Holley carb idle feed restrictor size i read an article in muscle machines magazine about how most universal holley carbs have an over rich idle circuit and how at steady low load road speeds the transfer slots are doing the fuel metering. Inside diameter jets includes billet storage plate kit 1 part number.
Carburetor Tuning The Scientific Way
Holley idle feed restrictor. Following the hp holley produced the hp ultra version which upgraded to black anodized billet metering blocks with screw in idle feed and emulsion jets and a billet baseplate. He was able to tune his transition circuit with t slot restrictors adjustable idle feed restriction and idle air bleeds to cruise at 151. Carburetor idle feed restrictors four 0029 in. The standard idle feed restrictor size for most 750 cfm holley carburetors is around 0034 0035 inch. In that case mike increased the size by 7 to028 being sure to blow out any shavings. Find holley carburetor idle feed restrictors and get free shipping on orders over 99 at summit racing.
By the end of the thread he was able to acheive 17mpg on the highway. A typical holley 750 double pumper 4150 style carburetor is generally fitted with an idle feed restrictor of 0034 inch an 850 will have a slightly larger 0037 inch and the idle air bleeds will measure between 0067 and 0070 inch. Most dominators are fitted with much larger 0041 inch idle feed restrictors. It turned out that this was enough to dial in a 1421 air fuel ratio at idle with the idle mixture screws turned out 2 12 turns. The restrictors in this carb had been drilled to a larger 0055 inch. On the right yellow arrow is the replaceable style for the ultra range of holley carbs.
The idle feed restrictor is a fuel jet so yes larger is richer. While this sounded bad. Idle feed restriction idle jets can be located in different positions for different metering blocks. Keep in mind that if the idle feed restrictor is enlarged too much itll have to be removed and replaced. Idle air bleed is opposite smaller is richer. On the left red arrow is the fixed type most commonly seen in regular metering blocks.
This was using a holley 4150 carb 870 cfm vs avenger which is very similar to the 3310 that i have which is a 4160 holley.
Gallery of Holley Idle Feed Restrictor
