Installed Valve Stem Height: Tip-to-Seat
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Thread: Installed Valve Stem Height: Tip-to-Seat

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    Opel Rallier since 1977
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    Installed Valve Stem Height: Tip-to-Seat

    I am having a '71 head reworked with the 2.0L valves from OGTS. Shop reports that the valves are installed with a good height relative to the seats looking from the chamber side. However, the stem height from the valve seats is ending up about .100" short of what their A.E.R.A. (?) book show.

    They are measuring .1800" from seat to tip on the intake side, and 1.980" from seat to tip for the exhaust side. These number are about 100" short of what their book shows. Does anyone have those numbers handy for a 1.9L and 2.0L?

    I found the info here for spring installed height for 1.9L being 1.57" IN and 1.36" EX. I'll head to the shop with some retainers and locks and stock 1.9L valves, and we'll see what we get that way, but knowing/verifying the seat to tip length would be appreciated... in case these valves ARE short and the keeper grooves have been moved up to keep spring height the same. That would make the spring height OK, but the rocker geometry would be off to some degree.

    Thanks! Mark B.

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    Member Mercougary's Avatar
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    I won't have those numbers until I get home to some reference material in my office. My guess is that 2.0 valves would also require a potentially different set of keepers and/or retainers and/or rotators. Most specs you are going to find will deal with spring height as in: free, installed, and coil bind.

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    OK, update time; went to the shop and got more complete info, so let me re-state the problem.

    They have installed new ex seats and guides and have finished up the 1st exhaust seat for the 2.0L valve. They are doing this on a Serdi cutter (nice!) and the finished seat looks great and is such that it will flow well at low valve lifts. The exhaust valve is not seated too deep and the edge if the seat blends nicely into the head surface and is not shrouded by any recess. (I should have taken a pix.)

    But here is the issue.... the valve tip to spring pocket is now 1.905"...and the AERA spec is 1.980" on the exhaust side. (And 1.800" for the intake side.) So to get to the AERA book spec, then the valve needs to be sunk another .075". That would make that nice exhaust seat not so nice anymore.

    Sooooo
    - Is the 1.980" spec right for the exhaust spring seat to tip?
    - If not, what is it supposed to be?
    - If yes, then I gotta look at the consequences of running the exhaust valve this shallow into the seat.

    With the valve shallow in the seat, I can use a set of 9 mm lash caps to get the geometry back to close. Not an issue there.

    But then I gotta work on staying away from valve spring bind. This project was going to use the stock ones; there are decent springs for stockers IMHO.. I can take out the exh spring cap and even the exh rotator (and shim the crap out of it!), but then the intake is another matter, if it ends up at the same tip height as the exhaust right now. The spring math does not look like I can do that with stock springs, the .407" lift of the Torquer cam AND the valves sitting .075" low in the head.
    Last edited by Manta Rallier; 4 Days Ago at 10:58 PM.

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    Quote Originally Posted by Mercougary View Post
    I won't have those numbers until I get home to some reference material in my office. My guess is that 2.0 valves would also require a potentially different set of keepers and/or retainers and/or rotators. Most specs you are going to find will deal with spring height as in: free, installed, and coil bind.
    Tnx Merc. I'd appreciate what you can find. I need to call the shop early tomorrow and give them direction; the head is set up but they need the Serdi open to get to other work.

    FWIW... I did measure the intake tip to spring seat on a stock '75 head and it averaged 1.770" which agrees decently well with the AERA number of 1.800". The AERA number may include some 'service' wiggle room.... i.e., in the case where you re-finish the seats and valves, the valves are going to sink a bit and the tip to seat height will increase a bit. I did not check their book to see if the AERA number is maximum or nominal. The shop guys said most of the time they get a range number, not just a single number.

    As for keepers, the stem grooves looked the same as for stock 1.9L valves, but I did not directly fit them up to be sure. So the retainers ought to work if the keepers do. Same stem diameter (9 mm).

    Tnx!

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    3000 Post Club Site Supporter P.J. Romano's Avatar
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    Installed height of valve springs for 1.9 engine is:
    Intake: 1.57" (40 mm)
    Exhaust: 1.36" (35 mm)
    Old racers never die. They just go bench racing.

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    Tnx, PJ. In actual practice, to work efficiently with the Serdi machine, the valve tip-to-seat number is what is needed.
    Last edited by Manta Rallier; 4 Days Ago at 07:54 PM.

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    The spec sheet I'm referencing only covers the 1.9L I did not find a dimension for spring seat to valve tip. Overall lengths are 4.843" (123mm) INT, and 5.021" (125mm) EXH. might give you something to go on for comparison. Sorry I can't be of more help.

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    Hey no problem.... I appreciate the look-see!

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    Quote Originally Posted by Manta Rallier View Post
    OK, update time; went to the shop and <SNIP></SNIP>
    But here is the issue.... the valve tip to spring pocket is now 1.905"...and the AERA spec is 1.980" on the exhaust side. (And 1.800" for the intake side.) So to get to the AERA book spec, ........<SNIP> ...
    AERA = Automotive Engine Rebuilders Association

    In case you were wondering (I was)!

    Doug
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    FWIW.... I'm heading down the road of switching valve springs and adding lash caps to accommodate the low valve stem tips. Another engine mod 'on-the-fly' LOL

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    An update on this matter FWIW. I got my head back ('71 casting) and partially assembled and got to directly measure tip-to-seat depths and also installed heights.

