3.0L engine swap

[Farrar]

I made another video trying to illustrate the problem and sent it to Bill. I am apparently the only human being on Earth who can hear the problem. However, I can say definitely that the steering wheel shakes like the handle on an old lawnmower. At higher speeds, it's more of a vibration than a shake, but that's only because the engine is turning faster.

Since there's no way of getting anyone to hear the problem, I can try to provide visual evidence of this, but I need to charge my videocamera's battery. Would it be enough to put a quarter on the air filter housing so that everyone can watch it bounce around? Maybe I could video the open door quivering like a leaf in a breeze? It's hard to show the interior of the car shaking, since it's mostly black in there.

Another problem, and maybe this is just endemic to carbureted engines: I can set the idle to 900 RPM when the engine is hot, but upon the next cold start, the fast-idle cam has the engine running at about 1,600 RPM and when I stomp on the throttle to disengage it, engine speed drops to about 700 RPM. I have to run the engine for about five minutes for the idle speed to get back up to where it was when I set it. So basically this means that I have to sit with the engine running for five minutes before I can go out and drive it with the air conditioning on. (This will be lots of fun in south Florida summers...)

None of this was happening when I first got the car back from Bill. This is the perplexing and very frustrating thing. It was all working perfectly. And then, suddenly, after sitting for several weeks, this all started happening. I don't get it. I had a leaky power valve and I replaced it, thinking it would solve the problem. It didn't. I'm back to square one.

Maybe it has always done this and I just didn't notice before. I doubt it, though.

I guess I can start pulling spark plugs and see what happens. But I want my wife to be there to call an ambulance right away if I suddenly get 40,000 volts up my arm.

[DMC5180]

Spark plugs are cheap, I’d replace them just for insurance, also confirm that the wires are securely attached to the plugs. Many years ago when Installed the Stage I exhaust with Nology wires, the engine ran very rough initially after the Wires were installed, it idled like a loping chevy 350. I discovered later, after having a conversation with Stephen Wynne, that the plug boots wire incorrectly positioned on the wires. The wire ends would not snap down to the plugs and this caused the coil energy to jump from the wires to the plug cap. After I fixed the boot positions on the wires and the wire ends were able to be snapped onto the plugs, the engine fired up and ran perfectly normal.


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[dn010]

40,000 volts? Are you using a flame thrower coil? For what it’s worth, I tried using one a long time ago in one of my Mustangs and the power of it melted my rotor inside the cap. Same goes with the aftermarket coil I got for my D back when I was running the stock engine. I can’t remember what coil it was but it wouldn’t run right until I put the stock Bosch back in.

There is no reason you need a high power coil on a 3.0 v6. You might experiment with a stock coil and check your cap/rotor.


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[opethmike]

I can *absolutely* hear the issue. That's a miss, through and through. I agree that the 40k coil is a complete waste and quite possibly problematic on this engine configuration. I know Bill would argue, but tough nuts, I'm a better engine tuner than him.

Check the inside of the cap and the rotor arm for any signs of corrosion and/or melting. Replace the plugs with new ones if you haven't already. Replace the coil with a stock coil and the plug wires with stock as well. Don't give up, but don't waste time doing anything else with the engine until you have *100%* gone through the ignition system.

[vwdmc16]

I totally agree you need to be 100% sure on the full ignition system, even try solve that by going back to older known good parts you may be able to get your hands on to verify exactly what you have that works now.

However may I also suggest once more that you go a little deeper than carb and ignition; check you valve timing too, for both cams.

This has been suggested before and discussed by Josh back in May 2018

looks perfect to me. Im sure bill is on it, but at this point it sounds like the timing (chains) are off.

Besides low vaccum

The engine will hesitate when you get on the gas
Performance will be poor across the power band
Poor fuel mileage

A worn out timing chain tensioner could also give these symptoms.

Its possible the cam timing has possibly changed again, or for the first time now due to the reasons above.
I don't mean to sound pushy on that but from all the symptoms you have discussed throughout this thread still sound like a mechanical timing fault to me and the heavy hybrid construction really adds alot more possibilities of issues that will not be obvious because it is never before documented or possibly tried in this exact combination before.

