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Ryan5895
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Joined: January 15, 2012
Posts: 27
Location: Bristol, IN
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 Posted: Tue Apr 17, 2012 2:54 pm Post subject: Dual springs question! |
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I have a 1200 engine and I bought a set of dual springs to complement a cam I bought. So I put the springs on and they are ungodly tough (Bent my diesel spring compressor).
So my first question is: are 40 hp heads shorter between the valve spring seat and the tip of the valve than regular VW heads?
My second question is: Are the dual springs even necessary? I have an FK41 cam with .364 cam lift and with my 1.25 rockers I'm looking at .455 valve lift. I'd rather not run the springs unless its necessary. The redline I'm looking at would be about 5400 max but more likely 4000 because of the crank.
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sgmalt46
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Joined: April 20, 2005
Posts: 433
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| Posted: Tue Apr 17, 2012 3:42 pm Post subject: |
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| don't think you need dual springs . single heavy duty's are enough. plus i think you normally need to cut the spring seats in the head for duals. ? probably why they where so hard to get on.anyway duals are over kill. |
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Ryan5895
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Joined: January 15, 2012
Posts: 27
Location: Bristol, IN
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| Posted: Tue Apr 17, 2012 4:12 pm Post subject: |
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Thats kinda what I figured.. The FK41 is a seriously mild cam and with such a low redline I kinda figured duals were overkill
I put them on a test head I cut for duals so that isnt why they were so hard to get on... legit, I leaned on just one spring with my entire 200 pounds and it moved maybe .100-.150
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slalombuggy
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Joined: July 17, 2010
Posts: 3718
Location: Canada 306
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| Posted: Tue Apr 17, 2012 9:30 pm Post subject: |
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HD single springs will be plenty. Whos duals were you using? Most aren't that bad until you get to the LS-1 Chevy style or K motion springs FYI my new springs are 385lbs over the nose, 250lbs at rest. I had to get the machine shop to put them on for me I bent our HD compressor......
brad
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Ryan5895
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Joined: January 15, 2012
Posts: 27
Location: Bristol, IN
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| Posted: Thu Apr 19, 2012 1:57 pm Post subject: |
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I'm just using some engle duals. I've never worked with true racing springs before so I really had no clue whether or not 200 pounds was alot or not
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slalombuggy
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Joined: July 17, 2010
Posts: 3718
Location: Canada 306
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| Posted: Thu Apr 19, 2012 2:19 pm Post subject: |
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I ran Bugpack HD singles on my 1776 (39x32 valves) with a 110 and 1.25 with steel pushrods for 15 years. Saw 6000rpm lots autocrossing. No problems.
brad
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BB Buggy 121.253mph @ Bonneville 2012
http://www.youtube.com/watch?v=57hMyJmIU10
Raisin cookies that look like chocolate chip cookies are the main reason I have trust issues |
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Busted Knuckles
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Joined: August 18, 2011
Posts: 16
Location: Pennsylvania
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| Posted: Tue May 01, 2012 6:31 am Post subject: |
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Contact the cam manufacturer and ask for specs for seat and open pressure with your valve train components instead of guessing at what should be used,
I've seen over-sprung valves wear down the lobes on cams especially now that the extreme pressure additives are gone from most motor oils. |
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