    Ex Installed Spring Height: 1.345"
    Ex Tip-to-seat distance: 1.905 without rotator

    In Installed Spring Height: 1.530"
    In Tip-to-seat distance: 1.755"

    If I normalize the installed spring heights to the standard 1.36" EX and 1.57" IN, and apply that change to the tip-to-seat heights, then I get:

    Exhaust Tip-to-seat height should be 1.920" without rotator. ..... Does not agree with the AERA number of 1.980". I think my number is correct.

    Intake Tip-to-seat height should be 1.795".... Agrees with the AERA number of 1.800"

    BTW, the local machine shop spoke to the AERA people and found out that this particular AERA data for the 1.9L Opel was 'field reported'...meaning it did not come from GM. So it could very well be in error.
    Last edited by Manta Rallier; 10 Hours Ago at 01:12 PM.
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    Quote Originally Posted by Manta Rallier View Post
    FWIW.... I'm heading down the road of switching valve springs and adding lash caps to accommodate the low valve stem tips. Another engine mod 'on-the-fly' LOL
    Hey Manta Rallier, I am having similar problems with my Bonneville bike. I installed Honda CBR600 F3 springs & valves (4 mm stems instead of 8mm) and the rocker arm (single cylinder) adjustment is causing me problems (very close to falling off the top of the valve). Are the lash caps custom and where do you get them? The basic Honda does not use any so I guess I need custom or universal.

    Thanks, Doug

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    Senior Member The Cub's Avatar
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    MR, Thank you for posting your information, can you please post the 2.0L stem heights once you get this all ironed out and have decided? Iím hoping to use your findings as a good reference for when I bring my head back in for when they reset the valves along with the replacement of the guides.

    I donít know why but the first go around with the 2.0 valve conversion for reasons beyond my understanding the machine shop had a devil of a time getting the stem heights right. I certainly didnít know what to tell him. He eventually worked something out on his own. Iím also curious as to what I currently have. Thank you

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    Hey TC, these are indeed for 2.0L valves in a 1.9L head. So that ought to do it for you.

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    Quote Originally Posted by slracer View Post
    Hey Manta Rallier, I am having similar problems with my Bonneville bike. I installed Honda CBR600 F3 springs & valves (4 mm stems instead of 8mm) and the rocker arm (single cylinder) adjustment is causing me problems (very close to falling off the top of the valve). Are the lash caps custom and where do you get them? The basic Honda does not use any so I guess I need custom or universal.

    Thanks, Doug
    Hey Doug, I'd guess part of your issue is from such a radical stem diameter change. Question: Is this 'falling off of the stem' just at max valve lift or is it near both open and closed valve positions?

    As for lash caps, you're in luck. I just researched lash caps for 9 mm which are getting to be a bear to find. This might be your best bet for a source of 4 mm lash caps; they custom make shims to order. You can request a quote through their site. They quoted me $9 AUD each for qty-8 of 9 mm lash caps, plus $29 AUD shipping.
    Lash Cap Shims

    And hare is another source I just found by googling '4 mm lash cap'; looks like they are selling lash caps from Cat Cams, so you might look there:
    https://www.peugeot-tuning-parts.co....rs-valves.html

    Kibblewhite Precision is another possible source but they don't list 4 mm in their on-line catalog.
    Last edited by Manta Rallier; 1 Day Ago at 06:04 PM.
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    Senior Member The Cub's Avatar
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    Quote Originally Posted by Manta Rallier View Post
    Hey TC, these are indeed for 2.0L valves in a 1.9L head. So that ought to do it for you.
    Are you going to use the lash caps to bring the heights up to the bold printed numbers then? When all is said and done you should be able to put a straight edge across the top of all 8 and they should be even, correct?
    The ladder, if Iím remembering correctly (it has been a while) was what the machine shop I used had trouble with.

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    Hey TC,

    Actually, no, I am very probably going away from the lash caps for a couple of reasons:
    - Finding 9 mm lash caps has become a bear nowadays.. this stem diameter is just obsolete now. I'd probalby end up getting them out of AU.
    - The exhausts as they set here are only .015" below where they ought to be... IMHO, not enough to worry over for any rocker geometry effects on what is just a warm-over of a stock engine.
    - The intakes are about .040" below where they should be. So, yes the intake tips are around .025" below the exhaust tips with the straight edge test. Mmmmm... might be worth worrying over with a true hi-po build. But I am changing valve springs now anyway and am trying a different retainer with a + offset on the intake side that I hope will raise the spring installed height.

    To further make a short story long.....Why change the springs? Well, I worked through the clearance to spring bind with the stock springs and stock valve tip heights, and did not like what I saw with even this mild Torquer cam.
    - With the stock springs binding 100% at .915" for the exhaust, and 1.090" for the intakes
    - keeping the exhaust rotator
    - using the .407" Torquer lift
    - you get .073" clearance to bind in the intake side, and only .038" clearance to bind on the exhaust side. That latter number in in no way acceptable.

    The actual lift is probably a bit less than .407" and you can remove the exhaust side spring 'cap' to get more clearance there, which help.....but the springs start to have coils touching at higher hard-bind heights than above, which makes things worse. And I am losing installed height, so it is just not acceptable in any way, shape, or form. I was really surprised that the stock springs have so little margin for more cam.

    So new springs, different retainers on the intake side at least.... typical snowball effect when one thing changes LOL. (And I can better set the spring pressures where I want.)

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