LS firing order on Gen 1

[c1500deathtrap]

Anyone here try a LS firing order on the Gen 1 blocks? And does anyone know of a place to get a step nose cam ground for it?

 

[Schurkey]

4/7 swap cams are surprisingly common.

The LS firing order is 2/3 and 4/7 swap. Less common for the older engines, but should be available.

Call any of the major cam companies--Lunati, Comp, etc. and ask an expert.

For the record, the LS engine uses the same effective firing order as many of the Ford engines--once you take into account the crazy way Ford numbers the cylinders.

 

[smdk2500]

What is the gain for doing this firing order swap?

 

[Schurkey]

What is the gain for doing this firing order swap?

There may or may not be a power gain.

There seems to be a reliability gain
1. Original firing order has #5 and #7 firing consecutively, dumping a double-load of heat into the left rear corner of the engine. With the new firing order, the double heat load is at the right front--next to the water pump. That's the coolest water in the engine.

2. GM Powertrain's crankshaft engineer said that the revised firing order removes load from #4 main bearing which was excessively loaded, and moves it to #2 main bearing which had a light load. The bearing loading became more even that way.

 

[smdk2500]

There may or may not be a power gain.

There seems to be a reliability gain
1. Original firing order has #5 and #7 firing consecutively, dumping a double-load of heat into the left rear corner of the engine. With the new firing order, the double heat load is at the right front--next to the water pump. That's the coolest water in the engine.

2. GM Powertrain's crankshaft engineer said that the revised firing order removes load from #4 main bearing which was excessively loaded, and moves it to #2 main bearing which had a light load. The bearing loading became more even that way.

OK that makes some sense. I had never heard of doing this untill now.

 

[c1500deathtrap]

4/7 swap cams are surprisingly common.

The LS firing order is 2/3 and 4/7 swap. Less common for the older engines, but should be available.

Call any of the major cam companies--Lunati, Comp, etc. and ask an expert.

For the record, the LS engine uses the same effective firing order as many of the Ford engines--once you take into account the crazy way Ford numbers the cylinders.

Tried lunati, comp, howwards cams, and crane cams. they all said they could not get a 4/7 3/2 swap cam core in a step nose oe hyd roller style

 

[Schurkey]

Tried lunati, comp, howwards cams, and crane cams. they all said they could not get a 4/7 3/2 swap cam core in a step nose oe hyd roller style

I'm kinda surprised.

 

[c1500deathtrap]

they offer them in retrofit hydraulic roller or flat tappet cores. Otherwise it looks like a billet cam.

 

[884x4310ci]

The retrofit cam should be the same as you want.they use lifters with bars to keep them from rolling instead of the dog bones used in stock applications. That cam should be fine. But double check to make sure.

 

[c1500deathtrap]

The retrofit cam should be the same as you want.they use lifters with bars to keep them from rolling instead of the dog bones used in stock applications. That cam should be fine. But double check to make sure.

Yeah but i would rather not have to use a thrust button on the nose. the retainer plate is a much better setup.