SBC NASCAR V8 firing order

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Re: SBC NASCAR V8 firing order

Post by induction apprentice »

cjperformance wrote: Thu Oct 25, 2018 2:37 am
Scott wrote: Thu Oct 25, 2018 2:10 am
Walter R. Malik wrote: Mon Oct 22, 2018 7:09 pm

Also, Ford 351 Cleveland, 351 Windsor and 351M-400 firing order since 1969.
" Cleveland firing order is 13726548 "
Think 'firing pattern', draw it out and all will be revealed.
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Re: SBC NASCAR V8 firing order

Post by andyf »

Walter R. Malik wrote: Mon Oct 22, 2018 7:09 pm
Newold1 wrote: Mon Oct 22, 2018 4:43 pm Firing order is still 18436572 in chevy's Nascar RO7 engine and that is mandated by the rules. If you want some better harmonic crankshaft loading, use the LS firing order, 18726543. This is what some now call the 4-7 & 3-2 swap.
Also, Ford 351 Cleveland, 351 Windsor and 351M-400 firing order since 1969.
That is why those Ford engines ran so good. The firing order! I never could figure why Ford won all the races but now I know.......
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Re: SBC NASCAR V8 firing order

Post by Ed Wright »

My NHRA Super Stock 350" LT1 neither sounds, nor runs any different with the 4-7 swap.
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Re: SBC NASCAR V8 firing order

Post by MadBill »

Yes, with a two plane crank, for any available firing order the rotational angle between either bank's successive cylinders EVO varies from 90°to 270° and since the pulses typically all come out of one collector, sound-wise it's irrelevant whether it's 5 and 7 or 4 and 2 that fire in sequence.
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Re: SBC NASCAR V8 firing order

Post by cjperformance »

The only time you really hear an exhaust note difference between any of the said firing orders/patterns is when uneven lengths headers or stock exhaust manifolds are used that tend to have shirt but quite different lengths from valve to flange(collector) point. The stacking of the exhaust pulses of the differing firing patterns thru the same given design manifolds is audible.
When even/close length piping from valve to collector point is used the firing pattern diferences are not audible.
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Re: SBC NASCAR V8 firing order

Post by Jeff Lee »

I ran the 4-7 swap on my AMC 390 Stocker long ago. I remember going down the track on the cam’s 1st pass. It was much smoother on the acceleration curve. I thought “that was a waste of money”. Picked up the ticket and it was fastest pass to date.
I use Spiro Jennings; Redline Racing Cams. Call him @ 408-292-0646 if you want a custom cam done right on the 1st engineering (as opposed to the 4th, 5th or 6th). Don’t call him if you’re in a hurry! All work is in house. He has a multi-million dollar CNC cam machine he bought recently from GM that is up and running. Turn-around time is decreased greatly.
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Re: SBC NASCAR V8 firing order

Post by cjperformance »

Jeff Lee wrote: Sun Nov 04, 2018 1:38 am I ran the 4-7 swap on my AMC 390 Stocker long ago. I remember going down the track on the cam’s 1st pass. It was much smoother on the acceleration curve. I thought “that was a waste of money”. Picked up the ticket and it was fastest pass to date.
I use Spiro Jennings; Redline Racing Cams. Call him @ 408-292-0646 if you want a custom cam done right on the 1st engineering (as opposed to the 4th, 5th or 6th). Don’t call him if you’re in a hurry! All work is in house. He has a multi-million dollar CNC cam machine he bought recently from GM that is up and running. Turn-around time is decreased greatly.
The main area where a possible power curve change can result from after a firing pattern is intake design and runner lengths and configuration. If you draw out the differing firing patterns and therefore intake draw pattern you can see how the differing orders place a different demand on runners.
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Re: SBC NASCAR V8 firing order

Post by ProPower engines »

Jeff Lee wrote: Sun Nov 04, 2018 1:38 am I ran the 4-7 swap on my AMC 390 Stocker long ago. I remember going down the track on the cam’s 1st pass. It was much smoother on the acceleration curve. I thought “that was a waste of money”. Picked up the ticket and it was fastest pass to date.
I use Spiro Jennings; Redline Racing Cams. Call him @ 408-292-0646 if you want a custom cam done right on the 1st engineering (as opposed to the 4th, 5th or 6th). Don’t call him if you’re in a hurry! All work is in house. He has a multi-million dollar CNC cam machine he bought recently from GM that is up and running. Turn-around time is decreased greatly.
Spiro is a good guy to work with.Used lots of his stuff for BBM engines he knows his shit but yes there is a time delay so its always advised to think farther down the road with custom stuff.
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Re: SBC NASCAR V8 firing order

Post by Newold1 »

I'll make a simple positive statement and you make the decisions of what to do and use, but-

If you are building and engine that originally has a 18436572 firing order and YOU ARE USING A NEW CAMSHAFT, order the camshaft with a 18726543 firing order and give yourself a better operating engine period. Less harmonics on the crankshaft at rpms and in many cases a better air fuel distribution to some cylinders in N/A uses.

These camshafts should not cost a lot more especially as more camshaft companies carry the cores at lower costs due to higher use volume. Don't let camshaft people in the industry feed you the "bullshit" that they cost more to make!

In earlier years the OEM engine makers did what with their technology and demands at the time was what was what they thought was the best firing order at the time and the demands and uses in racing were less then and that firing order was the use of that time. Today is a lot further down the road of technology and design and its obvious when you look at the stock OEM engine performance levels that it is an improvement or they would not bother.

This is one worthwhile change you should embrace if you are in a position to make that simple change. TRY IT YOU'LL LIKE IT! :wink:
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Re: SBC NASCAR V8 firing order

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Re: SBC NASCAR V8 firing order

Post by engineguyBill »

Newold1 wrote: Sun Nov 04, 2018 9:19 am
These camshafts should not cost a lot more especially as more camshaft companies carry the cores at lower costs due to higher use volume. Don't let camshaft people in the industry feed you the "bullshit" that they cost more to make!
Manufacturing costs are controlled by production run volume, regardless of whether the product is camshaft cores, hammers, golf clubs, door knobs, T-shirts, bras, etc., etc. The camshaft core suppliers run many more cores with the "production engine" firing order than those with "special" firing order configuration. Therefore they are able to produce the production cores for much less cost than the special cores. This is based upon cast cores that are typically used in most cam manufacturing. Billet cam cores, which have full-round raw lobe shape would be the same price regardless of firing order specifications - but the finished cam production cost is much higher than the cams with cast cores.
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