Just an update on my dual quad set-up. I took slumlords advice and ran them inline instead of progressive which helped greatly. I also set the timing and a/f mixture with a vacuum gauge to achieve the highest vacuum.

I also swithed out the points with the Accel points eliminator kit.

Now my vacuum is pretty steady at around 15" at idle.

When I tried to check the timing with the timing light I didn't see any marks so I think the balancer slipped greatly over the years.

I just lefted the vacuum advance disconnected and she SCREEEAAAAMS now, even chirps when that Fordo kicks in.

Thanks to all for the great advice.

58 Ford Custom 300 - San Pedro, CA (So-Cal)

I'm using the vacuum port above the thottle blades.

58 Ford Custom 300 - San Pedro, CA (So-Cal)

are you using the right vacumm port for the dist. ? NO vacumm at idle on a ford.

 lincoln/merc. y-blocks &mel's                                                               bucyrus, ohio.

JUST MY HUMBLE OPINION,AND I AM RUNNING A COUPLE OF MY CARS WITH DUAL QUADS, I THINK 1000 C.F.M. IS TO MUCH FOR A SMALL CUBIC INCH MOTOR WITH A STOCK CAM. TOM

  JUST A MIDNIGHT CRUISE DOWN THUNDER ROAD!!! TOM DRUMMOND MIDWEST DIRECTOR 57 FORD INTERNATIONAL

I've set the timing to 8 degrees but I'm not sure about valve adjustment.

If I disconnect the distributor vacuum advance it does'nt shut off on me when I'm on a hill or heavy load so I guess the vacuum advance canister has to be adjsuted.

As far as I know the cam in the engine is stock.

It runs now without shutting off if I disconnect the vacuum advance but the power is still weak when pulling away from a complete stop.

58 Ford Custom 300 - San Pedro, CA (So-Cal)

Don't know much about multi-carb setups, I'll be corrected if I'm wrong. I think it should have more vacuum than that, and it should be relatively steady. Check for vacuum leaks, check timing, check valve adjustment. Try adjusting the idle mixture screws for the highest vacuum reading. If everything else is functioning properly, the idle screws will alter the vacuum.


Lawrenceville, GA

I did a vacuum check and at idle it jumps around at about 12-15" of vacuum then when I put it in drive it drops down to 5". Is this a problem?

I've checked for leaks with no success.

I'll try and run them together rather than progressive and see if that helps. Thanks for the suggestion.

58 Ford Custom 300 - San Pedro, CA (So-Cal)

If you are running the Ford intake manifold, it is designed to utilize the idle circuits of both carbs. One carb feeds 4 cyllinders and the other carb feeds the other 4 cyllinders. It will not work as a progressive setup using only the idle circuits on one carb. The idle screws must be screwed in much further than on a single 4 setup because of this. This would cause the type of problems you are having. Try it and see what happens. You may still have to play with jetting and power valves to get optimum performance and driveablilty with this set up. It did not make a lot of sense to me when I first set up my dual quads in 1965 but that is the way it is designed to work with the Ford factory manifold.

Thanks Ted for the suggestions. I have not checked the vacuum yet. I'll run down to harbor freight to pick up a vacuum tester and check the vacuum when I drop it into gear. Should it be at a certain measurment?

As for the carbs I do have them set-up in a progressive set-up and I am using the rear carb as the primary with both carbs facing forward.

For the power springs, according to the edelbrock manual they suggested I go stiffer but what your saying makes more sense due to multiple carbs = divided vacuum. I'll try the lighter springs once I get a vacuum reading. Thanks again.

58 Ford Custom 300 - San Pedro, CA (So-Cal)

Have you performed a vacuum check on the engine when it’s in gear?  Depending upon the camshaft that’s being used, you may need lighter power valve springs in each carb due to the vacuum signal to each carb being cut in half when using carbs in pairs.  Some more initial igition timing advance may also help depending upon where the timing is currently set.  If you cannot kill the engine by turning the idle mixture screws in on the carbs, then you’ll have to address that; possible causes for this include retarded ignition timing, vacuum leak, wrong carbs for the application, or unsynchronized carbs among other things.

 

Are the carbs idling equally or is one of them treated as a primary carb and the other as a secondary carb.  If idling equally, then the idle mixture screws should be set the same for both carbs as well as both carbs having exactly the same throttle blade openings at idle.  If you’re treating one of the carbs as a primary carb, then the secondary carb should be set at almost dead closed with only anough idle speed screw adjustment to keep the throttle blades from sticking closed.  In this scenario, the carb that has the primary throttle blades closest to the center of the engine will be the primary carb.  If the carbs are facing forward (most common setup), then the rear carb would be the primary carb.  Backwards facing carbs would have the front carb being the primary carb.  On a primary and secondary carb scenario, staged or progressive linkage should be used so that both carbs reach full throttle at the same time while allowing 1/3 or more throttle opening on the primary carb before the secondary carb starts to open.  You're essentially doing your cruising on the primary carb with progressive linkage being used.

Lorena, Texas (South of Waco)