Camshaft 4/7 Firing Order Swap Explained
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- Опубликовано: 1 авг 2024
- David Freiburger explains what an engine's firing order is, describes companion cylinders, and shows how a camshaft can be used to swap firing orders. The most common for V8s are the 4/7 and 3/2 swaps for the 1-8-4-3-6-5-7-2 firing order, and when you swap 4 and 7 as well as 3 and 3, you get the LS firing order which is 1-8-7-2-6-5-4-3. Many Fords use these same principles, though the cylinders are numbered differently so the firing orders are expressed differently--and the reasons for this are explained in the video.
Why change firing order? Changing a 1-8-4-3-6-5-7-2 engine to a 4/7 swap sometimes makes a tiny bit of extra power. Swapping both 4/7 and 3/2 reduces crankshaft harmonics and evens out the load on the crankshaft mains, which can lead to smoothness and longevity.
Hit shop.davidfreiburger.com for one of the nifty Freiburger firing-order shirts! 
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Glad I’m not the only one that knows that about ford’s firing order. Most people just look at me like I’m crazy when I try to explain it to them.
I swaped the firing order on my single cylinder 2 stroke didnt notice much difference
I did it on my bike too, no change... 1-2-1-2...
@Swadian Knight lmao
thats rich
I heard Maurice saying that
You gotta swap out the cam for it to work.
That would be a cool engine masters video comparing different firing orders
I feel better about my organizational skills after seeing this.
Bet u david made this while wearing flip-flops
You can hearem as he walks off
Dave, that is a hell of a deep hoard in that shed. I would love to see a show where you just build something with a 35yrs worth of junk in a building.
well that comment aged well :)
This is one of the best trivia information videos you guys have produced! Thanks!
Ive been a fan of yours since I started reading hotrod mag in the 80s. Most of my knowledge came from you . I went to college for Auto/Marine Mechanic course. You are a fantastic teacher. Thanks Brother David .Finigan and of course my crush Steven Dolcich
Thank you for saying so!
THIS is something I’ll be heavily looking forward to seeing on engine masters, since my 350 has most likely wiped a lobe. I’d love to see it done on a small block or something mild.
I wiped a lobe last year. Now my oil pump only puts out 20 psi at idle, 50 psi @ 4000 rpm.
You’ll make a hair more power going with a 4/7 swap…worth the cost of the custom cam? Not much more than any other custom cam
Awesome video thanks so much can't wait to show it to a couple customers you explained way better than I can
I did it in my type 1 aircooled engine. Swapping from 1,4,3,2 (stock timing), to 1,2,3,4. It works very good, and I notice gains at middle and high rpms.
Great content bro!
Built a 302 years ago and wired it up with the 302 HO firing order. Never figured out why it wouldn’t run. Towed the truck to a mechanic and he got it going for me. One of those things you learn the hard way.
The reason they used 18436572 is to force exhaust through the crossover passage to warm the intake manifold and carb to prevent Carb icing , It does taste like gas so do not lick it. It also causes that off note in the exhaust sound as well as reducing the expulsion of gasses. With fuel injection you don't need to do this .
Love the sound of the early yblocks, they have a distinct hot rod sound.
I remember hearing something about this wayyyyy back in the day on Powerblock TV. Good to see I didnt imagine it
Don't forget... you also have to swap the plug wires... it's not just a camshaft change! Loving the cheap camera content, subscribed!
There's another piece to the puzzle here. Engines are capable of changing the firing order on their own without requiring a cam change. I've seen it first hand. My '99 F150 w/ 4.2L went from 1-4-2-5-3-6 to 1-4-2-_-3-6 immediately after throwing a rod. I was towing a trailer of about 6k lbs and made it another 10 miles before the firing order changed one final time.
Thank you!!! Ive heard of the 4-7 swap since I was in high school but never seen it done. I heard of a few people just swapping spark plug wires but that was stupid to me and they said it didn't work too well. Thanks for explaining it better.
