dual quad questions

bnichols04 said:

I just got the dual quad kit from summit for my mustang and I want to know why did one carb have electric choke and one manual? The other question I have about this is where do I hook all my vaccum lines up to. Thanks for all the help

Click to expand...

the carb with the electric choke is the primary carb. this is the one you run on in normal driving. if these are edelbrock carbs, the primary carb is the rear carb. hook up your vacuum lines to either carb, except for the vacuum advance line. you want that one hooked to the primary carb.

if you have holley carbs, the carbs are going to be mounted backwards and the primary carb is the front carb.

rbohm said:

the carb with the electric choke is the primary carb. this is the one you run on in normal driving. if these are edelbrock carbs, the primary carb is the rear carb. hook up your vacuum lines to either carb, except for the vacuum advance line. you want that one hooked to the primary carb.

if you have holley carbs, the carbs are going to be mounted backwards and the primary carb is the front carb.

Click to expand...

I think the backwards-carb thing is an FE-only setup to clear the distributer. I have a pair of Holley 390's on an original Shelby manifold and they mount forward, with only the front carb having a choke. I also run straight linkage and the car starts easily, idles well and has outstanding throttle response, even though I'll be the first to admit it's overkill. Tuning was a no-brainer, I just disconnected the linkage, set the idle to get an equal reading on each carb on my vacuum gauges, then reconnected the linkage. I set the idle mixture screws just like you would on a single carb and left the rest of the carbs just as they came from Holley.

most of the modern intakes that use holley carbs these days mount them backwards to make packaging easier. as a side note, there is a new dual quad intake for the 351w from price motorsports and they spec holley carbs and mount them backwards also.

I don't about all manifolds, but if I mounted my carbs in reverse, the air cleaner would hit the export brace, not only that, but I'd have to use the funky, cross-over linkage. I do know that different manifold manufacturers have mounted carbs sideways, backwards and diagonally to fit whatever airflow theory is prevalent for the period. What I do know is multiple carb intakes may not be the most effecient thing for the street, but with a little effort and some tuning, they work just fine. I get a laugh from people claiming they can't get their carbs to stay in tune on mulit-carb setups. Why? do the mixture screws vibrate loose? Are there evil forces at work? If it's right to start with, it's right. I'd put thousands of miles on street bikes with four carbs and never, ever had the carbs give me trouble. The trouble starts when people that don't know what they're doing start messing with things they don't understand. It doesn't matter if it's one carb or two, if you don't know what you're doing you can make a mess of it in a hurry. One final note: I think a stout ignition is ESSENTIAL to any carbed car, and especially so with multi carb setups. If you're still running points, you're just asking for headaches.

bnichols04,
I have the same setup. run the vac advance line from the dist to the "ported" side of the primary carb, which is the driver side vac tube on the front and at the base of the rear carb. plug the "unported", passenger side, primary carb port. Use the large vac threaded hole at the rear of the primary carb for your PCV hookup. plug all the other ports on the front carb and rear carb. I removed the entire choke valve plate from the front carb on mine and only use the rear choke, however, mine is a manual choke. I would not think you would need to choke both carbs. my works fine with the the single choke operational.
hope this helps,

outlaw66

I can't send any pics as the engine is not in the car at present. I pulled it last week. I checked some pics I had but there was no detail of the carbs to show where the vacuum lines go. You don't thave to run any vacuum lines to the front carb unless you choose to. I have a vacuum guage hooked to the front carb just for tuning purposes and actually ran the distibutor vacuum to the front carb for a while, but it should be hooked to the rear carb.
Sorry for not having any pics at present, I am building up a 302 and it is not completed yet.

outlaw