4/7 swap cam

[Mod66x]

Are these types of cams better then you reg. cams? If so whats the advantage?

[andy16]

they are a package deal. supposed to run diff headers w em. they change the vacuum pulse inside the intake and ex pulse through headers. better or not couldn tell ya sure there is plenty info to support both sides.

[perfconn]

Waste of money.
If you don't change the cubic inches or the weight of the crank and rods or the camshaft profile or the rocker ratio or anything else about the engine,how can you expect to make more power by changing the firing order?
The firing order change was originated by Ford when they came out with the 351ci engines because they thought that the extra ci would be harder on the cast cranks.It wasn't to make more power,it was to try to keep the cranks from breaking.
You don't need to change headers with the 4/7 swap unless you are using tri-y headers.
And don't try to use the better cooling argument.You are simply moving the 5-7 cylinders firing next to each other to the 4-2 cylinders firing next to each other.

[sj valley dave]

This has been talked about over and over and over...Just go to the search deal, type in the 4/7 swap and you will find pages and pages to read about it...

[Mod66x]

Did the search thing already. Not alot on the subject. If you don't wanna respond then don't and move on.

[joeltjen]

Are these types of cams better then you reg. cams? If so whats the advantage?

this is one of those topics, (like pinion angle) that has many opinions and usually just ends up in a pizzin' match. read this and make your own decision, research done by people with more time and money than most of us.

http://www.hotrod.com/techfaq/113_07...s/viewall.html

john

[Egoracing]

this is one of those topics, (like pinion angle) that has many opinions and usually just ends up in a pizzin' match. read this and make your own decision, research done by people with more time and money than most of us.

http://www.hotrod.com/techfaq/113_07...s/viewall.html

john

Believe about 70% of what you read in mags. Bill Hendren did an article about heads and he found brand X heads were mid pack in performance of the heads he tested and wrote it all up. When the mag came out they threw out all of the better heads and showed brand X as the best. When he questioned the mag they said that the brand spends a bunch of money advertising in the magazine and they were not going to make there products look bad so they changed the information. He posted it on here a couple times, he also posted that the 4/7 swaps were only good for Nitrous drag engines and then they were only minimal.

[perfconn]

Bottom line it is worthless.

[sj valley dave]

Whatever 66mod...You obviously didn't look too well...Over the last Six or Seven years there have been sooo many questions about this...jeez..Oh well

[rebel1mcelroy]

I seen it somewhere that by separating 5 & 7 in the order is to help with the heat of those two cylinders to be the same as the others. If u check your temps those two run alot hotter and usally 7 being the hottest
Jmo

[perfconn]

Read the previous post.All your doing is having 4/2 cylinders firing next to each other.

[Mod66x]

Thanks for the info. I've never run one before, but had a chance to build an engine with one. (My choice). I think I'll stick with the normal cam....

[sj valley dave]

Good choice...We have a cam in right now that is a LS-1 firing order 18726543..a 4 cylinder swap...Only thing is does is it seems to idle smoother...No power difference on the dyno sheets...It came that way and is the only reason..A standard firing order cam is fine..

[lovinlatemodels]

I agree are cam guy said the only thing is does is smooth out the harmonics of your motor thats it no power gains.

[joeltjen]

I agree are cam guy said the only thing is does is smooth out the harmonics of your motor thats it no power gains.

i think most will agree it smooths out the harmonics in an engine so for me it makes sense to do it . if you have a $3000 claimer then probably not.

[perfconn]

Not trying to be disagreeable but you guys need to use your head for something besides a hat rack.The sb chevy fires a cylinder every 90 degrees.It doesn't matter which firing order you use its still firing every 90 degrees.Changing the profile of a cam when you change the firing order will confuse the whole deal.You ever see anything any smoother than a stock engine that will idle at 800rpm.

[TBRE]

It would appear that firing 2, right after 4, would stop detonation because cold water is coming in at the front of the block, and to a point, thats true. When you fire 7 right after 5, it's being cooled by water that has already gone by 3 other cylinders. For drag guys that run an electric water pump, which BARELY moves enough water through the block to keep up (and keep water pressure up at the restricter holes in the head gasket, which makes the distribution equal), the 4/7 swap isn't a bad idea. Circle track guys run higher water pump speeds, lines of the back of the intake, ect.; so there are better things to spend your hard earned money on.
On a lot of our engines (budget allowing), we restrict the water pump hole, and feed the middle of the block. If you can get all 8 cylinders to run the same temp, I believe it's worth a few hp. My 2 cents.TB

[perfconn]

Read my post on rocker choices.Same thing applies here.If you will find a good engine builder and listen to him you will be dollars ahead.Old wives tales are as abundant in racing as any where else.

[DANNY]

Im not an engine builder nor a cam guy i dont know a thing even now im going to have to ask when i change heads what cam i need and i been told 5 times already... But to my knowledge what kills engines and breaks parts besides the obvious too much HP and RPM? Harmonics more then one post here has said that "it seems to run smoother" thus reducing the jitters in these HP giants wouldnt it be worth it to you if none other then maybe your motor doesnt wear the parts out so fast to try it... Dave said it in his LS1 cam that his SB2.2 runs smoother lol

[perfconn]

He also said it came that way.If it came that way then he has never tried the regular firing order in it.If you are going to buy a cam its your money.Buy what you want even if you are needlessly spending money.