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Just Some Dude in Jersey
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Since no one has answered you yet, I'll keep the kettle boiling with these questions:

Why do you want to know? What good would it do you to know? What is your evil master plan?

:veryhappy
 

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Discussion Starter · #3 ·
Since no one has answered you yet, I'll keep the kettle boiling with these questions:

Why do you want to know? What good would it do you to know? What is your evil master plan?

:veryhappy
With that kind of introduction/setup, I wish I had a more menacing reply, something along the lines of "Mark1 Conquers the Universe", (with the knowledge of the 2.4l spring lengths in hand). The plain vanilla, real reason is that I've gotten a 2.4 head, and I'm having a local machine shop assemble it. The machinist is not an old Opel hand, and by way of checking things he wanted to know what the installed spring heights should be. Seemed like a reasonable check to me, so I thought I'd ask.

Ultimately, I'm just trying to get a better motor, for a reasonable (for me) price. I got the head, which I believe should flow better than a X19 for a start on my motor which is bored to 2.0. Down the road, I'll install a 2.2l crank I found, with pistons from Venolia (I think), and get pretty near to a 2.2l. Good thing about that is I get rid of the dished pistons that are in there, that someone used when the car had a blower.
 

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... I've gotten a 2.4 head, ...which I believe should flow better than a X19 for a start on my motor which is bored to 2.0. Down the road, I'll install a 2.2l crank I found, with pistons from Venolia (I think), and get pretty near to a 2.2l. Good thing about that is I get rid of the dished pistons that are in there, that someone used when the car had a blower.
I haven't had the pleasure of working on a 2.4 yet, but IIRC, the chamber volume of a 2.4 head is quite large compared to the 1.9 and 2.0 heads. Even with flat top pistons, the compression ratio of a 2.4 head matched to a 1.9/2.0 crank throw will be very low. With dished pistons, I wonder if it will even run.
 

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I thought I remembered RallyBob saying way back that 1.9 & 2.0 head volumes are around 52cc (+1 to 2cc depending on valve seat wear) and the 2.4 head volumes were around 54cc ( again maybe a bit more for wear). Basically not enough to worry about.

And yes 2.4 heads flow much better the 1.9 and 2.0 so that's a good plan.
 

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Opeler
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You are right Vinnie, 2,4 compression chamber is approx 54 cc, not much larger than 1.9 head (52.5 cc). This is the reason why 2.4 has dished pistons.
2.0 engine has flat pistons, so the CR with 2.4 head should be (1979cc:4) : 54cc=9.2.

I am puzzled though, why is the shop interested in installed height of valve springs. I would be more interested to know the height of uninstalled springs, to be sure that they are not "tired".
 

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I hate to be captain obvious here
spring height and stem height are two very different things.

I've put money on the shop manic wanting to know the overall stem.
You can adjust spring heights with shims or by cutting the lands.
 

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Discussion Starter · #11 ·
You are right Vinnie, 2,4 compression chamber is approx 54 cc, not much larger than 1.9 head (52.5 cc). This is the reason why 2.4 has dished pistons.
2.0 engine has flat pistons, so the CR with 2.4 head should be (1979cc:4) : 54cc=9.2.

I am puzzled though, why is the shop interested in installed height of valve springs. I would be more interested to know the height of uninstalled springs, to be sure that they are not "tired".
I'd be interested in the uninstalled height, too. That would be helpful. If anyone know, please speak up. But, possibly, getting the installed height may be easier for most folks (say if they have a head on the shelf, or in the car). And that's what the machinist asked for.
 

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Discussion Starter · #12 ·
Rotators

Can anyone tell me if the rotators for the 2.4 are different than the rotators for the 1.9/2.0. I've gotten a set of rotators (turns out they're from a 1.9), and they measure 28.8 mm (across the raised circular ridge). And that dimension seems to be a bit too large for the springs I have.
 

