Too much power too quickly with 8 barrels !

[jhv48]

Some people aren't meant to drive these cars. Put a seat heater in the passenger seat and she'll never want to sit behind the wheel.
My wife drove my first cobra. It had a relatively mild 302 with about 350 horsepower. She handled it just fine. My current car has about 200 more horsepower and I offered her the drivers seat. She said "No thanks". She loves the car, but knows her limits. Now she only rides in the right seat. FYI, her daily driver is a 550 horsepower Shelby GT 500 mustang.
Go figure!

[CSX3183]

There is no such thing,, as too much power, too quickly

[fordracing65]

Originally Posted by CSX3183

There is no such thing,, as too much power, too quickly

For a non experienced driver there is. Ask him and his wife.

[twobjshelbys]

Originally Posted by fordracing65

For a non experienced driver there is. Ask him and his wife.

Yeah, I was going to say that. My daughters have driven manual transmissions since their first cars, and in the snows of Colorado to boot, but both were scared sh**less of the Cobra and the one that drove the GT said it wasn't as bad as the cobra but still got the squirelly sensation.

Nannies definitely help all of the above.

[DanEC]

Originally Posted by Antny

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.

If it's sucking air disconnected (and it would be unless the idle speed screw were backed completely out) - the idle circuit would still be working on it and introducing fuel in the normal fashion due to engine vacuum. The Ford FE dual quad set up idles on both carbs and except for idle mixture, the rear carb contributes nothing further until the throttle it opened 30% +/-. Basically, above idle and up to 30% throttle the engine is just running as a 2 bbl carb set up. But after 30% throttle I agree, you would get some pretty bad fuel distribution mixtures in a number of cylinders that would not be good.

[Luke427]

The real challenge is that she's an Italian red hair. All would be easier otherwise. But I guess that's why I married her

She doesn't shoot but if I took her to the field she would probably not want to play with a .22 and would grab the .50
Now that must be why SHE married me

[Luke427]

Originally Posted by DanEC

If it's sucking air disconnected (and it would be unless the idle speed screw were backed completely out) - the idle circuit would still be working on it and introducing fuel in the normal fashion due to engine vacuum. The Ford FE dual quad set up idles on both carbs and except for idle mixture, the rear carb contributes nothing further until the throttle it opened 30% +/-. Basically, above idle and up to 30% throttle the engine is just running as a 2 bbl carb set up. But after 30% throttle I agree, you would get some pretty bad fuel distribution mixtures in a number of cylinders that would not be good.

Yep, that's why I wouldn't go there. To block secondaries sounds like a much better idea. I'll give it a shot. Have some tuning to do on the ignition (received the recurved distributor, can't wait to try) and will use the opportunity to play with carbs...

[Gaz64]

Originally Posted by Dimis

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.

This the best way for the engine, and your wife's safety.

Cheap and simple fix, end of discussion really.

[wkooiman]

There are 2 progressive linkages - LR and MR.

The LR linkage opens slower, and has a single flat arm on the driver's side pointing down.

The MR linkage has a curved arm pointing down, and a curved arm pointing up - for the spring.

The MR linkage opens faster, so you have to be more careful with the go-pedal.

If you have the MR linkage, switch to the LR linkage.

[Luke427]

Interesting. Thanks, I'll definitely look into this.

[era556]

This thread should be removed, are you kidding me. Is this the geriatric club cobra now. Sheesh

[Antny]

Placed any kind of an obstruction anywhere near the GO pedal on any car, let alone a beast like a Cobra is a VERY BAD idea. Just my opinion.

[Luke427]

I looked into this over the week-end, and there are two factors:
1) the linkage isn't linear and let secondaries open suddenly at about 50% open throttle.
2) secondaries are vacuum actuated and don't open before somewhere between 3000 to 3700 rpm (hard to measure exactly, used a gopro and iphone to film then synchronized begin of video which might result into up to a good quarter of a second gap). They open almost instantly.

So now I have some thoughts and questions, which turns into a different topic:
- Is it normal that secondaries open only so high in RPM?
- Are they supposed to open instantly? I'd say no if both carburetors didn't act exactly the same, however they are almost perfectly synchronized.
- the recurved distributor kicks the advance around 3500 RPM, which is close to where secondaries open, and accentuates the uncontrollable aspect of the car around 4000 rpm. I have been surprised a couple times myself. Does this make sense to consider the spark advance curve? That said, I'll treat the advance separately once what I believe to be a problem with carbs has been solved.
- looks like the linkage can be modified to retain secondaries longer (until almost WOT) however I'm surprised that Holley's website doesn't offer alternative to the stock secondary linkage. Am I missing some parts?

Thanks!
Luke

[Gaz64]

Hi Luke,

If the secondarys don't start to open until 3000 rpm plus, and then open instantly, you certainly have a problem.

Vacuum secondary carbs don't open at that rate.

Starting at 3000, they should open gently and not wide open until about 7000.

Can you post some photos of your carbs and linkage please?

Fix the opening rate of the carbs and you will fix the dangerous concern you have.

Gary

[Racer_X]

Are you running a MSD or other electronic ignition ? Just put in a low RPM limited chip, like 3500RPM. Problem solved. Pull it out when you drive.

[Luke427]

Thanks Gary,
Thanks for confirming - that's what I though as well, otherwise the point of vacuum controlled secondaries doesn't make sense.

Here a zoom on the linkage. They're identical on both carbs:


Focus on a diaphragm/vacuum actuator:


I guess diaphragms need to be serviced/re-calibrated or at least spring replaced? I have never worked on Holley with vacuum secondaries so will have to start understanding them

Ignore the crushed air filters, they have been unfortunately damaged while I was working on the car last week-end.

[Texasdoc]

Put a heavier spring in the vacuum advance pod. You can get a quick change kit to make it easy. I think quick fuel makes a kit that removes that pod and replaces it with an easily accessible screw. It won't snap open and give that sudden boost.

Even with a heavier spring, you will still open the secondaries. Still doesn't fix your original problem.

[BossCER]

The most effective solution would obviously be to put a chevy in it!

[Tim7139]

We have 3 dozen posts here but the root of the problem is simply not equipment. These are all high power, lightweight cars....this we know.
You, or somebody else needs to get the Mrs. Out in a big, non scary environment, like a parking lot and spend a fair bit of time until she comes to terms wth pedal modulation. Barring that you're options are likely two.....another car, or she hurts herself or somebody else.
This is the same stuff as folks going to school to learn threshold braking, wet pavement counter steering, etc., etc.

[1985 CCX]

Only way to go!