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Discussion Starter · #1 ·
So I was out messing around looking at firing orders.

we have 3 options

18436572 - Stock
18736542 - 4/7 Swap
18726543 - LS1 and Ford

There are many arguements about fuel distribution or exhaust distribution.

What I have looked into is that there is no decernable fuel distribution benefit on a dual plane intake as they remain equally distributed between the sides of the carb and alternate.

On a single plane the LS1 firing order does seem to keep the various corners (2 siamesed intake ports) seperate. So there may be a benefit to an LS1 firing order on a single plane application.

The 4/7 swap does have the benefit of having only 1 pair of pulses on the same crank through 6-5. The rest have 6-5 and 4-3.

I am leaning toward a 4/7 swap merely because it more equally distributes the pulses on different crank throws, and I may scrap all my single planes for a weiand stealth.



Any other thoughts. I dont get in for sales speak.
 

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I don't really understand it very well, but so I hear the 4-7 swap is worth some 5% on power.... dunno about the LS/Ford sequence....

I can see maybe some improvement for a carb...maybe....

but with DPFI....:WTF is the differance??

I still see 4 corners 4 middles, 7218 4365

IF there is any power differance.....why did GM across the board use the old firing line?? seems to be a easy swap for any assy line to change all you need do is reset the cam grinder and reroute two wires....which makes me wonder about the supposed power gain.....:WTF :crazy: :cheers:
 

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Discussion Starter · #3 ·
As I was laying in bed last night looking out the window at the worst electrical storm I had seen since basic training in 99, I realized that the 4/7 swap has another pair of pulses on the same crank throw. the begining and end 1-2 are on the same through so there is another pair. In that light they all have 3 throws with sequential pulses.

So I am really trying to find out why they report the 4/7 swap as smoother, with a broader torque curve.
 
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