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i was looking up the specs for the 3900 cam, it appears they use the same profile for this one as for my stock 3400...lift is the same spring press is the same, spring installed height as well and pressures from what gm posts...
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Same specs, but different physically (IE wont work in a 3400). Interesting but not surprising.sigpic
New 2010 project (click image)
1994 3100 BERETTA. 200,000+ miles
16.0 1/4 mile when stock. Now ???
Original L82 Longblock with LA1, LX9, LX5 parts
Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.
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well yah thats why i said same grind(profile)...the cam is def different to take the actuator that fits on it. did joseph use the stock hollow lobe cam or a solid one for his regrind on his 3900?Comment
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cool, so do u like the cam specs and do you have some movement of the actuator or did the block make it inoperable...and what have u noticed on performanceComment
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There should be no movement independent of the crank and if I had it to do all over I would have been a little more conservative. Vacuum is lower than what I would have liked at idle at around 12 inches of vacuum, probably the bare minimum. I do have it to do all over again since I have another stock cam. I would probably aim for 212/212, .525 lift and leave the stock LSA in tact.Originally posted by gectek View Post
I would also block the cam to about the half way point so that I could activate the module with a steady voltage at about 4K to reach full retard from there for some additional bottom end. I still have a good bit of tuning to do but the one 3rd gear run I made before changing the chip for the worse was very impressive pulling strong at barely 7 psi of boost.
Then I made too many changes at once at the table instead of while in the car and suddenly I had some detonation and near complete loss of the tire chirp during the 1-2 shift.
Once I get the tune in good shape, install the water injection and turn the boost up to 12psi I believe I'll be satisfied.Comment
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so ur lift is ok at what .4xx right now, and u think u can run the .525 lift without the valves hitting one another, i thought i saw in the post by cnc that the valves would hit after .510 lift...or am i wrong again. a guy i know wants a cam to run on his 06 bu ss and i told him to look at my grind for the dur, like 206/208 with less than .500 valve lift and it should be good with a 112 lsa to keep the vvt in line and a good idle...what do you thinkComment
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My cam lift is .497Originally posted by gectek View Post
The lift should not be a problem because there is not enough overlap. What CNC was measuring for me was the intersect point in cosideration for larger valves at which point the intersect point during overlap would occur sooner if the valve diameters were increased since the valves are angled. If the valves are opening at the same time but further the chance of interference does not increase between them.
The exception is made by the VVT in which case you would have to check clearance at TDC at full advanced and retarded cam positions which I did after install to make sure there would be no piston to vavle contact and that's with increased duration. I don't remember how much clearance but there was a good bit.
I would be conservative on an engine with OE active VVT on a cam regrind and would not touch the LSA, that's part of how the EGR was eliminated.Comment
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yah well the stock is prob 112 anyway, and thats what i recommended to him anyway, you really cannot change the lsa anyway without major work. then my recommendation to him would be good...thanksComment
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also joseph have u found a use for the shroud on the bottom of the valve springs...i have 2 from an LZ9 and they have a small push on shroud on the bottom of them, possilby for oil control, idk, it looks with a high lift cam they would kill u on coil bind, not letting the spring expandComment
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The LSA is about 118 according to CNC and less than 112 according to Delta cams if I understood them correctly. I don't know who is correct but I had mine changed to 114 because I didn't want problems with overlap and turbocharging which really wouldn't have been a problem since I have high flowing exhaust by it being dual along with twin turbos.Originally posted by gectek View Post
I removed what is probably a valve spring dampner which provided about .040" less valve spring height however I felt I should have left it in since I planned to exceed 6500 rpm although the LS6 springs are still intalled at less than their rated height so tension should still be good for the range I'm running. The HO motor demo had them installed with the LS6 springs and I suspect the cam changes for that motor are slight and most of the power increase was from the head work and who knows, they may have bumped the compression up also since the engine is fine at 9.8:1 on regular unleaded.Comment
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i guess that is what you would call it, maybe they use it to quiet valve train noise huh. im just gonna use some comp springs the 26915, they are a little taller than the ls6 yellow and have a little higher pressure, so itll be ok without the dampner on there. so u r running ur springs with just the stock seats like on the other previous 3x00 engines didComment
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I don't believe the 3500 has the metal seat attached to the valve stem seal the way the VVT engines do and unless I read a typo the LS6 spring has higher spring pressure than the Comp springs, at least I saw the specs posted somewhere indicating that. I removed the dampner because install height for the LS6 spring is 1.8" and for the 3900 spring is 1.7" so I still have about .060 preload.Originally posted by gectek View PostComment
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no the 26915 spring has more press at the installed height than the ls6 yellow does IIRCComment
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I just looked on Ebay and found they appear to be close:Originally posted by gectek View Post
LS6 yellow 295 lbs @ 1.250
Comp 26915 293 @ 1.2
COMP
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