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Race Grade Valve Springs

 
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Mon Aug 30, 2021 11:31 pm    Post subject: Race Grade Valve Springs Reply with quote

My 7mm valve stem 931 head is stalled as the machinist I trust is 6 months behind, so I pulled out my spare 931 head and started chasing valve springs to work with the stock valves. It is well know that at higher RPM's the valves bounce off the seats when closing a couple of times and the way to help control that is to have a higher closed pressure, two motor builders I know recommended a closed pressure of 110 to 120 lbs in place of the stock 65 for a race motor.

After a long, unsuccessful hunt for some standard springs that would fit the 924 retainers, I had borrowed some paper catalogs that list springs by size as well as application, unfortunately none were European of Japanese for more options and could find nothing like this on internet. I contacted RD Spring a medium sized primarily motorcycle parts company who also makes high performance spring setups for 944's both NA and turbo and they have 9mm valve stems. After several calls and drawing up both the 931 and 944 heads I sent him a valve assembly including springs, retainer and keepers. His initial thought was to use the 944 arrangement with a spring of about 1.550 installed height. but with the deeper 931 pocket he did not want to use a spacer/seat of the needed depth when eliminating the valve rotator, He settled on using some rather light duty(rate 330 vs more typical 450-500)beehive spring for a LS Chevy motor with an installed height of about 1.850 with installed pressure of 110 and open of about 260lb at .500. Stock rates are approximately 65-225. His 944NA ones are 115-240(I believe for the Ford4.6/5.4 motor).

He had to modify the beehive retainers as the stock keepers are 6 degree versus the more normal 7 and made new valve seats and I'll use the stock guides and seals. The cost was under $350 and delivery was about 2 weeks. Much less expensive than the Ferrera small stem arrangement.

I weighed the stack valve train including 1/2 of the spring weight and had 266 gm, the new arrangement with lighter weight spring and retainer and a Parner/ACM lifter with Alfa shim for clearance will be about 210 gm a weight savings and force required to open it of about 20%.

I talked to him about the NA head where there isn't a rotator on the intake and he said he could figure out a setup for it, and could also do lower open and closed pressures for non race applications. I would have preferred the 1.550 lift springs and rate which would also have been more expensive, but he said that he would not make a spacer of the thickness required.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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gegge  



Joined: 27 Jul 2007
Posts: 1124
Location: Sweden

PostPosted: Tue Aug 31, 2021 6:06 pm    Post subject: Reply with quote

Interesting option. I belive I used a Ford spring in my 931 head with 6mm stems.

EDIT:

BEEHIVE VALVE SPRINGS
Type/Material/ Seat Open Rate Coil Max Net
Part# Application O.D. I.D. Press. Press. Inch Bind Lift

FORD 4.6L/5.4L - SOHC V8 - 24 VALVE - 2005-2007
S2007 Single Beehive Ovate.PAC Alloy .915 .567 105 lbs 270 lbs 300 lbs 1.060” .550”
Performance OEM replacement 1.025 .662 @1.670” @1.120”
This Spring requires Ferrea Steel Retainer #E10032 OR Ferrea Titanium Retainer #E12015 and Ferrea Spring Seat Locator # SL1088 OR
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Tue Aug 31, 2021 10:36 pm    Post subject: Reply with quote

We were headed that way until he figured out the thickness of the spacer required under the valve springs and just said no. It was definite enough I didn't question it. He is the third generation owner of the company and knows much more about it than me. It was also less expensive as the LS springs were $12+ each while the others were $26+.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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