Holley Vacuum Secondaries - Help
#1
Holley Vacuum Secondaries - Help
Ok, so Im a complete newbie with Holley carbs, but Im far from incompetent I would hope, haha.
I have what was sold to me as a Racing Beat Holley street port kit which has a vacuum secondary system that isnt working. I verified this twice by using both the bread tie and the paperclip tests (putting each on the vacuum pot shaft and driving full throttle through 3 gears), there was no movement at all.
I pulled the secondary vacuum pot and discovered the diaphragm was leaking (compressed shaft, held port covered), so I took it to a local muscle car shop and they got me a new one. They also got me new metering block and bowl gaskets about a week earlier as the carb had the wrong ones on it when I bought it. I also picked up a yellow secondary spring (very light) while I was there. I blew some light compressed air into the vacuum port, and air comes out the hole under the butterfly in the primary venturi, so its not clogged. I read about a hole possibly in the secondary venturi also, but I didnt see/hear one?
I got home, installed it all, and repeated the test. No movement still. I pulled the whole thing back off, put a new o-ring between the carb body and the secondary vacuum pot, reinstalled it all, still no movement. With the engine off and the throttle held wide open, the secondary linkage and butterflies move freely and easily, no binding at all.
Here is a link to the carb kit (which was bought used):
http://www.racingbeat.com/Mazda-Perf...rtNumber=18034
It also has these float bowls:
http://www.racingbeat.com/Mazda-Perf...rtNumber=16641
It does appear as if it has aftermarket metering blocks also since I can change the jets on both the primary and secondary sides, and Ive been reading the RB metering blocks have the jets built in. Also, it has the quick change secondary spring kit, and no check ball in the housing, but I read thats normal for RB carbs?
Vacuum advance is hooked up and running off the ported vacuum port on the metering block, manifold vacuum was running to a PCV valve, however I tried blocking off both the PCV valve as well as advance and trying to repeat the test hoping that maybe a leak in one of those two setups that was preventing something from happening, still no dice.
Im running a Holley blue pump and regulator, fuel is set to 6 PSI, float levels are correct. As I said, the carb was bought used, so its possible someone mucked with something, but it seems like a fairly simple system, and I dont get why it wont open the secondaries...
Thanks in advance!
~T.J.
I have what was sold to me as a Racing Beat Holley street port kit which has a vacuum secondary system that isnt working. I verified this twice by using both the bread tie and the paperclip tests (putting each on the vacuum pot shaft and driving full throttle through 3 gears), there was no movement at all.
I pulled the secondary vacuum pot and discovered the diaphragm was leaking (compressed shaft, held port covered), so I took it to a local muscle car shop and they got me a new one. They also got me new metering block and bowl gaskets about a week earlier as the carb had the wrong ones on it when I bought it. I also picked up a yellow secondary spring (very light) while I was there. I blew some light compressed air into the vacuum port, and air comes out the hole under the butterfly in the primary venturi, so its not clogged. I read about a hole possibly in the secondary venturi also, but I didnt see/hear one?
I got home, installed it all, and repeated the test. No movement still. I pulled the whole thing back off, put a new o-ring between the carb body and the secondary vacuum pot, reinstalled it all, still no movement. With the engine off and the throttle held wide open, the secondary linkage and butterflies move freely and easily, no binding at all.
Here is a link to the carb kit (which was bought used):
http://www.racingbeat.com/Mazda-Perf...rtNumber=18034
It also has these float bowls:
http://www.racingbeat.com/Mazda-Perf...rtNumber=16641
It does appear as if it has aftermarket metering blocks also since I can change the jets on both the primary and secondary sides, and Ive been reading the RB metering blocks have the jets built in. Also, it has the quick change secondary spring kit, and no check ball in the housing, but I read thats normal for RB carbs?
Vacuum advance is hooked up and running off the ported vacuum port on the metering block, manifold vacuum was running to a PCV valve, however I tried blocking off both the PCV valve as well as advance and trying to repeat the test hoping that maybe a leak in one of those two setups that was preventing something from happening, still no dice.
