Offshoreonly.com - Bench flowing carbs (How I spent my Saturday)

Quote:

Originally Posted by brian41 (Post 3105091)

The HP 950 carbs (830 cfm) are not going to get you over 800 HP. Check vacuum at WOT and you will most likely be above 2 inches. I bet you would need Dom 1250's with that combo, unless we are talking daul qauds here.

After reading this quote in another thread I decided to do some unscientific testing. I was at JimV's shop (Valako Race Heads) today and asked him if we could flow my old Holley Barry Grant 750's vs the new 950HP he had. We used his Superflow 600.

We flowed the carbs with @ 6" because anything over that the flow was 100% of flow. We used a straight 4 hole carb spacer, a full open spacer and a 4 hole machined spacer similar to a HVH but phenolic.

750-1
4 Hole spacer = 84.8%
Full open spacer = 92.8%
4 Hole machined = 95.9%

750-2
4 Hole spacer = did not try
Full open spacer = 90.0%
4 Hole machined = 91.5%

950HP
4 Hole spacer = did not try
Full open spacer = 90.0%
4 Hole machined = 91.0%

Jim thought it was odd that my matching 750's did not flow the same. So of course he had to take to the grinding bench an modify it somewhat. He also hand modified the 4 Hole straight spacer.

750-2
Full open spacer = 92.5%
4 Hole machined = 94.8%
4 Hole hand modified = 94.0%

Jim and I were shocked to see that the 950HP did not outflow my 750's, but as I stated this is an unscientific test. This only proved that my 750's could flow 600cfm easier than the 950HP's. When we started this experiment we were looking to see what % lower my 750's were than the 950's. Because I was going to buy 950HP's at a later time.

Also his 15 minutes of hand work on my carb netted me a 3.3% in flow to almost match my other carb. 3.3% x 600 cfm = 19.80cfm

Experts take it for what its worth or let me know why my findings might be wrong or skewed. I know I was not using full velocity or full cfm for the carb.