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Discussion Starter · #1 ·
Had the head magnafluxed and cleaned today for it's frshening-up. The machine shop had a question, so I'll post it here for Rally Bob.

The exhaust springs have cups, while the intake springs are on shims. They were wondering, "why?" As when they put the springs on a compression tester, one set went to 350, the other set went to 300.

Then they asked why one set of guides was brass, and the others weren't? I told them that I'm sure there is a reason.

They were transfixed with the head. "Whoever made this did a lotta work. We don't understand much of it, but it sure looks nice."

I told them not to fool with anything. Just do a valve job, and put it back together the way they found it.
 

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I only ported the head, I did nothing else to it. I didn't choose the parts either(springs/retainers), they were from apparently from Mantapart years ago. If I recall, the local machine shop put in 4 exhaust guides because they were badly worn, hence the bronze guides (this is what they had in stock). Sorry if I raised more questions than I answered! But it was a 'quickie' porting job for a friend of mine (Ernie Bello), I believe I didn't even get paid for it, but rather swapped some parts for my labor.

Bob
 

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Discussion Starter · #3 ·
Thanks!

Quickie job or not, it is really nicely done!

The machinist told me," Looks like a lot of thought is behind this work." He then took me through the head, and what he could tell was done. You sure did remove material from behind the valves. Because of my interest and questioning, I also got a 'quickie' education in outlaw Indy racing, which is the machinist's hobby.

The springs are doubled with a dampener, 1/2 with cups, 1/2 with shims. The head was machined 1/2 for cups, 1/2 for shims. The machinist was just curious as to why different compression rates were obviously created. I didn't know if there was an Opel specific reason, or not.

Speaking of Ernie, I'm going to get one of his shortblocks with 94mm pistons; Since, he moved up to 2.2l he offered one to me. He said it was recently rebuilt, and is now stored. Would you happen to know anything about that particular setup he used? I'll ask him as well, but figured I'd give him time to dry out from that last storm.
 

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Scott McDonald said:
The springs are doubled with a dampener, 1/2 with cups, 1/2 with shims. The head was machined 1/2 for cups, 1/2 for shims. The machinist was just curious as to why different compression rates were obviously created. I didn't know if there was an Opel specific reason, or not.
The reason for the cups is the exhaust rotators are usually not used with performance springs, and when removed they leave a large void which must be filled with something which will retain the springs and keep them from walking around at their base.

Bob
 

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Hi Pressure!

Those spring pressures seem pretty high - is that at the full lift point? The shims and cups should be to get the spring installed height the same on exhaust and intake - are you sure the shims don't belong under the cups?

BTW: Pictures of nice port work is always appreciated! ;)
 

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GTJIM said:
Those spring pressures seem pretty high - is that at the full lift point?
I agree those pressures are high. At what valve lift was that measured at? Makes no sense to measure at .550" lift if you have a .430" lift cam.....
 

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Discussion Starter · #8 ·
Rally Bob-The springs were removed from the head and placed on a machine that compresses them. On this machine, is a gauge. The springs are compressed all the way down with a lever, and the gauge was read. I hope I'm making sense, as I've no clue on the proper way to test valve springs.

The cups fit machined areas sized for them, while the shims fit the other holes. I saw the last cupped spring being removed, and there weren't shims in it.

Hi Tom-The shop is named, "X-Treme Machine," here in League City. Are you still planning on using these 2.0l valves?

GT Jim-I'll get pics as soon as I get it back.
 

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Discussion Starter · #9 ·
Oh yeah,

When I first checked the head I didn't notice the exhaust being any higher/lower than the intake springs, so I'm assuming that installed, they end up being the same height.
 

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Scott McDonald said:
Rally Bob-The springs were removed from the head and placed on a machine that compresses them. On this machine, is a gauge. The springs are compressed all the way down with a lever, and the gauge was read. I hope I'm making sense, as I've no clue on the proper way to test valve springs.

Yes Scott, that is the way to check valve springs - first compress to the installed height 9 about 1.65" to 1.70" usually; that gives the valve closed pressure. Then compress a further amount equal to the lift of the cam ( say .450" or what ever yours actually is) So the spring is compressed to 1.65" minus 0.45" = 1.20" and the pressure for the valve open read off.

The cups fit machined areas sized for them, while the shims fit the other holes. I saw the last cupped spring being removed, and there weren't shims in it.

The installed height of both springs should be close to the same measurement which is around 1.65" to 1.70" for the standard intake spring. THe exhaust spring seat is deeper into the head due to the valve rotator being under it in the standard setup. That is why there is a cup under the exhaust to bring the spring seat up to the same height as the intake spring seat. It looks like spacers have been used under the intake springs to fine tune the installed height.

Hi Tom-The shop is named, "X-Treme Machine," here in League City. Are you still planning on using these 2.0l valves?

GT Jim-I'll get pics as soon as I get it back.
Thanks, Scott pictures would be great - then we can all admire some more of Bob's porting work!
 

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Discussion Starter · #12 ·
GTJIM said:
Yes Scott, that is the way to check valve springs - first compress to the installed height 9 about 1.65" to 1.70" usually; that gives the valve closed pressure. Then compress a further amount equal to the lift of the cam ( say .450" or what ever yours actually is) So the spring is compressed to 1.65" minus 0.45" = 1.20" and the pressure for the valve open read off.
The spring was compressed fully, sans arithmetic. The rate was read just prior to the bottoming-out point of the spring only, and nowhere else :confused:. I gave them the specs to the Irmscher Sprint tyle cam as well.

Hopefully when I get the s/b, they can time the cam correctly.
 

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Relief!

Well that explains the 300 & 350 lbs rating for the springs - they were compressed past the open measurement. Usually Opels have spring pressures of about 95 to 105 lbs at closed length and 250 lbs at the open height.
One of the other things that can be tested using this sort of spring testing machine is how much further the spring can be compressed after reaching the "open" dimension - this is important as the spring should not be approaching "spring bind" or totally compressed att he fully open measurement. Looks like your springs are AOK and probably in the required specification range.

Timing the cam is one of Opels little endearing foibles! Even the Factory Service Manuals cam be misleading as the drawing of the engine is actually WRONG in some of them - nice huh! Fortunately the picture of the crankshaft keyway position and the text is correct. The keyway in the crankshaft MUST face upwards and #4 cylinder be at Top Dead Centre with the camshaft turned so that the valves for #4 cylinder are closed ( the cut outs in the cam for access to the head bolts will be in the correct position as this setting). Once the cam wheel is bolted on, with the dot lined up with the mark in the presssed sheet metal "shelf" that is bolted to the block beneath it, the motor must be rotated one complete revolution. This puts #1 cylinder at TDC with the valves shut and the motor is now in the postition to have the distributor installed and lined up for firing on #1 cylinder.

That is why Opels are usually timed 180 degrees out from where they are suposed to be - some twit in the design stages obviously put the cut outs on the camshaft in the wrong place and we have struggled to cope ever since!

HTH
 
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