• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Secondary springs??

440beep

FBBO Gold Member
FBBO Gold Member
Local time
9:24 PM
Joined
Aug 6, 2012
Messages
1,355
Reaction score
700
Location
NW Indiana
On my Six Pack I'm currently running the purple springs in the secondary diaphragms, was running the light yellow springs before. Since switching to the purples at times while accelerating I can feel a sudden kick in my pants as the car surges forward. Could this be the secondaries suddenly opening up more, or could it be from the clutch fan shutting down?

What springs is everyone else running in the secondaries? And would a stiffer spring make the sudden acceleration surge even more noticeable? I know I know, try other springs myself and see what happens, just curious what others are running. i read an article where someone states to use the black springs (the stiffest) as the surge is most impressive with the black springs. The only thing with the black springs is the instructions state that the secondaries won't open fully, whereas with the purples they open fully at a certain RPM.
 
I don't have much experience with six packs, however, I have a LOT of carburetor experience. With a vacuum secondary, usually what you want is the smoothest possible transaction when the secondaries open. The best possible scenario is not being able to feel them at all. If you can actually feel the secondaries open, then the car is actually slower than it would be otherwise. That is the general rule of thumb with vacuum secondaries, whether it holds true for the six pack, I do not know, but I suspect it does. If they are slamming open, I imagine some carbuertor "genius" has left the diaphragm check balls out. People do this all the time thinking it is an improvement when all it does is slow the car down.
 
Your spring combo depends on a # of factors. Is the motor stock? What jets are you running? How is the car being used? Cruising/racing? It is usually trial and error to find the combo that is right for your car. Different combos yield different results. Because of all the variables there really isn't any single clear cut answer. If you post your engine combo someone may be able to get you an idea of which spring will work most effectively?
KID
 
On my Six Pack I'm currently running the purple springs in the secondary diaphragms, was running the light yellow springs before. Since switching to the purples at times while accelerating I can feel a sudden kick in my pants as the car surges forward. Could this be the secondaries suddenly opening up more, or could it be from the clutch fan shutting down?

What springs is everyone else running in the secondaries? And would a stiffer spring make the sudden acceleration surge even more noticeable? I know I know, try other springs myself and see what happens, just curious what others are running. i read an article where someone states to use the black springs (the stiffest) as the surge is most impressive with the black springs. The only thing with the black springs is the instructions state that the secondaries won't open fully, whereas with the purples they open fully at a certain RPM.
purples are a nice street spring and were stock on 69 cars. 70 cars got yellow springs and can make a little difference in 1/4 mile times. some years back i did a track test with plain, purple and yellow springs on a stock engine. every step i went lighter from the plain springs the car went about a tenth quicker in the 1/4. blacks are ridiculous and probably will never open. the browns won't start working until 3500-4000rpm. the plains start opening around 3000rpm, purple around 2600rpm and yellows around 2200rpm.
 
To my knowledge, the motor's just a plain jane 440. Will stick with the purple's for now but may also experiment with others.

Thanks guys.
 
If the engine is close to stock, you don't want light springs in it. The engine aint gonna move 1200 CFM at 2500 RPM. MOst people think secondaries don't open with the brown or black spring. They are wrong.
 
I have some very recent data with a 6 BBL and slicks in a 3900 lb as raced car. In short the results were disappointing to say the least. You can read about my engine combo and experience here http://www.forbbodiesonly.com/moparforum/showthread.php?t=40984

I made a few observations and here they are: The Holley spring opening rates are most likely rated for standard vac secondary carbs, i.e. smaller diaphragms. I think the larger outboard carb diaphragm applies more force so it's possible the ratings are out the window.

All vac secondary Holley's have a bleed hole to soften the secondary opening rate. The smaller the hole the stronger the vac signal to the diaphragm. Plug this hole and you will have secondary action like a double pumper, even on a regular Holley 4 BBL. This can be another factor contributing to different opening rates regardless of springs used.

Bottom line: My car seemed to make good power on the street but as soon as I glued it down with slicks it fell flat on it's face shortly after take off. I believe this was due to the outboard carbs opening too quickly. I don't have a camera under the hood but I'm pretty darn sure all 6 BBL's are fully open. One run I even added a light spring to the outboard carb linkage and it still didn't help the bog. My next move is a chassis dyno and to watch what happens when I mash the go pedal. The mixture readout will be helpful as well.
 
