Valve spring pressure

[raycemon]

I just had my 1.9 head rebuilt with 2.2 intake valves and 2.0 exhaust valves. To test the closed valve pressure I used a 1.75" air cylinder with a 60 psi gage attached to the non rod end of the cylinder. The air cylinder was put in a radial drill with the cylinder head tilted on an angle plate to line up the valves with the spindle of the drill. I then lowered the air cylinder to apply an axial force on the valve. I had an indicator on the valve so I would know when it just started to open. I then read off the pressure of the gauge. I calibrated the gage with a valve spring that was checked in a valve spring tester ( it was very close to the cross sectional area times the pressure)

Now my question, both exhaust and intake pressures are about 5 pounds below the 93 and 97 pound spec. Is this a problem with these larger valves? I am using a OGTS combination cam. Should I put shims under the springs to increase the the closed force. I don't want to have a problem with valve float at a low RPM.

I'm surprised I have this problem because we tested the spring rates before putting the head together and they were dead on. I checked the heights of the assembled springs with calipers and they look to be right on too.

Thanks for your advice.

[jeff denton]

I never heard of such a method of testing spring pressure.
I've never had any problem with floating valves, either.
Good new stock springs installed at the proper height have worked just fine for me, at up to 7200 rpm or so. I've never exceeded that, that I know of, but you know I don't just sit there and stare at the tachometer... A quick glance there once in a while if I think about it, when there's nothing else to be watching real apprehensively, like a car in front of me. And it's not like conditions change enough to exceed that, we don't shift gears once we get into third. We're at full throttle at all times except at the apex of the turns, where we back off just a bit then stand on it again.
My valve sizes are identical to yours, yes just a tiny bit smaller than a Mustang's in case anyone notices, but nothing to complain about since they are not bigger than a Mustang's. Surely there isn't a huge weight difference between stock 1.9 valves and the slightly larger ones.
A competitor uses titanium retainers with holes drilled in them, quite visible to me but not the tech man. That is how you get effective weight reduction. Unless you want to get into exotic valves. What's gonna matter the most is valve lift, how far that spring has to move the valve back in what amount of time.
So as this all inches deeper and deeper into the world of extreme performance, next thing you know, lift and RPM exceed the limits of the rockers and there's the next problem. Where are you gonna get a rocker that can party that hard?

[tomking]

Since both are off the same amount, and at about the same value, I would suspect simply measurement and conversion error. Bottom line is dont worry about it as most likely that are right on target value. If you really want to know take the springs to the correct spring tester and retest. But I would go with what you got. IMHO.

[wrench459]

Originally Posted by raycemon Now my question, both exhaust and intake pressures are about 5 pounds below the 93 and 97 pound spec. Is this a problem with these larger valves? I am using a OGTS combination cam. Should I put shims under the springs to increase the the closed force. I don't want to have a problem with valve float at a low RPM. I'm surprised I have this problem because we tested the spring rates before putting the head together and they were dead on. I checked the heights of the assembled springs with calipers and they look to be right on too. Thanks for your advice.

If your using a non-stock cam forget those spring pressures.
Larger valves most normaly mean more weight.
Think light grasshopper.

This is only my opinion

[RallyBob]

Stock 1.9 valves and NEW stock 1.9 valve springs and a stock 1.9 hydraulic cam are good for +/- 7400 rpms before valve float. I once built a stock engine just to beat on it on the dyno and find out stuff like this! That was with +/- 95 lbs on the seat and 180 lbs open. Remember that the earlier engines with solid lifters had weaker valve springs (150 lbs open) for comparison.

If you're running bigger (heavier) valves AND a bigger cam profile than stock with stock springs then keep the rpms low...below 6000 rpms. Valve float trashes everything in the valvetrain, you don't want to encounter it!

Bob

[hrcollinsjr]

Originally Posted by RallyBob Remember that the earlier engines with solid lifters had weaker valve springs (150 lbs open) for comparison. Bob

When I had the machine rework a head for me I had them go through my box of used springs and toss the weaker (solid lifter) springs. The machine shop guy thought Opel was nuts when I told him that Opel used weaker springs on the solid lift cams.

Harold

[wrench459]

I see no one has given a number yet.
This is just a guess min. 115lbs. seat pressure should work.
Don't forget to check coil bind..I tend to like .100 clearance @ max lift. between the coils.
This is where the black magic of engine building comes into play.
The small stem head is running less spring pressures than spec. and runs just fine without a problem. The first time I took "the pumpkin" out
over reved the crap out of her 8 grand.

[raycemon]

Thanks for all of your input. I plan to keep the springs the way they are and keep the RPM's down for now.

thanks Bill

[Paul]

Well then keep it under 5500 for now. then work your way up later. It would be a shame to trash a couple of valves on the first time in the car.....
Its gonna pull so strong that you're gonna want to wind it up....

[Tru-Craft]

Under 90 doesn't sound like enough for larger valves from what I have read and the race shops I deal with.
I thought about 110 closed and 180 open was good, depending on the cam lift.
?
My Opel motor with Chevy valves has seen 8,000rpm many times with no problems. Thanks again RallyBob.
Lyle

[wrench459]

Originally Posted by Paul Its gonna pull so strong that you're gonna want to wind it up....

oh yes your spring pressures are very nice it will turn.
Just look out when you slam second gear.

[jeff denton]

What was your cam lift, Bill? And did you leave the shrouds off the retainers?
I still like Dan's "small stem" approach. I would go that way if I ever do another Opel race engine.

[raycemon]

Jeff the cam is hydraulic with a .430" lift and all the shrouds etc are on. I've tried to stay away from shimming because I'm worried about spring bind. I'll check to see how much extra valve travel I have when I get it assemble.