NASCAR Chevy based V8s run the 4/7 swapped firing order. There IS a reason....
I can listen to this guy talk engines all day!
The 351W has had the late firing order since its inception in 1969. So Ford had the LS firing order since '69. That's why Windsor motors and H.O. 5 liters always sounded so good.
love your shows. hope to meet you and the roadkill crew one day. burnouts forever....
Hell yeah I'm glad I found this channel
My machine shop recommended this when I did a no budget rebuild on a 289. We used a HO 302 cam
U know what, even tho I know most of this, it was good to have U dumb it down and explain it for others to know and get it, thank U, keep up Ur amazing work U do, love all roadkill shows
Love the show.. thanks lots of fun to watch...
Great explanation, well done.
My 4/7 swap 540” has had the same main bearings for about 4 years 400+ passes, 2 sets of valves springs. Spinning to 7600. And they still look great. So I’d say, in a high rpm application it’s easier on the main bearings. A stock firing order stroker BBC spun high is tough on the mains.
Wow, a Freiburger video I don’t have to pay for! I figured he forgot about what made him such a star.
Cool video David! I love watching Roadkill and Roadkill Garage on Motortrend!
I actually didnt know this I learn something new
Same here. I've known Chevy v8 firing order since I was 13. I'm 66 now but never heard of this. Yep, you can teach an old dog new tricks!
Hey was up ✌ keep it up david I'm a huge fan thanks for the infomartion
Holy cow! What an amazing video.
Did I spy a 598? You were always good at explaining these things so the non-experts can understand these technical things.
I see your making good headway on cleaning up the garage.
Very informative , thank u Sir.
Warren Johnson was doing the 4,7,2,3 swap firing order back in the late 60's with a SBC 350 with 6 inch old's connecting rods. He brought it to the KALITA TEAM BACK IN 95 WITH THEIR MOPAR PROGRAM. THEIR WOULD BE ANY GM WITHOUT WARREN JOHNSON/SMOKEY YUNICK. THE NASCAR 4 PATTERN CAM IS ALSO INTERESTING WITH A SINGLE PLANE INTAKE.
That’s the firing order of my ‘62 Buick. I’ve had it memorized for years.
more videos like these please
Great video!
Nice lil shoutout to the big inch Caddy 👌🏻
Just placed the order for this shirt, and the Crusher Wheelie hoodie last night.
Great video
Great info
Was new to me 👍🏻
Very cool info!
I used to think that all you had to do for the 4/7 swap was swap the spark plug wires. So I did. It was a 406 sbc. I didn't know at the time it also required a special cam. My way of swapping made no difference that I noticed. That 406 rand so good even on 7 cylinders, so my screwed up swap just wasn't noticeable.
That's wild about the ford small block and sbc firing order. I knew the cylinder's were marked differently but never tried to decipher it. The number came out to 21843657 sbf numbered like a sbc. Same rotational order
Thank you!
Id really like to dig through that garage.
That shed looks like a "cave of wonders" for gearheads : ]
He's got a deep hoard in there.
I need one for my car. I was just talking about this with my uncle on Saturday
For a long time I kept Knocking, asking for Dave, and someone kept saying "Dave's Not Here"
I've been wondering where he went.......But look !!! *Dave Is Here !!*
It was Cheech and a Parrot.
Great video...I love that t-shirt
Thanks shop.davidfreiburger.com
If you renumber the cylinders on a SBC the firing order is the same as an early ford 302. The HO 5.0 firing order used on later engines uses the 4-7 swap. The 5.0 firing order sounds different (as does the the 4-7 swap on a SBC) when running but i dont think power is any different. Would like to see results of using a cam with same specs on both firing orders. Long term reliability of engine may be effected by the swap.
Guess I should have watched the video before commenting🤣
Furburger is awesome
It helps with heat between cylinders and makes for a smoother running motor
You forgot to explain WHY??!
That is what I was wondering. I have heard of this and people doing this, but why?
