Technical > Matt Shaff's Engine Shop
4 7 and 4 7 2 3 swap cams
coupemerc:
The 4-7,2-3 switch (18726543) firing order is actually the same as the small block Fords if you look at the way Ford assigns their cylinder numbers.
From Dave Reher..."The order that we call the "4-7 switch" (1-8-7-3-6-5-4-2) has produced 5-8 more horsepower in our pro stock engines and was a well kept secret by racing teams for years."
dusterdave173:
Exactly my experience--like I said before big inch high RPM units seem to like it a little bit
most other applications not so much--
dreracecar:
I had lunch with Ed Iskindarian and asked him about the swap, Got a chuckle out of him
ricardo1967:
--- Quote from: dreracecar on June 15, 2017, 04:24:00 PM ---I had lunch with Ed Iskindarian and asked him about the swap, Got a chuckle out of him
--- End quote ---
C'mon Bruce, spill the beans man...
dreracecar:
They grind them on request, But not really a consistent gain to warrant a production.
What he did say was that "Grumpy" had him make a few sets of roller lifters that the rollers were offset so he could adjust cam timing to each individual cyl just by swaping lifters. I sumize that he had is cam grinder do a standard profile without letting him know what the true numbers were and having his secrets known
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