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

[steve cowan]

Hey mag,
Yep I agree, just a quick throw together so I can nut something that caters for more applications, I have been looking at a sliding bar type deal like I have seen the pros using

[MadBill]

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.

Or, for the Imperialists among us, a 1/4" x 20 NC thread advances 0.050" per rev.

[cjperformance]

Long live the imperialists !! I just wouldnt feel right saying i had a 13.2mm lift cam in my 351 Cleveland !

[steve cowan]

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.

Or, for the Imperialists among us, a 1/4" x 20 NC thread advances 0.050" per rev.

Funny how over here in Australia we have been metric since the 1970s I think and I was brought up in school using metric system but a lot of guys my age use imperial and personally I think metric thread should be banned lol, although some of my measuring instruments are metric and I have to convert back to imperial ( 25.4) and I hear some of the USA guys talking metric must mess with your heads I recon

[gnash]

Higher depression will show things that can't be seen at lower,

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.

Do you have an example you can offer of this that indicates the unique value available at higher test pressure that is not present at lower depression.

[MadBill]

Considering that the ports and valves see high, low and in between depressions through their lift cycles, it might be best to test at deltas typical of an actual running engine at each lift point. (easier done on the intake of course...)

[FC-Pilot]

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

I built two of these(one for bbc and one for sbc) and they are quick and easy to use and setup. For quick and dirty being that I used a 1/4 theaded bolt I can just use the threaded rod with just one turn to get quick measurements.

Paul

[mag2555]

It's been said that testing at even only 5" at high lift will give a representation of what's going on, comments anyone?
Depression of over 120" have been seen at low lifts on very high rpm motors as I have read.

[Scotthatch]

It's been said that testing at even only 5" at high lift will give a representation of what's going on, comments anyone?
Depression of over 120" have been seen at low lifts on very high rpm motors as I have read.

A flowbench is designed to measure airflow in a calibrated manner ... do not make it what it is not ...it will not ever mimic a running engine ...use it for what it is intended .... flowbench work is what has gotten us the HP we make today as compared to years ago ... the goal with any bench is to show how well the porting work is going in not just flow numbers but quality ..... does running up the pressure drop help find little problems ? Yes sometimes it does but the number means nothing at that point you are just looking for spots that are not right that you can't seem to pinpoint .... will a small bench help even though it can only do a low drop ? Yes as compared to no bench it will put you ahead by letting you test what you have done .... everyone who has a bench and ported heads has done something to a port that did not help even when they where sure it would ... it is why we have and use the bench .... is there things that don't show up on a bench? Yes not just because it's not an engine but because you move fuel and air on the intake side and very hot air on the exhaust side but you will still build better engines with the use of a bench then without ... I test stuff for other people all the time ... they home port it and when done it gets tested and sometimes it is very eye opening for them when all the work did not help or made it worse ... you can play with cross-section all you want but just measuring will not show a short side that's wrong or a sear point after a pitch that needs more blending or when a backcut on the valve is wrong ...

[pcnsd]

Higher depression will show things that can't be seen at lower,

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.

Do you have an example you can offer of this that indicates the unique value available at higher test pressure that is not present at lower depression.

Yes. In 1978 Gordon Jennings published an article in Cycle magazine describing how to port a Yamaha SR500 cylinder head. His testing was conducted at Branch Flowmetrics using equipment provided by Jerry Branch. All testing was conducted on a SF110 at 10" H2O. The article became the basis of a generation of garage built porting attempts for the sound of single and various FT racing devotees. It is mostly correct in the basic shape it suggest, but there is one notable aspect that is very wrong and will cost you ~20cfm above .45" when measured at 28" H2O. That one aspect, if followed causes the flow to back up as lift passes the convergence at higher depressions. The specific recommendation was to cut a channel around the chamber side of the valve to deepen the bowl. This shows improvement at 10". At about 20" of depression the error starts to be apparent indicated by a growing howl from the port. What the port really wants is a wing behind the valve to stabilize the flow exiting the valve. You won't know that at 10".

My original question still stands and remains unanswered.

[engineguyBill]

Precision Measurement Supply in San Antonio, TX has a modified dial indicator with heavy duty stem that can be used directly on the valve stem to open the valve.

[Morgo]

Well,as I do mostly 4-valve heads I have about 48 different opening devises I made up.Just the M6 nuts welded to some moulded sheet metal and of cource the thread bar cut to apply.1mm per turn is quite accurate.
And in my opinion anyone using Imperial units should be shot!

[engineguyBill]

Why would you want to shoot us??? Opening a valve a certain distance is not a scientific endeavor . . . . . . . Anyone can do it.

[gnash]

Higher depression will show things that can't be seen at lower,

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.

Do you have an example you can offer of this that indicates the unique value available at higher test pressure that is not present at lower depression.

Yes. In 1978 Gordon Jennings published an article in Cycle magazine describing how to port a Yamaha SR500 cylinder head. His testing was conducted at Branch Flowmetrics using equipment provided by Jerry Branch. All testing was conducted on a SF110 at 10" H2O. The article became the basis of a generation of garage built porting attempts for the sound of single and various FT racing devotees. It is mostly correct in the basic shape it suggest, but there is one notable aspect that is very wrong and will cost you ~20cfm above .45" when measured at 28" H2O. That one aspect, if followed causes the flow to back up as lift passes the convergence at higher depressions. The specific recommendation was to cut a channel around the chamber side of the valve to deepen the bowl. This shows improvement at 10". At about 20" of depression the error starts to be apparent indicated by a growing howl from the port. What the port really wants is a wing behind the valve to stabilize the flow exiting the valve. You won't know that at 10".

My original question still stands and remains unanswered.

So you saw no drop in cfm at 10" and then you saw a cfm drop at 28", assuming the flow bench using 10" was sensitive enough to see a drop.

[FPV_GTp]

Late reply but I had too, travis not knowing what cylinder heads you are working on? Most valve opening fixtures are purpose built for specific application head.

Not all women like BIG things , isn't it the way you use it ? sorry for the innuendo I have gone of track, you get the picture. I started of with a two vacuum cleaner motor DIY bench and served me well. I only wish my home garage had a fuse box big enough to handle 120"WC - 140"WC so i could drive my neighbours wild!

Just search for " bill jones " website, he has some very good examples

Also use the speedtalk search engine.

Also here is a few nice example of a fixture from a thread in here " Flow Bench cylinder head adapters - Speed Talk " by R.Brown https://www.speed-talk.com/forum/viewtopic.php?t=2261

Converting measurement from imperial to metric sucks just another task.

Cheers