mig controlwasteTOMindexlogo 



Vacuum Secondary Performance

MIG Gas Delivery and the Small Block Chevy Evolved in a Similar Way and Time!

 Both had Advances and Setbacks Before

They Were Optimized!


Click for a PDF Report on the Similarities



See Video " Tuning Holley Carb"



See YouTube Video Discussion of Our

Patented Shielding

Gas Saver System


The Vacuum Secondary Holley 850 CFM Carb that came with the ZZ502 Chevy engine was model number 0-80531.  It came with  #78 Primary Jets, a 30CC accelerator pump with 0.035 Squirters, a 6.5 Power Valve with Power Valve Fuel Passages of.0.045 inch diameter. The Secondary came with #82 Jets, a 6.5 Power Valve with 0.049 inch diameter Power Valve fuel passages and a Pink spring on the secondary opening diaphragm.

Out of the box the car was obviously running rich at idle and when cruising. It also had a Bog when trying to accelerate.  It was fowling plugs so the Primary Jets were decreased to  #76.  Plug fowling was eliminated but there was the same slight Bog when the accelerator was rapidly depressed.  It appeared the mixture needed to be richened and the following table presents the various modifications tried over a 6 month period:


Test # Spring Color Needle Valve Setting, Turns Out * Changes Made Comment When Accelerating Air/Fuel Meter Reading when Aceller.
1 Pink na* #76 Pr. Jet;4.5 Pr. PV Bog na**
2 Pink na* .045 Squirters; 50cc Pump Bog na**
3 Pink na* .057 Pr. PV Fuel Passage Bog na**
4 Plain na* .067 Pr. PV Fuel Passage Less Bog but slight Hesitation na**
5 Pink na* #84 Sec. Jets: and  3.5 PV Slight Bog na**
6 Pink na* .070 Pr. PV Fuel Passage

Slight Bog

7 Pink na*  J Extensions Added to Sec.

Very  slight Bog

8 White 1 1/2  

Very  slight Bog

9 Pink 1 1/2   Slight Bog improvement but slight Hesitation na**
10 Purple 1 1/2   Slight Bog improvement but slight Hesitation na**
11 Purple 1   Bog almost gone na**
12 Purple 5/8   Bog almost gone na**
13 Grey 5/8   Slight Hesitation Very Lean
14 Grey 5/8 .052 Squirters Slight Hesitation Very Lean
15 Grey 1 .o45 Squirters Slight Hesitation Very Lean
16 Grey 1 Rubber Band on Sec. to hold it shut No Bog but sluggish response Very Lean
17 Plain 1 .031 Squirters No Bog but sluggish response Very Lean
18 Pink 1   Slight Hesitation Very Lean

*Adjustable Needle Valve Diaphragm not purchased until 2nd half of tests

**  Air/Fuel meter was not installed until near the end of the Vacuum Secondary carb tests

The above tests were made with the various Secondary Diaphragm springs and the Special Adjustable Secondary diaphragm purchased.  The special diaphragm housing incorporates a needle valve so the rate of vacuum applied to the diaphragm can be controlled.  It was not significantly better than using a stiffer spring which can eliminate the Bog (a drop in RPM upon opening the secondary quickly) but created a Hesitation (the Secondaires open so slowly you don't get a Bog but you can feel the slow opening).  The springs were ranked as to stiffness by using a postage scale and measuring the force at two points.  The following table shows the force when fully opened and when the secondary butterflies are closed:


Spring Color Force in oz when throttle open Force in oz when throttle closed
Black 20 8
Brown 17 11
Plain 13 7
Pink 9 6
Purple 8 4
Yellow, Long 7.5 4
Yellow, Short 7 3
Grey * 6 2




* Came with the Adjustable Secondary Diaphragm

Return to Modifying Holley Home Page

Go to Double Pumper, It Solved the Problems !!


Engineering a 1934 Pro Street Street Rod


Click for a 67 Page PDF


Click for YouTube Video Overview of Car


This Ad Helps Bring You  Free Information on Welding Race Cars & Street Rods

Have a Welder?   Improve Weld Starts and Have Shielding Gas Cylinder Last at Least Twice as Long! 

Note: Our Patented GSS is Not Available in "Stores"

A home shop fabricator in Georgia with a Miller TM 175 amp welder purchased a 50 foot Gas Saver System ( GSSTM ) so he could use a larger cylinder and mount it on the wall of his shop.  He wrote:

"The system works great.  Thanks for the professional service and a great product."   Click To See His Home Shop


A Professional Street Rod Builder Had This to Say:

With their standard MIG welder gas delivery hose the peak shielding flow at weld start was measured at 150 CFH. That caused air to be sucked into the gas stream causing poor weld starts.  With the GSS replacing their existing hose, the peak flow surge at the weld start was about 50 CFH.  Total gas use was cut in half.

Kyle Bond, President, quickly saw the improvement achieved in weld start quality as a significant advantage!   Kyle, an excellent automotive painter, was well aware of the effects of gas surge caused by pressure buildup in the delivery hose when stopped.  He has to deal with the visible effects in the air hose lines on the spray gun in his paint booth!  The paint surge is visible and creates defects unless the gun is triggered off the part being painted!  We can’t do that with our MIG gun!


(Note: Thanks to those "Car Crazy" folks who have purchased the Gas Saver System and commented on the improved starts and reduced gas usage they have achieved.  Many purchased our 6 foot prefitted GSS, Part Number WAT FB6.  We also added  3 and 4 foot prefitted GSS, Part Numbers WAT-FB3, FB4.

Improve MIG (GMAW) weld start quality while cutting shielding gas usage by 25%, 50% or more!!  Simply replace the shielding gas delivery hose from cylinder or pipeline gas supply to the wire feeder with our inexpensive, Patented**  hose system  Click Here. 



Click on Products Overview Button in upper left to see Shielding Gas Savings Products



"WARNING: "Weld Safely"


Details of the 1934 Pro Street Rod