How to set and hold valve lift on a flow bench?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

travis
Guru
Guru
Posts: 1611
Joined: Sun Mar 15, 2009 5:31 am
Location:

How to set and hold valve lift on a flow bench?

Post by travis »

I’m looking at getting a small flow bench...how do you set and hold valve lift for testing at different lift points?
statsystems
Guru
Guru
Posts: 1508
Joined: Sun Apr 03, 2016 1:17 am
Location:

Re: How to set and hold valve lift on a flow bench?

Post by statsystems »

Save your money and get a full size bench. Preferably a bench that will pull at least 40 inches of water on a decent BBC head.
superpursuit
Pro
Pro
Posts: 214
Joined: Sun Apr 20, 2014 11:07 pm
Location:

Re: How to set and hold valve lift on a flow bench?

Post by superpursuit »

You can either buy a valve opener or you can make one. What you need depends on the type of head you are testing. Google 'flow testing cylinder heads' and see what others are using.
David Redszus
Guru
Guru
Posts: 9633
Joined: Tue Nov 27, 2007 9:27 am
Location: Chicago
Contact:

Re: How to set and hold valve lift on a flow bench?

Post by David Redszus »

travis wrote: Wed Jun 13, 2018 9:37 pm I’m looking at getting a small flow bench...how do you set and hold valve lift for testing at different lift points?
Install the valve using low rate checking springs.
Build a fixture to incorporate a threaded bolt contacting the valve stem. A M6.0 x 1.0, produces 1mm of lift per turn which is very convenient.

Or, forget the flow bench. Buy a good shop vac and some electronic pressure sensors with the signals fed into a data logger.
mag2555
Guru
Guru
Posts: 4584
Joined: Sun Sep 18, 2011 11:31 am
Location: Heading for a bang up with Andromeda as we all are.

Re: How to set and hold valve lift on a flow bench?

Post by mag2555 »

Come on guy, even a bench that can only pull 10 inches is help full to a beginner for Gods sake!!
Even a set up the can only push or yank 5 inches is good for low lift work!

The Brezinski fixture is nice, but over 500 bucks, I have a old Comp cams one that did not break the Bank at the time, and I think silver seal products sells a similar one and it's well under 300 bucks.
The main thing with any fixture is that they are rock solid, because at low lift even a change in .003" can change your flow numbers by more then the accuracy of your bench!

Also you do not need very stiff springs on the exh side for a test , as the bench is trying to close the valve, not open it as on the intake side.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
User avatar
Dave Koehler
Vendor
Posts: 7197
Joined: Mon Oct 04, 2004 11:19 pm
Location: Urbana, IL USA
Contact:

Re: How to set and hold valve lift on a flow bench?

Post by Dave Koehler »

^^^agreed.
Most everyone in this biz started small or budgeted and then steps up if the interest, skills and money are warranted.
Dave Koehler - Koehler Injection
Enderle Fuel Injection - Nitrous Charger - Balancing - Nitrous Master software
http://www.koehlerinjection.com
"Never let a race car know that you are in a hurry."
pcnsd
HotPass
HotPass
Posts: 677
Joined: Thu Dec 13, 2012 12:04 am
Location: North County San Diego CA

Re: How to set and hold valve lift on a flow bench?

Post by pcnsd »

What are you testing?. There are lots of V8 compatible ideas for fabrication to be found in the internet. Mag is 100% on "it has to be stiff" I think this favors steel construction in most cases. Use light test springs. 2 valve? 4 valve? 5 valve?. Higher depression will show things that can't be seen at lower, but any bench is better than none if you are a hobbyist working the obscure.
- Paul
gnash
New Member
New Member
Posts: 39
Joined: Thu Apr 28, 2016 7:36 pm
Location:

Re: How to set and hold valve lift on a flow bench?

Post by gnash »

Testing at low test pressures will show things that can't be seen at higher pressures.
pcnsd
HotPass
HotPass
Posts: 677
Joined: Thu Dec 13, 2012 12:04 am
Location: North County San Diego CA

Re: How to set and hold valve lift on a flow bench?

Post by pcnsd »

gnash wrote: Thu Jun 14, 2018 10:29 am Testing at low test pressures will show things that can't be seen at higher pressures.
Do you have an example you can offer of this that indicates the unique value available at lower test pressure that is not present at higher depression.
- Paul
Scotthatch
Pro
Pro
Posts: 311
Joined: Sat Apr 14, 2018 11:12 pm
Location: 7000 ft up

Re: How to set and hold valve lift on a flow bench?

Post by Scotthatch »

You can always use a height mic on the valve to set lift for the flow test ..... I do this on heads that don't fit my opener..
Rick360
Guru
Guru
Posts: 1104
Joined: Sun Oct 03, 2004 9:55 pm
Location: Missouri

Re: How to set and hold valve lift on a flow bench?

Post by Rick360 »

On sbc heads and many others with stud mount rockers you can use a short piece of all-thread with a nut on the pushrod side with the end above the guide plate and a polylock on a rocker to adjust the valve open. Use a dial indicator with a long tip to touch the retainer and measure the movement.

Rick
foxchassis
New Member
New Member
Posts: 37
Joined: Thu Feb 08, 2007 8:57 pm
Location: springfield ohio

Re: How to set and hold valve lift on a flow bench?

Post by foxchassis »

Image


This is the best one i have made over the years, only thing i would do different is use a course thread on the adjusting screw.

Used on numerest heads, it tilts for the correct valve angle and slides in and out.

Dwight
V Remian
Member
Member
Posts: 141
Joined: Sun Feb 13, 2005 11:34 am
Location: Central Massachusetts

Re: How to set and hold valve lift on a flow bench?

Post by V Remian »

I use a contraption similar to that but I use micrometer heads you can buy on e-bay for short money, no indicator required.
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: How to set and hold valve lift on a flow bench?

Post by steve cowan »

could not buy a valve opener in Australia,and nobody from USA would answer my emails so i made this one,and buy the way the anodizing is the colour of salmon not pink LOL
flowbench 003.JPG
flowbench 004.JPG
flowbench 005.JPG
flowbench 006.JPG
flowbench 007.JPG
flowbench 008.JPG
You do not have the required permissions to view the files attached to this post.
steve c
"Pretty don't make power"
mag2555
Guru
Guru
Posts: 4584
Joined: Sun Sep 18, 2011 11:31 am
Location: Heading for a bang up with Andromeda as we all are.

Re: How to set and hold valve lift on a flow bench?

Post by mag2555 »

Sweet work there Steve, but for us guys that also work on heads with rocker shafts you will have to modify that a ton!
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Post Reply