First run with Thermoquad

[Dino]

Now that all the cooling issues are dealt with, it was time to test the TQ I rebuilt.  My very first!  After it warmed up it never got a degree above what I had before btw, the new fan and clutch work great.  Only when you hot start it, the temp goes up 10 degrees more and then drops back down, must be the clutch at work. The adjustments I had to make the carb were pretty severe, some linkages were bent and the fast idle cam was bent as well.  The body and internals however only needed a good cleaning, courtesy of a soda blaster which made short work of that.  I had a lot of fun fixing everything so I was ready to accept this would not work as I wanted and go out to buy a new carb.   

I followed the adjustment procedure and set the idle screws at 2 1/2 turns out.  I don't have a choke because the crossover is blocked so it idled a bit rough at first, but it ran, and never stalled.  I let it run for a minute or two in the driveway and slowly put-putted down the subdivision.  After about 30 seconds I noticed the carb started to breath a it better so I kept it slow, about 20-25 mph in 3rd.  With 2.96 gears you can see I'm pretty much idling along.  I took it on a very quiet road where funny enough the limit is 55.  So I gave it a bit more and by the time I reached the end of the road I knew something had changed with my car.  Friggin' everything!   

When I removed the eddy carb, the linkage was real sloppy.  After studying the linkage and the TQ I started fine tuning it and found a good guide to help me along.  This car is about 180 degrees of what it was a week ago.  The throttle is as crisp as a modern car, the transmission shifts way cleaner and way later.  It finally makes sense!  I thought the trans was just slow but I guess it was the setup.  Right now the entire driving experience took a dramatic turn for the better.   

I then pushed the pedal a bit and the damn thing spun the tires!  It never did that before, not at speed anyway! 
This car drives like a raped ape.  I can't believe what a difference this all made.

It's only the first run and I know the car needs more work, exhaust the most pressing by far but damn this is just shocking.  I've never heard a V8 scream like that when those secondaries opened, holy cow!

It also seems to startup hot or cold without any issues although running without a choke into November is gonna be tough.

I know I'd have a tough time setting the idle perfect with this cam so I hope the vacuum, gauge will do the job for me.  I'm looking for the highest number setting each screw right?

I'm gonna fill this thing up and go lay down some rubber, catch you guys later.   

[Dino]

Took the long way to the gas station and back and the car runs like a dream.  I can't believe what a difference this is.

It now moves when I want it to and how I want it to.   

I think I need to adjust the metering rods a bit because when I'm in 3rd doing 40-50 and I mash the pedal, it goes to second and takes off without the slightest hesitation, but as soon as it shifts to 3rd it starts to bog at or near wot.  A little less and it's fine again.  I thought it was lean at first but the second time I tried that I could smell gas so probably running a bit rich here.

I probably should have my timing checked before I do that.  What should I be looking for?

[flyinlow]

Normally you  tune the ignition first, then carb. Assuming you have a healthy engine.

Most stock BB Mopars run about 5-10* BTDC idle timing and about 20-25* of centrifugal advance on top of that by about 4000rpm. Vacuum advance would be on top of that. It works but you are leaving power and gas millage on the table.
For better performance, you want to run as much idle timing as possible . The limits will be, does the engine ping and will it restart on a hot day. Total mechanical timing, base + centrifugal should be in the 32-38* range by 2500 for an auto car.  Running vacuum advance is  personal preference (I do).
Heads, cam, CR. axle ratio, A/F ratio ,pistons, fuel, mini starter  and thermostat temperature are some of the variables that affect how much timing you can run. Don't mean that to sound intimidating, if you are within a few of degrees of perfect it will run well. A modern MP or Firecore distributor will make it easier to tune, but you can re-spring and weld an old stock one.

[Brightyellow69rtse]

sometimes i miss the old thermoquad. you really felt it when the secondaries opened up!

[Dino]

I drove it all over town yesterday, 70-75 degree weather.  Without a choke I have to feather the gas when the engine is cold but nothing abnormal there.  Once I start driving I need to be light on the gas but really no issues here either, I can still get it up to 55 without any problems and without having it bog or stumble.  Once it warms up it runs absolutely stellar.  The throttle reacts instantaniously in any condition, the idle is nice and low.  

I still have this one problem though.  I kinda made a mess with all my separate threads here so I'll stick to this one for everything TQ related.

