Vacume Spring??

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69signetv8

69signetv8

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Need advice...
My car won't kick *** from a stand still! This motor "kick *** big time" when in the kids duster but I'm not sure whats-up and why it's sleeping from a "stand still". On the move it digs in pretty good, however I can't even scratch the rear tires...I'm thinking maybe the 4Bs are not opening from a stand still. The car does'nt really bog out...it just granny aways up to speed quick.

Excellent compression 318 with 360 heads, 340 Cam, 600 cfm, dual performer, MSD, ect. The 727 trans was re-built with a TF-2 kit. Rear tires are 8" wide. It also has 3:91 gears.

WHAT I HAVE DONE...
I adjusted the kickdown so it's completely to the rear during WOT. The kickdown can also move forward on it's own will. I think... the carb is set-up correctly, however I'm wondering if I should swap out the vac spring to a lighter one so the 4B open up sooner. That's my guess.
Idea's please...I think..I should be able to get at least a few feet of scratch :cussing:
 
The secondaries on a vacuum secondary carb do not open from idle no should they. Also, they will not open when you wing the throttle with the car in neutral. The open based on the velocity of air going through the primary venturi's.

Most Holley (I am assuming it's a holley) vacuum secondary carb come with the "plain" secondary spring. This is the middle of the range of springs offered. Holley's recomended method for determining which spring to use is to keep going lighter until you feel the distinct opening of the secondary then go one spring stiffer. That feeling of the secondary opening is actually a bog caused by the secondaries opening before the egine can use the additional air flow and actually results in slower acceleration than if you go one stiffer. Lighter cars with lower gears tend to like lighter springs.

You can check to see if the secondaries are opeing by placing a paper clip or a tie wrap (not too tight) on the arm and run the car up through the gears.
 
dgc333 said:
The secondaries on a vacuum secondary carb do not open from idle no should they. Also, they will not open when you wing the throttle with the car in neutral. The open based on the velocity of air going through the primary venturi's.

Most Holley (I am assuming it's a holley) vacuum secondary carb come with the "plain" secondary spring. This is the middle of the range of springs offered. Holley's recomended method for determining which spring to use is to keep going lighter until you feel the distinct opening of the secondary then go one spring stiffer. That feeling of the secondary opening is actually a bog caused by the secondaries opening before the egine can use the additional air flow and actually results in slower acceleration than if you go one stiffer. Lighter cars with lower gears tend to like lighter springs.

You can check to see if the secondaries are opeing by placing a paper clip or a tie wrap (not too tight) on the arm and run the car up through the gears.
Click to expand...

I can understand not in neutral because no load...So your saying that the Holley's 4 never open during accel from a stand still?
 
They do open as you accelerate from idle but the rpm at which they start to open is quite a bit above idle rpm, guess my statement was confusing.

If you pick up a set of the Holley secondary springs they have a little chart that gives you an approximate starting rpm and rpm for full open of the secondary by spring color and engine displacement. This like is to the instruction sheet that comes with the springs and has the table.
http://www.holley.com/data/Products/Technical/199R8219-2.pdf

With a 350 engine the starting rpm is around 1600 with a the short yellow spring and over 2000 with the plain. It would be higher with a 318 because it doesn't draw in as much air as the bigger engine.
 
heres something that may help change the shooter on the main side to a #31 with the extention tubes it will get the fuel to the venturies quicker i like a 68 to 70 jet on the main side you will just have to experiment read the plugs etc. till you get the right size figured out .also how much vaccumn do you have at idle? you need to know this so you know which power valve to use. you may have the wrong one and the enrichment circuit will not work if it is too small. most holleys come with a 6.5 power valve which is a good starting point but you can tune from there to suit the engine based on the amount of vaccumn.
 
69signetv8 said:
I can understand not in neutral because no load...So your saying that the Holley's 4 never open during accel from a stand still?
Click to expand...

What is your initial timing set at and what total mechanical(no vacuum) timing do you have and at what rpm is it all in by?
 
