Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine> Holley 850 CFM Vacuum Secondaries.. PITA..!!
User Name
Password
lost password?   |   register now

Thread: Holley 850 CFM Vacuum Secondaries.. PITA..!! Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
04-12-2006 07:54 PM
coldknock I forgot to mention that with the short yellow spring the secondaries begin to open much sooner than 5200, on my engine anyway. That's the rpm in which they are completely open by. With 100 extra cubes and much better heads the airflow should be more than enough to open them up sooner with the same spring, even in an 850. Oh yeah, I tossed the check ball too. It made them open too slow for my taste.

Just try it.


Larry
04-12-2006 05:36 PM
1ownerT It was worth mentioning, you never know. I don't think the removable covers were available when I was tunning on mine. It was a PITA to have to remove and replace the thing to change springs.
Hopefully you find the culprit soon.
04-12-2006 04:51 PM
Viet Nam Vette
Quote:
Originally Posted by 1ownerT
This is a very long shot, but possable. Several years back I bought a Holley 750 vac secondary, new out of the box it did not have the acceleration I thought it should. I had a secondary spring tunning kit and went to do the same as you (install the lightest then work heavier) when I removed the secondary chamber it had a solid gasket in place where it should have had approx a 1/8" opening in the center of the gasket. It could not get a vac signal to open the secondarys. I replaced with the proper gasket and proceeded to my "test track", where on my first pass I twisted the end off of the driveshaft.
They have done it once, maybe they did it a second time?
Heh Thanks for the Reply 1 OwnerT....

Good point. I also had bought the Kit with the removable Diapharam top. This lets you remove the top cover to change springs with out removing the choke and Vacuum diaphram assembly.

Of course to install this cover you have to remove the vacuum diaphram. In the kit is a brand new cork gasket. It is mounted on an adhisive backing ..and you peel if off and install it on the chamber.

Now ..I can see how this happen to you as you must remove the center piece of cork from the ring before mounting or sticking it on to the chamber.
So..when they built yours ..someone forgot to remover the center!!!

So....Good call ..but I did install it and I know I removed the center piece.
04-12-2006 04:20 PM
1ownerT This is a very long shot, but possable. Several years back I bought a Holley 750 vac secondary, new out of the box it did not have the acceleration I thought it should. I had a secondary spring tunning kit and went to do the same as you (install the lightest then work heavier) when I removed the secondary chamber it had a solid gasket in place where it should have had approx a 1/8" opening in the center of the gasket. It could not get a vac signal to open the secondarys. I replaced with the proper gasket and proceeded to my "test track", where on my first pass I twisted the end off of the driveshaft.
They have done it once, maybe they did it a second time?
04-12-2006 03:26 PM
Viet Nam Vette
Quote:
Originally Posted by coldknock
Try the short yellow spring. I have a 750 with that spring on a 400 small block and it's wide open at 5200 rpm. No bog at all.


Larry
Heh Larry..

Yeah But....... ... The White is the lightest..and I want them suckers open way before 5200. The max RPM on the 502 is 5500 RPM's. The MSD Rev Limiter is set for 5200.There's gotta be a way to get the secondaries open sooner then they are.

I mean...you read the instructions...you buy the top cover kit... then you buy the spring kit. It says ..use the spring that causes a bog then work up from their.

Ok I did all that..and the POS carb still won't do what it's suposed too. Then people tell you ..take out the check ball in the housing ..some tell you ...cut the spring....Holley Tech Guy says's noooooooooooooooooo..!!!! don't you dare do that it's wrong.!!!!!

It'll Blah ..Blah ...Blah... So what's all this tell you..... It tells me GMPP should have gone to Edelbrock and had them flow one of there new AVS..(Adjustable Vacuum Secondaries) Carbs for the 502..instead of this leaky POS that's on my 502 now.

If I wasn't so lazzy.. I'd but an Edelbrock and Flow one for my ride. But that would take alot of time and Jet changes to do. At least if I wanted to adjust the secondaries all I would need is a screwdriver.. .. Not a bunch of freaken springs and covers and....still the POS won't work...

I feel better now that I Ranted this off my chest.

Thanks for listening..

Maybe I'll email Holley and dump on them.....
04-12-2006 02:47 PM
coldknock Try the short yellow spring. I have a 750 with that spring on a 400 small block and it's wide open at 5200 rpm. No bog at all.


Larry
04-12-2006 02:23 PM
Viet Nam Vette
Quote:
Originally Posted by hotrodf1
Did you say you had a white spring in there? I could be mistaken but I thought the two lightest springs in the HOlley spring kit were Yellow (Short) and yellow (long).

Also I looked on the package and they show values for opening and fully open based on the displacment of engine. On a 400 CI engine, with the lightest spring, you still don't open all the way until over 5000 RPM.

So a vac. sec. will never be like a mech. sec. carb in my opinion. But I run a vac. sec. in my camaro and my 48 PU and I think they work quite well so i stick with em.
I would assume that with a 502 it would be fully open at a much lower RPM
with a lighter spring

What's weird here is that the 20-13 Kit comes with a White spring. But The instruction sheet that's in the box says nothing about it ..Not listed.

Now go out to Holly.com Here's the link..

http://www.holley.com/data/Products/...199R8219-2.pdf

And look on page 2 of the PDF.. and you'll see the white spring listed as the lightest.

If the link does not work go to holley.com and punch in 20-13 and it will come up .then look for the instruction sheet.

