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Too much power too quickly with 8 barrels !
Hi folks,
I purchased an original Ford riser with the dual Holley carbs and got all this setup in the Cobra. I can handle it, however the car has become too scary for my wife to drive it, and I'd like to keep her alive. I don't drive the car much because of health issues, however when I do, I love the kick in the butt when the eight barrels open! But it's true that it becomes very aggressive - the car feels like a race car, no longer a street car even with the fairly conservative cams. My other sport cars now feel like the most boring cars compared to the Cobra :cool: Is there a trick to easily tranquilize the engine? I was thinking of removing a rod to keep one of the two carbs closed, but this will obviously result into terrible carburation for the affected cylinders. Something to trick spark advance easily, maybe? Thanks, Luke |
What is your wife doing to make it undriveable for her?, matting the throttle?. If that's the case limit the throttle rod movement. If it's the short wheel base light weight, 427 combination which is what the cobra is all about,-- undriveable can happen in 1st gear off idle. A corvette with traction control would be another option.
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I have the Ford dual quad intake with Holleys and I suspect it's not the secondary barrels that are coming in so strong - but the primary barrels on the rear carb. I have a zip tie tail on my rear secondaries shaft to let me know if I managed to open them on a drive. I too have the really strong boot in the back upon giving it some throttle, but based on the degree of throttle opening and the fact later I often find my secondaries never opened, realize it was the primaries on the rear carb kicking in at about 30% and more throttle.
If the secondaries are properly adjusted on a Holley you really won't experience much of a boot or jump as they open as they should open gradually as throttle increases and vacuum drops. You might play around with the linkage adjustments a little and you may be able to fine tune the coordination between the front and rear primaries a little to bring them in a little sooner and less dramatically. I don't mind the boot in the back on mine, but it definitely gets your attention. |
Some additional response - if you have stock, reproduction dual carb linkage, it is progressive and the rear carb primaries don't start to open up until about 30% throttle and then they are levered to open faster than the front carb so that they both reach full throttle at the same time. I don't know if it can be modified - or if a non-staged linkage system is available - to run off of both carb primaries from idle up. There is some adjustment in the linkage that you might play around with. After any adjustment open the throttle fully and make sure the primary blades on both carbs are able to open fully. I suspect if the stock linkage is used to bring the rear carb in too early, it may prevent the front carb primaries from opening completely.
If I'm wrong - and it is your secondaries that are slamming open to fast with a big boot in the back, then a couple Holley secondary spring kits should be able to tame that somewhat by going with a stiffer spring to slow down their opening. Holley vacuum secondary carbs are supposed to work without a noticeable power surge from primaries to secondaries to prevent bogging. |
I don't know if you have a cable-actuated throttle, or a mechanical linkage like mine. If it's a mechanical linkage, you can adjust the geometry to give you a wider range of "pedal", to help you control it better. I played with my bellcranks (sounds kinky) until I was happy with the pedal "feel". Another option for you...
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If all else fails, You could always replace the carbs and manifold with a single four barrel carb and manifold.
Much easier to limit one carb than two. |
A smaller tamer engine. Much cheaper than trying to detune what you have.
I really think you're trying to talk yourself out of this car. Your question is more like "gee, I put a jet engine in a F14 and while I can taxi it if my wife hits full throttle it wants to fly". |
I would just adjust the linkage so she couldn't get full throttle.
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Look guys, with a Cobra and its light weight and short wheel base the only safe engine for someone without performance driving experience is a one lunger Honda lawn mower engine. Detuning a 427 is not going to keep someone from spinning the rear wheels around on cold tires/pavement if they aren't experienced.
If the OP wants to keep Cobra he can't drive because of his back - which I can't believe he could ride in either - and turn it into one that his wife can drive (safely), instead of detuning the 427 he could (1) pull it out and drop a 302 in its place and keep the 427 for resale, (2) sell it and by a small block car, or (3) sell it and buy something else like he says he might do in his other topic. |
Great idea, send me the motor and tranny and I'll send you my 302 and T-5. :3DSMILE:
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Why not just go back to the induction system that you had prior to the 2x4's? Like they say, "marriage is all about compromise".
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Quote:
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I don't want to detune the car when I drive it. On the opposite. I love the blast of torque and peak power. Otherwise I would simply put the Holley 750 cfm in there and the car would be relatively safe to drive.
I'm concerned for my wife and possibly other drivers. Anyway DanEC gave me what seems to be the best idea: prevent secondaries from opening. That's easy to do and can be reverted in less than a minute for when I drive the car :) |
Is this thread really happening?
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Duct tape the air cleaner when she's driving it, that should do it! :3DSMILE:
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Wow. You guys are very innovative.
I'd have gone for a cheap & simple fix. Put a block behind the accelerator when she drives to limit the pedal movement. Remove the block when you want to play. ;) Simple, and no screwing around with the carb, linkages, jets tuning or other... Enjoy. |
Disconnect the rear carb and run it on front carb only. I think this is what
Tony Hogg of Road and Track did when his wife was driving the Cobra. |
If I had a wife she would never drive my cobra. Even if it was Danica. It's kind of like saying your bazooka has to much kick for your wife to shoot. Get her a 22 cal or a Miata.
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I can't get my wife to even go for a ride in it - no worries about her wanting to drive it. And mine is a relatively tame street roadster.
You could probably disconnect the rear carb from the linkage fairly easily and quickly when your wife or friends drive it. It shouldn't be a problem running off of the front carb primaries since it's in the approximate center of the engine. But with the secondaries all the way at the front of the intake, fuel mixture distribution when the throttle is matted will probably be pretty poor and may cause some lean cylinders. |
Simply "disconnecting" one carb would lead to very poor performance. The carb will still suck air without any gas in the mix....leaning out the resulting mixture pretty badly. A dangerous state of tune. You'd need to adjust the linkage to ensure that the butterflies close 100% tightly. Not sure that's possible.
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