FE428, cable throttle linkage, brackets springs etc

[KevinW]

Engine: FE428 running Holley Street Avenger on an Edelbrock manifold.

Getting frustrated trying to work out whats needed here, need some help here please.
Seems some forums are saying i need dual throttle return springs? Diversity of views on how to mount these (need to buy some first).

I see some brackets are commercially available, but which ones? they all seem designed for autoboxes. Also been told I could just make one up from a piece of angle.

I'd like to install an assembly that wont need re-jigging once I get the turkey pan fitted - its off atm so I can fiddle with carb setting at a later date if needed.

Any knowledge and pics requested, please - have never owned a Holley carb before, so I'm on a learning curve!!

[DanEC]

Can you post a picture of what you have so far? Dual return springs are primarily a safety issue to avoid a stuck wide open throttle in the unlikely event that a spring breaks or comes loose. Good idea for a light car with a big engine. I would suspect that the bulk of replicas with FE motors have mechanical linkage rather than a cable so you will probably have to do some fabrication work.

[patrickt]

The Turkey Pan makes it easier to fashion your dual springs, whether your TP is removable or not, because you can drill a notch or hole in the pan, or its base, to suit your setup. My TP is removable, and here is a pic of my spring setup. You definitely want two springs. An unexpectedly broken spring during WOT, when you've only got one, makes for a very bad day.

[KevinW]

Patrick - thanks for the pic. It looks like you have a removable turkey pan with some sort of 3mm-thick base? Maybe I should just cut my base out and make it removable? What are the 2 horizontal rod-like structures underneath the base?

[patrickt]

Originally Posted by KevinW

Patrick - thanks for the pic. It looks like you have a removable turkey pan with some sort of 3mm-thick base? Maybe I should just cut my base out and make it removable? What are the 2 horizontal rod-like structures underneath the base?

They're for the Terry Body Springs that hold the outer shell down to the base. Like this:

[KevinW]

OK thanks....starting to understand what those cut outs on the base of the T/Pan are for.

[KevinW]

Dan, I'll post a pic, there isn't much to show. The Crendon is designed to have a cable linkage rather than mechanical, and being UK, my car is RHD. It is possible to have a mechanical linkage on a RHD car, but its more complicated. Biggest problem for me is the top of the footbox being higher than an original car and the throttle (gas) pedal, being RHD, therefore being on the far opposite side rather than inside top corner of the footbox. So its cable linkage for me as the easiest way forward. I can make a bracket if i have to....just want to make sure I understand whats needed before i start my usual process of making at least 1 or 2 prototypes that end up in the scrap bin

[Luke427]

Hi Kevin,
I have installed weber carbs on old Italian and English cars (and some of them where RHD, by the way). Cables were always a pain in the butt. We would systematically install a rod across the firewall when carburetor linkage was on the wrong side - you could consider this.

Now just asking: why do you keep the turkey pan? Patrick - I would keep the lower plate, which seems convenient, but I don't believe the pan itself does anything but restrict airflow to the intake. Unless you have a gigantic hood scoop?
On my Cobra, before it received the 8 barrel intake a few weeks back, I had gotten rid of the turkey pan and put a 3" tall, 45 deg aluminum plate in front of the crossmember to push fresh air inside the engine compartment as suggested by a guy on cobra talk. Outcome was obviously positive, especially above 4000 rpm in 3rd and 4th gears.

[KevinW]

Thanks Luke.
Valid pints on the intake. I may well fit a rubber trim round the turkey pan perimeter so that it seals on the hood - I have seen a few cars do this to maintain the cold air feed.

Actually I wanted the turkey pan for looks as much as anything - they are a rarity item in the UK. My engine builder was pretty unhappy with the S&H filter i added, telling me i'd loose horsepower. But for me, anything above 400hp and similar torque is way more than anything i ever drove in my life, so it'll keep me happy for a good few years. And I wanted the engine bay to look like an original as much as possible.

