My 408 SB has
Dart pro 1 215 cc heads
10:1
Lunati hdy roller .530/530 ?duration
1 5/8 headers, 2 1/2 Flowmaster exhaust.
RPM Air Gap intake.

I have a crappy looking old 750 vac with a quick change kit on it to get it running but it doesn't idle well.


I have a new 850 from a ZZ 502 engine that could go on it but for street use I was thinking a Holley Street Avenger 770 for go and show.

The 850 is nice with the Zinc finish. But is it over kill?

Or should I look for a 750 double pumper?

Car has 3.73s with a 700R4 it is my 66 Wagon.

Comp 1.5 roller rockers, 1 5/8 headers short/ mid length, 2 1/2 Flowmaster exhaust, MSD ingition, RPM Airgap intake, 750 Holley, Lunati/UD .530/.530 Hyd roller, 110, intake is 234/242, exhaust 288/296,

it's overkill, but will work till you come up with something more suitable. IMO, you need a 750 vac sec, but the 770 is close, just avoid the double pumper with the automatic. You could just build the 750, keep your wallet happy. Those 770s are not cheap. If you're not familiar with rebuilding Holleys and don't know anybody that is, email me and I'll get it taken care of for you. Change it over to a secondary metering block too, if it has the plate. Not a big deal.

Tom

I rebuilt it. I didn't get it fully cleaned out but a friend solved that problem. It does have dual metering blocks. I figure I'll run it as is. The air cleaner covers most of it any way.

The 850 is a back up.

So stay away from the double pumper?

It depends on the stall, it is where you start to load the motor down. I tried one on my 405 and it had a little bit of a bog off the line (at the strip - worked fine on the street). I might have been able to ajust it out, but it wasn't a drop it on and go deal. My car only has a 2500stall.

Does anyone remember that the original Z-28s (302 cubic inches) had a 780 vac secondary? And the optional 2x4 setup used two 600s (total of 1200cfm)?
The point is, the carb will only supply whatever the engine demands.

so why is it that we had a low compression 454 with a edel 750 that would foul the plugs almost instantly (jetting and metering up and down,down to the point of it stumbling,with no happy medium)
then put on 600 jetted accordingly ran great..
shane

Edelbrock AFB 750 is a POS, IMHO. I've worked 3 of them, new out of the box, no good. I think Edelbrock pooched the design when they took it from 600 to 750. ovelle's story just above is normal for those carbs, near as I can tell.

Ditto. But I didn't want to be the one to say it!

Actually Edelbrock didnt design that carb. The second gen AFB's were designed decades ago by Carter.These were a slightly different design than the origional OE type designs.The 2nd gen ones were specifically designed for aftermarket use.

Carter has been a company whom had been bot and sold a few times.ACF Industries , a comglomerent who
I think at one time also owned Harley Davidson and had an intrest in Bowling and.... I digress...

Anyhoo Carter Carburetor designed these aftermarket carbs back in the 70's .... They were good carbs but some did have an off idle stumble that needed to be corrected.... easy to fix tho...required drilling..... anyhoo Carter got shopped around and ended up being bot by Federal Mogal.... another comglomerant.... Well after a period of time ( years) , it finially dawned on FM they had no clue how to build a carb.... so they endeing up contracting with Weber USA to build them for them...... Edelbrock around that time wanted to get into the carb business and they had some ideas..... They contacted Weber and discovered that FM never had made any language that Carter had an exclusive on these carbs....So Edlebrock had the cure for the legendary off idle stumble and the made a couple other mods and presto.... Weber took the designs by Edelbrock and
made the improved design exclusively for Edelbrock.Carter couldnt have the improved version but could of course have their own version....

Anyhoo long story short.... Carter aint around any more of the Edelbrocks are.... Now these carbs may have had their basic " tune ups " changed throughout the years . IE the idle and main clusters and the jetting/rods changed.... but the actual design of the basic carb is Carters.... The Edlebrock fix of the off idle stumble was pretty much a small drilled hole was mostly all that was needed...

The Manual and Electric choke carbs of any size are different tuneups.... It's more than just a choke option... the manual choke version have a tuneup abit richer to deal with the rumpity rump cams and the Electric choke versions are leaner to work with mildier cammed everyday drivers who are also looking for economy.... The carb designs are the same but the tuneups are different...

Today the Edelbrock Carbs are being made by Magneti Marelli in North Carolina.

Well a great friend has been working on my car and we got it fired up today with the 750 but it had no snap. Slow. graemlins/sad.gif

If we had more time we could have put the 85o on or his 750.

It may have needed more timing but it just didn't jump when you hit the throttle, like it should. My BB jumps but it has a 50CC pump up front and perfect springs in the 870.

I'm looking to just replace it. So Sreet Avenger Holley 770. My 850 or a new 750 double pumper but I hear with the auto trans and heavy car a vac sec is best.

What to do?