changing firing order

we are getting ready for next season bbc 468, 8.71 blower 30psi, alcohol, will changing to 8.1l firing order 18726543 make any difference the two other motor already have a 4-7 swap?

 

I use the LS firing order in my 540 and as far as I can tell it makes no real difference. I haven't put a real heavy load on the engine so I can't tell for sure. Also haven't checked any bearings yet either. One other note, I have heard people say they can tell an LS firing order in a blown alcohol car because they "sound" different, they sound no different.

Corey

 

thank you for the reply, I would have thought that more people would have tried it by now!

 

I can tell yoy from MANY Dyno Pulls...the 4/7 swap netted ZERO gain in HP! But I WILL tell you...it DOES "sound" ..."different"....but I have a "good ear" ...I can hear things going on in a motor that my Crew couldn't! hahah Sorry Guys!!

 

So it sounds better or worse?....

 

Still waiting for any clear, definitive, info that cam firing order changes do anything.

 

Firing order

I have been told by many that the firing order doesn't seem to change power, on a BBC it supposedly makes a much smoother torque curve and on all engines it is supposed to improve harmonics. I am now trying a 4-7 and 2-3 swap, was told by previous owner the 4-7 alone did nothing and he was yet to try the 2-3. I'll compare dyno notes on your motor if I can ever get it dynoed Tim

Oh and Tim, if this motor I bought from you 7 years ago sounds funny I'll be expecting a refund....lol

 

I think I started something, we are only allowed run 8 injectors in the hat and no-longer allow to run an offset mag and had to move the blower forward, on the old set-up we exceeded the dyno capabilities of 1500hp trying to find more hp without blowing -up

 

I'd be especially curious if it has done much for the crank & rod bearings when tested back to back in a seriously boosted supercharge application these days?

Breathing wise, NA with a common plenum, makes much sense. For supercharged, not so much obvious sense.

There "might" be a small benefit in terms of the crank life & bearing life (due to forces). I suspect not a huge bunch though. Would like to hear other's thoughts good/bad/neutral.

Thanks.

 

Check this out...........

http://www.youtube.com/watch?v=jxyEtC6G5U4

 

Fontanas rule!

just for information, the Fontana hemi cams used to be normal firing order with the small cam bearings, the new ones im getting now have larger cam bearings and have the 4/7 swap built it. im told the only cam cores are made by miner. ive never asked how much or if any difference it makes, but if you put the wires on wrong, it does! I can only imagine that If it didn't do anything, they would go back to the old style. I think reher Morrison has some good info on their site http://rehermorrison.com/category/tech-talk/

 

From my standpoint it is hard to really tell from power or sound, but it should keep the crank happier.

 

Have you seen a happier crank and/or bearings since switching?.......

Thanks.

 

I can assure you the ONLY reason to do is for longevity on the #2 main bearing. My father proved it 25 years ago on his Blown Small Block TAD.