A 750DP on a 330hp-400hp 5.7 with a dual plane intake (performer rpm) is easy to tune and will make max power to boot.

Just as an example...........

Missed this.

Yess, it is.

If this is used on a 500hp or higher hp BBC engine I'd strongly recommend a 1" open spacer. I'd demand the 1" open spacer if using a small (for the application) carb like the mentioned 750 on a 500hp BBC.

It's a .030 over 454 290 big oval heads with big valve bowls worked runners worked emi thunder exhaust Bob M roller cam rpm performer intake 9.2 to 1 CR

The 750 carb is square bore edelbrock
The 800 carb is spread bore Holley
Both are mech. Sec

Interesting, I tried going from a vacuum secondary 850 to a mechanical secondary on my boat this year. If you are interested in an 850 I'll cut you a pretty good deal, I bought it brand new in July for $591 off Amazon with electric choke and had it on my boat for literally 3 days. We thought initially when I began having issues this year I was having fuel problems so I rebuilt the carburator, that didn't help but it was quite corroded inside so I bought a new one to try assuming I'd use it at some point anyhow. That turned out not to be the problem so I re-installed the stock carb.

Let me know if you'd be interested, otherwise it will be sitting on my shelf for some time, or maybe I'll throw it on ebay...I'm in no hurry to get rid of it but if someone else needs it, hey what the heck.

Items Ordered Price
1 of: Holley 0-80443 850 CFM Marine Four Barrel Mechanical Secondary Automatic Electric Choke Carburetor
Condition: New
Sold by: Amazon.com LLC
$591.41


Order Placed: July 23, 2011
Order Total: $591.41

Item(s) Subtotal: $591.41
Shipping & Handling: $0.00
-----
Total Before Tax: $591.41
Sales Tax: $0.00
-----
Total for This Shipment: $591.41

Please double check your carbs.

Edelbrock carbs are vacuum secondary. Never heard of a mechanical secondary EDDY carb.

I know of the spreadbore 750 Holley carbs...never heard of a 800 spreadbore. BTW: I have not liked the automotive nor marine spreadbore Holley carbs. Don't seem to tune in as well as their squarebore carbs and require more labor.

I put a new Edelbrock marine 750 on my new 468bbc. It was running lean on the dyno with the stock jets, we had to put in the biggest jets Edelbrock makes to get it to run safe and my engine only made 407hp. Go with a Holley carb much better tune ability.

Holley 800 part# R84017-1

Edelbrock Design
 

I believe the Edelbrock secondaries are not the same as the Holley vacuum secondaries. The Edelbrock secondaries work off an Air Valve with a counter weight just above the secondary throttle plates. IMO the Edelbrock Air Valve secondaries should work better than a Holley with vacuum secondaries. Holley Mech Secs are more for the marine application

Both the Edelbrock 1409 600cfm and the 1410 750cfm are square bore carbs.

Guys -if you have a blower does that impact the CFM of the carb or is the flow a restriction in the venturi?

sorry to jump into this thread..