Idle problems, Replacing 440 cam without pulling motor?

[dailydriver]

I appreciate the guidance. It's good to know the cam is replaceable without pulling the engine, and that there are some other things to try first. My mechanic did float the idea of drilling small holes in the butterfly, and we do plan to plan to play with the mechanical advance first. I had not considered a new ignition system that allows for more adjustment. Seems there are many options there.

 

[biomedtechguy]

My mechanic did float the idea of drilling small holes in the butterfly, and we do plan to plan to play with the mechanical advance first. I had not considered a new ignition system that allows for more adjustment.

Those are all commonly discussed where 6bbl engines are concerned, so I felt like it would be helpful for me to chime in.
The 6bbl center carb metering block is known for not "playing well" with a low vacuum cam, the outside carbs have been known to have the blades drilled to (IMO) bandaid a poorly adjusted tune on the 6bbl, and I know that my FBO Ignition system from Don at foursecondsflat.com helped, a lot, but I am moving beyond that with an even more customizable Ignition system.
If you start with a tunable vacuum can and total advance limiter, I don't see how you can go wrong, because it may solve the stated problem, and if not, I think that it's always a good idea to have the best Ignition system possible.

 

[dailydriver]

Update to this, I did talk with Don at FBO and his assistant Dana as well. Both really helpful. I got his advance limiter plate on, replaced one of the springs in the distributor as well. At Don't direction set the initial timing to 20, put a low vacuum advance can on there as well, adjusted the timing using the can up to 34, and then up to 36. No signs of detonation and the car now can idle reliably at 800 RPMs and it sounds great too. I'm so used to it wanting to stall at a stoplight, it's just an unbelievable difference. I'm still going to order FBO's upgraded ignition controller and coil package, which should help further. I have the stock controller and an older Accel Supercoil on there now.

The other thing I did is replace the recessed set screw for the secondary throttle plates on the underside with a longer thumb-turned screw. It clears the intake and now I can adjust the secondaries without taking the carb off. Turns out the primaries were open a bit too much. Reset the primaries to a square transfer slot, closed the primaries a little and she wants to idle at around 800 there in gear, and I've got no hesitation, no bogging down, instant acceleration. The idle is still a little stinky but I think the fuel mixture screws are about as good as they are going to get. Still thinking about drilling tiny holes in the primary throttle plates.

The new problem is while I was at it I put a 1/2" birch spacer between the carb and the intake and although the hood still (barely) clears I think the angle of my kickdown linkage is now too steep. I already have a Weiand Team G intake that I think is taller than the stock intake and kickdown was working fine then. But now when I tighten the air cleaner down too much the slotted linkage hits the bottom of the air cleaner and wanted to get hung up there a couple of times; if I don't torque it down too much it seems fine. I am going to attach a couple of pictures and see what people think. I was tempted to just bend the threaded throttle kickdown rod connector so it would sit more horizontally, but I'm sure that isn't the right fix. I could just take the spacer out, but it's already helping with a hot start problem so I'd rather keep it.

This was originally a 361 car, now with a 440. So I'm wondering if the kickdown linkage is even correct for a 440?

Any suggestions? I know Lokar cabled kickdown is an option, but would rather not if I don't have to. I will include a couple of photos.

 

[66Satellite47]

I've made new brackets for accelerator cable and kickdown at the back of the intake to level out that angle some. Easy to add a little length back there.
The Team G must be about 1" taller than an OEM manifold.

 

[1967coronet]

Update to this, I did talk with Don at FBO and his assistant Dana as well. Both really helpful. I got his advance limiter plate on, replaced one of the springs in the distributor as well. At Don't direction set the initial timing to 20, put a low vacuum advance can on there as well, adjusted the timing using the can up to 34, and then up to 36. No signs of detonation and the car now can idle reliably at 800 RPMs and it sounds great too. I'm so used to it wanting to stall at a stoplight, it's just an unbelievable difference. I'm still going to order FBO's upgraded ignition controller and coil package, which should help further. I have the stock controller and an older Accel Supercoil on there now.

The other thing I did is replace the recessed set screw for the secondary throttle plates on the underside with a longer thumb-turned screw. It clears the intake and now I can adjust the secondaries without taking the carb off. Turns out the primaries were open a bit too much. Reset the primaries to a square transfer slot, closed the primaries a little and she wants to idle at around 800 there in gear, and I've got no hesitation, no bogging down, instant acceleration. The idle is still a little stinky but I think the fuel mixture screws are about as good as they are going to get. Still thinking about drilling tiny holes in the primary throttle plates.

The new problem is while I was at it I put a 1/2" birch spacer between the carb and the intake and although the hood still (barely) clears I think the angle of my kickdown linkage is now too steep. I already have a Weiand Team G intake that I think is taller than the stock intake and kickdown was working fine then. But now when I tighten the air cleaner down too much the slotted linkage hits the bottom of the air cleaner and wanted to get hung up there a couple of times; if I don't torque it down too much it seems fine. I am going to attach a couple of pictures and see what people think. I was tempted to just bend the threaded throttle kickdown rod connector so it would sit more horizontally, but I'm sure that isn't the right fix. I could just take the spacer out, but it's already helping with a hot start problem so I'd rather keep it.

This was originally a 361 car, now with a 440. So I'm wondering if the kickdown linkage is even correct for a 440?

Any suggestions? I know Lokar cabled kickdown is an option, but would rather not if I don't have to. I will include a couple of photos.

View attachment 1126328 View attachment 1126329

I would drill a new hole for your linkage pin mabey 1/4" lower or what it takes to get the rod to clear the base.
May have to readjust trans red and throttle cable when done. Just be careful when figuring hole placement so the pull is not to close to the throttle shaft.

 

[pnora]

Do not drill and lower anything. You want to keep the linkage ratios and geometry as close to original as possible.The best way I have found to correct the linkage is this. On the main bracket an inch or so above the bolts cut it horizontal into two. Hold the cable attachment part it the approximate position it would be from the factory. Measure to the bolted part and make a piece up and weld it up. Now the throttle cable part will be correct. Next cut the rod that goes to the transmission just below the top pivot an it is fairly straight. Again mock it up and figure the extension rod length. The piece you need will be about the same as the bracket piece you previously used. Weld it to the old rod and all you will just have to do is make minor adjustments. The ratios and geometry will be the same. You also need to correct your return springs with a taller bracket. Once ground and painted it will look close to stock.

 

[dvw]

Big cans cle rough do to overlap. More overlap means less idle vacuum. Less vacuum means less fuel flow at idle. Opening the throttle uncovers the transfer slots in the carb. A good start would be as much ignition advance at idle as possible. Drilling the throttle blades will allow more airflow at idle without uncovering the transfer slot. If your mechanic doesnt real use these theories you need someone with more knowledge of big cam street stuff. My 572 race motor has a [email protected] cam. It would idle at 800 rpm in gear if I let it
Doug