@@NN072288Helps #7 to not be starved from #5 that's sitting next to it and taking its intake mixture right before
The why was to sell t-shirts 😝
For more even fueling to help cyl 7 from running lean and to keep that corner of the engine from getting hot
Exactly so frustrating. I kept waiting and nothing!
Man your garage looks like mine, throw nuttin away. I finally started tho. Feels good
Hey man you guys should make this an Episode of Engine Masters 👍👍👍 do some Dyno comparisons on it
I lov this Stuff
Thanks for the shirt Dave! Just ordered mine.
What's the purpose for the firing order swap? Why would somebody build an engine with that?
Nice to see you back with the common folk. Lol. Ordered mine.
On most Ford V8s the left bank is forward of the right bank but they still start the numbers on the right.
I always understood the 47 swap made more power but also created more vibrations in the small block chevy. Never tryed it myself
I want to see you and Richard Goldener do a side-by-side video showing power loss on a LS engine going from it's standard firing order to a SBC firing order.
Why would you want to see a swap that deliberately tries to lose power? A better swap would be to show power GAIN on the original SBC with an LS firing order......
One take! How does he do this in ONE TAKE?!! #respect 💪🏻
He did it in one take because he eats lives and breathes that stuff!
It's called experience........
I thought that was the deal with fords firing order but never was sure.
I also assume that’s why the 80s 90s 5.0 H.O. Have a slightly different sound to em.
They sound awesome.
On a 90 degree V8 with a 90 degree crankshaft you will not hear any difference in sound due to firing order. Why? Because no mater what you do with the firing order you still always have two cylinders that fire 90 degrees apart on each bank.
The two things that every internet/old-school car guy knows are that:
1) Back pressure makes horsepower.
2) Different firing orders (on a cross-plane V8) sounds different.
Hey, maybe they all still feature two opposing-bank pulses followed by two same-bank pulses... but whatever. It's that TONE.
Bonus:
3) The two-man bleed is obviously the best, most efficient brake bleeding technique. Open the bleeder with a clear hose (if you want to see what's happening) attached running vertical and just pump until bubbles stop? Blasphemy.
Gotta love how Ford can look at an industry standard and think "No, I'm going to make it difficult."
I had a small heart attack when i found out my cam for my 302 had the H.O. firing order since my 302 isnt an h.o. then i looked into it and realized itll all work the same, if not better. 😊
Biggest thing on the ho Ford is the distributor is on the other side of the cam so it rotates backwards. Changes the numbering on the cap.
13726548 302H.O. firing order..
question does firing order impact the sound an engine produces? and are there particular reasons why they switch the firing order? does it improve engine balance? or something
Awesome information! Would like to know a little more about why swapping the firing order offers an advantage and should it only be done when swapping camshafts or is there an advantage when the engine is stock? Also does this also work on modular V8 engines like the Ford 4.6?
probably if u can swap both cams. since the 4.6 is SOHC
I've read articles from several top name engine builders and they seem to be split right down the middle on this subject.
It's sound reasoning that it should be effective, but it just seems odd that not everyone is on the same page.
Sounds like an engine masters video to see if doing thise swaps on a 350 make a difference in power and torque.
The Buick Nailheads are also passenger side bank 1-3-5-7 driver's side 2-4-6-8
Makes me wonder what a 454with a flat plane crank, and the 4/7+3/2 swap would sound like.that is, if those swaps can be done like that with that type of crank. I'd like to try that, but not with a production iron block 454. After all, if it works, why have all that weight? I'm thinking all aluminum big boy under the hood of maybe a lighter car like a nova or corvette.Hey Dave, what are your thoughts about the combo I mentioned?
Thank you David you're the best buddy
Is there a future engine masters episode to do a good old comparison of the swaps?
I discovered this with my 1990 Bronco it has a 5.0-302 but has the 351-5.8 firing order. My neighbor is a Ford Mechanic it turns out someone in the past has installed a 351 Windsor cam in my Bronco.
