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Valve spring testing on Rimac ( help needed )

General engine tech -- Drag Racing to Circle Track

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Eagle1903
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Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Fri May 22, 2020 2:45 pm

Dear Friends,

I am confused with valve spring testing.

I want to test dual valve springs and my first question is; is it a good idea to test inner and outer spring separately at the installed and open heights and then add both figures to find the total poundage ? Or I should always test them together.

My second question is; is it common to use the spring retainer ( cap ) or not ?

My third questions is; which is actually the case with the engine I am working on; there is a quite thick rotator under the spring ( inner and outer springs both sit on this rotator) and the inner spring sits slightly higher on the step of the rotator. Shall I measure the springs with the rotator ( as it is the actual base for the springs ) on Rimac or without ?

I believe the valve spring installed height data ( 42.34 mm for this engine ) shoud be measured from top of the rotator to the bottom of the retainer. I think I am correct to accept this gap to establish the given installed height of 42.34 mm since the base of the spring is the top of the rotator ( but not the cylinder head’s valve spring pocket ) like there is spring locator there.

Kind regards
Kerem

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Re: Valve spring testing on Rimac ( help needed )

Post by BillK » Fri May 22, 2020 4:14 pm

Kerem,
You have to use the retainer with double springs because it typically pushes the inner spring down more than the outer one. I just use a pair of dial calipers and look carefully. If there is a step on the rotator for the inner spring then you should use the rotator and the retainer when checking the spring.

rimac.jpg
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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Fri May 22, 2020 4:50 pm

BillK wrote:
Fri May 22, 2020 4:14 pm
Kerem,
You have to use the retainer with double springs because it typically pushes the inner spring down more than the outer one. I just use a pair of dial calipers and look carefully. If there is a step on the rotator for the inner spring then you should use the rotator and the retainer when checking the spring.


rimac.jpg
Hi Bill,
Fully understood. Thank you very much for your kind reply.
Certainly, I am reading different poundages without the retainer and also without the rotator.
I imagine there is no such a thing that inner and outer springs should be checked the numbers be added to find the total poundage ( again with the retainer and rotator fitted and the correct related height taken into account)

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Re: Valve spring testing on Rimac ( help needed )

Post by Diodedog » Fri May 22, 2020 5:24 pm

The inner step on a retainer is typically about .100" so I use a .100" washer under the inner of a double spring, it will stay right on the tester as you do each set. On the BB and SB Mopars that haven't been cut down the heads have a .100" inner step, on these I use two washers.

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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Fri May 22, 2020 5:37 pm

Diodedog wrote:
Fri May 22, 2020 5:24 pm
The inner step on a retainer is typically about .100" so I use a .100" washer under the inner of a double spring, it will stay right on the tester as you do each set. On the BB and SB Mopars that haven't been cut down the heads have a .100" inner step, on these I use two washers.
Thank you very much Diodedog.
The idea is to simulate the actual heights during the test when testing double springs. But if I understand correct always test them together. Unless, may be we are in a situation which we want to test and compare various inners and outers individually ( select & match )to make a usable set from a bunch of springs for a given engine.

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Re: Valve spring testing on Rimac ( help needed )

Post by modok » Fri May 22, 2020 9:18 pm

IMO the simplest way to test a spring is....
first find bind, then back off .060 or .100 (whichever you plan to run) and read the poundage there. THat's your open pressure. Most cases that's all you need to know.


When you have have dual springs..... one will bind before the other, or, rarely at the same time, maybe.
You just have to figure it out. I think the outer spring should bind first, but sometimes I find the inner does.
If it's good, great!
If not, fix it.

