Proper Transfer Slot Position

[jmanhoff]

That is always a possibility but the base plate is small and held on with enough fasteners that it shouldn’t be an issue. When I put a carb together I hit all machined flat surfaces with a file and if anything is noticeable they go on a sheet of glass with some 600 grit.

So a warped base plate could explain my sticky throttle that isn’t related to the linkage and cable, and could be causing a vacuum leak making the idle stupid high?

I do have an “old” brawler 650 that I could slap on setup the exact same as the Holley, that should in theory determine if the issue is plate related right?

 

[TT5.9mag]

So a warped base plate could explain my sticky throttle that isn’t related to the linkage and cable, and could be causing a vacuum leak making the idle stupid high?

I do have an “old” brawler 650 that I could slap on setup the exact same as the Holley, that should in theory determine if the issue is plate related right?

Yes and yes

 

[TT5.9mag]

Alright. Does it look like the gasket is squishing out too much? I haven’t seen enough carbs to know what’s normal, and this carb is stamped 0225 on the choke horn so I’d imagine that’s its date stamp. Is it possible it’s just lazy production?

Again it’s possible. It doesn’t look like the gasket is pooched out too much to me but it’s hard to tell really. If you have the carb off it only takes a few minutes to pull the main body and the baseplate apart. You’ll need a gasket if you do, they’re hardly ever savable. A lot of the time you’ll find the screws loose.

 

[jmanhoff]

Again it’s possible. It doesn’t look like the gasket is pooched out too much to me but it’s hard to tell really. If you have the carb off it only takes a few minutes to pull the main body and the baseplate apart. You’ll need a gasket if you do, they’re hardly ever savable. A lot of the time you’ll find the screws loose.

Rebuild kits are cheap enough, I might buy one and throw it together just to do it. Wouldn’t hurt and then I can really get a gauge on how to do it

 

[jmanhoff]

Threw the brawler back on, I remember why I hated this carb lol the side hung bowls constantly wanted to flood and I could never figure it out, luckily because they’re both 4150 carbs i just threw the Holley center hung bowls on and go figure they work fine lol. Going to drive around for a couple days and see where this ends up with the sticky throttle.

I’d imagine if the throttle was sticking with the throttle body bent, then that would cause a vacuum leak at the base of the carb right? I remember spraying there before with carb cleaner while I was looking for leaks and it never made itself apparent

 

[jmanhoff]

Rebuild kit is coming today, I put a straight edge on the base of the Holley and it’s flat all around. Interestingly the brawler is able to hold an idle, so seemingly it’s something to do with the Holley. I also ordered a new 4 hole gasket for my spacer as well, so I’ll be replacing the bottom gasket under the spacer, and the one between the carb and spacer just for sanity even though I did that recently. I also went ahead and loosened the screws holding the throttle blades to the shaft and let them snap back into place and then tightened them again, just for sanity as well.

 

[jmanhoff]

Welp, got the carb back together and thrown onto the truck. T slot squared, secondaries as shut as they could get without binding, and it still idles around 900. The idle screws are still functional, if I have them set to 7/8 of a turn out and I close any of them the engine starts to die, same goes with putting my finger over the idle air bleeds.

I’ve been reading about the adjustable pcv valves and also thinking about pulling some initial timing so it’s around 10-12, and compensating for it with the timing curve? Or would that not work how I’m thinking it would

 

[Bewy]

What happens if you seat the sec idle mixture screws, & just idle on the primaries?

 

[jmanhoff]

What happens if you seat the sec idle mixture screws, & just idle on the primaries?

I’ve heard that in the past, I’ll try it again today and see

 

[Illahe]

I have nothing against Holleys or double pumpers . I was just thinking if this is in a daily driver truck a TQ would really shine ! AND get good mpg/ driveability.

Agree. I get 14-16 mpg with an 800 Rochester on a 318 3/4 ton 2WD doge pick up.

 

[jmanhoff]

Agree. I get 14-16 mpg with an 800 Rochester on a 318 3/4 ton 2WD doge pick up.

I did get 16mpg on a 150 mile highway trip last weekend with almost 1000 pounds of extra weight and all I changed was putting a giant front valence on so I’m definitely thinking once I get the tuning in it’ll be better.

At least now I know my 1/4 ton is getting the same mpg as a 3/4 ton lmao

 

[Illahe]

I did get 16mpg on a 150 mile highway trip last weekend with almost 1000 pounds of extra weight and all I changed was putting a giant front valence on so I’m definitely thinking once I get the tuning in it’ll be better.

At least now I know my 1/4 ton is getting the same mpg as a 3/4 ton lmao

Spread bores work really well on Mopars! Holleys are good units but the equal bore diameters don't seem to eek out the last 15-20% of fuel mileage. Carter is about the same as Holley in that respect as well.

 

[jmanhoff]

Spread bores work really well on Mopars! Holleys are good units but the equal bore diameters don't seem to eke out the last 15-20% of fuel mileage. Carter is about the same as Holley in that respect as well.

It’s because of the smaller primary bores right? So they get higher velocity?

 

[Illahe]

It’s because of the smaller primary bores right? So they get higher velocity?

That's the way I look at it. The signal to the booster venturi is more sensitive. The lower the sensitivity the wider the calibration window becomes for drivability off idle.

There are far more capable tuners on this forum than I, but with a reasonable budget and no 02 sensor one can achieve good calibration following Cliff Ruggles calibration methods.

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

 

[jmanhoff]

That's the way I look at it. The signal to the booster venturi is more sensitive. The lower the sensitivity the wider the calibration window becomes for drivability off idle.

