gains with 4 7 or 4 7 2 3 swap cams

[wideopen231]

Have to order new cam for 482 TFX hemi. Its 48* cam and cost right at 600 bucks. Figure Might as well get everything possible for my buck. A custom girnd not much more. Wondering how much gain there is in 4 7 swap cam and maybe 4 7 2 3 swap If I can find a core for that. 4 7 swap is pretty easy find.sUnderstand biggest gain is smoother running engine and with cost of thses cranks being 2800 plus that in itself can be worth any extra cost.

Anyone with experience or knowledge of gains good or non existence chime in.Hey opions welcomed also.

[Schurkey]

Understand biggest gain is smoother running engine

I didn't realize that "smoother running" was part of the 4-7 or 4-7, 2-3 swap.

[j-c-c]

I'm going that route on my SB A8 Mopar, haven't which one yet though. I don't see much of a downside.

[roc]

Some good info here: http://garage.grumpysperformance.com/in ... swap.5508/

[utmost]

did a cam swap on a two cyl , firing order was 1-2 and I did a 2-1 cam swap and engine ran smoother and picked up 10 hp.

[andyf]

Have to order new cam for 482 TFX hemi. Its 48* cam and cost right at 600 bucks. Figure Might as well get everything possible for my buck. A custom girnd not much more. Wondering how much gain there is in 4 7 swap cam and maybe 4 7 2 3 swap If I can find a core for that. 4 7 swap is pretty easy find.sUnderstand biggest gain is smoother running engine and with cost of thses cranks being 2800 plus that in itself can be worth any extra cost.

Anyone with experience or knowledge of gains good or non existence chime in.Hey opions welcomed also.

It will run like a Ford.

[bigjoe1]

I have seen a 7 or 8 HP gain on the dyno on our 900 Hp drag race engine, but the car did NOT run any faster on the drag strip .They cost about 50 dollars more from Comp Cams, so I do not bother to get them unless the customer really wants it




JOE SHERMAN RACING

[GARY C]

I have seen a 7 or 8 HP gain on the dyno on our 900 Hp drag race engine, but the car did NOT run any faster on the drag strip .They cost about 50 dollars more from Comp Cams, so I do not bother to get them unless the customer really wants it




JOE SHERMAN RACING

That is what everyone I know that tested them said.

[user-17438]

I have see the ls firing order help fuel distribution. otherwise no remarkable gain.

[user-612937456]

I have no practicle experience but from my research in consideration of using one, I concluded the benifit is limited to high horsepower sustained high rpm operation like dirt, NASCAR, and marine. Advantage being reduced harmonics with a more even tortional power load on the crankshaft. Less broken crankshafts, small Horsepower gains due to less wasted energy overcoming harmonic vibrations that are reduced. Very little advantage in drag applications

[Schurkey]

There was an article, which I have been ENTIRELY unable to find for the last ~3 years, that was an interview of various engineers of the LS engine.

What I remember of it, the "crankshaft guys" told the "camshaft guys" that they wanted the firing order changed.

At least for the LS engine, it wasn't done for power, it was done based on measuring main bearing loads. With the "old" Chevy firing order, the #4 main bearing was overloaded, while the #2 main was under-loaded. The firing order change removed load from #4 and placed it on #2, so that the bearing loads were then more even.

I wish I could link to that article. I've done internet searches to find it again, (multiple times) and I've come up empty. It's like it's been scrubbed from the internet.

[John Wallace]

There was an article, which I have been ENTIRELY unable to find for the last ~3 years, that was an interview of various engineers of the LS engine.

LS Firing Order

Not sure if same as you talked about?

[DaveMcLain]

I was told by a very very good source why the firing swap was originally done on the Small Chevy V8. It was not done to revise main bearing loading, make more power or other stuff it was done for other reasons. In the mid 1980's a prominent Nascar team was looking for an advantage on longer race tracks. They wanted to be able to run the engine at a higher temperature without problems. On the Chevy and any other engine that uses that firing order including some Fords cylinders 5 and 7 or 7 and 8 in the Ford numbering scheme fire 90 degrees apart, they are also right next to one another and in the back of the engine which makes cooling them more difficult. Changing the firing order moved those two cylinders that fire 90 degrees apart to the front of the engine, cylinders 2 and 4. This allowed them to run the engine a little hotter and have more tape over the grille opening and thus go faster. It cost a lot of money to do this because special cam cores were required but that's why it was done originally, believe it or not...

[statsystems]

IIRC, the first drag racer I heard of changing firing order was a guy named Colman Roddy. I can't remember if he was in Modified or Comp eliminator but, IIRC he did it because they found some power doing it.

When I can get the cores I always do the swap. Even if you don't ever gain power with it, I've never seen a swap lose power.

BTW, I don't remember if it was the 4/7 swap or the 4/7 5/2 swap or whatever the other swap is that I can't think of right now was actually used by Cadillac way back in the day.

[Schurkey]

There was an article, which I have been ENTIRELY unable to find for the last ~3 years, that was an interview of various engineers of the LS engine.

LS Firing Order

Not sure if same as you talked about?

THANK YOU!

when we questioned Gen III valvetrain engineer Steve Pass, he said the firing order was dictated by the crank guy. That was Bill Compton, who had this to say via e-mail: “Since the G3 engine was a clean-slate project, each group looked at things that they could change to optimize the performance of the small-block. Although we did not have an issue with crankshaft loading on the older V-8s, there was room for improvement in the area of distributing the peak firing loads among the five crankshaft journals. Analysis showed that main 4 had peak loads significantly higher than main 2. By changing the firing order, the peak loading on main 4 was reduced and the peak loading on main 2 went up. Overall, the loading through the mains was much better balanced.