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Re: Valve spring testing on Rimac ( help needed )

Post by hoodeng » Sat May 23, 2020 12:28 am

Upper and lower retainer steps vary considerably between manufacturers also as pointed out bind occurs at different points with double and triple springs. With one type i use regularly [it has a tight application] if installed with the supplied upper and lower retainers binds at .880" If i make the lower retainers without a step the bind is now .730" ,There is no location problem as the upper is stepped to locate the top and the lower inner is shouldered and interference with the outer so i can run no bottom locator.
I try and keep my installed seat pressures even just for conformity on my build sheet, there may be a little variance at full lift .

All that said, back to your test, i use machined spacers in the tester to replicate the installed condition, one for doubles, two for triples, you could test every spring separately and add up the results but that is making a long job out of a short job.
If your tester is the old analog scale type you could fit a digital linear scale to the machine to introduce better accuracy.

A calibration spring run regularly is a must.



Cheers.
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Re: Valve spring testing on Rimac ( help needed )

Post by benno318 » Sat May 23, 2020 3:32 am

yes, as most folks above have written, measure the step of the retainer and the spring seat if any, and replicate with washers, or machine up a suitable spacer if washers cannot be found in the correct size.

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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Sat May 23, 2020 4:51 am

Dear Friends,
First of all, many many thanks for all your valuable answers and inputs !!!
I fully understood all your comments and the confusion is gone.
I mainly work on inline 4 cyl (8 and 16v) rather old school European engines ( fast road and competition engines)

I have one last question at this stage. I usually come across with brand new springs which has %3-7 open pressure variations out of the box. And the springs I work with has generally in the range of 180-220 lbs open pressures depending on the engine.
What should be the max variation ( in a set of springs) to be an acceptable limit at open pressure for a 7000- 7500 rpm kind of engines in your opinion

Regarding the rotator which I mentioned in my first post; this is a Porsche 924 Turbo 2.0 engine and it has got the rotators as part of the valve train design. It was so difficult to find the correct valve spring data from various sources ( I even wrote to Porsche classic) so that I could test the bunch of used springs against. Finally, I have found this data in a Porsche forum. So now I can use the data and the correct method of testing the springs as described in your posts.

Again, many many thanks for all your help.

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Re: Valve spring testing on Rimac ( help needed )

Post by benno318 » Sat May 23, 2020 6:15 pm

for jobs that are "budget" and may not get all installed heights equal, these are usually the very jobs that use a cheaper spring with some variances as you have found.
i use it to advantage in this case, it takes no time to check all springs and sort the low from the high, and selectively fit them to the low or high installed heights to try and make the best job of it.

probably does little to nothing at the end of the day, but at least trying to make the best of what we have separates us from the run of the mill type shops that dont care.

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Re: Valve spring testing on Rimac ( help needed )

Post by hoodeng » Sat May 23, 2020 9:12 pm

Funny you should mention an air cooled boxer, it reminded me of a situation some years back. A friend was involved in the maintenance of a Formula V engine, it would start off the season at the pointy end of the field then progressively peg back mid field as the season progressed, the driver was consistent but the car was not top ending on long straights like the front runners,,the engine was not displaying any distress in its performance and to the drivers description was RPM'ing same as the start of the season. In a discussion the engine builder was changing springs among other parts religiously in the between season freshen up, i asked if he was checking his springs poundage pre and post season, he said no as he was installing new every time.

I got him to bring his new springs around for check, he arrived with a large bag of new springs as he was buying in bulk for his businesses consumption. We checked every spring [there were a lot] we found a greater percentage would not even make service spec, we made up a couple of sets of the best of the bunch. If it was noticed that times were increasing a new set was installed, bingo, back to on par.
These springs were purchased from a recognized parts supplier as being a retro part for the engine.

One thing about recording your installed seat pressures is that you can do an in situ spring test to see how things are going as a season progresses,LSM along with others make in situ testers, i understand that not all top ends are readily accessible, some ingenuity in tool modification would work here.

Not knowing Porsche engines specifically, but by nature and history of that manufacturers performance record, their spring specs for performance application and quality of supply would seem a good place to start.

Cheers.

