Mike1234

iTrader: (4)

I'm posting in this forum because I expect significant angst in other forums with little, if any, real scientific data for backup.

I have a Gen1 400 SBC waiting for a rebuild. I've been researching the LSx/351+Windsor/302 HO firing order for some time now and it seems this is the best option for performance and longevity.

I'm SERIOUSLY considering a custom "C-Swap" cam to fit my needs but custom-ground cams are EXPENSIVE!!

BTW, this QUESTION involves FIRING ORDER ONLY... or the "C-Swap" for SBC!!

What got me started was, many years ago, I notice just how powerful and tough my father's 302 HO was in his Ford Maverick and also in a friend's Ford Torino. There has to be some reason for this, yes? These motors seem to last FOREVER under a very heavy foot!! And they seemed to run VERY SMOOTHLY.

So... if a cast iron block has good cooling and is made of tough materials (high nickel 509 block) and is well-designed on all aspects then the remaining factor is something else, right?

I'm 99 percent convinced it's the firing order.

Enlighten me, PLEASE!!

nobodyknows

Are you talking about the 4-7 swap on the sbc?? Supposed to be worth about 30hp throughout the curve. I never messed around with it myself but i know there are some cams on the market for this

LS1MCSS

iTrader: (18)

This is what I found on another board. It's not my writing, just copy/paste.

"Well, GM made the change on the Gen III SB engine, which by sheer volume, mostly goes in trucks, for reasons of improved main bearing load distribution."

Mike1234

iTrader: (4)

nobodyknows... Yes, I've heard that too.

LS1MCSS... Yes, from what I've read the main bearings wear better and there is significant decrease in crankshaft torsional deflection resulting in an 8+ percent decrease in crankshaft harmonics.

SOMbitch

iTrader: (8)

Reher-Morrison has those cams as shelf cams IIRC. Not sure of price or if they have one for your application. I do recall reading about this somewhere. I think some pro stock engine builders do this because having #5 and #7 firing in succession creates more heat and causes fuel distribution to be poor.

racer7088

The firing order makes the crank happier is why. No matter what you always have two cylinders somewhere that can't get along but that firing order is the best for the crankshaft harmonics apparently according to all the real engineers that do that stuff at GM, Ford, and Chrysler.

1997bird

iTrader: (2)

The LSx firing order is really the same firing order that came out in your 1954 Cadillac's and was adopted back in the 80's by Detroit Diesel to solve their crankshaft breakage issue's. The Ford 351W/302 HO's have a different firing order all together. The altered firing order gives the engine a more rythmetic beat (almost the same as human heartbeat), as it fires the outer cylinders first and then the inner's. The upper rpm HP gains are another by-product of the decreased crank harmonic's that are tranmitted through the timing chain, into your cam, through the lifter's, up the pushrods, through the rockers, & into the valve springs.

racer7088

You You need to look at the actual firing order when you renumber the 5.0 ford like a small block chevy as it is the same.

The old SBC is the same as the older SBF too when you renumber them as well.

1997bird

iTrader: (2)

With Ford's CCW firing order the cylinder's would have to be fired 1-8-4-5-3-7-2-6 to be fired the same as the GM "LSx" firing order. As it is the 351W/302 HO has a CCW firing order of 1-3-7-2-6-5-4-8 and would need to be modified to 5-4-2-6-3-7-8-1 to be fired the same as an Gen 1 SBC.

I know that you are a very smart & well respected member/sponsor to this board so please don't take my post the wrong way.

hammertime

iTrader: (1)

Without looking at the documentation, I'm pretty sure racer7088 is correct. I'm not sure what you mean by Counter-Clockwise, unless you mean distributor rotation. The numbering system used by Ford has always been different, but distributor rotation should have little to do with it. It's just a matter of swapping plug wires to match the cam phasing.

1997bird

iTrader: (2)

I'm sorry hammertime, I should have said CCW distributor rotation vs. the SBC CW distributor rotation. Remember that the Ford's are 1-2-3-4 on the passenger side of the block & 5-6-7-8 on the driver's side. There is more to it than just swapping the spark plug wires around, the cam core has to have the lobes in the right orientation in order to work properly.

hammertime

iTrader: (1)

Found it

Lunati Cams - Firing Order



There is a bunch more info in the link listed above, pretty much encompassing everything listed in the previous replies. In the end, it was worth a few ponies, and would be an advantave from the outset of a new build, or where you are class limited and need a competitive advantage.
Mike1234, I hope you aren't expecting miracles from a simple cam swap with similar lift duration figures. I'm not certain you'll find other empirical evidence here since Gen III engines already have the "magic" firing order.

Good luck with your build.

Also, 1997bird, I hope you didn't take my post wrong either.

1997bird

iTrader: (2)

No, not at all hammertime, I had just looked into the Ford firing orders for a customer about 1 1/2 years ago. I have been useing the LS1 FO cams from Erson Cams for several years now and have liked the smoothness that the engines run with (even if they don't make anymore power, they will help keep some of the wear/stress down on the internals).

Mike1234

iTrader: (4)

Yes, this is why I'm so keen on this firing order.

Mike1234

iTrader: (4)

Nope... I just want a longer lasting motor that sounds great and makes a few more HP/TQ. It seems a small price to pay if the return is another 50K on the motor. Plus these just sound BAAAD!!

gectek

iTrader: (2)

well i believe that comp already makes the "swap" firing order cams...are you running a flat tappet or a roller? they are in their catalog.