new swap firing order camshaft

[J&S Racing]

I recently had a 565 built by Schmidt, the father of the 7/4 swap. He put a cam with the LS firing order in it so I sat down with him and talked if it would benefit my stocker motor.

He basically said the 7/4 swap usually sees a small gain in HP but no big difference with the 4cyl swap. He said the advantage with the LS firing order is it drastically improves harmonics in the motor and is easier on the bearings.

Sitting in my rail the LS firing order definitely is a lot smother at idle.

More than likely I’ll have a cam ground with the LS firing order when it’s ready for its 1st rebuild.

[SSDiv6]

Originally Posted by J&S Racing

I recently had a 565 built by Schmidt, the father of the 7/4 swap. He put a cam with the LS firing order in it so I sat down with him and talked if it would benefit my stocker motor.

He basically said the 7/4 swap usually sees a small gain in HP but no big difference with the 4cyl swap. He said the advantage with the LS firing order is it drastically improves harmonics in the motor and is easier on the bearings.

Sitting in my rail the LS firing order definitely is a lot smother at idle.

More than likely I’ll have a cam ground with the LS firing order when it’s ready for its 1st rebuild.

If your Stock Eliminator engine has a dual plane, save your money. The pulses on the intake manifold will be disrupted by the changed firing order.

[jmantle]

Originally Posted by SSDiv6

If your Stock Eliminator engine has a dual plane, save your money. The pulses on the intake manifold will be disrupted by the changed firing order.

Trying to figure this out in my head. By what I remember, an LS is 18726543.
On a dual plane, this would be alternating between planes so why would there be an issue?

Jim Mantle V/SA 6632

[Bobby Lundholm]

I spoke with Chris at Bullet and he said no benefit on power for a Stocker setup.

[SSDiv6]

Originally Posted by jmantle

Trying to figure this out in my head. By what I remember, an LS is 18726543.
On a dual plane, this would be alternating between planes so why would there be an issue?

Jim Mantle V/SA 6632

When intake runners are designed, the location of the planes and fuel/air distribution of the intake are based on the firing order pulses, especially for torque and low end power. The runner length, size and height are not always the same on OEM dual plane intakes. A changed firing order also may effect the location of the primary tubes on the exhaust collector.

[Adger Smith]

Bobby, if you spoke to Chris then you probably spoke to the real "Father" of the swap. First one I had was back in the 70's from Lunati (M/P tunnel Ram application) and I was later told he was the brain child. I never have ask if that was really the case. Guess by now it doesn't matter who gets the "Father" tag because all the companies have turned it over to the marketing Guys.
BTW if you guys take time to trace the firing impulses vs the runner locations on dual plane intakes you should be able to see how the change just causes more induction problems on most dual planes.