Don Terrill’s Speed-Talk

I’m looking at getting a small flow bench...how do you set and hold valve lift for testing at different lift points?

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.

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.

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.

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.

^^^agreed.
Most everyone in this biz started small or budgeted and then steps up if the interest, skills and money are warranted.

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.

Testing at low test pressures will show things that can't be seen at higher pressures.

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.

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..

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

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

I use a contraption similar to that but I use micrometer heads you can buy on e-bay for short money, no indicator required.

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

Sweet work there Steve, but for us guys that also work on heads with rocker shafts you will have to modify that a ton!