So, here's the scenario:  Regardless if I'm cruising in third or I start from a stop.  With the pedal to the floor, it pulls through first and second flawlessly but once it shifts to third it starts to stumble and stutter.  Even when I let of the gas a bit it keeps doing it.  I tried with 1/2 - 3/4 throttle and it's the same issue.  When I slowly let the speed climb with throttle only depressed partially it goes fine.  So it looks like I'm not getting enough fuel.

Could it be that my floats are set at the wrong height and I'm draining the bowl faster than it can fill?

I have the aftermarket brass floats.  Does anyone know the exact setting for those?  I find conflicting numbers online.  My rebuild instructions said the aftermarket (not the original) brass floats should be set the same as the foam floats at 29/32" so that's where they're at.  Do I need to raise them a bit?

Can the metering rod have anything to do with this issue?  

[flyinlow]

So it looks like I'm not getting enough fuel.

I'm draining the bowl faster than it can fill?

ICan the metering rod have anything to do with this issue?  

If it was a metering rod problem it would run bad in 1st & 2nd gear too. I think you are right about the fuel delivery  not keeping up with demand at high power settings. The carb starts off full and runs well until it gets low on gas. Accelerating slowly lets the fuel delivery keep up. Do a fuel delivery test.

The primary metering rods on a TQ are controlled by two things : intake manifold vacuum and throttle position.
When your engine is off (intake vacuum is zero ) the stirrup that controls the metering rods is raised in the full rich position by its spring. When you start the engine and it is idling or part throttle, the high vacuum in the intake is applied to the stirrup plunger drawing down to the lean (normal) position. As you open the throttle a cam on the primary throttle shaft raises the stirrup and rods as you open the throttle. At low vacuum the plunger spring is stronger vacuum force is and the rods are raised to full rich. So two conditions can raise the metering rods to full rich. To see this ,with the engine off, push down on the stirrup until it bottoms. Open the throttle and you will see the stirrup raise with increasing throttle. Notice the small screw in the stirrup. You can fine tune your part throttle A/F ratio with it.

[Brightyellow69rtse]

i also think your running out of gas. my car was doing that a while back and i unhooked the fuel line and blew it out with a compressor. alot of crap came out and she ran great after that. shortly after i replaced the line completly as it was pretty crappy. never had the problem again.

[Dino]

I'm going to check the metering rod tonight.  As I recall, I set it to the base specs.  I forget exactly how it worked but you had to turn it one way until the rod stopped moving, then go the other way...funny stuff.  

Anyway, fired up the Charger this morning and without the choke it stalled about 8 times, no kidding.  Pretty annoying but I guess at least it's not running rich!  It even gave me a small backfire.

Once I got it to move all seemed fine until I got on the main road and slowly pushed it up to 55.  I didn't make it, it started shaking around 50.  I feathered it to get up to 55 but it was clear the car was not happy doing this.  I turned into a side road and turned around to go back home.  At this point the engine started warming up so it went a bit smoother but still it would act up around the 55 mark.  If I gave it more throttle then it would simply bog.  It really felt as if there was no fuel available.  When I turned into my street I got a tiny bog as well so I think an empty fuel bowl may indeed be the problem here.  What concerned me is that my garage smelled like fuel when I pulled it back in.  Is it flooding instead of not getting enough?  I'm way confused here...

The only thing I changed, apart from carb, is a short rubber fuel line going to the carb and I exchanged the wix cannister filter with a bigger version.

I will be buying a sending unit soon and am looking for a new 3/8" and 1/4" line to install, along with the vapor cannister.

[maxwellwedge]

Vapor cannister?

[Dino]

Vapor cannister?

Hey look I spelled it wrong again!   

The black charcoal canister that's hooked up to the fuel pump.  My car was a sb car so I only have a single fuel line, no return, no canister.  Now that it has a 440, it's time to add it.

[maxwellwedge]

Oh OK - Vapor separator is what you mean.......that charcoal canister (got it!)  stuff was used in later years. 

[Dino]

Oh OK - Vapor separator is what you mean.......that charcoal canister (got it!)  stuff was used in later years. 

Separator!  That's the one, sorry man I'm just a mess today.   

Just to be sure the filter is not the culprit, I'm trying my old one tonight.  I doubt the new filter is the problem but stranger things have happened.

