Vacuum secondary, mechanical secondary, part numbers, stock engine, etc????? Lots of variation in carb models that are 600 cfm. The only thing consistent is they're all way too small for a 400.
Depending on internal modifications, and driving habits, either one may be too small. But, it sounds like you have access to both? Try both, and see which one runs better
For power go with a larger carb. if it's a driver a 600 Edelbrock will give you plenty of punch and good gas mileage
Edelbrock is my choice. Way easier to rejet. Need about 800 cfm to get the most out of a 400 though. But they came with 2 barrels so 600 cfm will do ok. Make sure you dont run it lean with a 600.
on my 406 the edelbrock 750 went 12.71@113 the holly 3310 750 went 12.93@108 the holly has a better idle than the edelbrock. try them both if you have them
600 cfm is fine for a relitivley stock 400. i had a 400 sbc, with a very mild cam, edlelbrock performer intake, and headers (stock pistons, stock crank, un-ported heads and an hei dist.) a 600 cfm vac. secondary worked excellent on this motor. i tried a 650, and it seemed over carbed. and bogged alot in the lower rpms. jetted it down a bit, and had the same results. i can not remember what the jetting was, but the 600 ran 10 times better right out of the box, and the car was actually quicker in the 1/4 mile with the 600. it was in a 71 chevelle with 3:73 gears and nitrous. it ran low 13's with the 600, and the times slowed to mid 13's with the 650...but mph increased a little bit. it had more top end once the 650 started flowing, but less bottom end.
I actually just removed my Edelbrock 600 and replaced it with a Holley 600. My motor is much happier now. Had weird problems with the Edelbrock, and it was brand new. The Holley has been great and problem free so far.
a .030 over 400, 882 heads with steam holes drilled. Pretty much a stock bottom end rods etc nothing outrageous. 1972 motor 4 bolt main with new arp main rod and head bolts. Performer rpm intake double roller timining chain. precision crank 10 10. Cam specs are 454 480 lift 272 284 duration 216 228 @ .050. JD
quadra jet if you want to drive it every day. if you want power more than milage then go with a holley. edelbrocks are good for street rods.
600 seems a little small but I've had both and I'll never go back to Holley. Edelbrock has no power valve, much easier to dial inwith 5 differant spring choices, only 1 gasket on the body and that's above the gas level( makes adjusting floats a breeze). They are mechanical and once dialed in have no bog or hesitation at all, just instant rpm response. You can take it out of the box, put it on and go down the road and tweek it to your motor as you go.If it runs too rich, put a smaller spring in or visa versa if too lean.Spring kits run about 15 bucks and well worth it. Good luck
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