[dmruschell]

I can *absolutely* hear the issue. That's a miss, through and through. I agree that the 40k coil is a complete waste and quite possibly problematic on this engine configuration. I know Bill would argue, but tough nuts, I'm a better engine tuner than him.

Check the inside of the cap and the rotor arm for any signs of corrosion and/or melting. Replace the plugs with new ones if you haven't already. Replace the coil with a stock coil and the plug wires with stock as well. Don't give up, but don't waste time doing anything else with the engine until you have *100%* gone through the ignition system.

So can I. As soon as I heard the engine revving on acceleration, I could tell it was a misfire. A slight misfire will usually clear up above 2,000RPMs, but a complete miss will not. I think your slight misfire is now a complete miss.

Coils only produce the amount of voltage that the spark plug gap or their design allows them to. If there is a huge gap that takes 40,000 volts to bridge, then that is what the coil will produce. If it is unable to produce that much voltage, then the engine will not run. If there is a small gap that takes, for example, 5,000 volts to bridge, then the cap will only produce 5,000 volts, even if it's advertised as a 40,000 volt coil.

Putting large plug gaps on a small cap distributor can be potentially problematic if the spark decides to jump from one terminal to the next inside of the cap. When GM started using HEI (which included large plug gaps), they switched to large cap distributors.

I doubt your coil is the problem. A shared coil (one coil for the whole engine as opposed to one coil per cylinder) that is going bad will not cause a steady misfire like what you have. It will cause a random misfire or just not run at all.

I saw you reference the stock idle speed of the 3.0 engine. That specification means nothing as far as your engine is concerned since yours is modified.

Your RPM drops from Park to Drive and with the AC on are about right based on my own experience. The idle speed solenoids also don't really work that well. They have enough power to keep the throttle linkage from returning past its set point, but they don't have enough power to push the throttle linkage. So, your compressor will kick on and your idle speed will drop, even with the solenoid engaging. Blip the throttle, and the solenoid will extend and the idle speed will settle at a raised speed. Then, the Ac compressor disengages, which disengages the solenoid and returns the throttle linkage to the lower idle speed. This repeats every single time the compressor cycles.

Would that solenoid could do is allow you to set the idle speed screw at its lowest setting and then set the idle speed using the solenoid. Connect the solenoid to a switched electrical source. This will minimize dieseling. Though, if your engine is dieseling with an idle speed of 900, something is not right.

I suspect that, because of your misfire, the throttle blades are opened more than they would normally be, as a 6 cylinder running on 5 cylinders isn't running as efficiently as it should. Because of the wider opening, each cylinder is able to draw more air and fuel at idle than it normally would and can run-on more easily. There is also a dead cylinder that may have a lot of carbon build up that could self-ignite, also causing the dieseling (assuming compression is good on that cylinder).

Do exactly as Ron said and pull one plug wire at a time. When you pull a wire and it makes no difference in idle speed or how the engine runs, you've found your dead cylinder. You could also try aiming an IR gun at each of the exhaust header tubes and see if there's one that is colder than the rest; the cold one will be the dead cylinder Find the cause of that dead cylinder and service it as needed, replacing the plugs and wires as a set if one of them needs replacing. Best case is that something with the ignition system (a plug, wire, or cap/rotor) is malfunctioning. Worst case is that the cylinder has been gradually losing compression and now won't fire. Plugs and wires are cheap, so start there lol.

[Ron]

+1!

========

Some 2100s require another bracket you may have to scrounge through the junkyards to find.

Another problem, and maybe this is just endemic to carbureted engines: I can set the idle to 900 RPM when the engine is hot, but upon the next cold start, the fast-idle cam has the engine running at about 1,600 RPM and when I stomp on the throttle to disengage it, engine speed drops to about 700 RPM. I have to run the engine for about five minutes for the idle speed to get back up to where it was when I set it.

Sounds like the fast idle cam is moving past the fast idle adjusting screw to soon (choke setting) or the the fast idle screw is set too far away from the cam step to do any good (fast idle screw setting). Your rebuild kit should include detailed instructions on how to set both...Make sure you do things in order and set the choke when the engine is dead cold, on a cold day.