[maxwellwedge]

Just make sure you get one of the good ones - there were some bad ones out there that will make your problem worse.

Good idea to check the filter. 

Can you adjust the secondaries to open later on those carbs? Never played with one - so I'm not sure. Fuel pump ok?

[Dino]

I got the separator from Megaparts and I was told this is the one I want.

The adjustment on the secondaries is one of those that you need to do in a specific sequence, which I did.  I guess I can have it open later but it will likely knock the other adjustments out of alignment.

I would think my fuel pump is okay as I could floor the car with the eddy carb.  It was badly tuned but never did anything like this at higher rpm.  Of course it could have an issue now so I'm contemplating getting a new pump as well.  Looks like I'll be spending a bit on those fuel lines as well.  $50 + each...dammit...

[flyinlow]

Fuel test is cheap . Warm up engine so it will idle. Disconnect the fuel line at the carb. The engine will run at idle for a minute or so on the fuel in the bowl. Add what ever hose you need to run it into a two liter bottle. Start engine, idle at normal speed, fill the bottle in 60 seconds. Life is good. . Pressure test needs a gauge . 5-7 psi is good for Carters.


TQ trivia : Do not wire the secondary air valve open. Set air valve max opening to spec. Bending the door to make it "open" more messes up the vacuum signal to the secondary fuel tubes changing the A/F ratio (I have tried both).

[Dino]

Fuel test is cheap . Warm up engine so it will idle. Disconnect the fuel line at the carb. The engine will run at idle for a minute or so on the fuel in the bowl. Add what ever hose you need to run it into a two liter bottle. Start engine, idle at normal speed, fill the bottle in 60 seconds. Life is good. . Pressure test needs a gauge . 5-7 psi is good for Carters.


TQ trivia : Do not wire the secondary air valve open. Set air valve max opening to spec. Bending the door to make it "open" more messes up the vacuum signal to the secondary fuel tubes changing the A/F ratio (I have tried both).

Just so I'm clear...

After warming up the engine, I shut it off and disconnect the fuel line.  Do I stick the fuel line in a bottle so the fuel pump fills the bottle?

[flyinlow]

Yes , not sure what you current pump to carb line is, you just want to run the fuel into something to measure the volume. My FSM says min. 1 quart in a minute. My current  pump will fill a 2 liter pop bottle in a minute at idle. Engine does not need to be warm, as long as it is idling at its normal speed. Make sure you do not have any arcing plug wires or ignition sources.  Don't let it spray on the headers. I would do this outside with a fire extinguisher handy. Remove the fuel line from the carb slowly with a rag around it to bleed off any residual pressure.  Buy 5-10 feet of  fuel hose and run from the carb line to the bottle beside the car on the floor

[Dino]

I haven't touched the car since it acted up last Friday so here's the plan, before I change fuel lines/sending unit and all that fun stuff.

Replace the new fuel filter with the old and see if it changes anything.  Get some fuel line and do the fuel pump test.  I do have a vacuum gauge/fuel pressure tester so can I use that instead?  How do those things work?

I'll then take it to a garage to do timing unless I can do this at home easily.  I have never done it, I do have an old but rarely if ever used Craftsman timing light but I have no clue what to do with it.  Can I do this by ear?

If all that checks out and it still won't run properly in 3rd then I will reset the TQ floats.  I have no clue what to set them at though so I'll be looking for some numbers.

Currently, measured with the air horn upside down and the gasket in place, I have 29/32" from the gasket to the lowest top part of the float.  With the same orientation, if I want more fuel in the bowl that measurement has to be less correct?

[flyinlow]

Some fuel system basics. Excuse me if you already know this stuff.

On level ground, with a slight rake to the car if you remove the suction line from the fuel pump, fuel from the tank will slowly siphon on to the floor. So At a traffic light or cruising down the road, the fuel pump does not have to suck very hard to get fuel to the pump. During acceleration, going up a hill or when the tank is almost empty the pump has to work harder to get fuel to the pump . The pump is a diaphragm style pump operated by a push rod that is activated by an eccentric on the camshaft. It pumps one stroke every  two revolutions of the engine. When you run the fuel line into a jar to test its output volume, it will come out in pulses, this is normal. The pump has an inlet and output check valves that work with the diaphragm and its spring. The spring is what determines the pumps max fuel pressure . If the diaphragm is torn(pump will usually leak) , the spring gets weak, a check valve fails or the push rod wears too short, the pump will not deliver its normal rating.