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Can anyone tell me if the rotators for the 2.4 are different than the rotators for the 1.9/2.0. I've gotten a set of rotators (turns out they're from a 1.9), and they measure 28.8 mm (across the raised circular ridge). And that dimension seems to be a bit too large for the springs I have.
The 1.9 heads use two different sprint types. A taller, straight spring on the intakes, and a shorter tapered spring (wider at the base) on the exhaust side. The exhaust rotators are therefore large in diameter to correspond to the spring OD.

The 2.4 heads use straight (symmetrical) springs on both the intake and exhaust....and the exhaust rotator is smaller in diameter than those used on a 1.9 head.
 

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You are right Vinnie, 2,4 compression chamber is approx 54 cc, not much larger than 1.9 head (52.5 cc). This is the reason why 2.4 has dished pistons.
2.0 engine has flat pistons, so the CR with 2.4 head should be (1979cc:4) : 54cc=9.2. <SNIP>
PJ and all, remember that the compression ratio measures ALL the air in the engine (including that in the compression chamber) and then compresses it to compression chamber volume!

The formula reads CR = (SV+CC)/CC where SV is the swept volume. That means the 2.0 engine (1979 cc) has a CR = ((1979/4) + 54)/54 = 10.16 to 1 (not 9.2).

It is a common error so I thought I should point it out.

HTH -- Doug

Once an engineer, always an engineer! :yup:
 

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Discussion Starter · #15 ·
You are right Vinnie, 2,4 compression chamber is approx 54 cc, not much larger than 1.9 head (52.5 cc). This is the reason why 2.4 has dished pistons.
2.0 engine has flat pistons, so the CR with 2.4 head should be (1979cc:4) : 54cc=9.2.

I am puzzled though, why is the shop interested in installed height of valve springs. I would be more interested to know the height of uninstalled springs, to be sure that they are not "tired".
Here's another reason the shop might be interested in the installed heights; from my '73 GT FSM, p. 6A-29:

I n t a k e Exhaust
Valve Spring Pressure
Valve Closed _______........___..,,,,,,............ 1.57 In. at 93 Lbs. 1.36 In. at 97 Lbs.

So I'm sure the machinist is looking at a similar manual for say a Frontera A, or something with a 2.4l motor, trying to check things, and the number that is available in the FSM is the installed height (that's what the above is, right?); so you check against what the manual gives you.
 

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Discussion Starter · #17 ·
The 1.9 heads use two different sprint types. A taller, straight spring on the intakes, and a shorter tapered spring (wider at the base) on the exhaust side. The exhaust rotators are therefore large in diameter to correspond to the spring OD.

The 2.4 heads use straight (symmetrical) springs on both the intake and exhaust....and the exhaust rotator is smaller in diameter than those used on a 1.9 head.
Thanks.
And on the 2.4, are the intake and exhaust springs the same length?
 

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<SNIP> As I remember the length is 40mm, the idle stroke is 13mm and the spring rate is 115Kp</SNIP>
OK Norbert, I am reading this in 2 different ways: 1. the "installed length" is 40mm (1.57") and the "free length - idle stroke" is 13mm more (40+13) or 53mm (2.087"). However, for a spring "rate" of 115Kp we need to know what the lineal dimension is in the Kp: kg per mm? If so, 13 mm x 2.2 lb/kg x 115 kg/mm = 3289 lb (however this is NOT lb force so must be "corrected" for gravity (engineering blab) so divide by 32.2) or 102 lbF on the valve seat (I hope)! The installed height compares well with the 1.9L head and the 102 lbF COULD also make sense because the larger valves(?).

2. The other way I was reading your input was a "free length" of 40mm and a valve closed ("idle stroke") compression of 13mm (which is still 102lbF) for an installed height of 27mm (1.063"). This installed height is too low as it wouldn't provide for more than about 1/4" of valve lift.

I've tried to think of another way to read the "spring rate" but cannot right now. Any suggestions?

HTH -- Doug
 

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The formula reads CR = (SV+CC)/CC where SV is the swept volume. That means the 2.0 engine (1979 cc) has a CR = ((1979/4) + 54)/54 = 10.16 to 1 (not 9.2).
Don't forget H/G dia. and thickness,valve/dish of piston and crown to top ring space.
 
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