1:1 holley throttle linkage set up

[steve cowan]

@steve cowan
I know this is an older thread… but how’d this work out?

Up until this year I used the 1:1 with good results,square jetting and powervalves front and rear.
I have been as fast as 11.10 @ 118 mph @ 3650 pounds with this set up with zero issues.
I have gone back to a progressive secondary as the car runs a bit faster now and I don't want to have a potential issue of uncovering secondary powervalve on hard acceleration.

20221002_054736.jpg

No issues with transfer circuit/ slots that I have seen but I always have a adjustable transfer circuit jet fitted in main body of carb.

20201003_171930.jpg

[Robban 54]

Even with the adjustable linkage if you look carefully it is not possible to get absolutely 100% 1 to 1 function.
With the roller linkage and a homemade curve at the beginning, you get absolutely 100% 1 to 1 function.
It made a big difference for me, I wouldn't have believed it if I hadn't tried it.
Robban

[Robban 54]

I drive without power valves and larger main jets,

[steve cowan]

I drive without power valves and larger main jets,

I dynoed my 383 with a 850hp carb no PV but on the street it was a dog so I went back to front PV.
I am glad you are having good results with your set up.

[In-Tech]

Robban is correct, that holley adjustable "tie bar" cannot achieve absolute 1:1 activity without a ton of work. Most times it is close enough but not the same as his pictures he posted of what needs to really happen. I bet that took some time for him to get perfect, cheers
As Steve noted, in drag racing with a rear power valve, it it hard for that circuit to not get "uncovered".
I do 1:1 on all my circle track carb's and front/rear power valves mainly because progressive linkage is a bitch to get the transitions sorted. Imagine the primary on a roll in of the throttle and all that signal on the primary, then introduce the secondary...the primary looses signal and a whole other secondary circuit comes into play with almost no signal. Most people cover this with huge AE. Tuning that is highly dependent on the driver, whereas, you can get rid of most of the AE problems with 1:1 linkage regardless of driver differences. Custom AE cams sometimes, depends on CU IN and manifold. Most of my 1000+ cfm 4150's only have 25cc pumps

[1980RS]

@steve cowan
I know this is an older thread… but how’d this work out?

Up until this year I used the 1:1 with good results,square jetting and powervalves front and rear.
I have been as fast as 11.10 @ 118 mph @ 3650 pounds with this set up with zero issues.
I have gone back to a progressive secondary as the car runs a bit faster now and I don't want to have a potential issue of uncovering secondary powervalve on hard acceleration. 20221002_054736.jpg
No issues with transfer circuit/ slots that I have seen but I always have a adjustable transfer circuit jet fitted in main body of carb.20201003_171930.jpg

That's a good time Steve.

[Walter R. Malik]

Robban is correct, that holley adjustable "tie bar" cannot achieve absolute 1:1 activity without a ton of work. Most times it is close enough but not the same as his pictures he posted of what needs to really happen. I bet that took some time for him to get perfect, cheers
As Steve noted, in drag racing with a rear power valve, it it hard for that circuit to not get "uncovered".
I do 1:1 on all my circle track carb's and front/rear power valves mainly because progressive linkage is a bitch to get the transitions sorted. Imagine the primary on a roll in of the throttle and all that signal on the primary, then introduce the secondary...the primary looses signal and a whole other secondary circuit comes into play with almost no signal. Most people cover this with huge AE. Tuning that is highly dependent on the driver, whereas, you can get rid of most of the AE problems with 1:1 linkage regardless of driver differences. Custom AE cams sometimes, depends on CU IN and manifold. Most of my 1000+ cfm 4150's only have 25cc pumps

Signal strength and modulation ability is the main reason Holley came-up with the NASCAR linkage. A roller type linkage where the secondary opens at half the rate of the primary until half throttle then twice the rate of the primary the rest of the way.