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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Sun May 24, 2020 9:13 am

benno318 wrote:
Sat May 23, 2020 6:15 pm
for jobs that are "budget" and may not get all installed heights equal, these are usually the very jobs that use a cheaper spring with some variances as you have found.
i use it to advantage in this case, it takes no time to check all springs and sort the low from the high, and selectively fit them to the low or high installed heights to try and make the best job of it.

probably does little to nothing at the end of the day, but at least trying to make the best of what we have separates us from the run of the mill type shops that dont care.
Hi,
It is very much the case with the aftermarket springs around here so certain amount of poundage variation could be compensated as you described. I have checked quite a few brand new springs ( i4 Kent Xflow ) and almost found % 3-5 and in couple of boxes up to %7 poundage differences.
I fully agree with your last paragraph, this has to be the proper approach, no doubt.

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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Sun May 24, 2020 10:22 am

hoodeng wrote:
Sat May 23, 2020 9:12 pm
Funny you should mention an air cooled boxer, it reminded me of a situation some years back. A friend was involved in the maintenance of a Formula V engine, it would start off the season at the pointy end of the field then progressively peg back mid field as the season progressed, the driver was consistent but the car was not top ending on long straights like the front runners,,the engine was not displaying any distress in its performance and to the drivers description was RPM'ing same as the start of the season. In a discussion the engine builder was changing springs among other parts religiously in the between season freshen up, i asked if he was checking his springs poundage pre and post season, he said no as he was installing new every time.

I got him to bring his new springs around for check, he arrived with a large bag of new springs as he was buying in bulk for his businesses consumption. We checked every spring [there were a lot] we found a greater percentage would not even make service spec, we made up a couple of sets of the best of the bunch. If it was noticed that times were increasing a new set was installed, bingo, back to on par.
These springs were purchased from a recognized parts supplier as being a retro part for the engine.

One thing about recording your installed seat pressures is that you can do an in situ spring test to see how things are going as a season progresses,LSM along with others make in situ testers, i understand that not all top ends are readily accessible, some ingenuity in tool modification would work here.

Not knowing Porsche engines specifically, but by nature and history of that manufacturers performance record, their spring specs for performance application and quality of supply would seem a good place to start.

Cheers.
As a matter of fact, this little Porsche 924 2.0 Turbo engine is not the air cooled boxer type. It is an single overhead cam solid lifter water cooled inline 4 cylinder engine which Porsche borrowed from Audi during the late 70s then developed the very same engine with different internals etc to 2500 cc. Later on they have used the very same base for Porsche 944 and possibly 928 as well.
Unfortunately the 2.0 liter parts are becoming extremely rare and to date I couldn’t locate other than one supplier which may have the springs. And some performance companies doesn’t deal with the 2.0 engine and valve train parts are not interchangeable with the 2.5 liter etc.
I currently have 2 sets of used springs and will try to make a set out of it with careful measuring.

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Re: Valve spring testing on Rimac ( help needed )

Post by Krooser » Sun May 24, 2020 10:32 am

Eagle1903 wrote:
Sun May 24, 2020 10:22 am
hoodeng wrote:
Sat May 23, 2020 9:12 pm
Funny you should mention an air cooled boxer, it reminded me of a situation some years back. A friend was involved in the maintenance of a Formula V engine, it would start off the season at the pointy end of the field then progressively peg back mid field as the season progressed, the driver was consistent but the car was not top ending on long straights like the front runners,,the engine was not displaying any distress in its performance and to the drivers description was RPM'ing same as the start of the season. In a discussion the engine builder was changing springs among other parts religiously in the between season freshen up, i asked if he was checking his springs poundage pre and post season, he said no as he was installing new every time.

I got him to bring his new springs around for check, he arrived with a large bag of new springs as he was buying in bulk for his businesses consumption. We checked every spring [there were a lot] we found a greater percentage would not even make service spec, we made up a couple of sets of the best of the bunch. If it was noticed that times were increasing a new set was installed, bingo, back to on par.
These springs were purchased from a recognized parts supplier as being a retro part for the engine.

