Author |
Message |
gimmesomeshelter Samba Member
Joined: May 08, 2004 Posts: 1468 Location: San Carlos, CA
|
Posted: Sun Dec 09, 2012 6:30 pm Post subject: Beehive valve springs |
|
|
Hello-
I would like to install beehive valve springs on my Okrasa repro heads, but so far, I haven't found anything that fits. The stock installed valve height is only 28mm (1.1 inches), and most springs have installed heights of 1.5 inches and larger. So far, the only thing I've found are Yamaha motorcycle springs with an installed height of 1.25, and a max lift of .4 (not so good for my 1.4:1 ratio rockers).http://www.racingsprings.com/Yamaha/sku/145
I suspect I have the following options:
Order custom made springs.
Gain more height by boring into the head.
Gain more height by installing valves (custom?) that have their retainers very close to the tips (btw, stock valves have a ~ 8mm tip. Some valve tips are as small as 2mm).
Comments anyone?
Cheers,
Paul _________________ "I would rather have questions that can't be answered than answers that can't be questioned."
Richard Feynman
Last edited by gimmesomeshelter on Mon Dec 10, 2012 3:07 pm; edited 1 time in total |
|
Back to top |
|
|
Rwoodshvac Samba Member
Joined: March 21, 2010 Posts: 202 Location: VA
|
Posted: Sun Dec 09, 2012 7:03 pm Post subject: |
|
|
Paul
Those springs look nice. You have another option since you will most likely need custom retainers. You. Could have them cupped so that your install height matches the install height of the springs You will still have plenty of valve spring stem with lash caps to get good geometry _________________ 57 Ragtop Semaphore Sedan
48 Aluminum Case drilled tapped, Full Flow Filter
Porsche 356 B Crankshaft 74mm
Porsche 356 B Rods
Shasta Cylinders with JE Pistons 80mm
WW Okrasa Heads worked by Ron Chuck
Speedwell Ratio Rockers 1.25
Dual Valve Springs w/Lash Caps
Blackline Racing Lifter Inserts, Manton Push Rods
34 Pbic Carbs rebushed by Mr Okrasa
Custom Okrasa Intakes enlarged to 34mm
Gene Burg Sump
Fram bypass Filter with Okrasa Oil Cooler
Last edited by Rwoodshvac on Sun Dec 09, 2012 7:05 pm; edited 1 time in total |
|
Back to top |
|
|
modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
|
Posted: Sun Dec 09, 2012 7:03 pm Post subject: |
|
|
1.1 inches? Sorry but I do not believe you. Measure again.
Some snap gauges will not fit, so try this; grind a piece of welding rod/coat hanger to the size that bridges from retainer to seat, then measure that. |
|
Back to top |
|
|
Beetspeed Samba Member
Joined: July 30, 2004 Posts: 429 Location: The Netherlands
|
Posted: Wed Dec 12, 2012 1:36 am Post subject: |
|
|
I just measured my stock 36hp heads roughly and they came out to 33,8mm which is about 1.33".
Nothing suggests WW Okrasa heads having a different installed height as stock.
Then, with custom valves with higher placed retainers, I think you can win 4-5mm at the valve head, making the installed height approaching stock type 1.
IF you're considering beehives, your getting serious about a good valvetrain and if so, replcing that stock ancient valve locating method is the first thing to get rid of.
Getting custom valves also opens the road to much better valves, so you can use even lighter parts (valve, retainer etc).
I don;t think you can or should do this half-way. Either use the stock WW parts or make it all custom. 'Custom' is not neccesarily a high $$ one-off set of parts, but can can also mean using other make stock parts and/or modifying those
I think you're on the right track Paul
Regards,
Walter _________________ '75 SB 1303 2,4ltr T4 turbo: 10.58 @ 129.9mph
'65 Ruska buggy 1192cc EFI 80hp N/A |
|
Back to top |
|
|
modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
|
Posted: Wed Dec 12, 2012 10:12 pm Post subject: |
|
|
Perhaps i was too sharp in that answer.
Just in general a valve spring for this kind of engine should be expected to have approx .150 wire, and 5-6 coils. If we do the math
With some margin away from bind the full open height should be no less than .900"
With modern tech we can bend these rules and make shorter more powerful springs, but okrassa did not have such stuff. Surely there is something wrong, either with your measurement, or with the reproduction heads!
I'd be looking to the ford "modular" beehive springs. They are both common and very good, and available from several manufacturers and a few levels of strength.
To mount the top of the spring above the top edge of the keepers is possible, but only if the top diameter of the spring is large enough to allow enough section for the retainer to have enough strength. If the top diameter is too small, you will have to use different valves, as said, to move the keepers up. |
|
Back to top |
|
|
gimmesomeshelter Samba Member
Joined: May 08, 2004 Posts: 1468 Location: San Carlos, CA
|
Posted: Wed Dec 12, 2012 10:52 pm Post subject: |
|
|
Hello-
BTW, the only information I have about the valve springs comes from the '52 - '57 workshop manual. It indicates that the valve spring free length is 43 mm (1.69") and the loaded length is 28mm (1.10). My heads are bare (no springs, seats, etc.) so I can't really measure anything. They're going to the head porter tomorrow, and I ask him about this when I drop them off.
Cheers,
Paul _________________ "I would rather have questions that can't be answered than answers that can't be questioned."
Richard Feynman |
|
Back to top |
|
|
modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
|
Posted: Thu Dec 13, 2012 12:03 am Post subject: |
|
|
ah, ok
The manuals only say with certainty that 28mm is a "checking height" for pressure.
It may also be the open length, I always thought it was, but I have no proof |
|
Back to top |
|
|
|