There are far more capable tuners on this forum than I, but with a reasonable budget and no 02 sensor one can achieve good calibration following Cliff Ruggles calibration methods.

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

I think one day I’ll actually look into the quadrajets, when I have a great understanding of the fundamentals of a carb in general lol. I feel like if I swapped over to one now I’d just put myself back to square one and I don’t have the patience or the financials to do that right now lol

 

[Illahe]

I think one day I’ll actually look into the quadrajets, when I have a great understanding of the fundamentals of a carb in general lol. I feel like if I swapped over to one now I’d just put myself back to square one and I don’t have the patience or the financials to do that right now lol

If you have an older wreaking yard around. The 800 cfm (the best one) can be found on BB Pontiacs cheap!

I suggest Cliffs book even if your not going the Quadrajet route. The fundamentals of the three fuel circuits are well laid out and he explains why and how idle bypass air affects calibration. I have nit seen this mentioned in the Holley or Carter books and that is part of the off idle tuning issues.

 

[jmanhoff]

If you have an older wreaking yard around. The 800 cfm (the best one) can be found on BB Pontiacs cheap!

I suggest Cliffs book even if your not going the Quadrajet route. The fundamentals of the three fuel circuits are well laid out and he explains why and how idle bypass air affects calibration. I have nit seen this mentioned in the Holley or Carter books and that is part of the off idle tuning issues.

Interesting, I’ll definitely keep that in mind. I’m in the Hampton roads area of Virginia so junkyards are kinda dotted around near Norfolk, just not sure how many of them have older vehicles in them

 

[Illahe]

Interesting, I’ll definitely keep that in mind. I’m in the Hampton roads area of Virginia so junkyards are kinda dotted around near Norfolk, just not sure how many of them have older vehicles in them

Best of luck!

 

[jmanhoff]

Alright, so I went ahead and I shut the secondary idle mixture screws fully, and put the primary side at about 1.5 turns. It runs, no off idle stumble, nothing of the sort. But when I open the throttle to a point where I’m borderline into the main circuit (at a low rpm mainly), it feels like it wants more fuel. I see my afr gauge go lean but I know that’s just a helper, not something to completely watch. Vacuum is about 12-14 when this happens, which is above the point where my PV opens, but the airflow isn’t high enough either for the power valve to actually start flowing fuel (I can tell because if I open the throttle further it still doesn’t get richer until about 1800-2000rpm)

Should I open the primary mixture screws more, crack open the secondary side, or is this something else entirely?

 

[Illahe]

Alright, so I went ahead and I shut the secondary idle mixture screws fully, and put the primary side at about 1.5 turns. It runs, no off idle stumble, nothing of the sort. But when I open the throttle to a point where I’m borderline into the main circuit (at a low rpm mainly), it feels like it wants more fuel. I see my afr gauge go lean but I know that’s just a helper, not something to completely watch. Vacuum is about 12-14 when this happens, which is above the point where my PV opens, but the airflow isn’t high enough either for the power valve to actually start flowing fuel (I can tell because if I open the throttle further it still doesn’t get richer until about 1800-2000rpm)

Should I open the primary mixture screws more, crack open the secondary side, or is this something else entirely?

Install a power valve that opens sooner. Think about the power valve as if its gaining sensitivity to the load on the engine. Or swap a main well air bleed to introduce the main well enrichment sooner.

Your secondary circuit is not part of the problem. If you need to add secondly idle circuit you'd likely be between 10-12hg at idle. Say 240* duration cam@.050".

 

[jmanhoff]

Install a power valve that opens sooner. Or swap a main well air bleed to introduce the main well enrichment sooner.

Your secondary circuit is not part of the problem. If you need to add secondly idle circuit you'd likely be between 10-12hg at idle. Say 240* duration cam@.050".

Doesn’t the power valve add fuel to the main well? I have a 10.5PV currently, and at low rpm where the main circuit isn’t flowing, wouldn’t the power valve not be either? Or do I have that wrong

 

[Illahe]

Doesn’t the power valve add fuel to the main well? I have a 10.5PV currently, and at low rpm where the main circuit isn’t flowing, wouldn’t the power valve not be either? Or do I have that wrong

Its a crutch. The main well is calibrated by the air bleed. Just because the power valve is introducing fuel to the booster venturi its not "activating" the main well to its calibrated potential. Once your engine load stabilizes the power valve will close.

 

[jmanhoff]

Its a crutch. The main well is calibrated by the air bleed. Just because the power valve is introducing fuel to the booster venturi its not "activating" the main well to its calibrated potential. Once your engine load stabilizes the power valve will close.

So if I got a PV that opened around 12-13 inches, it would be flowing fuel even at low rpm? I thought that even if the power valve is open, if the mains aren’t flowing the extra fuel won’t make it to the engine anyway

 

[Illahe]

So if I got a PV that opened around 12-13 inches, it would be flowing fuel even at low rpm? I thought that even if the power valve is open, if the mains aren’t flowing the extra fuel won’t make it to the engine anyway

Power valve comes in under high load when the calibration is correct.

(?) if your going lean why do you think that's happening...?

From what your posting, it seems that your vehicle has a tight converter, and or tall gears with a fuel curve that's calibrated for the opposite.

 

[jmanhoff]

Power valve comes in under high load when the calibration is correct.

(?) if your going lean why do you think that's happening...?

From what your posting, it seems that your vehicle has a tight converter, and or tall gears with a fuel curve that's calibrated for the opposite.

It’s a 5 speed, 3.83 2.33 1.44 1.00 0.79 1-5 with 3.55 gears, 235/75r15 tires so roughly 29.5 inches