What type/model carb(s) are you using?

[undy]

Originally Posted by ERA Chas

Dave, How far do the secondarys open at WOT on your 482? What are the cam specs and valve sizes?

On the chassis dyno they were 100% open by the end of the pull. On the street (not track) I probably don't have enough road to keep my foot in it long enough to get them both open, at least without fear of incarceration. I'm running Blue Thunder's re-pop version of the OEM progressive linkage. Acceleration through the RPM band is very linear with no flat spots or bogs, overall I'm very pleased.

The cam is a KC/Comp Cams hydraulic roller, 242/248 w/ .644 int, .633 exh

The cam's pretty tame as I can cruise at 1300/1400 RPMs w/no bogging or bucking. The idle's a different story, a bit radical (as I like it).

2.19" intake with 1.76" exhaust on the valve sizes... KC's stage II Ebok heads.

[ERA Chas]

Originally Posted by undy

On the chassis dyno they were 100% open by the end of the pull. On the street (not track) I probably don't have enough road to keep my foot in it long enough to get them both open, at least without fear of incarceration.

The cam is a KC/Comp Cams hydraulic roller, 242/248 w/ .644 int, .633 exh

2.19" intake with 1.76" exhaust on the valve sizes... KC's stage II Ebok heads.

Thanks for the reply. I have 55 inches less displacement and wanted to compare our data.

The dyno's brake load helped get your secondarys full open.
At the dragstrip, I could get mine fully open but 2/3 that on the street, even given a lot of room.

Our cams are very similar but mine is solid and has more exhaust duration. My Shelby heads have 2.250 intakes.

Your 482 uses all 1500 cfm of breathing, my 427 breathes 1308. I wish I knew how but I'd like to know the VE of both our engines. Does using all the cfm mean 100%?

Thanks for sharing.

[Zoom This]

Originally Posted by ERA Chas

Thanks for the reply. I have 55 inches less displacement and wanted to compare our data.

The dyno's brake load helped get your secondarys full open.
At the dragstrip, I could get mine fully open but 2/3 that on the street, even given a lot of room.

Our cams are very similar but mine is solid and has more exhaust duration. My Shelby heads have 2.250 intakes.

Your 482 uses all 1500 cfm of breathing, my 427 breathes 1308. I wish I knew how but I'd like to know the VE of both our engines. Does using all the cfm mean 100%?

Thanks for sharing.

One way I have found reliable in measuring a carbs efficiency at full throttle is to read your vacuum gauge during a dyno pull. If the vacuum is flat at zero inches vacuum throughout the pull you more than likely have too much carburetor. Many tuners look for zero inches vacuum at low rpm's but no more than .5 - 1" of vacuum at the top end. The more the vacuum at top end indicates carb may be too small for your motor. I went from my 850 Holley to a BG 650 Mighty Demon on my 418W, lost 15 hp at the top but gained 19 lbs. torque in the middle. I was willing to stay at that. Vacuum was zero inches at start of pull, .5" at 4500 rpm and 1.5-2" at 6000 rpm. Cam is .565 intake .552 exh., 232/242 duration at .050 and 110 lobe separation. 72/77 jets and #25 squirters.