Im running a Holley blue pump and regulator, fuel is set to 6 PSI, float levels are correct. As I said, the carb was bought used, so its possible someone mucked with something, but it seems like a fairly simple system, and I dont get why it wont open the secondaries...
Thanks in advance!
~T.J.
#2
OK I am a Holley noob as well. But I know my Nikkis. One thing you could test is to see if there is vacuum in the line leading to the diaphragm, or the diaphragm box itself. Is there any way you could tap into it with a vacuum gauge to test it? The amount will only be small ~1PSI but its still noticable.
P.S. what is this "paper clip and bread tie" test. It sounds useful for testing the operation of secondaries...
P.S. what is this "paper clip and bread tie" test. It sounds useful for testing the operation of secondaries...
#4
There is no line leading to the diaphragm, its an internal passage.
As for the paperclip test, below is a Googled image. I dont bend the clip to fit the rod like the picture, I just clip it on the same way you would clip it on papers.
Basically, clip it on, slide it up to the top of the shaft so its touching the vacuum pot and take it for a drive. If the shaft pulls up to open the secondaries, the clip will be pushed down the shaft (as shown in the picture) and show you how far they opened.
This is also useful for seeing if the spring in your vacuum pot is too hard (not opening all the way). The bread twist tie works the same way, or a small zip tie snug but not tight. I prefer the bread tie/zip tie because theyre smaller and seem like they wouldnt get in the way as much towards the end of the stroke if the secondaries are in fact working.
~T.J.
As for the paperclip test, below is a Googled image. I dont bend the clip to fit the rod like the picture, I just clip it on the same way you would clip it on papers.
Basically, clip it on, slide it up to the top of the shaft so its touching the vacuum pot and take it for a drive. If the shaft pulls up to open the secondaries, the clip will be pushed down the shaft (as shown in the picture) and show you how far they opened.
This is also useful for seeing if the spring in your vacuum pot is too hard (not opening all the way). The bread twist tie works the same way, or a small zip tie snug but not tight. I prefer the bread tie/zip tie because theyre smaller and seem like they wouldnt get in the way as much towards the end of the stroke if the secondaries are in fact working.
~T.J.
#5
Anything specific you would like to see? These arent great, just what I had on hand already uploaded. Theyre also not current as I have since hooked up the throttle cable with the linkage pieces, replaced the return spring, took out a plug on the primary metering block and added a 1/8" NPT to 1/8" barb for the vacuum advance. I also finished the fuel lines with clamps and things. These are just pictures of the mock up/install process from my build thread. I was told the OMP linkage was removed in favor of premix (which Im also running). It came off a car with full RB street port exhaust which I also bought and am running. Oh, and the choke has been removed also.
~T.J.
~T.J.
#6
use the lightest secondary spring. The ones on the carbs I used to race and tune with were white or no color. Hardly any resistance at all.
The vaccum secondaries just seemed inconsistent so I always made my setups to the double pumper ones......
try changing the spring.......they make a big difference even though the resistance seems similar between the colored springs.....
The vaccum secondaries just seemed inconsistent so I always made my setups to the double pumper ones......
try changing the spring.......they make a big difference even though the resistance seems similar between the colored springs.....
#7
there's alot about that carb that tells me it's not from rb. specifically how the throttle linkage where the cable would connect to looks. the vac pod doesn't look the same either. keep in mind this is comparing how urs looks to mine.
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#9
I have the yellow sping in it now, the lightest one they have. White is heavier.
Also, its been modified as I said. The throttle linkage is hooked up with the same pieces I've seen on other RB carbs (the two flat pieces), and the vacuum pod has the quick change spring cover on it.
I will take some pics specific of the carb today. Thanks everyone.
~T.J.
Also, its been modified as I said. The throttle linkage is hooked up with the same pieces I've seen on other RB carbs (the two flat pieces), and the vacuum pod has the quick change spring cover on it.
I will take some pics specific of the carb today. Thanks everyone.
~T.J.