There isn't a spec shown for the opening RPM or the Full Open RPM. FREAKEN Neat huh..... That's why I'm not a big Fan of Holley Carbs. But I'm stuck with this sucker as it is flowed for this motor. And I'm to lazzy to start pulling stuff off and on.

I guess I just want An "Easy" Button to Push.
04-12-2006 02:02 PM
hotrodf1 Did you say you had a white spring in there? I could be mistaken but I thought the two lightest springs in the HOlley spring kit were Yellow (Short) and yellow (long).

Also I looked on the package and they show values for opening and fully open based on the displacment of engine. On a 400 CI engine, with the lightest spring, you still don't open all the way until over 5000 RPM.

So a vac. sec. will never be like a mech. sec. carb in my opinion. But I run a vac. sec. in my camaro and my 48 PU and I think they work quite well so i stick with em.
04-12-2006 09:18 AM
Viet Nam Vette
Quote:
Originally Posted by jtybt
Do you have a vacuum gauge to hook up to the intake manifold? This will help to explain what's happening while the engine is running I have a large vacuum gauge on the dash so I can monitor the engine all the time.

At idle (throttle plate closed) the engine is sucking air but the throttle plates aren't allowing air in so there's high vacuum in the intake manifold(assuming you don't have too radical of a cam). As you open the throttle, the primary plates let in more air and the vacuum lowers. The power valve starts to dump extra fuel when the vacuum reaches the rating of the power valve. in tour case, 3.5 and 4.5 in/hg(vacuum). The more load the engine is under the lower the vacuum reading will be for any given throttle opening. By putting in a higher vacuum power valve, the sooner the PV will open which corresponds to lower throttle opening or lower load that the engine feels. You want to adjust/change the vacuum spring to correspond to the PV opening.

But remember, I work on boats and a boat is under ever increasing load as the throttle is opened. It's like towing a trailer uphill in 4th gear. Also a boat engine has to be run richer because of the load(to reduce the chance of detonation)

I have a Gauge but not dash mounted. The motor pulls about 15Hg's at idol.

I'll have to get further into this . Thanks
04-11-2006 10:39 PM
jtybt Do you have a vacuum gauge to hook up to the intake manifold? This will help to explain what's happening while the engine is running I have a large vacuum gauge on the dash so I can monitor the engine all the time.

At idle (throttle plate closed) the engine is sucking air but the throttle plates aren't allowing air in so there's high vacuum in the intake manifold(assuming you don't have too radical of a cam). As you open the throttle, the primary plates let in more air and the vacuum lowers. The power valve starts to dump extra fuel when the vacuum reaches the rating of the power valve. in tour case, 3.5 and 4.5 in/hg(vacuum). The more load the engine is under the lower the vacuum reading will be for any given throttle opening. By putting in a higher vacuum power valve, the sooner the PV will open which corresponds to lower throttle opening or lower load that the engine feels. You want to adjust/change the vacuum spring to correspond to the PV opening.

But remember, I work on boats and a boat is under ever increasing load as the throttle is opened. It's like towing a trailer uphill in 4th gear. Also a boat engine has to be run richer because of the load(to reduce the chance of detonation)
04-11-2006 07:51 PM
Viet Nam Vette
Quote:
Originally Posted by jtybt
I work on boats so this may not apply.

What power valve do you have(in/hg)? The higher the #, the earlier it will open. Normal street operation for economy would probably have a 5.5. Try a 6.5 to 7.5 or higher PV and lighter spring. Matching power valve to secondary opening should give you a kick in the pants.
Here's the read out from the PDF on the Carb

Prim Jet 78...../Sec Jet 82/ /Pump Discharge Nozzle .040/ Primary Power Valve ..45/ Secondary Power Valve 35 / Stock Spring ..Pink/ Now has the lightest one in the Vacuum dia White.
04-11-2006 07:39 PM
jtybt I work on boats so this may not apply.

What power valve do you have(in/hg)? The higher the #, the earlier it will open. Normal street operation for economy would probably have a 5.5. Try a 6.5 to 7.5 or higher PV and lighter spring. Matching power valve to secondary opening should give you a kick in the pants.
04-11-2006 05:30 PM
Viet Nam Vette
Quote:
Originally Posted by johnsongrass1
Why not convert to 1:1 secondary's?


You should never feel the secondary come in. Verify the secondarys even open with a paper clip on the linkage.
Heh Thanks for the reply......

Yep..I know you'r not supposed to feel them suckers come in.

Ok Edge-A-Ma-Kate Me here....

(1) How and where do I put the Paper clip to check the opening of the Secondaries....

(2) How do you convert to 1:1..are you saying ..both sets of Throttel plates working at the same time??
04-11-2006 05:24 PM
Viet Nam Vette
Quote:
Originally Posted by 302/Z28
The seat in pants feel of the secondaries coming in is actually detrimental to performance. As stated above, you should not feel the secondaries come in.

Vince
Heh Thanks Vince... Yep I know all about the secondary operation. Like you say if you feel that learch or slight bog ..there set wrong.
I'm just at a point where I have done all the factory adjustmets and I'm not happy with the results.

I used the lightest spring and it still doesn't bite like I think it should ..
04-11-2006 05:19 PM
Viet Nam Vette
Quote:
Originally Posted by 1ownerT
I think the point was that he wants to feel the bog, then stiffen the spring until it is gone.

We have a winner.. That's excactly what I'm talken about...Don't want to feel the bog or the lag ..that's a no good... as stated above.

Just want some more balls....
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -6. The time now is 04:47 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.