You should make the firing order shirt with the 4/7 crossed off and put them above the other number
Did not mention the advantages! I know the 4-7 swap is for cylinder reversion of cylinders 5-7 in the exhaust but 3-2 what is that for?
For those of you wondering about the significance of the 4/7 swap and why this is important/worth doing (bear with me, this isn't an easy or short explanation):
Note: I'm basing the history portion off of what I've been told by local engine builders and my dad/grandpa; the rest is based on college-level understanding of metallurgy, fluid dynamics and heat transfer...
Way back in the golden era of hot-rodding (early 1960-s to early 1970's) drag racers were starting to climb towards the maximum of what their vehicle's engines could achieve, which led to finding the limits of stock hardware. However, there were a few problems that were commonplace amongst the hot rodding community that no one seemed to be able to escape. This phenomenon was what's called (and I'm ad-libbing here because I don't know the correct terminology off the top of my head) butting the ring ends.
Butting ring ends together happens when cylinder temperatures get too hot, allowing excess heat to be retained in the compression ring material. As material increases in temperature, it tends to grow in size (volume), and this expansion process follows the path of least resistance, which ends up with rings growing to a larger diameter than normal, which shrinks the ring end gap. This continues until there's no room left for expansion, and then suddenly, the ring ends butt together, then simultaneously catch on and seize to the cylinder wall. Since there's not a lot of piston material above the compression rings, the piston material fails under tensile stress, fracturing into multiple pieces and causing catastrophic cylinder damage.
So the question is: how does this happen?
The main culprit is the design of the engine block itself. Back when the Small Block Chevy (sbc) was introduced in 1955, it was designed to be a relatively simple engine. However, this came with a myriad of problems once the design was pushed well beyond it's intended purpose. The most damning of these shortcomings was the design flowpath of the engine's coolant through then engine block, combined with the other culprit: the stock firing order.
As Freidburger stated earlier, the firing order for most classic american V8's was 1-8-4-3-6-5-7-2 (when looking at it through the layout of a chevy engine). The coolant flowpath through a sbc goes from the water pump, into the front of the block, through the water jackets to the back of the block, then up through the cylinder head, into the bottom of and through the intake manifold, then through the thermostat and its associated housing at the front of the intake manifold, out via hose into the radiator to cool off, then sucked back into the engine via water pump once again to start the flowpath once more. This is where the issue resides.
For context, there's always one pair of cylinders in a crossplane V8 that are part of one cylinder bank that fire right after one another, that are located right next to each other. For the original sbc, this is cylinders #5 and 7. For the late model Ford Coyote 5.0 V8's those cylinders are #4 and 2 (still using sbc numbering) and for LS/LT engines, the cylinders in question are #3 and 1. These two cylinders firing right next to each other AND right after one another generates a 'hot spot' in the engine; a concentrated are of higher temperatures compared to the overall engine.
So the issue with sbc's and their original firing order is that it places the 2 consecutive cylinders at the back of the engine, which is furthest away from the coldest coolant entering the engine (remember that coolant flows from the front to the back of the block). This presents an issue where the two hottest cylinders are receiving the lowest amount of cooling. Hot cylinders transfer heat to compression rings, which causes ring ends to butt together, which causes the failure that i mentioned above in paragraph 3. So how do you fix this?
Simple. You move the hot spot as close as possible to the front of the engine, where the coldest coolant is. Granted, this doesn't 'get rid of' the hot spot, it moves it to a place where it can't cause damage to the engine.
So now you've done the 4/7 swap. What does that mean? It means that now our firing order is 1-8-7-3-6-5-4-2. This means that our two hot cylinders are at the front of the engine, on the passenger side, identical to a Ford Coyote (funnily enough, doing a 4/7 swap on a sbc dues give you an IDENTICAL firing order to a Coyote...), and now the problem has been mitigated.
I hope this helps.
