Nice trick for a 4150 holley

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Cudafever

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You know how it is. You go searching around trying to find something out and find something else instead. found this trick, that i wish i had found before i gave up on my vacuum secondary Holley!
found it. here
Frequently Asked Questions

Question: I can rev the engine when it is in park and the secondaries will not open. Why is this?

Answer: The secondaries will not open by free revving the engine. The engine needs to be under a load before they will open. If you are still uncertain if they are opening or not you can take a normal paperclip and clip it onto the secondary diaphragm rod. You will then push it up against the bottom of the secondary diaphragm housing, now you will need to go out and drive the vehicle. When you return you will be able to look at the position of the paperclip on the rod. If it is lower on the rod then you can tell the secondaries opened and how far they opened. This is useful in determining if you need a heavier or lighter secondary spring. For additional information, you can watch our video on Holley TV that explains all about the vacuum secondary system on 4150 carbs.

I have alway wanted to know just how far the secondaries were opening, when i was running my 4150 carb.
I didn't copy the video link cause it don't work any more.

A simple paper clip, what a concept!!!
 
I've used a dab of grease too. Same concept, put the grease up top and see how far it is smeared down the shaft for the same results
 
Oh that's a cool trick! When I was a teen I was running a vacuum secondary Holley, I was always concerned the secondaries weren't opening! Pretty much why I always run mechanical secondaries now! Good to remember though, thanks for sharing!
 
Your welcome guys, glad it can help someone. Wish i had found it years ago and some 10 spring kits and diaphragms before.
I even when as far as to build/make it machanic and remove the spring.........would make this cool little whistle noise when i would release the long skinny peddle.
In the end learned that it was the fastest with the short yellow spring, but more consistent with the purple.Couldn't fill it come on, so back to the short yellow,which was behind my back seat with all the other spring. Paint fell off, can't tell which one it is.....Back to the parts store to buy another spring kit. always wished that i could mount a camera under the hood to watch it. My thoughts never got past that point.......don't have a camera but it would be nice to know............Duhh, a simple paper clip!:poke::D
 
hmmmmm... both mydemon and duster make that cool little whistle noise, havent figured it out yet,but it sounds neat
 
After getting a double pumper, I decided I no longer had any use for a vacuum secondary
 
forphorty said:
After getting a double pumper, I decided I no longer had any use for a vacuum secondary
Click to expand...

Yup me too! past on a couple of them, now i own a couple of them. The vac sec 600 is wrapped in plastic with cardboard inside to trap any moisture........for some project down the road.(to good of a carb to let go of. )
 
with a vacuum secondary carb if you can feel the secondaries open you have messed up. what is happening is they are opening too fast as compared to the flowing over the tube in the venturies. what happens is there isn't enough vacuum over it to pull fuel up and out of the boosters yet and you feel the motor studder until there is enough air speed to start the fuel up an out. to tune them use the lightest spring and keep going to heavier ones until the studder stops.
 
bOb shingler said:
with a vacuum secondary carb if you can feel the secondaries open you have messed up. what is happening is they are opening too fast as compared to the flowing over the tube in the venturies. what happens is there isn't enough vacuum over it to pull fuel up and out of the boosters yet and you feel the motor studder until there is enough air speed to start the fuel up an out. to tune them use the lightest spring and keep going to heavier ones until the studder stops.
Click to expand...

Yeah i understand all of that now and read it when i was younger, would follow directions, but my butt odometer keep telling me YOU were wrong.
The problem is that you don't fill the studder or pay attention, that it is happening. but the kick in the pants when it come back alive, you can.........now that was much faster.:BangHead:
Sometime we run around in circles because we can't accept the truth! :thankyou:
 
With a DP my right foot controls the secondaries. Me Likey. I can whaaaack them open from idle if I so choose. And I so choose, a lot! Sometimes I do it just because I can....Almost nothing amazes me more than idle to 7000 with tires ascreaming, and smoke apouring.Yeah, dump the clutch and nail it,YEEHAW!
My 750 Vacuum secondary is also mothballed, as are all the other stuff I ever tried.
 
I am changing now to DP. But I was very happy so far with the vacuum. Do you Performance guys run the 50cc pumps? Or just the 50cc pump in the secondaries and 30cc in the front? does that make sense?
 
Run it the way it came, then decide. Most don't need a 50 cc squirter. You can change the plastic cams that move your squirter to get more if you need more volume, without starting all over with a 50 cc
 
well, it came with the 50cc pumps. Did run that way on a well made high compression low vacuum Signal 302 Mustang Motor. Mine is a new 6.1 HEMI with lower vacuum due to the new cam. So I will try it with the biggies and see if it is too much. Stepping down in the Primary side to 30cc. will use it this season for a bit drag racing. So ist Strip / street...
Do you think I can take over the Jet sizes from the vacuum carb for Initial start? carb size are both 750. But the DP is more a Performance carb 1000 years ago made by Blake carburation... i bet the carb went through 20 engine bays in his life... :)
 
Buschi340 said:
well, it came with the 50cc pumps. Did run that way on a well made high compression low vacuum Signal 302 Mustang Motor. Mine is a new 6.1 HEMI with lower vacuum due to the new cam. So I will try it with the biggies and see if it is too much. Stepping down in the Primary side to 30cc. will use it this season for a bit drag racing. So ist Strip / street...
Do you think I can take over the Jet sizes from the vacuum carb for Initial start? carb size are both 750. But the DP is more a Performance carb 1000 years ago made by Blake carburation... i bet the carb went through 20 engine bays in his life... :)
Click to expand...

Check the throttle shafts, they could be worn out and leaking.
I'm no carb gu ru but i think you should start out with the jet side that the carb came with. It is usually a touch on the rich side(safe place to start)
somewheres on the holley site, there is a chart that shows all the carb list ## and what jets they came with.
 
unfortunately it has no carb number anymore. The Company made their own number. Oh, forgot to mention the carb is apart. No jets, nothing. Just the main parts. Well, I put the jets sizes in I have on my current one plus 2 sizes and will start from there and will see what i have to change. Same for squirtes and cams. I have a A/F meter so it will be safe i hope. requires a bunch of test driving i'm afraid. :)
 
yep, but ist a Long way. first the Primary jets. no Connection to secondaries, no pump. then adding the prim. pump. than adding secondaries than sec. pump... something like that... :)
 
Anyone know how to change the title of a thread? Just realised that i put 4150 and the trick is for a 4160 aka vacuum secondary carb.
Mod's can you help me with is. I know this thread has run its course, but it would be nice when someone is doing a search that it be right.

If it is something that i can do my self, please pm me how and i will take care of it.
Thanks
 
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