[Tom Vaught]

One comment this morning on the Carb Air Flow number. It is a NUMBER.

How people use that number and what their expectations are means a lot.

I knew people that had perfectly good #4781 850 cfm at 20.4" water test pressure remove that carb and purchase a advertised "950 HP cfm" carb on their engine and not see any performance benefit. Maybe the carb was a bit more responsive but that would be expected with a actual 100 cfm less airflow carb installed.

The situation is the same with the 1000 cfm reported carb that has the 850 cfm dimensions and in reality might be 10 cfm better in airflow (minus the choke airhorn). But people want to brag about their cfm numbers, including me.

The difference is the cfm numbers I reported in this thread in the last couple of posts were under-rated cfm numbers in the advertising.
They were playing games with the Tech Inspectors and the Chebby Guys. They lied too but they lied DOWNWARD. No one got hurt on the deal in the advertising game and spent more money for less cfm air flow.

Barry Grant started that inflated cfm number crap years ago. Well Barry is gone, Holley owns his company and his carbs, and the cow is out of the barn.

Based on the info provided here people can go thru the math and evaluate carbs a bit more carefully. The rule of thumb is:
The only Holley Carbs with a TRUE 950 cfm were the 3-BBL carbs. The only 1050 cfm (850 style carbs, not Dominators) were the Rear tube nozzle 3-BBL carbs.

The early Dominators actually flowed either 1050 cfm or 1150 cfm.

All of this HP1000 (850 carbs) is advertising.

Yes, the carbs do flow 1000 cfm but at an inflated test pressure vs a test pressure that was standardized by all of the major carb manufacturers: Holley, Carter, Rochester, Autolite many years ago.

As posted before, the fact that Smokey Yunick Dyno corrolated better on his SB Chebby engines when airflow was tested at 28" of test pressure thru the head does not mean that another dyno engine (HEMI for example) tested accurately with Bob Mullins 5" of water test pressure.

Many people just want to take a single data point and run with it, whether it is valid in all cases or not.

Have a great day and no more long posts about carb test pressure testing.

Tom V.