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PacerLarry 
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Joined: Aug/02/2010 Location: New Lenox, IL Status: Offline Points: 103 |
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 Posted: May/12/2019 at 1:06pm |
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You are not a downer at all Ken. I appreciate the knowledge, which is why I came to the experts. The way you explained everything makes perfect sense to me. My dad and I built the heads ourselves, and we measure and shimmer the installed height on each spring, so I am confident in that. We checked the sear pressure of each spring during assembly, but I have not gone back through after running the motor. A weak spring could be possible, but I also wonder if the springs are just not strong enough. They were matched to the cam by Comp, but I wonder if my one piece stainless valves are heavier than the stock valves, thus requiring more spring pressure all together.
So I could spend money and time on stronger springs, and limited travel lifters and getting everything into that perfect window you talked about, or I can cut my losses, get a recomendation on a good solid cam with springs to match and swap it out and be done. So the million dollar question I need to ask, if I go with a solid cam, how much can I trust the spring recomendation I get?
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Ken_Parkman
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Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1814 |
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Posted: May/12/2019 at 6:34pm |
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That's a tough one. Those spring specs are in the ballpark of where I would think you should be, maybe the load over the nose could be a bit more, but it does seem basically good. There are a lot of factors, and lobe design/profile is a big one. We did chase valve float on a BBC with a XE HR cam, so I'm starting to get suspicious of the XE lobe design. And you have almost no room to shim anyhow as the 986 spring is listed @ 1.15" coil bind, so you are only .075" off now at an installed of 1.75".
You sorta have to trust Comp, but your experience so far is only fair. I'd give the tech line a call and explain what has been happening and see what they say. But a lot of those guys are just cam pickers for street cars, a lot easier job. There smallest solid in the Comp catalog is the 290B-6 which is 255 degrees intake@ .050"; I've used it a bunch of times with good success. It's sorta my "cookbook" cam, add it to a good 8" converter, torker, 850, a bit of head work, and some good bracket set up and tuning and it has never failed to run in the 10's. But your converter is a little mild for it so you might want a little milder cam, something in the 240-245 degree area. Really that should not be a hard combination to spring, something in the 130 seat and 330 nose area. BTW run a race oil with these FT cams - I run the Joe Gibbs stuff.
Edited by Ken_Parkman - May/12/2019 at 6:36pm |
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PHAT69AMX
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Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5926 |
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Posted: May/12/2019 at 10:58pm |
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Would / are these Crane Valve Springs at 1.88" Installed Height be any good for the existing Cam ?
Head Spring Seats may need work to fit, Crane 99893-16, 120# at 1.88", 315# at 1.38, 1.080" Coil Bind Ht., 391 lbs./inch Rate vs existing Comp Cams 986-16, 1.150 in. Coil Bind Height, #322 lbs./in. Rate Edited by PHAT69AMX - May/13/2019 at 10:59am |
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Posted: May/13/2019 at 1:02am |
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What machining is required on the heads to accommodate the valve springs for the 290B-6 cam. I'm thinking along the lines of a solid flat tappet as well.
Crower 45316 is about the smallest off the shelf solid I've been able to find: Performance level 4 - Compu-pro - High torque, all purpose camshaft with emphasis on mid to top end power.
INT/EXH - Dur @ .050” Lift: 246°/250° RR: 1.6/1.6 Gross Lift: .499”/.509” LSA: 108° RPM: 3000 to 6500 Redline: 7500 |
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I've finally given up drinking for good...........now I only drink for evil.
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PHAT69AMX
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Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5926 |
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Posted: May/13/2019 at 11:09am |
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Resizing or removal of the stock locating step / shoulder that fits / locates the ID of the Stock Valve Springs
and turning down the OD of the Valve Stem Guide Boss to fit / locate the ID of the new Valve Springs or Spring Locator Cups and / or Shims, as well as for the Perfect Circle style of Valve Stem Seals. You don't want the inner of a dual valve spring sitting on that stock single spring raised location shoulder. 
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PacerLarry
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Joined: Aug/02/2010 Location: New Lenox, IL Status: Offline Points: 103 |
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Posted: May/13/2019 at 12:15pm |
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Doing some researching today and came across this cam - Crane #861201 .512/.533 238/248 @.050 RPM range is 2800 to 6400 112 LSA Crane recommends 3200+ converter and 10.0-11.5 compression Might be a good option
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PHAT69AMX
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Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5926 |
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Posted: May/13/2019 at 12:53pm |
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I'm no expert, but I like that solid lifter Crane Cam for your application, and those 99893-16 Crane Springs I posted go with it per a 1987-1988 Crane Cams catalog I have, and it does say the spring seats need machined with Crane Tools # 99402-1 Combination Tool Cutter Body & # 99028-1 Machining Tool Arbor.
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Ken_Parkman
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Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1814 |
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Posted: May/13/2019 at 5:41pm |
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I like those 99893 Crane springs and have used them a lot. They are also nice in that they are also used with older mild roller stuff and have the coil bind dimension such that they can be installed at a shorter height. Allows flexible installation at a range of seat loads. Use the different height retainers and lock combinations and it gives you a lot of flexibility.
I always machine the heads and use the inside pilot hardened valve spring seats. Had one years ago that was bouncing around and wearing the cast iron. That's a mild solid cam really pretty close in concept to the one you have. Don't worry a lot about the compression they suggest - that'll work with about any compression. It should work pretty well with your combo and will rpm better, but it is not really any bigger. For comparison purposes add about 8 degrees to a hydraulic when comparing to a solid to compensate for the take up ramp, so that 238 would be close to the 230 Comp.
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PacerLarry
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Joined: Aug/02/2010 Location: New Lenox, IL Status: Offline Points: 103 |
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Posted: May/14/2019 at 2:36pm |
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Did a little more digging...
Comp: We would have to do a custom grind cam here. The specs would be 236/242 duration @ .050", .534"/.546" lift and cut on a 108 lsa. I would bump up to our 987-16 springs and keep them at the 1.750" install height. This will bump the spring pressure up to where it needs to be. 987-16 springs are rated as 121@1.750" 343@1.200" 1.150 coil bind Spring rate 370 Bullet Cams: The springs you are using now are not enough pressure for the 230-236 camshaft. It needed to have 145 to 160 closed and 340 to 360 open for that RPM. Recomendation: Intake 245 @.050” .350” lobe lift, .560” with 1.6 rocker 274 @.020” .012” valve lash Exhaust 250 @.050” .353” lobe lift, .564” with 1.6 rocker 279 @.020” .016” valve lash 108 lobe separation 104 intake centerline IO 19 For this solid lifter camshaft I would use 160# closed pressure and 360-380# open. From what I am seeing, Comp is a little lower on their spring recommendations, but Bullet is right in the area that Ken was talking about. If I went with the 99893 springs which are 130 lbs at 1.85, but I keep my 1.75 installed height, this would give me a seat pressure of 169. 390=(x - 130)/.1 (because the shimmed installed height would simulate an open pressure) Then I add the .1 to my lift height on the Bullet cam and get 387 lbs open 390=(x-130)/.66 To me, this falls right where it should. Does this math look right? Thoughts on the feedback I recieved? Thoughts on just increasing my spring pressures? |
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PROSTOCKTOM
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Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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Posted: May/14/2019 at 2:56pm |
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That's why they say to take new springs and cycle them a dozen times in a vise or press prior to installing them. Because whatever you measure them at at installed height they lose pressure once they get heat cycled a few times. I always get a spring with 10% more pressure than what I want to to be for this reason. I'll take a little extra any day over a little less.
Tom
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