*Side note: Due to the more even firing order between banks, this configuration tends to have better fuel-dispersion properties, meaning that your air-fuel ratio disparity between cylinders is decreased by a noticeable margin.
Hi your explanation is fairly correct but we always were taught to file ring end gap for expansion and the 4 7 swap cam was used in corvettes as early as the late 50s as I was taught that from a gm engineer that worked on them anyways thanks for your explanation it was great
With this being said could you technically make an Ls have the same firing order as a old school small block chevy? And would it sound like a sbc? I would assume it would. Did they change the firing order from the sbc (18436572) to the Ls firing order (18726543) because it was more efficient and or made better power?
Also note... the 4/7 swap actually changes it to the Flathead Ford/Buick Nailhead pattern!!!
Now that 2 of the 4 patterns have been discussed then theres the modern hemi pattern and the last one is the flatplane like the 5.2 voodoo
Chev firing order is shared by some Fords as well. Just Ford calls the cylinders different numbers.
So what if you had all the companion cylinders firing together with a duel rotor (hypothetical)? Like a 4 banger with duel pistons...just wondering.
At least motor trend can't take over this channel, I hope
Mikey Don't be to sure about that.
I think he does these to try & drive traffic to MT
Sandkei If anything, It's driving me Farther away from mtod.
bigpigslapper Oink I am not missing out on anything. I sub to Mike's you-tube channel that's good enough for me. Why do people whine and cry about it your words not mine, The fans made Roadkill what it is today and they feel like they have been stabbed in the back. Because everything no matter what , It all comes back to money.
@bigpigslapper Oink I'm 100% with you. It's because they feel like they should have to get everything for free. Nevermind that RK has a high production cost, and youtube wasn't paying the bills anymore.
Crane cams sent me a Cam for a 5.0 SBF that had the firing order from the 351 Windsor. The cam card was wrong and by the time I figured it out the flat tappet cam went flat from attempted starts. Of course Crane just wanted to replace the cam, even though I had to do a complete rebuild! Negligence as far as I'm concerned, what do you think?
i have 94 e150 5.0 enginei got it back from the rebiulder but my problem with the firing order oem wont start and with old firing order like1989 it will start but is missing this is efi can the cam got replace and wont work ?
All us gear heads drooling over the horde of goodies in the background 🤣🤣🤣🤣🤣
I never realized Ford numbered their cylinders that way, always thought they just had an oddball firing order.
So if I turn the shirt inside out does it give me more power?
Yes ! But it has to be backwards. With the tag in the front.
No no no, then it will fire on the inside
Eldon Erc if you put the shirt on a beach bunny, the firing order will go variable when she's jogging
Fantastic... So... why didn’t you explain WHY the swap is done or to what advantage there is?
Love it
I tried to on my 7.3,
But I gave up after I couldn’t find it
THAT'S WHY HE'S THE GOAT, THE GOOAAATTTT
Dave, why not have a Twingle cam cut? one that fires a pair of cylinders at the same time. should be easy with coil pack ignition modules.
I think it’s time for a masters course on engine building.
I got screwed badly rebuilding a 5.0 ford in a mercruiser sterndrive.
Threw new ring, bearings ect into it and set up the distributor as every widsor before and it flat refused to run. Would just start to light off but not pick it up. Played for ages ,fuel, spark ,compression, all present. Timing only thing left and the givaway was the standard firing order was ground off the intake. Rang a mercury dealer and got the firing order and shonuff , bastards for no apparent reason were running different cam events to street engines. Swapped 4 leads and all was good.
Yeah most of your marine engines have the swapped firing order. Even the Chevy's. That's why the swapped cam is usually called a marine or boat cam.
David you never told us.what benefits. The swap does.? Is it less stress on the bottom end?
Has anyone tried 1-5-7-3-6-8-4-2? Seems that every other firing order hits the same crank throw three times in rapid succession per firing cycle, while the Odd-then-even only hits one throw twice in rapid succession.