Your gauge should work fine for the pressure test. Tee it in the line or just leave the  pump to carb line hooked to it. If you Tee it in and have enough hose you can drive the car and see if it maintains pressure. I have driven with test gauges duck taped to the windshield before.

[Dino]

Some fuel system basics. Excuse me if you already know this stuff.

On level ground, with a slight rake to the car if you remove the suction line from the fuel pump, fuel from the tank will slowly siphon on to the floor. So At a traffic light or cruising down the road, the fuel pump does not have to suck very hard to get fuel to the pump. During acceleration, going up a hill or when the tank is almost empty the pump has to work harder to get fuel to the pump . The pump is a diaphragm style pump operated by a push rod that is activated by an eccentric on the camshaft. It pumps one stroke every  two revolutions of the engine. When you run the fuel line into a jar to test its output volume, it will come out in pulses, this is normal. The pump has an inlet and output check valves that work with the diaphragm and its spring. The spring is what determines the pumps max fuel pressure . If the diaphragm is torn(pump will usually leak) , the spring gets weak, a check valve fails or the push rod wears too short, the pump will not deliver its normal rating.

Your gauge should work fine for the pressure test. Tee it in the line or just leave the  pump to carb line hooked to it. If you Tee it in and have enough hose you can drive the car and see if it maintains pressure. I have driven with test gauges duck taped to the windshield before.

You rock!  You just answered half my questions!  I am such an amateur when it comes to this stuff.  Body work I can do easily but mechanical is a world of mystery to me!

I tried installing my old filter to make sure the new was okay and there is no change so that's out.  When I fired it up yesterday, it had sat for 6 days.  I had to crank it several times to keep it running without choke but once it ran it idled very nicely.  I slowly drove around the neighborhood, gently warming the engine but it's getting worse, it's now not wanting to go above 40, anything above quarter gas pedal down and it'll act up.  Very strange.

I read somewhere (probably one of your posts) that the distributor vacuum advance should be hooked up to the manifold, mine's hooked up to the front port on the throttle body.  I'm going to pick up a longer vacuum line after work so I can connect advance to the rear port of the manifold for now.  A/C is not installed os I don't need that hose connected for now. 
I'll also get more fuel line so I can connect the gauge and drive it. 

I hope my mechanic can check the timing some day soon, I don't think I can do this on my own but I understand it's priority.  When that's done I'll check the secondary air door to make sure it opens as it should and also check if the secondary throttle opens as it should.  I can do that with the engine off.  I hate hanging over the engine while it's running, especially after that fan blew up!

Funny enough, even with this issue, it runs real crisp with excellent throttle response so I really hope I can get it dialed in with this cam.  When I do get it running properly I'm going to have to tear up the road a bit before I can drive normally and find out what the fuel consumption is.

[flyinlow]

Yes the fuel level in the carb will be higher with a  setting or 27/32" rather than 29/32". You still can't go very far very fast if the fuel delivery does not satisfy the carbs needs.

[flyinlow]

Setting the timing should be a priority .  Here's a video on the basics. They used a SB Chevy with a nice degreed harmonic dampner. You will just have the basic timing marks on your car.  Chevys and  SB Mopars have their distributors in the different place and they spin backwards , but the concept is the same.

http://www.youtube.com/watch?v=wifTHbb06_I

[Dino]

Thanks again for the info!   

I never knew there were timing marks on the balancer, I'll have to take a look tonight.

I did some more reading and now find posts that say the vacuum advance needs to be on the carb and not on the manifold.  So...wich one do I pick?  I've had it on the front of the carb all this time.

[Dino]

I keep forgetting to mention this...

With the car idling and the choke plate open, the sound of rushing air is really prominent.  It makes the same noise while driving but because of engine and exhaust noise it's not as noticable as at idle but still very audible.  Is this normal?  It sounds like I have a small vacuum cleaner running.
I wish I had a good audio recorder so I can record what it's doing.  Hmm maybe my mp3 player can pick up the sounds.

[bakerhillpins]

Here is a pic of how mine was plumed before I pulled the AVS to rebuild it.