Schneider cams stage 2 or 3 differences and recommendation

[Thumper]

I am looking at getting a cam for my new 260z. I am looking at either the stage 2 grind #17033 or stage 3 #17034. The car specs are a n42 block/e88 head, 3-angle valve job, zx flat top pistons, 10:1 comp, mallory unilite distributor, msd 6al, blaster 2 coil, 71 rebuilt carbs with sm needles, n36 intake manifold, msa 6-2 header, 81 zx n/a 5-spd, 3.9 rear end. My plans are solo-II and daily driver. I will be getting the rocker arms and spring upgrade with either cam. I do not mind a higher idle or a loopy idle. No low-end grunt would be problem because of daily driver so stage 4+ is out of the question. Recommendations? Also why does the stage two have more lift and more duration on intake, but the stage 3 has more exhaust duration, less overlap, less lift? Thanks for you input and time.

 

WEBSITE WITH CAM SPECS

http://www.schneidercams.com/cams/50.htm

 

Ted

[technicalninja]

I have installed both grinds and find the 17034 as the better choice. What the charts don't show is the lobe profile. The 17033 has a symetrical profile (both opening and closing side of lobe are the same-or very close) the 17034 is an asymetric profile (opening side is a far sharper curve that closing side). This opens the valve more quickly and closes it more slowly than the higher lift symetrical profile. The top of the lobe is "fatter". First time I ever saw an asymetrical cam was a beautiful electromotive (Nissan Motorsports) L7. This is a proven preformance benefit and leads to a more stable valve train and higher engine speeds before valve float occures. Lobes look funny though.

Both cams have to be properly dialed in as the valves do get close to the pistons on a flat top motor. Either cam will work well in your application. Both will have plenty of low end grunt and the carb choice should help low to midrange power anyway. my vote is the 17034.

 

Rick

[Thumper]

Thanks for you input. Hate to throw another log on the fire but I was looking at the stage 4 #17036 I was looking at the numbers and it seems milder then when I looked at it a week ago. Next the stage 6 will look decent:twisted: Would this be agood street cam or just stick with the stage 2 or 3. Thanks

[Thumper]

Please any input would be appreciated. I am looking to purchase tomorrow but will wait intill I have more data if need be. Thanks

[technicalninja]

I have not seen a 17036 or the 17035 but the Electramotive cam I put in was a 290/.490 (very close to the 17036) and it did exhibit a minor drop in lower end power. Your carb choice is a little small for such a cam. The engine I put the L7 in was a 10.5 N42 flat top with 44mm triple Mikunis. It definitly had enough carburation for the cam. This engine was built with extreme attention to detail. Combustion chambers were all optimised to each cylinder/piston set to end up with exactly the same comp ratio across all cylinders. This took far more time than it was probably worth and I am not planning to go to this level again on a 10.5-1 motor. Note: a 13-1 engine requires this level of build as comformatey across the cylinders becomes more difficult to achieve the higher the compression gets.

I advised my customer that he would have a lumpy idle and lower end drivability would suffer some. After completion the engine would idle rock steady at 600 rpm and although the lower rpm range was not nearly as strong as the upper end it would pull smoothly from idle in all but 5th gear.

Point is-properly built even a fairly strong cam can work on the street.

The L7 cam was CRITICAL on piston to valve clearance and almost needed valve reliefs. if you make a mistake on dialing with a cam like this sever engine damage becomes a factor.

I rather like the 17035 specs but I still would choose the 17034 over it if it did not have the same fat asymetric profile as the 17034.

I would not choose the 17036 unless higher flow carbs were fitted. you SUs will work with this cam, just not as well as you might like. Right in the middle of the cam's power band the carbs would become a limiting factor.

Schnieder cams will probably say that all of their cams are asymetric (and they most likely are) but some are more asymetric than others.

It would be nice if plotted profiles for their cams were available as it is hard to really see what a cam is doing with just the few numbers they publish.

Increasing valve lift does have a detrimental effect on spring life and stresses the entire valve train more. It requires a more precise installation and can create issues with seal height, increased valve guide wear, and other problems .

One other problem that needed to be carefully addressed with the L7 (290/.490) cam was rocker wipe pattern. This was difficult to set up and required some fitting of different thichness lash pads. Frank Honsowetz book "How to Modify Your Nissan/Datsun OHC Engine" has a good description of checking this pattern. I use wide black magic marker to "paint" rockers for this test. The 17034 cam is much less demanding to set up for rocker wipe pattern. it should still be checked but usually will work with the lash pads they supply.

 

Well, probably more info than you wanted, hope I did not create more questions than I answered.

Rick

[technicalninja]

Found this cruising E-Bay

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7969870147&category=33614

 

Don't know seller- just thought you might be interested

[Thumper]

Thanks for link and info. I can never have to much engine information. It looks like I will be going with the stage 3. I started to watch the auction, also part of the reason for urgency. It looks like it's going to get up there though quickly, plus I will be buying the rocker arms and springs; I might just get the kit from msa. Thanks for your time.

 

Ted