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914World.com _ 914World Garage _ Valve geometry hell

Posted by: malcolm2 Jun 25 2020, 09:19 PM

Help me out here. Working on the subject and can’t figure it out.

9590 cam. 0.426 lift on the card. Adjustable pushrod tool.

I get to 0.426 lift. But the geometry between the swivel foot and the valve is wack. That is shortening the PR.

Stretch out the PR and i get 0.430 lift and almost straight valve to adjuster. The foot is too tight to the 1.7 rocker boss.

Bought some shims to lift the rocker stand and try that.

Question is: why am I so far off the card lift? Does it matter?

Posted by: wndsrfr Jun 26 2020, 05:53 AM

QUOTE(malcolm2 @ Jun 25 2020, 07:19 PM) *

Help me out here. Working on the subject and can’t figure it out.

9590 cam. 0.426 lift on the card. Adjustable pushrod tool.

I get to 0.426 lift. But the geometry between the swivel foot and the valve is wack. That is shortening the PR.

Stretch out the PR and i get 0.430 lift and almost straight valve to adjuster. The foot is too tight to the 1.7 rocker boss.

Bought some shims to lift the rocker stand and try that.

Question is: why am I so far off the card lift? Does it matter?

Len Hoffman is the one to listen to....HAMInc.... shoot him a PM if he doesn't get here first

Posted by: Olympic 914 Jun 26 2020, 06:03 AM

When using the swivel foot on the 1.7 rocker arms you have to grind back the bottom of the rocker arm.

Some do it on a milling machine , but you can do it with a grinder. Just be sure to keep it level.

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Posted by: malcolm2 Jun 26 2020, 06:23 AM

I do plan on removing material. Is it about 0.060” that needs to come off?

It just seems odd to have a published lift that can’t be used.

Posted by: nditiz1 Jun 26 2020, 07:15 AM

I had my rockers milled, but I can't remember how much. I rebuilt this assuming a mild cam. I think I was right around your numbers. I remember needing to shorten the stock PR by a very small amount.

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Posted by: 914werke Jun 26 2020, 08:33 AM

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Posted by: Mark Henry Jun 26 2020, 09:49 AM

Don't worry about the lift vs the card.
Instead worry about getting the geometry correct.
I take more than .060 off and the countersink must clear the foot in all directions.
I don't use shims, at least not much shim.

I cut the swivel foot down and recut the slot, as the screws can/could hit the valve cover.
The cool trick for doing this is to put two 32T blades in your hacksaw, first cut the slot deeper, then grind off the excess thread.

Posted by: malcolm2 Jun 26 2020, 09:49 AM

The counter sink is a nice touch. great picture. Tells the whole story. Not sure I can do that. Might have to take them somewhere.

I measured the boss (isn't that what the threaded part of the arm is called?). I got 0.492 on two, 0.502 on one and 0.496 on the last.

I figured to take the 0.060 from the 0.492 and get 0.432. Then shoot for that on all 4.

So at this point all my lift attempts with the adjustable push rod tool have yielded a lift with in +/- 5% of the card. So I should not worry about the final lift result?

Posted by: malcolm2 Jun 26 2020, 09:55 AM

QUOTE(Mark Henry @ Jun 26 2020, 10:49 AM) *

Don't worry about the lift vs the card.
Instead worry about getting the geometry correct.
I take more than .060 off and the champher



Cool. That is the direction I was heading. Don't really have much choice otherwise.


Posted by: Mark Henry Jun 26 2020, 11:03 AM

QUOTE(malcolm2 @ Jun 26 2020, 11:55 AM) *

QUOTE(Mark Henry @ Jun 26 2020, 10:49 AM) *

Don't worry about the lift vs the card.
Instead worry about getting the geometry correct.
I take more than .060 off and the champher countersink



Cool. That is the direction I was heading. Don't really have much choice otherwise.


Take the .060 off the smallest rocker then match the rest.
After a generous countersink it won't look like much thread left, maybe less than a 1/4", but it's never been an issue.
To get very little shim you only have the screw about 1-1/2 turns in, that's why you need a generous countersink and thus you have a lot of thread sticking out the top.
If you need reassurance it's how Raby does them.

The geometry... well I see some of the threads and giggle at all the complication biggrin.gif
At one half of measured lift the the adjuster screw should be in line with the valve stem. The rock (degrees) of the swivel foot from open to close should be equal. That's about all you need to know.

Just an FYI If you have well machined heads, like Len's, then all the valve stems are equal, if you start into needing different lengths of PR there's something wrong with the head machining and/or case deck.

Posted by: malcolm2 Jun 26 2020, 11:35 AM

Thanks for the input. Heads are camper specials.

Posted by: malcolm2 Jun 29 2020, 05:05 PM

I have removed about 0.060”. There is no way i am gonna be able to counter sink. I tried a shop today. He wanted nothing to do with it. He did try one, but just succeeded in heating up the rocker and was pissed that he may have ruined his tool. I have another to try tomorrow. But that guy succeeded in bending my 1.8 crank 7 years ago. Maybe one other shop to call in Nashville tomorrow.

So 8 rockers don’t weigh that much. Who has a shop i can send them too?

Thanks.

Posted by: wndsrfr Jun 29 2020, 09:19 PM

QUOTE(malcolm2 @ Jun 29 2020, 03:05 PM) *

I have removed about 0.060”. There is no way i am gonna be able to counter sink. I tried a shop today. He wanted nothing to do with it. He did try one, but just succeeded in heating up the rocker and was pissed that he may have ruined his tool. I have another to try tomorrow. But that guy succeeded in bending my 1.8 crank 7 years ago. Maybe one other shop to call in Nashville tomorrow.

So 8 rockers don’t weigh that much. Who has a shop i can send them too?

Thanks.

Send a PM to Len Hoffman HAMInc......

Posted by: Highland Jun 29 2020, 11:14 PM

I used this guy and he seemed to do a good job.

https://www.thesamba.com/vw/classifieds/detail.php?id=2130116

Posted by: BeatNavy Jun 30 2020, 04:27 AM

QUOTE(Highland @ Jun 30 2020, 01:14 AM) *

I used this guy and he seemed to do a good job.

https://www.thesamba.com/vw/classifieds/detail.php?id=2130116

I used him as well. He's responsive and reliable.

Posted by: TheCabinetmaker Jun 30 2020, 04:48 AM

My 9550 Cam, .426 lift ended up at 436. Bonus!

Posted by: nditiz1 Jun 30 2020, 06:44 AM

QUOTE(BeatNavy @ Jun 30 2020, 03:27 AM) *

QUOTE(Highland @ Jun 30 2020, 01:14 AM) *

I used this guy and he seemed to do a good job.

https://www.thesamba.com/vw/classifieds/detail.php?id=2130116

I used him as well. He's responsive and reliable.

I also used him for my build.

Posted by: malcolm2 Jun 30 2020, 07:53 AM

Len and i talked about other machine work. IIRC he does not do walk in stuff. Mostly his own head work. I was lucky on my 1911 build in 2012. HAM found a 2nd 1.8 head for me and rebuilt 2 for me. This time i went with new type 4 store camper specials. Built by HAM. I got better service working with LEN the 1st time vs TIV store.

As of right now I ended with IN 0.430 and EX 0.408 both yielded a good 1/2 lift angle. Just a smidge of swivel foot clearance with no counter sink.

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