First Craig Blood dialed-in the engine using a Quick Fuel double-pumper on a Blue Thunder dual-plane with medium-riser ports. Next, Blood fitted dual Holleys on a Blue Thunder dual-plane with medium-riser ports, and lastly tested dual s using the same intake. Production Ford FE 2x4 carbs ranged between and cfm each depending on application, but even on this big stroker motor, the dual s made a smidge more power and torque than the s, and were surprisingly just equal to the 4-barrel.
Our testing would seem to indicate dual s would be the clear choice on a smaller FE in the to inch range. We had our eyes opened when we went to bolt the Holleys to our test car's We previously discussed the merits of buying new carbs, and stand by that recommendation, but even that doesn't preclude the possibility of something being amiss. Our s were just as you'd expect, in perfect new condition right out of the box, however, both of our new s had a small glitch: one had a sticky throttle-blade action, the other was missing an idle air bleed.
Fortunately, Blood recognized the problems before he even bolted the carbs down, and made quick work to remedy the problems. The point is, we'd have had issues if we'd assumed everything was golden. Vacuum connections. Air cleaners. Vacuum secondaries. There are lots of items to sort-out in an 8-barrel application, and you'll need to spend some time to figure each one out. Linkage for popular dual setups can be purchased, and generally work well, however, if you dip your toe into something a bit unusual, say a vintage Mickey Thompson crossram for example, then expect some fabrication to be involved.
Your application may allow you to choose between vacuum and mechanical secondaries on your 2x4 setup. Nearly all s use vacuum secondaries, so be sure to connect the two vacuum diaphragm housings by using housing lids with a vacuum port to connect the two, stocked by Carl's. Blood explained that in the absence of a single vacuum signal that's achieved by linking the diaphragms, the secondaries will open at a slightly different point on each carb, which then causes a teeter-totter effect due to the individual vacuum signals.
The secondaries that opened first will want to swing closed when the second secondaries begin to open, resulting in something short of full secondary activation. Figure that a good tune at a dyno shop that knows carbs inside and out is mandatory for dialing in your dual quads. Next to none, of course. Blood Enterprises was a great place to test our combinations of a single , dual s, and dual s, due in part to their Mustang MD chassis dyno.
Pingback: 68 Running Rich? More torque and better throttle response -especially for a heavy Suburban that needs torque. A big help when tuning the system is to balance all four idle mixture screws. Hope this helps…. Thanks for any Info you can send along Chuck. Hi Jeff have a blue print stroker motor bpct1 that I want to put the edelbrock dual quad carb with the cfm carbs. What should i set the jets at so there is not too much fuel for that engine or are they right with the settings out of the box.
Gerald, I talked with Edelbrock about this and they have already made adjustments to the twin cfm carburetors to lean them out. The only place where this might be an issue is on the idle circuit. But likely this will still be workable. If the adjustments are less than one full turn out, this indicates that the entire circuit is too rich, but install them first and then make careful adjustments.
With four idle screws, a very small adjustment will have a greater effect. Hope this helps. I read on the dual quad that the font carb the idle screws should be half a turn out.
The rear carb the primary should be tuned as per the instructions. What are your finding? Not to much documentation on the dual quad tuning. Jeff: I have a small block in a t-bucket with an edelbrock duel quod set up. It is an older build ,but great motor. I want to replace the old carbs with edelbrocks. Will they work well out of the box? It now has them both tied straight together an am having trouble adjusting them.
I would like your input and thank you. Have a question have a Chevy comp heads large solid cam have tunnel ram with two edlebrocks on cold start it idles well once you drive it idles erratically from to rpm while adjusting mixture screws it do change sound of motor any and motor only makes 6lbs of vacuum cause of cam any info to make the idle better would be great thanks. Bruce, A 10 percent number might be a bit too much.
Holley suggests one jet size for every 2, feet of altitude. Each jet is roughly 2 percent flow change so for 6, feet — that would be roughly 3 jet sizes that would equal a 6 percent change.
Jetting is also dependent on temperature, and humidity as well as pressure altitude so start with a roughly 6 percent change and see how that works and then fine tune from there. Hi Jeff, With this set-up, is it better to run a progressive linkage or a straight linkage? What is Smitty Smith linkage like? We are going to run 2- cfm Edelbrocks on a Chevy motor just like Smitty. I have a rebuilt ford I would like to install the dual quad intake manifold with the dual cfm carbs but my mechanic said that would be to much fuel.
I am running a 31 Ford with a Chevy Stroker 14 inch tunnel ram with dual Edelbrock CFM carburetors what should my main Jets size be to start with I seem to be able to have good Idle No high-end or bad idle good high-end. Do you have pics or diagram of the linkage from the car to the carb? It appears to attach to the rear carb. Stock bracket is too close to activate the throttle. I just picked up this same 2 x 4 for my Tech Support. Easy Returns. Fast shipping. Edelbrock prides themselves in ensuring all products are shipped as quickly as possible.
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