#10
In my kit the white is the lightest......this is from the Holley kit 20-13
COLOR
RELATIVE LOAD
350 CID ENGINE
OPENING RPM
402 CID ENGINE
OPENING RPM
Initial
Full
Initial
Full
White
Lightest
---
---
---
---
Yellow*
Lighter
1620
5680
1410
4960
Yellow
Light
1635
5750
1420
5020
Purple
Med. Light
1915
6950
1680
6050
Plain
Medium
2240
8160
1960
7130
Brown
Med. Heavy
2710
8750
2380
7650
Black
Heavy
2720
Not Fully Open
2390
Not Fully Open
COLOR
RELATIVE LOAD
350 CID ENGINE
OPENING RPM
402 CID ENGINE
OPENING RPM
Initial
Full
Initial
Full
White
Lightest
---
---
---
---
Yellow*
Lighter
1620
5680
1410
4960
Yellow
Light
1635
5750
1420
5020
Purple
Med. Light
1915
6950
1680
6050
Plain
Medium
2240
8160
1960
7130
Brown
Med. Heavy
2710
8750
2380
7650
Black
Heavy
2720
Not Fully Open
2390
Not Fully Open
#12
You may simply be over carb'd. Provide all details on the engine and again the carb list #. Your carb pics are missing the racingbeat omp activation rod.
I run a holley 670 avenger on my supercharged 13b, purple secondary spring and I use the quick fuel secondary diaphragm. I am dialed in almost perfect. For ***** and giggles I tried a 870 avenger once, even with the lightest spring it only pulled the secondaries open once.
I run a holley 670 avenger on my supercharged 13b, purple secondary spring and I use the quick fuel secondary diaphragm. I am dialed in almost perfect. For ***** and giggles I tried a 870 avenger once, even with the lightest spring it only pulled the secondaries open once.
#14
You may simply be over carb'd. Provide all details on the engine and again the carb list #. Your carb pics are missing the racingbeat omp activation rod.
I run a holley 670 avenger on my supercharged 13b, purple secondary spring and I use the quick fuel secondary diaphragm. I am dialed in almost perfect. For ***** and giggles I tried a 870 avenger once, even with the lightest spring it only pulled the secondaries open once.
I run a holley 670 avenger on my supercharged 13b, purple secondary spring and I use the quick fuel secondary diaphragm. I am dialed in almost perfect. For ***** and giggles I tried a 870 avenger once, even with the lightest spring it only pulled the secondaries open once.
So now the question is, what do I do with it? I have all the parts to drop a 465 CFM (1848) on there, but its not "modified" by RB. I can get a brand new 1848 for about $200 less than buying JUST the carb from RB.
When I called RB and explained the situation, they told me they do a lot of custom machine work on the metering plates, making new passages, blocking off others, getting new parts from Holley, making their own parts (linkages), etc. I dont know how much of that is true, but it makes me wonder about one thing - if they modify the metering plates (which dont have changable secondary jets), how can I tune my secondaries? Not everyone is at the same elevation, and not all motors run the same after all. I would never buy an "off the shelf" kit and expect to not have to do SOME tuning on it. Wouldnt I have to swap to different metering plates, thus eliminating their "modifications" in essence? I dont think they do anything to the bowls either (except add the fittings for the OMP) since the race float bowl conversion they sell would eliminate those modifications as well.
Basically Im almost tempted, as much as Ive seen it bashed, to just get an off the shelf 1848 465 CFM Holley body, slap it on, swap my metering plates, race float bowls, fuel lines, quick change spring kit, etc on it and start tuning the thing. It just seems like thats the most cost effective way to get it going seeing as I have ALL the other parts to support a Holley on a rotary. I used to run a 45 DCOE on my last motor, but getting back into that setup would be even more money I dont want to spend on this thing, lol.
~T.J.
#16
Forgot to mention its a Pineapple rebuild bought used about 3 years old. 85 PSI on both rotors, intake irons are street ported, exhaust is not (I know, lol). Im running the Holley setup above, plus the RB full street port exhaust, Holley blue pump and regulator at 6 PSI.
Everything else is golden really, seems like a good strong motor, no leaks, no smoke, good oil pressure, etc (knock on wood). It runs pretty damn good for running on 2 barrels, but I bet it could open up more in the mid-upper end. Low end is pretty good actually.
~T.J.