[dmruschell]

+1!

========

Some 2100s require another bracket you may have to scrounge through the junkyards to find.

Sounds like the fast idle cam is moving past the fast idle adjusting screw to soon (choke setting) or the the fast idle screw is set too far away from the cam step to do any good (fast idle screw setting). Your rebuild kit should include detailed instructions on how to set both...Make sure you do things in order and set the choke when the engine is dead cold, on a cold day.

I've also run into this problem on various carburetors. Edelbrock/Carter carburetors are the biggest offenders, followed by Holleys.

Quadrajets, on the other hand, won't disengage the fast idle until the choke is almost fully opened. This can lead to the fast idle (nominally set for 1200RPMs) getting much faster than that as the engine gradually warms up.

I think Holleys and Quadrajets have a stepped fast idle so that as the engine warms up and the fast idle speeds up, it will step down the the next step, but not all the way down to the base idle speed screw.

Adjusting the choke to be a bit richer could help solve this problem, as long as the choke still fully opens when warm. But, if the engine doesn't die when put in gear during warm up, I woudln't worry too much about it.

Carburetors are not self-adjusting like EFI or even KJet is, and there are a lot of factors that affect engine idle speed and fuel mixture. Because of this, there will be some changes in how the engine runs based on the weather, altitude, engine temperature, etc. that can't fully be corrected. The only carburetor that even attempts to account for some of those are 1975-1980 Quadrajets. In the 70s, GM also started using air cleaners that would regulate the intake air temperature, balancing pulling in hot air from next to the exhaust manifold (stove pipe) with cold air from outside of the car. This, combined with the later Quadrajets, did make for a more consistently running engine, but with neither of those things, you'll notice inconsistencies.

[Farrar]

Wow, this thread has been busy while I've been away!

One of my jobs has has me getting up at 3:15am two days a week. It's played hell with the rest of my schedule... well, life, actually.

Today, I drove #2613 to my job in Miami. This involved 20+ minutes of driving at interstate speeds. I now concur with everyone who said it sounds like a misfire, because the engine runs perfectly smoothly at higher RPMs, except that on occasion while driving at speed, I will experience a loss of power and at the same time hear that "lawnmower" sound.

The fact that the sound and the loss of power happen at the same time clinches it for me. Even though my timing light registers on all six plugs, I am going to have to believe my ears.

Additional note for those interested in the cooling system: the temperature warmed up to about 250 degrees and stayed there, if the JEGS gauge is to be believed. That gauge's sensor is just below the water pump. Ambient temperature is 80 degrees.

I'm going to change the spark plugs tomorrow.

I'm still pretty happy that I can hop in the car and drive to Miami and back, though. That's pretty neat, considering what a disaster this car was just a couple of years ago.

[dmruschell]

Wow, this thread has been busy while I've been away!

One of my jobs has has me getting up at 3:15am two days a week. It's played hell with the rest of my schedule... well, life, actually.

Today, I drove #2613 to my job in Miami. This involved 20+ minutes of driving at interstate speeds. I now concur with everyone who said it sounds like a misfire, because the engine runs perfectly smoothly at higher RPMs, except that on occasion while driving at speed, I will experience a loss of power and at the same time hear that "lawnmower" sound.

The fact that the sound and the loss of power happen at the same time clinches it for me. Even though my timing light registers on all six plugs, I am going to have to believe my ears.

Additional note for those interested in the cooling system: the temperature warmed up to about 250 degrees and stayed there, if the JEGS gauge is to be believed. That gauge's sensor is just below the water pump. Ambient temperature is 80 degrees.

I'm going to change the spark plugs tomorrow.

I'm still pretty happy that I can hop in the car and drive to Miami and back, though. That's pretty neat, considering what a disaster this car was just a couple of years ago.

Does the timing light register steadily on all 6 plugs? A weak spark could still cause a misfire and register on the light, but possibly intermittently. If a wire is arcing, the timing light would also register a spark, but the spark isn't making it to the plug.

If replacing the plugs, wires, and making sure the cap and rotor are in working order doesn't solve the issue, you likely have bigger problems that won't be fun.