firing order swap.

I am looking into having a custom ground cam to swap 4 and 7 on a small block chevy. From everything that I have read there are advantages from increased
horsepower to lower engine temps. It smooths fuel distribution and even exhaust pulses.. From anybody who has done this, or know of someone who has, what are the disadvantages of doing this.. other then a non-standard firing order..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I believe that it's called the Mercedes firing sequence and I've been told that you will gain horsepower (about 5-15). A friend of mine told me about it a few years ago but I've forgotten what the desired firing order is. Any cam grinder can grind the cam to fire any sequence that you desire.
****************************************** I would rather be exposed to the inconveninces attending too much liberty than to those attending too small a degree of it. ~ Thomas Jefferson ~
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have also wondered about different firing orders. What if you made it 14587632? Draw the pattern out on paper and follow the trail. The best balance would seem to come from this order.
Some of it may have to do with stress in the block.

increased horsepower to lower engine temps. It smooths fuel distribution and even exhaust pulses.. From anybody who has done this, or know of someone who has, what are the disadvantages of doing this.. other then a non-standard firing order..

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have also wondered about different firing orders. What if you made it 14587632? Draw the pattern out on paper and follow the trail. The best balance would seem to come from this order.
Some of it may have to do with stress in the block.

increased horsepower to lower engine temps. It smooths fuel distribution and even exhaust pulses.. From anybody who has done this, or know of someone who has, what are the disadvantages of doing this.. other then a non-standard firing order..

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I dont think you would need a different crank if you changed the firing order to the EXACT opposite. I am assuming if you are swapping 4 and 7, both pistons would be in the TDC position, one on the compression stroke, and one on the top of the exhaust stroke. Since both pistons are up, it would be nothing more than a lobe change to get the valves to open at different times, and swapping wire position on the distributor. I would be curious to know if this works. Sounds like a trick I can use at the dirt track.....
Just a thought.....
John

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
hotrod magazine has a small write up at: http://www.hotrod.com/tipstricks/34219/index25.html for those wanting some info, www.ultradyne.com is willing to grind a cam with a 4-7 swap for an extra $60. seemed reasonable.
On Thu, 07 Aug 2003 04:01:27 GMT

chevy. From everything that I have read there are advantages from increased horsepower to lower engine temps. It smooths fuel distribution and even exhaust pulses.. From anybody who has done this, or know of someone who has, what are the disadvantages of doing this.. other then a non-standard firing order..

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.