I currently have a Holley 4BBL 750 with vacuum secondaries. Currently sitting on a 454. I was told that an Edelbrock would be a great carb to switch to. However, I learned today that the Edelbrock (#1411) also has vacuum secondaries. So in my mind I really do not gain anything. Whaty is the main difference between vacuum and manual secondaries? This is for street driving, basically hat rodding it around town. NOT A DAILY DRIVER.

Are you having problems with the Holley? If not stick with it. If you were running the Edelbrock with no problems I would say the same thing.

Vacuum secondaries supposedly open as the engine needs the gas, manual secondaries open for sure !!!

The Edelbrock has mechanical secondaries as does the Q-Jet. Both have air doors that make them act like vacuum secondary carbs. Just a technical point.

Personally, I'd stay with the Holley you have. if you were dragging the car then a change to a double pumper might be a good idea. The gain you make on the street (minuscule) isn't worth the drop in mileage (could be big).

If you really want to , you could play with the secondary springs to open them faster, but watch for a bog (lean).

My 750 vacuum Holley (3310) works mint on my 454..
"hot rodding around town" on street tires is fun..I can light the tires up at 35-40 MPH no problem,and it runs well at the dragstrip on sticky tires.

I have a 454 with a 750 (3310) holley with a 50 cc accelerator pump. My combo loves it. I did try an out of the box edelbrock 750 and drove to CB03. Eight hour drive and scored 16.5 MPG. performance wise I'd have to lean tward the holley. When I'd mash the peddle on the edel. it had a stumble and the holley just seems to be a 10 in my book. Stacey

robert,great quote!!! graemlins/thumbsup.gif --67rat