I am considering using one of these cams in my nail. Has anyone used these cams? Let me know your thoughts and/or experiences. Thanks.
I'm using an old Isky grind that might be comparable. It's 245* duration at 0.050", 108* lobe centers and 28* of overlap. Lobe lift is 0.290" It has a lumpy idle, not much vacuum for power brakes, feels kinda lazy on the street, but rips in the 1/4 mile when the RPM's are up.:grin: I'd be interest to see full specs for any of the Poston cams, if anyone has them...
I use the NH400 and it seems perfect for a street cruiser, good idle, reasonable vacuum, and pulls pretty good from 2000 on up. Mike
Here's a complete set of specs for all nailhead cams. Dennis Manner prepared this for publication in the ROA magazine some years ago. The "Super Wildcat Cam" is really a myth. It's the same cam that was used in both the 1963 and 1964 425 single four barrel engines. Ed PS - If you have to ask "Who's Dennis Manner" you need to start from scratch.
PS - If you have to ask "Who's Dennis Manner" you need to start from scratch.[/quote] Who is Dennis Manner?
Here's an important note about those factory Buick specs!.... While the advertised duration is near 295 degrees, the duration at 0.050" lobe lift is approx 208 degrees. Apparently, Buick used a lifter rise (or lobe lift) of 0.002" to calculate their duration. Other cam manufacturers often use 0.004 to 0.006" to calculate duration.....that sure makes difficult to compare cam specs :rant: Last week I profiled a 66 401 cam with a solid lifter, degree wheel, and dial indicator. Here's what I came up with: Intake: duration @ 0.002"= 300* duration @ 0.050"= 209* Lift at lobe= 0.448" Lift at valve with stock rockers= 0.448" Lift at valve with Toms Rollers= 0.514":laugh: :laugh: :TU: For the Poston cams I have From some old notes): NH400 Adv duration of 272/282 NH500 Adv duration of 280/280; lobe sep of 114* NH600 Adv duration of 310/320; lobe sep of 108* My Isky 310 is closest to the Poston NH600, maybe a bit milder. If anyone out there has more specific specs on the Poston cams, we can make a better comparison. Mike do you have a cam card from your NH400 cam?? The specifics would be appreciated!
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Thanks for all the replies. A friend of mine is using the nh400 cam in his 65 gs and I was thinking of going a little bigger. I just received my set of roller rockers from Tom earlier this week. What a work of art. I am very impressed. Great job Tom!
Bob, thanks for posting those specs.:TU: The Poston NH400 looks similar to T/A's TA-25. Peter, the Poston NH600 looks close to my Isky 310. It's not a great cam for the street, it really comes alive over 40 mph, and that's with a 4.11 rear. Carmen Faso offers a W-30-10 grind that is more radical than the NH400, and milder than the Poston NH600. I'll try to get more info posted this weekend. Be aware with a radical cam change, you will most likely need the pistons notched for valve clearance, and might need to cut down the valve guide retainers for clearance as well. Are you rebuilding an engine, or just planning a cam swap?
I had the W30-10 in my 65 GS with stock heads and the stock AFB and it really woke the car up. I was running the 3.08 rear and 275/60/15 tires in rear W-30-10 Camshaft.. Caremen Fasco Cam doctor analysis-- Buick 57-66 364-401-425 intake & exhaust Lobe center seperation --------------- 109.6 cam degrees valve overlap ------------------------------ 13.4 crank degrees Intake valve opening ------------------------------ 6.7 btdc lobe center ----------------------------------- 109.7 atdc Valve closure -------------------------------- 45.7 abdc Duration @.050 ----------------------------- 232.4 crank degrees max cam lift --------------------------------- .29149 inches net valve lift--------------------------------- .46633 inches Lobe area ------------------------------------ 24.52 in * deg Exhaust valve opening ------------------------------ 45.9 bbdc lobe center -----------------------------------109.4 btdc Valve closure -------------------------------- 6.7 atdc Duration @.050 ----------------------------- 232.6 crank degrees max cam lift --------------------------------- .29094 inches net valve lift--------------------------------- .46551 inches Lobe area ------------------------------------ 24.47 in *deg
Thanks for the add Bob:TU: Those specs put it halfway between the Poston NH400 and the Poston NH600/Isky310. Another one that is close to the W-30-10 is the Comp Cams with 224/231 Duration (at 0.050) and .31/.32 lobe lift. That's a bit less duration than Carmens W-30-10, but with more lift. Erik, (our Dyno-tester), has it in his Riv.