6pkmopar said:
heres something that may help change the shooter on the main side to a #31 with the extention tubes it will get the fuel to the venturies quicker i like a 68 to 70 jet on the main side you will just have to experiment read the plugs etc. till you get the right size figured out .also how much vaccumn do you have at idle? you need to know this so you know which power valve to use. you may have the wrong one and the enrichment circuit will not work if it is too small. most holleys come with a 6.5 power valve which is a good starting point but you can tune from there to suit the engine based on the amount of vaccumn.
Click to expand...

I'm at 18-19 vac at idle max. I got the tric kit, but I think they were just a re-build kit with standard replacement parts.
 
dgc333 said:
They do open as you accelerate from idle but the rpm at which they start to open is quite a bit above idle rpm, guess my statement was confusing.

If you pick up a set of the Holley secondary springs they have a little chart that gives you an approximate starting rpm and rpm for full open of the secondary by spring color and engine displacement. This like is to the instruction sheet that comes with the springs and has the table.
http://www.holley.com/data/Products/Technical/199R8219-2.pdf

With a 350 engine the starting rpm is around 1600 with a the short yellow spring and over 2000 with the plain. It would be higher with a 318 because it doesn't draw in as much air as the bigger engine.
Click to expand...

I change from the purple to small yellow, didn't notice much of a change. I'll have to take it on a better run. Thanks
 
388dart said:
What is your initial timing set at and what total mechanical(no vacuum) timing do you have and at what rpm is it all in by?
Click to expand...

Read my post (timing) I have to do it by ear or max vacume to get close :-|
 
When you say excellent compression what numbers are you talking about? Every post that I've read say that the best way to kill bottom end is put some 360 heads on without any work done to raise the compression. Did you mill the heads or deck? Or did you replace the pistons? Also, was there any changes in the torque converter, did you use the same one? Just trying to help you solve it.
 
63dartman said:
When you say excellent compression what numbers are you talking about? Every post that I've read say that the best way to kill bottom end is put some 360 heads on without any work done to raise the compression. Did you mill the heads or deck? Or did you replace the pistons? Also, was there any changes in the torque converter, did you use the same one? Just trying to help you solve it.
Click to expand...

The motor was completely re-built by qualified motor shop, 30 over, new flat tops, the works.
They are 318 HP heads cast in 360. They have 360 valves but don't require any milling. I was told I had about 9:1 comp. The convertor is a 2500 stall.

Note, this motor, trans came out of my kids duster and kicked ***, so it's got nothing to do with the guts. I'm just have problems tweaking everything I guess.
 
what's your plugs look like with that set up it should boil em at ease you should have traction problems you running the same carb? i've upset carbs. before doing engine swaps them holleys are easy to upset
 
mr.318 said:
what's your plugs look like with that set up it should boil em at ease you should have traction problems you running the same carb? i've upset carbs. before doing engine swaps them holleys are easy to upset
Click to expand...

Mr.318, Hi..I just got her flashed up so I haven't looked at the plugs as yet. She gos like hell when on the move, a little ruff (like slight miss now and then) just crusing. I'm not the guy that just wants too burn up tires, but I should be able to spin if matted from stand still. BTW yes, running the same carb...it was in my sons duster with motor and trans.
 
It just occured to me that one thing that could be causing your problem. Have you checked to make sure the that when the gas pedal is on the floor that the primary throttle blades are fully open? If they aren't it will also restrick how far the secondaries will open.

It's amazing how much difference even the being 10 degrees away from fully open will make. I learned that when i swapped on a Demon carb to try and the car ran like a big. Checked the throttle blades and they were about 15 degrees away from fully open.
 
dgc333 said:
It just occured to me that one thing that could be causing your problem. Have you checked to make sure the that when the gas pedal is on the floor that the primary throttle blades are fully open? If they aren't it will also restrick how far the secondaries will open.

It's amazing how much difference even the being 10 degrees away from fully open will make. I learned that when i swapped on a Demon carb to try and the car ran like a big. Checked the throttle blades and they were about 15 degrees away from fully open.
Click to expand...

Thanks Dave, checked that when set-up the kickdown....and re-check again. keep the idea's coming :lol:
 
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