I'm running MT ET street radials, so the car sticks and launches very well from a dead stop, no bogging whatsoever. I will keep messing with the springs and see what happens. Thanks for the input on the springs.
 
I have some very recent data with a 6 BBL and slicks in a 3900 lb as raced car. In short the results were disappointing to say the least. You can read about my engine combo and experience here http://www.forbbodiesonly.com/moparforum/showthread.php?t=40984

I made a few observations and here they are: The Holley spring opening rates are most likely rated for standard vac secondary carbs, i.e. smaller diaphragms. I think the larger outboard carb diaphragm applies more force so it's possible the ratings are out the window.

That makes sense. I am SURE at one time there was some form of spring chart either from Holley, Mopar Performance, or both. Although I've never seen one.


All vac secondary Holley's have a bleed hole to soften the secondary opening rate. The smaller the hole the stronger the vac signal to the diaphragm. Plug this hole and you will have secondary action like a double pumper, even on a regular Holley 4 BBL. This can be another factor contributing to different opening rates regardless of springs used.

Yup, which is why I always tell people, START with the brown or black sprAng first. The lighter the sprAng, the earlier (lower RPM) the secondaries open. I've never been able to figure why people want their vacuum carbs to open up at 2500 RPM.

Bottom line: My car seemed to make good power on the street but as soon as I glued it down with slicks it fell flat on it's face shortly after take off. I believe this was due to the outboard carbs opening too quickly. I don't have a camera under the hood but I'm pretty darn sure all 6 BBL's are fully open. One run I even added a light spring to the outboard carb linkage and it still didn't help the bog. My next move is a chassis dyno and to watch what happens when I mash the go pedal. The mixture readout will be helpful as well.

Puzackly. Because in order to RUN in race trim, you need to TUNE in race trim. Contrary to popular belief, Holley knew what was up. Most cars in general respond best in the black, brown, purple range. I mean honestly, why would you want secondaries opening when it's least effective? But still, people put them white sprAngs in and SWEAR their car hauls ***. 99 out of 100 of them have never used a time slip to verify their "findings".
 
That chart is right on the money. BUT, it can be misleading to some folks because they think they need the secondaries open all they way. In most cases, that ain't true.

You want to choose a spring that allows the latest opening possible. In other words, right before the primaries run outta steam. Any sooner and the carburetor will bog, even though you may not think it is.

This is why you need to use a spring that allows the smoothest transition possible going into the secondaries. If you can really feel them open, they are opening too soon.
 
Last edited:
And I will say again, that chart assumes a typical Holley 4 BBL and not the larger 6 BBL diaphragms. My thought is the larger diaphragm applies more force, which may make that spring chart useless. I believe the best solution is what Rusty said above, and the only way to get it right is tune it under load, either at the track or on a dyno.
 
Yup cause I diddlydanggarrantee you them big *** diaphragms have a completely different rate, just like Meepomous says. More diaphragm surface area. Only stands to reason. What "I" always do is tune from the heaviest spring DOWN. Because nine times outta ten, you're gonna end up on the heavy side of the spectrum. I believe that would also hold true for the six pack....but you never know till you do it. Just so many variables.
 
"That chart is right on the money. "

No, Rusty, I mean't you were right about the transition into the secondary carburetors should be so smooth that you don't know it's happening. Seamless, if you will.
 
"That chart is right on the money. "

No, Rusty, I mean't you were right about the transition into the secondary carburetors should be so smooth that you don't know it's happening. Seamless, if you will.

I THINK that holds true for the six pack stuff, too. It certainly would make sense. I meant as a guide for four barrel vacuum secondary carbs that the chart was right.....I guess I should convey a little more of what's rattlin around upstairs. lol I think the chart can be loosely applied to six pack stuff, but pay attention to the all knowin Meepomous, cause he's dead right. You know......I wonder if somebody with a six pack and good tuning skills would put it to the test somehow.....if we only KNEW somebody like that. Six pack.....good tuning skills........has a green B body.......oh I'm sorry. LOL
 
Auto Transport Service
Back
Top