Thanks Bill

[GTJIM]

The intake valve springs are longer than the exhaust springs with more coils and a slightly higher spring rate.

If the exhaust rotators are removed and replaced with a suitable spacer (about 0.300" thick) and Intake springs, set to about 1.650"-1.700" installed height, used on both valves then the whole valve train is a little more balanced and will rev a bit higher. Also choose the lightest spring retainers - from memory Intake ones are lighter than exhaust ones. The use of valve seals on the stems also allows the removal of the 'umbrella' shields and sealing rings - which further reduces weight in the valve train.

Got to be very careful that there is at least 0.040" clearance between the coils at full lift to make sure the springs don't bind up solid. Opels do not have a pushrod to bend so at coil bind the whole valve train goes 'solid' ... with disastrous results.

As the coils get closer and closer together huge amounts of heat are generated by the over-fexing of the spring wire - enough heat to eventually remove the temper from the springs and/or cause stress fractures in the metal leading to spring breakage.

[Paul]

Another trick on the exhaust side of the business is to trash the exhaust spring and rotator and use the intake spring in its place.

[RallyBob]

Originally Posted by Paul Another trick on the exhaust side of the business is to trash the exhaust spring and rotator and use the intake spring in its place.

Or, upgrade to the complete 2.4 spring/retainer/rotator/viton valve seal combo. You end up with straight springs (no tapered exhaust springs), and a newer, slightly stiffer spring setup that allows for about .045" more lift than the 1.9 springs.

The 2.4 retainers are heavier, however they are infinitely stronger than the 1.9's as they are only heavier in the *right* places. Stock 1.9 retainers like to split right in half when the keepers pull through the thin center section of the retainer body...7800 rpms seems to be the breaking point!

[trlmr]

My book says on my 69 motor that Intake closed is 72.7 lbs at factory lift it is 125.6(about .32). The exhaust is 68.4 seated and 132.3 at factory lift (about .32 ). I realize the older cams had weaker springs. When I installed chevy valves I kept the weight as close to factory as possible. I figured this combo would be good for the same rpm's as a factory motor which is fine with me as I don't plan on racing it anyway. I played with them alittle with shims to get as much spring pressure as possible and still have clearance for .43 lift, but I don't have much more than 78lbs on the intake and 70 on the exhaust, and I measured them with the proper tools. It seems to run fine but I won't rev it over the yellow line. Question: GT Jim, Why would you want to take out the rotators? they don't add any weight to the mass. And Paul, my exhaust springs are "behive" I thought they reduced harmonics. The exhaust springs are different dimensions on the bottom than the intake valves, at least on my 69. Did you mill the spring seats to get them to work? I wasn't willing to do that since I didn't know the thicknes of the casting there But I will admit I had to do alot of screwing around to get the retainers how I liked and after 3 different sets I finally made my own because the chevy retainers that were light enough didn't hold the springs properly.

[GTJIM]

Originally Posted by trlmr Question: GT Jim, Why would you want to take out the rotators? they don't add any weight to the mass.

... to make room for the longer intake springs which are less stressed because of more coils and have slightly a higher rating ... and to remove the slightly heavier exhaust spring retainers (they are different to allow rotation of the exhaust valve).

With hardened seats rotation of the exhausts is no longer needed.

[trlmr]

The spring seat diameters are different for the intake and exhaust on my particular motor so, the intake springs won't even seat on the casting - on my motor anyway. Is it possible that the dimensions are different for different years? I've got a head off a 72 in the shop but I've never checked. The retainers I removed were exactly the same dimensions and weight, int and exh. but it is possible someone was in there before me.
Added questions: It would appear to me the exhaust has a higher rate as you can see by my previous post If you look at the ratings seated and at max lift. The exhaust has more pressure at max lift. I would think the rotators would be of benefit since a spring will rotate as it compresses and the rotator would absorb this motion if it rotates on the compresion stroke of the spring. But I don't know if they rotate on compression or rebound.

[GTJIM]

Originally Posted by trlmr (1)The spring seat diameters are different for the intake and exhaust on my particular motor so, the intake springs won't even seat on the casting - ... Added questions: (2) It would appear to me the exhaust has a higher rate as you can see by my previous post If you look at the ratings seated and at max lift. The exhaust has more pressure at max lift. (3) I would think the rotators would be of benefit since a spring will rotate as it compresses and the rotator would absorb this motion if it rotates on the compresion stroke of the spring. But I don't know if they rotate on compression or rebound.

1) The spacer which is used to replace the exhaust rotator is about .300" thick and has a spring seat cut to size for the intake spring.

2) The intake spring has higher closed pressure - reduces 'valve bounce' and the extra coils are less heavily stressed. The exhaust spring quickly runs out of movement if shimmed for higher preload.

3) The rotators just take up valuable spring length after hardened valve seats have ben fitted and the rotators are no longer needed.

BY all means try exhaust valve springs on both Intake (with appropriate spacers) and exhaust with rotator and do some tests to see how they perform as we may be missing something!

[trlmr]

Thanks for your reply GT jim. I won't be installing my exh valve springs on the int or removing the rotators. I was just trying to figure out if I was missing something here. I will do some searching to see what the factory service manual says the spring pressures and rates are for the hydraulic cam motors. In the meantime if anyone out there has one maybe they could look it up. Thanks.

[wrench459]

Originally Posted by trlmr In the meantime if anyone out there has one maybe they could look it up. Thanks.

73 FSM states

closed intake 93 exhaust 97

open intake 182 exhaust 180

The 73 FSM is still available in the download section. Opel File Downloads - Opel Community Forums

[trlmr]

Yep I found it too, but thanks anyway. I guess It would be more accurate to say I found where the service manual is on this site, But with my slow dial up I was having trouble getting what I wanted . so thanks