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302-351 firing order
Has anyone done a comparison of the two different firing orders for Ford small block.
I am thinking of just changing cams and firing order in a 289/302 not HO and a 351. Which cam and firing order would produce the better dyno numbers? Anyone know? Anyone done it. I do have a Comp cams 289 cam in my 351. Runs the 289 firing order and it runs great. Fred |
Fords theory was that this changed the way the main bearings were loaded.The one thing that the 13726548 order does is shift the consecutive firing cyls to the front of the LH bank- ie in the 15426378 they are 7/8, on the other 5/6. this can /does cause a bit of a problem with cooling in the two front cyls as they receive the cooler radiator water first and I am sure that many nascar folk used to reduce the comp ratio/ and or the ign timing on that #5 cyl in order to address this. From memory it was a case of that #5 cylinder running less effective clearance due to the cyl being cooler and the piston running hot with mixture being lean also partly due to #6 getting first bite at the cherry on a single plane intake. I dont ever remember having a problem with the early 15426378 order and in fact the only 'good' cams we could get back then were of that type. Also note that the FE & 429/460 all use the early order.
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On the Dyno question, I saw a HP TV show where they tested a small block chevy. Then they installed a cam with a different firing order, but exact same lift, durration, etc. Ran it on the dyno and got around 25 hp more (my memery is not that great). The cam manufacturer is claiming that the engine picks up the Hp by getting better scavenging affect. I didn't get the firing order change, so I could not compare it to the two SB Ford orders. Any way from this, I guess it could impact Hp. |
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