Everything else is golden really, seems like a good strong motor, no leaks, no smoke, good oil pressure, etc (knock on wood). It runs pretty damn good for running on 2 barrels, but I bet it could open up more in the mid-upper end. Low end is pretty good actually.
~T.J.
#17
Trust me, "try an open carb spacer" before you make any rash decisions!!!!
I would suggest a wideband at some point to help tuning. Yes you need to swap out secondary metering plates to adjust secondary fuel, however you can buy a rear metering block kit and just change jets to do the same.
If you decide to replace the carb, go with an edelbrock 500cfm "thunder series". You get the functionality of mechanical secondaries plus infinite adjustability of vac secondaries with the turn of a screw driver. Adjustable jetting for primary and secondaries and the metering rods make adjusting and tuning the primaries a snap, never have to touch the fuel!
I would suggest a wideband at some point to help tuning. Yes you need to swap out secondary metering plates to adjust secondary fuel, however you can buy a rear metering block kit and just change jets to do the same.
If you decide to replace the carb, go with an edelbrock 500cfm "thunder series". You get the functionality of mechanical secondaries plus infinite adjustability of vac secondaries with the turn of a screw driver. Adjustable jetting for primary and secondaries and the metering rods make adjusting and tuning the primaries a snap, never have to touch the fuel!
#18
put the check ball back in the secondary housing
try the stiffer yellow spring
check to make sure the diaphram is sealed properly which is diffucult with the quick change setup
test it by sucking on the hole where it mounts to the carb there should be a round cork gasket
if sealed correctly it should move the lever into the housing
secondaries only operate when driving not free revving the engine
try the stiffer yellow spring
check to make sure the diaphram is sealed properly which is diffucult with the quick change setup
test it by sucking on the hole where it mounts to the carb there should be a round cork gasket
if sealed correctly it should move the lever into the housing
secondaries only operate when driving not free revving the engine
#19
I guess I could look into the carb spacer. It seems that letting the mixture collect before it goes into the runners (so they all see the same thing basically) might be good anyway, and then vacuum would form on both sides of the rotor and possibly pull more air in I suppose.
As for the check ball, I was thinking of trying that, but I don't have one - never came with one. I will see about getting one when I go to the shop to see about the carb spacer.
Also, putting a heavier spring in doesn't seem like it makes sense. If they can barely open with no spring at any RPM, a heavy spring won't do anything but hold them closed I would think.
Thanks for the other tips, but I already said I did all that. That's the point of the paperclip and or bread tie tests I was talking about. Also, I said there is an o-ring between the vacuum pot and body, not a cork gasket. I would think an o-ring seals
better as long as it isn't compressing so much as to block the port, but I would think its not because I do get some operation from the secondaries with no spring.
~T.J.
As for the check ball, I was thinking of trying that, but I don't have one - never came with one. I will see about getting one when I go to the shop to see about the carb spacer.
Also, putting a heavier spring in doesn't seem like it makes sense. If they can barely open with no spring at any RPM, a heavy spring won't do anything but hold them closed I would think.
Thanks for the other tips, but I already said I did all that. That's the point of the paperclip and or bread tie tests I was talking about. Also, I said there is an o-ring between the vacuum pot and body, not a cork gasket. I would think an o-ring seals
better as long as it isn't compressing so much as to block the port, but I would think its not because I do get some operation from the secondaries with no spring.
~T.J.
#24
Put a 1" thick wet sponge on top of the air cleaner, shut the hood and look for a wet spot. Then use a thicker one and see. You get the idea.............just like teasing a woman, once you find a wet spot you know you're do'in something right.
#25
Well, I picked up a 0.5" open phenolic spacer and slapped it on. Wouldn't you know it, it runs way better and the secondaries are moving! The idle smoothed out and overall drivabilty has gone up 10 times what it was and I haven't touched an adjuster or jet yet. Time to start jetting this puppy!
Thanks for the tips everyone! I will continue my saga of learning the Holley and jetting I'm sure, lol.
~T.J.
Thanks for the tips everyone! I will continue my saga of learning the Holley and jetting I'm sure, lol.
~T.J.