Biggest problems for the linkage are the height of the footboxes (several inches higher than an original, and interfacing to the gas pedal. Original cars had a nice pendulum fixing on top of the footbox. Thats not possible for me without a lot of retrofitting and fettling. So, in the interests of actually getting the car on the road sometime soon, its a compromise I'll have to make.

[patrickt]

Last year I replaced the restrictive, but attractive, air cleaner with the K&H X-Treme filter that significantly enhanced airflow. That thread is deep in here: OK Chas, See If You Can Tell What's New... The increase in airflow was so dramatic that I had to modify the spring for my vacuum secondaries to open properly. That was done on a subsequent thread.

[DanEC]

Originally Posted by KevinW

Biggest problems for the linkage are the height of the footboxes (several inches higher than an original, and interfacing to the gas pedal. Original cars had a nice pendulum fixing on top of the footbox. Thats not possible for me without a lot of retrofitting and fettling. So, in the interests of actually getting the car on the road sometime soon, its a compromise I'll have to make.

I think you are describing the 289 cars throttle linkage. The 427 cars have a little different system that comes off of the side of the foot box, up front. Our ERAs are a little different than original cars I'm sure, but similar.

I don't have the best picture of it but if you look at the side of the black metal bent plate on the side of the left foot box, you can see the shaft and bellcrank that comes out there.

[cycleguy55]

Originally Posted by KevinW

Engine: FE428 running Holley Street Avenger on an Edelbrock manifold.

Getting frustrated trying to work out whats needed here, need some help here please.
Seems some forums are saying i need dual throttle return springs? Diversity of views on how to mount these (need to buy some first).

I see some brackets are commercially available, but which ones? they all seem designed for autoboxes. Also been told I could just make one up from a piece of angle.

I'd like to install an assembly that wont need re-jigging once I get the turkey pan fitted - its off atm so I can fiddle with carb setting at a later date if needed.

Any knowledge and pics requested, please - have never owned a Holley carb before, so I'm on a learning curve!!

Same carb and similar manifold setup on mine, albeit no turkey pan. I used a bracket and dual spring combo, basically the same as the Lokar SRK-4000 ( https://www.summitracing.com/int/parts/lok-srk-4000 ).

The slotted hole fits over the rear left carb stud, on top of the carb base, and is secured by the nut. The tiny little set screw is to adjust the angle of the bracket to get it square (and hopefully keep it there). The top hole is for the throttle cable. You can see how the dual springs mount, just outside the throttle cable with the springs connecting to the throttle arm assembly on the carb. This s/b narrow enough to fit inside your turkey pan.

[Luke427]

Patrick, nice! I had a similar air filter on the 750 cfm and I plan to use a pair of smaller ones on the 8 barrel. Mine didn't have the thick aluminum pan though and maximized surface of filtration. It was the cheapest K&N

These don't look original though, and I completely understand Kevin's perspective. As a matter of fact, I have almost always put the original filter back in place to show the car...

[patrickt]

Originally Posted by Luke427

Patrick, nice! I had a similar air filter on the 750 cfm and I plan to use a pair of smaller ones on the 8 barrel....

You know, since installing that X-Treme filter, and then having to recalibrate my vacuum secondaries opening, I've run across several threads, elsewhere, where the poster writes "I installed the X-Treme filter and my engine runs slower than it did before -- this thing is crap." Just remember, if you increase the volume of the air coming down through the filter, the velocity will be reduced and you'll have to change the spring in your vacuum secondary canister (or they won't open right). Once you do that, the easier breathing that the X-Treme filter (or something similar) affords really makes a difference (both at slow speeds and high).

[Detroit Bill]

It is aluminum. It mounts on two studs.



Good luck!

