Here is a schematic for those who need it.
If you have an older cam that probably is correct. Could you have a newer cam that would switch the 4-7 firing order?
If you have an older cam that probably is correct. Could you have a newer cam that would switch the 4-7 firing order?
Probably correct??????? I got this from a Chevy publication and the vast majority of the Hot Boaters are running the older style Mark IV motors if they are running a BBC. Stack it up against the thousands of publications that list this exact same firing order. If you are running a new generation motor, there may be an exception, but that is exactly what it is. Hope that helps.
I've got two gen VI motors in my boats and they boat have the standard firing order. The 4 and 7 swap cams have been around for 20+ years.
I know there was a swap for the older motors, there was a post somewhere on here when somebody said he picked up an extra 200 rpm out of it. As usual, the drama took off from there. I know for the Mark IV and Gen 5 motors that this is the standard, I would assume the same for the Gen 6 as well. As for everything newer....????
yes this is the same old standard forever firing order. the 4/7 switch was/is a custom cam grind and is not that common.
I did not mean to start anything, but the 4/7 swap is not that unusual today. That includes the 4,5 and 6 generation. It is an option. Comp cams tends to promote it, I have a crane that is the 4/7 swap and have been running it for several years in a Merlin/chevy IV style block. Reher morrison uses it in a number of there motors also.
Some claim it helps a few hp, others claim more, but generally it is thought to help on the bearings. When I changed cams, I talked to a number of people that I felt should be knowledgeable and the one thing they all indicated was that it did not seem to hurt anything.
General motors has changed to that firing order in many of their newer motor for some reason.
My comment about the possibility of it being a 4/7 swap was intended to be just that - a possibility.
My comment and observation for what it's worth. 2 CENTS
I did not mean to start anything, but the 4/7 swap is not that unusual today. That includes the 4,5 and 6 generation. It is an option. Comp cams tends to promote it, I have a crane that is the 4/7 swap and have been running it for several years in a Merlin/chevy IV style block. Reher morrison uses it in a number of there motors also.
Some claim it helps a few hp, others claim more, but generally it is thought to help on the bearings. When I changed cams, I talked to a number of people that I felt should be knowledgeable and the one thing they all indicated was that it did not seem to hurt anything.
General motors has changed to that firing order in many of their newer motor for some reason.
My comment about the possibility of it being a 4/7 swap was intended to be just that - a possibility.
My comment and observation for what it's worth. 2 CENTS
No worries, just adding my two cents too. Just curious, you run a 4/7 swap. I'd be interested to see/hear one run. I wonder if they sound any different? the comment about the bearings is interesting. I'd be all ears to hearing more about it saving bearings.
Hear are a few articles on the 4/7 swap.
Isky is now offering # 4 & 7 cylinder firing order Swap" camshafts for Small & Big Block Chevy V8s . All cams are SPECIAL ORDER, custom grinds. Please allow up to 1 week for shipping. The 4/7 Swap reduces crankshaft torsional vibration for smoother dampening & more power.
Memphis, TN--LUNATI, The Racers Company, is proud to announce the availability of their new line of 4/7 SWAP Camshafts for small and big block Chevrolet solid roller applications.
The 4/7 firing order SWAP configuration decreases crankshaft deflection, delivers a smoother torque curve, and aids acceleration. 4/7 SWAP Camshafts also provide an incremental horsepower gain in the engine. 4/7 SWAPS were track tested in a wide variety of applications and all results were improvements over the standard firing order. Dyno results have shown a 3 to 12 HP gain with the SWAP. The only change that must be made to the engine is to swap the 4 and 7 plug wires to reflect the alternate firing sequence. 4/7 SWAP Cams are available in most popular grinds and on custom ground camshafts.
Whats the SFO?* -* What some camshaft grinders are touting as a new development in technology, is old news at Crane.* For over two decades now, Crane has offered SFO cams for many popular V8 engines. What's SFO?* That's Special Firing Order.* It's what many folks refer to as 4-7 firing order swap camshafts (1-8-7-3-6-5-4-2).* Many Chevrolet 262-400 V8, Chevrolet 396-454 V8, and Chrysler 426 Hemi V8 2.125" journal diameter finish ground camshafts with SFO, are offered on Crane in-house manufactured 8620 and 9310 steel billet carburized cores. This is at no additional charge from standard firing order versions!* Custom round lobe blank camshafts can be produced for most other V8 engine applications.
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The 4-7 swap firing order can help intake manifold distribution inequities, reduce the load on the rear main bearing, and perhaps gain torque and horsepower in certain RPM ranges. Although some drastic claims have been made for this modification, a power increase of 1 to 2 percent is realistic in some situations. No machining is necessary, just slide the cam in, swap some spark plug wires, and there you go!
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The 4-7 swap appears to be most beneficial in multiple carbureted and large cubic inch single carb applications.* For folks limited to one "small" four barrel, we can produce SFO1 firing order camshafts (1-8-7-2-6-5-4-3) on special order. Many racers use this as their secret weapon in Super Stock type engines.* Some folks might recognize this as the Chevrolet LS1 type firing order, while the Ford enthusiasts might note that it's the 351W firing order when renumbered to the Chevy layout.
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There are many other firing order combinations that can be produced for special applications. We've even done some "Big Bang" applications, where two cylinders are fired at once, but that's another story.
I just went to the web and typed in "chevy 4/7 swap", for these. There are many others if you would like more information.
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