Blog | Air Fuel Spark

Air and fuel bleeds

I get a question like this fairly often: “Hey Drew, my carb is rich at idle, should I drill out the air bleeds?” My answer is almost always “absolutely not.” Maybe it’s due to many modern carbs that are available with changeable bleeds, but generally speaking unless you are really deep into fine tuning, there should be no reason to change the idle or high speed, airbleeds. I really don’t care for this new “change the airbleeds!” Fad. If the issue is strictly at idle, it can

AirFuelSpark

6 days ago4 min read

How to Properly Box Up Your Carb for Shipping

Here is a handy video for boxing up your carb before shipping it.

Drew Pojedinec

Nov 201 min read

Visual comparison on various Ford 3x2 setups

260/289 vs FE setups. First a chat about the different sbf carbs: I was asked via email about the 260 and 289 3x2 carbs. Basically a guy was shopping for some and needed info to make sure he was making a wise purchase. So lets have a talk. mid 1963 is the earliest I’ve seen an over the counter 260/289 Ford 3x2. I have seen them as late as early 1967. These were very small. The 260 setup: Primary carb C4GF-9510-H List 2867 Metering block 3673 47 jet Outboard carbs C4GF-9510-J

AirFuelSpark

Nov 133 min read

Lemans bowl endcaps

Lemans bowl tips. The original endcaps were a soft brass. They sealed really well. Replacement ones are steel and are really bad about leaking. When I had 1000s of replacements machined I used the original style brass. Yes they seal well, but also easier to damage. The tips below can aid you and being able to tighten the end caps properly without damage. I use a seal with these, but I strongly suggest using a thread sealant. A tiny amount of teflon paste (not tape) or Loctite

AirFuelSpark

Nov 131 min read

Throttle plate thickness

Saw someone ask about the different throttle plates on a forum the other day. So here: Why are some throttle plates thicker than others? In the case of 172 and 173 as shown, the thinner plates almost never seal as well. With closed throttle airflow moving in the primaries more and the secondaries closed, the pull seen at the fuel bleeds is vastly different. Primary plates don’t need to seal as well as they are going to be held open to attain no load idle speed. Some carbs lik

AirFuelSpark

Nov 31 min read

SK race carbs

So to explain what these are as invariably a bunch of people will decide to throw their opinions around without much back info. Before someone says “oh those are 660s!” They are not. These are from 67-68. Center squirters were not available until later 69 (I believe). These are the second evolution of the center squirter. The first hand made ones I have seen are from 1965. In the 1960s (and before) Ford and Holley were very intertwined. Just about any performance Ford came

AirFuelSpark

Nov 33 min read

Reading the Holley Parts Manual

How to read the “Holley Black book.” Part #36-51 1. Find the part in question (I normally double check jet and pv) 2. Find part on the chart 3. Look up and cross reference it with your list number. In this case, List 4511 jet size is 68 and 82. Throttle plates 224/172 Pump nozzle .026 Metering blocks 6211/6213 Power valve 6.5 Etc

AirFuelSpark

Oct 301 min read

Adding a Power valve to a full race carb

660 center squirters and many other Holleys did not come with an enrichment circuit. Due to this they are very effective race carbs but often not suited for street usage. Ideally you want a rich no load idle, with a transition that leans out as vehicle and engine speed increases. As the main circuit starts to contribute more to the running of the engine, the carburetor should seamlessly add fuel without being overly rich. As the light load continues the engine tends to want a

AirFuelSpark

Oct 203 min read