Just for grins, here's a spec sheet on a Poston's NH300 cam. It's in a 425 I built a number of years ago.
Attached below is another of Carmen's cams. This one will go in the 425 with Tom's rockers one day in the 4-speed 66 GS vert. The heads are ported Magnotti's that are good to a mid .600 lift, and it will be using a modified Q-jet on a ported Q-jet manifold. One day, one day! Cheryl PS: The NH 400 at .050" seem almost the same as the KB MCK 114A cam here. This is currently in the 425 with Gessler heads.
Another Carmen grind. This is what he set me up with for a 65 401 with 3:36 rear, trying to keep it close to stock "sounding": Intake and Exhaust Lobe Center Sep 114.5* Cam Deg Valve Overlap 3.2 Crank Deg Intake: Valve Opening 1.6 'BTDC Lobe Center 112.9 'ATDC Valve Closure 47.2 'ABDC Duration 228.8 Crank Deg Max Cam Lift .30331 In Net Valve Lift .48529 In Lobe 'Area" 24.83 In * Deg Exhaust: Valve Opening 54.4 'BBDC Lobe Center 116 'BTDC Valve Closure 1.6 'ATDC Duration 236 Crank Deg Max Cam Lift .32197 In Net Valve Lift .51515 In Lobe 'Area" 26.72 In * Deg
Guys: Thanks for all the input on the cams. As just a reader, your information has been really helpful. The one Question I have is: With the Valves as small as they are without the ability to put larger ones in, why would cams with very high lifts and very long durations NOT be the goal for a top performance cam for the Naiheads? You could always Run an LSA of 112-115 and keep good vacuum and idles quality, in addition, It should make a good blower cam. (Low Overlap) If this question is ridiculous, please tell me, everything I read about the stock heads or ported heads leads me to this same conclusion. Thanks, Ty
Ty, there is a very good article on cam design here in the 'Techside' section: http://www.aera.org/ep/index.html The problems with high-lift in a stock nail are 1) the valve retainer-to-valve guide clearance is about 0.515" on the exhaust....so guides may need to be cut down. 2) at some point, the the valve spring will compress all the way and become solid...coil bind. Anyone know what the spec is on stock springs? Adding alot of duration has a downside. Compression of the fuel/air mixture doesn't start until the intake valve closes. So with more duration, you also end up with less effective compression. That term is called 'Dynamic compression Ratio' (DCR). Do a Google search. LOTS of info out there. That's why big cams are recommended for engines with higher compression ratio....to make up for the lost DCR by the later closing intake. For example, for a stock 401, the intake closes at 36* ABDC (at 0.050") resulting in a DCR of 8.95:1. Add a long duration cam like my Isky which closes at 50* ABDC, and the DCR is reduced to 8.15:1. After the above cam swap, low-end power would be reduced due to the lower effective compression, but high-rpm breathing would be improved for more power. Ideally, the CR of the engine should be increased to make up for the lost DCR....with bigger piston domes or milled heads/block. Valve-to piston clearance is also tight on the Nails. Even the Poston NH400 requires valve reliefs be cut into the piston. EDIT>>> The Poston NH400 cam I installed in 2008, JUST fits with 0.065- 0.095" valve-piston clearance. That's with Toms Roller Rockers, and a steel 0.015" head gasket. VP clearance is tightest when the exhaust valve is closing, and the intake is opening....basicly from 20*BTDC to 20*ATDC. It's more of a problem with long duration and overlap, than it is with valve lift. The nice thing about the Roller Rockers is they don't reduce the effective compression (DCR) and other positive benefits of a smaller cam, but they add alot of lift for better breathing. I graphed a few cam profiles with stock and roller rockers. I'll have to get it posted. That's all for now. :TU:
