[carbking]

Originally Posted by David Jones

I think what I'm going to do is go up to .039, like Tom suggested. The wife and I went for a little ride this afternoon and it was fairly good when it got warm. How much more fuel percentage wise is .039 vs .033? Jon, if you have a minute, I'd like to give you a call Monday.

I'll be available Monday.

Jon.

[Cliff R]

Going from .033" to .039" is monumental as far as idle fuel increase is concerned. This tells me that it probably has some pretty large idle airbleeds. If you still have to run manifold vacuum to the advance to get decent idle qualities, and still get a 200 rpm drop when placed in gear, you still haven't cured the problem(s).

Next time you get it running, lock the park brake or have someone sit in the car and hold the brakes. At idle speed, gently place your hand over the choke housing. Don't clamp it off and choke out the engine, just richen things up a bit. See if idle quality improves, or is more stable with a slight load on the engine?

I haven't got into our TQ yet, but when I do I'll measure the idle tubes and idle airbleed sizes and let you know what they are?......Cliff

[Tom Vaught]

Area of a .033 orifice is .000855 sq inches

Area of a .039 orifice is .001195 sq inches

Difference is .001195 - .000855 = .00034 sq inches

.00034 divided by .000855 = 39.77 percent change.

A big change (like Cliff says) but if the carb you have was designed for a 340 cubic inch street Mopar engine and you now have it on a 400 plus engine with a small roller cam you might need the extra idle air flow.

Cliff's test with the engine in gear and lightly using your hand to add slightly more enrichment with a "Choke" strategy has been used for years. A reduction in air bleed size will possibly do the same thing as was mentioned by several. A typical air bleed to idle feed restriction relationship is .033 idle feed = .070 idle air bleed (on older Holleys). A .039 idle feed restriction = .073 or in some cases .076 idle air bleed. It will be interesting to have David and Cliff post the idle air bleed sizes they measure on their Thermo-quads.

Tom V.

[David Jones]

I took the car out after Church today and tried Cliff's test after I got it warmed up. It still doesn't like to idle completely cold once it comes off of fast idle, either in park or in gear. I can keep it running with gentle foot persuasion. As it warms it will gradually get to where it will run in park and as it reaches operating temp now, it will idle in gear. About 150 rpm seperates warm idle in park to warm idle in gear.A little over 800 rpm, park and about 700 +- in gear. Manifold vacuum. I tried Cliff's test and could detect no difference in the idle smoothness or stability as I slowly closed off the air right up until the engine choked out. Did it 5 times. I haven't had it apart again to measure the air bleeds. Next couple of days, depending on little league demands. Tom, this carb is a 9800 TQ. Carters hipo carb, not tuned for any particular car and set up for a GM product linkage wise. Jon can probably explain it's intended use better.
Thanks again guys.

[David Jones]

I drove the car in to work this morning. What a beautiful day. 41 degrees when I left headed to the lower 70's and an amazingly clear blue sky. The first few minutes through town required a lite foot on the pedal when stopped, but as the car warmed, the idle stabilized and stopping wasn't an issue. I went the back way, which cuts about 10 miles of off the freeway and then hopped on the freeway for the last 15 miles of the trip. Car ran great after it warmed and cruised smoothly at 75mph on the freeway. I did have opportunity to hammer it at high speed and detected a VERY light surge (slighty lean?) just before the transmission went into 3rd gear at about 85mph. I'll address that after I dial in the idle and before I take it to the drag strip. What an amazing sound the open element air filter was playing during that brief run! I talked with Jon this morning and we discussed my (our!) plan on tuning this carb idle deal out the rest of the way. I typed (our!) because he has really worked with me on this deal. Having dealt with both Jon now and Cliff in the past on my Qjet, I can tell anybody that is interested that they are both stand-up guys.
This has been frustrating but fun and quite a learning experience for me. TQ101 will continue soon.............

[carbking]

Tom - I didn't have the idle sizes readily available over the weekend. Gave these figures to David this morning:

idle tube 0.033
bypass (lower air bleed) 0.052
air bleed (upper) 0.055

Jon.

[Tom Vaught]

Thanks Jon!

Tom V.

[David Jones]

This evening I dove in again for a little measuring and drilling. This is what I found. #95 primary jets. 2110 primary metering rods. 5137 secondary jets. .055 air bleeds. .052 bypass. My idle restriction tubes originally measured .033. I started out opening them up to .036 and at the same time drilling the primary plates with a 5/64 hole. I then opened up the restrictions to .038 and opened up the holes in the primary plates to 3/32. Some improvement was noted in the idle each time. Tonight I opened up the restrictions to .040. For the first time, after a few quick adjustments to the mixture and idle speed screws, it idled on its own in park when it was fairly cold. I made no changes to the timing or where the advance can gets its vacuum (manifold). It still has about a 150 +- rpm drop going from park to drive. Could the converter have some bearing on this? It's a 13" Dynamic with about 500 rpm over stock stall. My initial impression is that there is still room for improvement. I want to crank it from stone cold as it sits now and see how it acts.
Suggestions and comments welcomed (and needed!) as always.

[Tom Vaught]

Quote:

"Tonight I opened up the restrictions to .040. For the first time, after a few quick adjustments to the mixture and idle speed screws, it idled on its own in park when it was fairly cold. I made no changes to the timing or where the advance can gets its vacuum (manifold)."

David, sneak up on the idle fuel now without changing the air holes.

It might take a .041 or .042 to be rich enough cold.

Quote:

"It still has about a 150 +- rpm drop going from park to drive. Could the converter have some bearing on this? It's a 13" Dynamic with about 500 rpm over stock stall."

Converter is causing the drop in rpm. Not a loose converter.

Quote:

"My initial impression is that there is still room for improvement. I want to crank it from stone cold as it sits now and see how it acts."

The engine should fire and run with a pump shot to set the choke and possibly one more. Then should run assuming the choke settings are right.

Tom V.

[David Jones]

I tried cold cranking this morning and it tried real hard to run, but wouldn't hold it cold. Just a minute or so and it idled in park by itself, which it wouldn't do for quite a while before. Much, much better than anytime before. I'm going to study up on how the choke/fast idle should be set and verify my settings before I do anything else internal to the carb. If someone could point me the right way on the choke, I'd appreciate it. I might know something about a carb when I get done.

I bought the converter when I had my previous cam and I'm stuck with it. So it goes.

[carbking]

David - the choke butterfly should just TOUCH closed at 68 degrees F. (65~70 degrees is close enough). When starting the vehicle, pump the footfeed 3 or 4 times to prime the intake, push the footfeed once all the way to the floor and then release. Remove your foot from the footfeed and start the engine. Engine should immediately go to a high idle. The RPM of the high idle is adjusted by use of the "fast idle adjusting screw".

Jon.

[David Jones]

Originally Posted by carbking

David - the choke butterfly should just TOUCH closed at 68 degrees F. (65~70 degrees is close enough). When starting the vehicle, pump the footfeed 3 or 4 times to prime the intake, push the footfeed once all the way to the floor and then release. Remove your foot from the footfeed and start the engine. Engine should immediately go to a high idle. The RPM of the high idle is adjusted by use of the "fast idle adjusting screw".

Jon.

If needed the butterfly is adjusted with the canister on the pass. side where the coil is hidden? Loosen the screw(s) and rotate as needed?

[David Jones]

I'm seeing an end to this carburetor deal. It really has been interesting for me, hopefully for some of you folks too...
Yesterday evening I tinkered around with the choke/fast idle on the TQ. What an amazing assortment of rods/bells/whistles etc, that make this thing operate. I do have voltage to it and the body of the choke gets warm. Thats normal I hope. As I have it now the choke flap will close and the fast idle will settle in at about 1100/1200 rpm on a cold engine. One tap on the "footfeed" (thanks Jon, I love that term! ) knocks both of them off. That doesn't seem normal, but thats the best I could come up with. After a short period on the fast idle the engine will settle into an idle in park. Not particularly smooth, but OK. Gets better on its own in just a couple of minutes. I'm still of the opinion that I should open up the idle restrictions to .041 or .042, but I'm going to live with this for a while and play with the timing/mixture before I drill any more. Still takes a few minutes before it will hold an idle in gear without help from my foot. After it warms it has no issues and has a very pleasant lope in gear. The idle mixture screws are at 2 3/4 turns out from lightly seated. This gives the highest vacuum reading I've seen recently @ just over 15". in park when warm at just over 800rpm.
I installed my dual snorkle also. It sits about 3/16" higher than it did on the Qjet. Thats strange because the TQ is 1/8" shorter where the air cleaner sits. Nothing is interfering and it is sitting flat on the thin gasket. Plenty of room between it and the accel pump and also the bowl vent. Maybe an angle thing. The driver side snorkle vacuum can was slightly touching a hood brace, but I cured that with a slight bend upward on the edge of the brace. I run a 1" carb spacer. Without it, there would be plenty of room. The dual snorkle really kills the intake scream. I hate that. When I need a sound fix, I'll have to put the open element cleaner back on. The dual snorkle also covers that big wide SOB up........
I thought I felt a slight surge (lean?) the other night just as the engine was winding out fixing to shift into 3rd. Last night I took it out to my "test" road (you guys have one?) and hammered it again. The shift from 2nd to 3rd came at 5300/5400 rpm with no trace of a surge. I ran the car on up to an indicated 115 and it was smooth. Well, as smooth as a 37 year old car can be. Never had it that fast before. Never wanted to. 103 on the dragstrip once and an indicated 105 once on the freeway. I'll see how it does and mess with the jetting later if needed. I've got a pair of 255/60-15 BFG T/A's and 15 X 8" Cragars on backorder with Summit. When they come in, I'm going to try some of this new hardware (cam/heads/gasket matched, aligned intake/rebuilt trans/converter and front end since my last trip a couple of years ago)out at the strip. Summit says they'll be in 1st of the month. It did 13.6 @ 102.5 last time. Hoping for at least 13.5 this time.................
Thanks again guys. I think I've learned something about a carburetor during this. Before, I just pumped gas into the tank, which went through the fuel pump and then just exploded in the cylinders. I've gotten a little better understanding on how it gets there now. A little.......

[grandville455]

13.2@105

[Tom Vaught]

Well David, Glad I could help you out.

I am still learning about the TQs also.

Quote:

"When starting the vehicle, pump the footfeed 3 or 4 times to prime the intake, push the footfeed once all the way to the floor and then release."

3-4 pump shots! I would have a quart of fuel in the intake with 4 pump shots from a Holley! JK!

I will have to remember that deal when I get mine going.

Tom V.

[Holeshot71]

Quote:
The dual snorkle really kills the intake scream. I hate that. When I need a sound fix, I'll have to put the open element cleaner back on. The dual snorkle also covers that big wide SOB up........

Hey David when I need a fix I just flip the chrome lid over and let her rip!!
Glad to hear you worked things out...