[davids2toys]

Mine is similar but my springs go to different locations. I was told somewhere a lighter spring should go to the carb linkage to avoid damage, and a heavier one to another linkage location other than the carb.
No issues

[undy]

Originally Posted by patrickt

You know, since installing that X-Treme filter, and then having to recalibrate my vacuum secondaries opening, I've run across several threads, elsewhere, where the poster writes "I installed the X-Treme filter and my engine runs slower than it did before -- this thing is crap." Just remember, if you increase the volume of the air coming down through the filter, the velocity will be reduced and you'll have to change the spring in your vacuum secondary canister (or they won't open right). Once you do that, the easier breathing that the X-Treme filter (or something similar) affords really makes a difference (both at slow speeds and high).

Also, the air coming in from the top and the air coming in from the sides collides and creates turbulence, impeding flow. I've heard the reports of HP loss many times before.

[patrickt]

Originally Posted by undy

Also, the air coming in from the top and the air coming in from the sides collides and creates turbulence, impeding flow. I've heard the reports of HP loss many times before.

The real problem with the "internet reports" is that they are coming from guys, the majority of whom, really have no idea how to do anything other than just change the air cleaner. Without changing the vac spring, my switch to the X-treme filter had the effect of pulling my four barrel carb off and replacing it with a two barrel. My secondaries would not open with the same spring that had opened them (a little bit) just going to the grocery store. (That's really no exaggeration.) Of course, replacing the vac spring, with a correct one, made all the difference and the overall improvement, at both low speeds and high speeds, was significant. The increase in air flow from my original S&H air cleaner was really quite noticeable.

[davids2toys]

Originally Posted by undy

Also, the air coming in from the top and the air coming in from the sides collides and creates turbulence, impeding flow. I've heard the reports of HP loss many times before.

Along with my air breathing top, I am running the K&N stubstack and have a Holley 750 with mechanical secondary's. Can't say that I notice any difference with our without the stubstack.
Patrick, what are your thoughts for mechanicals vs. your vacuum in this situation?

[patrickt]

Originally Posted by davids2toys

Patrick, what are your thoughts for mechanicals vs. your vacuum in this situation?

The goal of secondaries, be they mechanically operated or vacuum operated, is to provide just the right amount of increased air/fuel at just the right time when the engine is calling for that increase. If you have your mechanicals, or your vacuum, adjusted perfectly, then it doesn't really matter which one you have. Your car will run as perfectly as possible for the condition that you adjusted them for. It's very easy to mis-adjust mechanicals and very easy to mis-adjust vacuum secondaries. If your secondaries don't open when they're needed, you're robbing your engine of performance. If they open too soon, then you get a bog. If they open "unsmoothly," then you get unsmooth performance. In a light weight, powerful car, like a Cobra, the last thing you want is an unexpected blast of power, maybe after a subtle bog. It makes the car more dangerous to drive.

The physical act of adjusting mechanical secondaries is easier than adjusting vacuum secondaries, because you don't have to take the canister apart and pull the spring out. With mechanicals, you can do your adjusting by the side of the road, as you're testing your acceleration and, most importantly, testing the smoothness. I know Holley has a "quick change" kit for their vacuum secondary spring, but I've never used it, and I have my doubts that it's that "quick." Personally, I always drop little springs, and I always rip holes in diaphragms. That's why I bought the Quick Fuel adjustable vacuum canister for my Holley:



It makes adjusting the opening of the vacuum secondaries as simple as turning a screw. If you can just avoid dropping the screwdriver, you'll be fine.

My personal opinion is that a "perfectly adjusted" vacuum secondary will be preferable to a mechanical secondary, especially in a light car like the Cobra. It will give the engine all the fuel/air it can handle, and it will do it nice and smoothly, so you don't get any unexpected surprises. Here, all I do is turn the screw, circled in yellow, and I can control how quickly (too much creates a bog) the secondaries open, or how slowly (too little and I'm leaving power on the table) they open. It does not take long to find the spot that is "just right." Anyone can do it, even RodKnock.