wire is the signal wire, with a MSD 6A box it needs to be pluged in to the single spade plug on the same end of the box as the wires come out. The red goes to an ignition hot source. There should also be a black for ground, and either white or brown for the light.
A note on ignition timing,
This is how I set up all my (and my customers) motors, some will argue but this IS what works best for most motors like yours. With the vacuum line to the distributor unplugged you will generally want as much timing at idle as will get you your highest vaccum, and this will also get you your highest idle speed for a given throttle adjustment. So get the motor idleing and warm, unplug the vacuum can and adjust timing for highest vacuum, don't bother yet with a timing light just look at your vacuum gauge, then turn down the idle speed to a reasonable speed and do it again.
What you will usually end up with the timing over 20 degrees, at this point you need to make sure that the timing is steady and the centrifigal advance isn't kicking in yet. To do this put a timing light on it and check it as you lower the idle speed, the timing should stay steady.
The problem that will arive is that with this much timing you will have a hard time starting the engine. The timing will be so advanced that the first time a cylinder fires the mottor will stop or kick back. This is why you need a timing compromise (and why you need the vacuum advance set up as described below) it will run best at the timing we just found, but won't start. So now turn back the timing just enough for it to start reliably. This will depend on your compression ratio and how strong your starter is. (This is a good reason for those crazy strong starters) you will probably end up about 16 degress. Then readjust for idle speed.
Once you find this point, plug your vacuum advance back in, which port? (You ment Edelbrock 1405 carb right?) There are two small vacuum ports on the front, use the one for manifold vacuum, it's on the drivers side, it's the lower one. When you plug it in the idle should speed up. This is because the vacuum can is adding timing back in to a point where the vacuum goes up increasing the idle speed. Readjust for idle speed.
yes it is a Edelbrock 1405 600CFM. I don't have a vacuum distributer, it is aftermarket full electric MSD system. I think I will play with the timing some more. The biggest thing I don't get is the fact the needle screws are not making the motor fall off right.
Sorry hadn't had time to mess with it. I will have the tach on tomorrow afternoon. Don't remember if I mentioned it. When I first start it it runs great, no miss at idle, but when the electric choke opens the butterfly it misses at idle. If I close the flap almost closed the RPM's go up but the miss is not noticeable. Closed all the way of course the carb doesn't like that; sputters. Let the flap go back open; misses on idle. I played with the cap on the choke, but no help. I wonder if it is trying to vapor lock (thin non heat absorbant gasket) or it needs down or up size jets and rods. After all Edelbrock and Summit only suggested a 500CFM. Even with that said, when it runs hard, raps hard, pulls hard I don't see why 100CFM would make a difference. Again I have never messed with an original smog motor, I hope there aren't any surprise holes on the motor to plug up (ether hasn't found it, if so).
Sorry hadn't had time to mess with it. I will have the tach on tomorrow afternoon. Don't remember if I mentioned it. When I first start it it runs great, no miss at idle, but when the electric choke opens the butterfly it misses at idle. If I close the flap almost closed the RPM's go up but the miss is not noticeable. Closed all the way of course the carb doesn't like that; sputters. Let the flap go back open; misses on idle. I played with the cap on the choke, but no help. I wonder if it is trying to vapor lock (thin non heat absorbant gasket) or it needs down or up size jets and rods. After all Edelbrock and Summit only suggested a 500CFM. Even with that said, when it runs hard, raps hard, pulls hard I don't see why 100CFM would make a difference. Again I have never messed with an original smog motor, I hope there aren't any surprise holes on the motor to plug up (ether hasn't found it, if so).
If it runs better with the choke flap partally closed, then it's to lean not rich! turn out the idle screws!
The Tach is hooked up. I started with 1100 rpms to make sure it wouldn't die, pulled each plug off one by one. The rpms dropped slightly about 100 rpms and did its usual wavering idle (up and down). I could even see the balancer going back and forth about 4 degrees (high 12 to 14rpms "set too", then would waver down to about 8 to 10 rpms).
Lean: I just went out on the screws to about 3 1/2 turns out, I thought for a minute it helped, but about 30 seconds went back to its usual wavering and speeds up when closing the carb butterfly. The distributor was fully refurbished by MSD in El paso, TX, new electric coil, the box isn't too old itsself. The MSD box passed all the checks as I was talking to MSD techs on the phone.
The Tach is hooked up. I started with 1100 rpms to make sure it wouldn't die, pulled each plug off one by one. The rpms dropped slightly about 100 rpms and did its usual wavering idle (up and down). I could even see the balancer going back and forth about 4 degrees (high 12 to 14rpms "set too", then would waver down to about 8 to 10 rpms).
Lean: I just went out on the screws to about 3 1/2 turns out, I thought for a minute it helped, but about 30 seconds went back to its usual wavering and speeds up when closing the carb butterfly. The distributor was fully refurbished by MSD in El paso, TX, new electric coil, the box isn't too old itsself. The MSD box passed all the checks as I was talking to MSD techs on the phone.
1100 is high get it warmed up and get it down
Balancer moving 4 degress?
3 1/2 turns that's huge, why so hasty take it slow.
I never run it 1100 degrees, but it does the same around 800rpms. Was trying crap.
Balancer moving 4 degrees: when it idles up it is about 12 to 14, then when it starts its idle problem it drops to between 8 and 10rpms, back forth.backforth.backforth 8/10 to 12/14(watching the degrees the balancer is turning back and forth as it makes the messy idle sound).
3 1/2 turns haste: I agree, but I have tried every spot for over 6 months (lost with this one).
Vacuum gauge needle does the same movement as the timing and idle sound when hooked to the carburetor, I would like to hook it to the intake manifold, but this new Edelbrock Performer doesn't have a place, especially since the only vacuum I use is for the Tranny (even eliminated a possible leak on the auto tranny hose).
Dizzy controls the timing: Hopefully I understand the question, but Yes it is playing with the timing. There's only one wire that feeds the MSD system and it is good, therefore I am lost unless it is the MSD box that passes all of MSD's self tests. If you have anymore helpful ideas, please give me a shout. Thank you in advance!
One other re-attack that I wouldn't think would be a problem (some motors it can, this one I don't know), but with my racing aluminum radiator using a 185 thermostat, I only heat up to about 170 to 180. On a 95-100 degree day it is running that temp with about 25 to 30 minutes of idling.
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