SB, the Dart manifold was made for the 8.1 so I would think it would be setup for the LS firing order. From the picture of it on summit looks to be true.

Regarding the cams, they have the distributor gear because they still need to drive the oil pump. The 3 bolts on the front are a non issue, just thought I'd mention it.

Ugg. Do people read what I write. Doh.

Sorry, I miss understood your post

420hp cam is GM part number 12558912. Most places have them for around 300 bucks new.

No need to call a custom cam guy for an over the counter GM camshaft.

http://www.gciron.com/GM_Parts_GM_12...m-12558912.htm

I have a take out 496HO cam for sale. PM me if you are interested.

Come to think of it, won't make a diff. Any 2 cyls you could switch firing order on have to be 4 cyls in firing order, 360 crank degrees apart. Both draw from the same plane. The firing order swap is to get the exhaust pulses on cyls firing one after the other physically seperated farther.

8__7
6__5
4__3
2__1

8.1L firing order = 1 8 7 2 6 5 4 3
Gen VI/V/Mark 4= 1 8 4 3 6 5 7 2


As a note to some that do not know: A dual plane intake manifold is set up so that there will never be one cylinder directly after another drawing from the same plenum half so that you won't be competing for air. If you do have a cylinder drawing directly after another, you'll choke the schit out of it, because a dual plane has tiny plenums. Remember, it has two plenums. A single plane has 1.

Here is the intake, so , again, to double check you can look at this and follow each firing order to make sure.

I quickly checked, and I agree...unless I made a mistake, that the dual plane would be fine with the older Gen VI camshaft.

Bigger pic, click : http://www.raylarengineering.com/img...e-manifold.jpg

7-4 swapped. both on top plane. 2-3 swapped, both on lower. keeps the 1 pulse each plane order.

Would anyone Know the specs on this cam? Can I use the stock valve springs and pushrods?

Just call Raylar and do their BP-203 kit that includes roller rockers. Its a tiny bit hotter than the Mag HO camshaft. For what its worth, change the springs to the Raylar kit springs. The stock springs are junk.

Donzi Matt (above) has take out 496 Mag HO cams left over from his Raylar build. Probably has the springs too as he did new heads I think.

No matter if you use the stock springs and or the stock cam and or the raylar or stamped rockers you use the same pushrods.