[ArizonaGuy]

I’ve been screwing around with this a little. I have a 650 that runs like a raped ape at 1:1, but a bigger bore 4150 that isn’t as cooperative. As good as the little carburetor runs, the big one might be just a bit much for only 331 cubic inches. It is interesting how different the calibrations are, 1:1 vs progressive. Obviously the boosters see a different pull when the throttles all open at once. For my deal, both these carburetors needed more fuel across the board (jets, PVCRs, IFRs, cams, shooters). Fun experiment so far, but I’m not done yet as always, thanks all for your help

[steve cowan]

I’ve been screwing around with this a little. I have a 650 that runs like a raped ape at 1:1, but a bigger bore 4150 that isn’t as cooperative. As good as the little carburetor runs, the big one might be just a bit much for only 331 cubic inches. It is interesting how different the calibrations are, 1:1 vs progressive. Obviously the boosters see a different pull when the throttles all open at once. For my deal, both these carburetors needed more fuel across the board (jets, PVCRs, IFRs, cams, shooters). Fun experiment so far, but I’m not done yet as always, thanks all for your help

Sounds like you have made good progress so well done.
I agree some carbs and combinations don't like a 1:1 set up but don't know till you try.

[rgalajda]

1:1 holley throttle linkage setup

Factors to consider
The carb is way too small for the application
Stall speed of the converter is above or near the rpm of peak torque.
The vehicle gearing and weight are contributing factors.
The car transitions through first gear to rpm somewhere at or above peak torque rpm very quickly.
If torque output of the engine , ( approx ) below 4,000 rpm for small engines and 3,000 rpm for larger engines is part of the engines operating range you should be looking at progressive linkage or better yet a vacuum secondary carb.

For a true street car the progressive linkage will produce more torque and drivability below 3,500 rpm (all things considered above )
Opening the secondaries too late reduces power and operating it too soon effects best torque.
Fuel atomization can be effected by the secondaries opening too soon because it effects booster signal.

These effects may not be felt “ by seat of the pants”

The example “ArizonaGuy “ gave of his 650 holley may fall into “carb too small for application”
Also as stated these linkage setups are not truly 1:1 but probably just more progressive.

[sam385s4.14]

so could someone explain why some standard 4150 base plates have only 2 holes in the primary throttle shaft linkage as opposed to some aftermarket shafts that come with 3 and what is the mystery behind the hole that is not drilled the same size as the others. if the second hole is not offered and someone like myself was to drill it out and add the adjustable link and find out my throttle response just kicks ass why is the second hole option not even offered on some high end base plates such as BLP. The hole i drilled was half way in between the 2 existing holes, In the 3 hole positions offered in the aftermarket shaft like quick fuel it is just above the bottom hole and i plan to try this next. also using the adjustable link that is listed in this post is what i used for the hole i drilled and could then adjust throttle plates vertical to each other. https://www.ebay.com/itm/324850627209?_ ... 101224.m-1

[1980RS]

I have run the 1:1 linkage and the others and never noticed much difference on the track with my car, but then again I don't make a lot of power.

[63qcar]

FWIW , I have a Cobra replica with a 482 FE , 680 hp ,5 speed and it weighs under 2700 lbs with me in it . It`s a street car that sees occasional road course use , but mostly just street .
Just finished playing with the 1:1 linkage on one of Mark W`s 4150`s and finally set it back to the progressive linkage . I loved the response and the way the WOT came on , and I could modulate it fairly well and had no problems coming out of a corner as long as I rolled into the throttle . Sudden openings only produced lots of wheel spin . The two problems I wasn`t able to work out to my satisfaction where low speed operation and the huge drop in mileage ( probably because I couldn`t keep my foot out of it ) .
So , in my opinion , for my specific application , the stock linkage worked out better , however , on a road course , I`ll be using the 1:1 since low speed and mileage don`t matter .

[ArizonaGuy]

“Uncovering secondary power valve”
I’ve seen that^ posted a time or two… what does it mean?

[greenhj]

The fuel wants to move away from the power valve under heavy acceleration when fitted to the secondary metering block.

If you are relying on it for enrichment under power and no fuel is there, it will go lean.

Think about why people fit main jet extensions on the secondaries, same principle.