One thing about recording your installed seat pressures is that you can do an in situ spring test to see how things are going as a season progresses,LSM along with others make in situ testers, i understand that not all top ends are readily accessible, some ingenuity in tool modification would work here.

Not knowing Porsche engines specifically, but by nature and history of that manufacturers performance record, their spring specs for performance application and quality of supply would seem a good place to start.

Cheers.
As a matter of fact, this little Porsche 924 2.0 Turbo engine is not the air cooled boxer type. It is an single overhead cam solid lifter water cooled inline 4 cylinder engine which Porsche borrowed from Audi during the late 70s then developed the very same engine with different internals etc to 2500 cc. Later on they have used the very same base for Porsche 944 and possibly 928 as well.
Unfortunately the 2.0 liter parts are becoming extremely rare and to date I couldn’t locate other than one supplier which may have the springs. And some performance companies doesn’t deal with the 2.0 engine and valve train parts are not interchangeable with the 2.5 liter etc.
I currently have 2 sets of used springs and will try to make a set out of it with careful measuring.
If you know your valve spring specs you can look thru any spring mfg. catalog and try to find a comparable spring for your engine.
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Re: Valve spring testing on Rimac ( help needed )

Post by Eagle1903 » Sun May 24, 2020 11:56 am

Krooser wrote:
Sun May 24, 2020 10:32 am
Eagle1903 wrote:
Sun May 24, 2020 10:22 am
hoodeng wrote:
Sat May 23, 2020 9:12 pm
Funny you should mention an air cooled boxer, it reminded me of a situation some years back. A friend was involved in the maintenance of a Formula V engine, it would start off the season at the pointy end of the field then progressively peg back mid field as the season progressed, the driver was consistent but the car was not top ending on long straights like the front runners,,the engine was not displaying any distress in its performance and to the drivers description was RPM'ing same as the start of the season. In a discussion the engine builder was changing springs among other parts religiously in the between season freshen up, i asked if he was checking his springs poundage pre and post season, he said no as he was installing new every time.

I got him to bring his new springs around for check, he arrived with a large bag of new springs as he was buying in bulk for his businesses consumption. We checked every spring [there were a lot] we found a greater percentage would not even make service spec, we made up a couple of sets of the best of the bunch. If it was noticed that times were increasing a new set was installed, bingo, back to on par.
These springs were purchased from a recognized parts supplier as being a retro part for the engine.

One thing about recording your installed seat pressures is that you can do an in situ spring test to see how things are going as a season progresses,LSM along with others make in situ testers, i understand that not all top ends are readily accessible, some ingenuity in tool modification would work here.

Not knowing Porsche engines specifically, but by nature and history of that manufacturers performance record, their spring specs for performance application and quality of supply would seem a good place to start.

Cheers.
As a matter of fact, this little Porsche 924 2.0 Turbo engine is not the air cooled boxer type. It is an single overhead cam solid lifter water cooled inline 4 cylinder engine which Porsche borrowed from Audi during the late 70s then developed the very same engine with different internals etc to 2500 cc. Later on they have used the very same base for Porsche 944 and possibly 928 as well.
Unfortunately the 2.0 liter parts are becoming extremely rare and to date I couldn’t locate other than one supplier which may have the springs. And some performance companies doesn’t deal with the 2.0 engine and valve train parts are not interchangeable with the 2.5 liter etc.
I currently have 2 sets of used springs and will try to make a set out of it with careful measuring.
If you know your valve spring specs you can look thru any spring mfg. catalog and try to find a comparable spring for your engine.
Exactly if I can not make a good set and if I can’t source the original Porsche springs, I will try to find a comparable spring which must work with the existing rotator and the retainer. Thank you very much.

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