IROCVegas

I've seen some cams with a 4/7 swap in firing order and was wondering what it does. I'm new to chevrolet so if forgive if it's obvious.

IROCVegas

spicy chicken

a 4/7 swap cam along with swapping the 4/7 spark plug wires changes the firing order and helps by getting better fuel distribution to cylinder #2 because in the conventional firing order #5 and #7 pull fuel to the back of the intake then #2 has to pull it to the front. the 4/7 swap eliminates some intake manifold turbulence but mainly in carbureted single plane manifold cars, and even more so at high rpm's.

a 4/7 swap cam isnt really worth it for a fuel injected car or anything that doesnt have a single plane manifold but it wont hurt anything if you decide to try it.

IROCVegas

Right on. Thanks for solving that mystery. I know some cam tricks for Fords but I couldn't understand why would you swap just two cylinders. Makes sense now.

J91

Not really worth it unless you are trying to make big power, like a race engine...

Air_Adam

Didn't Ford do a 4/7 switch on the 5.0 HO Mustangs? I remember hearing something about them having a different firing order than a standard 5.0L...?

chas0218

If you are looking at the Comp Cams XE284H-10...You dont have to swap the firing order with that cam unless its before a certain year. I swapped mine and it idled like crap but then i looked into it more and i figured out it was only on engines before 1968 i think.

AlkyIROC

The 4/7 swap just moves the fuel distribution problem from cylinder 5 and 7 and moves it to 2 and 4.

Only on a real high end performance engine would you see any real gains. If the price of the cam was the same as a regular cam then I'd suggest using it but for the increased cost of a 4/7 swap cam, it's not worth the minimal if any performance gains.

Chev numbers their cylinders 1,3, 5,7 on the left side and 2, 4, 6, 8 on the right.

Normal firing order is 18436572. 5 and 7 are beside each other in the firing order and take air/fuel from the same intake runner.
4/7 swap order is 18736542. 4 and 2 are beside each other in the firing order and take air/fuel from the same intake runner.

Ford firing order is different but they also label the cylinders differently.

IROCVegas

You're right. Don't know how it works, but it does. same block same stroke. Last two pistons in firing order are reversed. Extra horses for free. Actually it was an 8/7, or 4/8 swap (don't remember).

All I know is that if you put a 60's/70's 302 cam in a 60's/70's 351 windsor block you get an additional 100+ hp. Maybe the HO cam will up it even more. I have tried the 302 cam in a 351, but I haven't tried the 302 HO in a 351.

I know the '69 351 with 302 cam runs like a scalded b*tch when I put my foot in its ***.

F-Body Demon

iTrader: (1)

Im sorry but I gotta call BS on this one.

We all know, no Ford has ever even made it to the 100hp mark in the first place .

IROCVegas

OK. I stepped into the chevrolet lunacy because I found an 87 IROC on craig's list for 500 bucks. When I bought it it was shooting fuel out the exhaust thanks to a brainy fuel pressure regulation scheme. I've worked on this thing all over the place and although it's not as bad as I expected, there are still a lot of problems and downright head-scratching why in the hell did they do that issues.

From what I've read on here, these cars are prone to some serious level problems and I've been experiencing one of them since I finally got it together. Chevrolet can't even design a fuel delivery system that will work in 100 plus degree weather. I'm not overly impressed with this car to say the least.

All I know is that in my 69 351-powered eliminator (with a 302 cam, stock heads/intake, edelbrock 4-bbl, and mallory coil and distributor--nothing special), I do NOT have to touch the brakes to roast the 11 inch wide posi-driven rear tires right off of it. I have driven fords and I have driven a hunk of chevy now. I'm convinced that the die-hard "chevy guys" are the same types of people that would marry the first piece of a-- they get in their lives as well. There's more out there if you could open your eyes and look around.

Too bad I'm in Nevada and my car's in Kentucky right now or I'd take a vid and show you. That 351 has 8 more inches (bored over .30) than the more modern and supposedly more advanced 350 in my IROC and all I know is my Cougar would kick the living dog-sh-t out of my IROC. And another thing, if the 5.7 is so great stock, why does everybody rave about the bosch type3 (FORD) injectors when they put them on?

whatever man.

You think it's an amazing feat when your 350 narrowly outruns a 302. Well, gee... that little 302 is giving up 48 inches.

Have you ever heard of a 347 stroker? What's the difference between the 302/347 (which builds a lot more horsepower and torque) and the 351 W? 4 inches of displacement and FIRING ORDER. Maybe you can't comprehend that one I don't know. Call BS all you want, but I would LOVE to see you run a 347 and see what happens.

resinlake

I do love those 450-550 hp 347's. Considering one for the 55 f100 probably sticking with the Cleveland though stroked to 408. Low mileage out of a Pantera.


ooo that would be nice in the Iroc, and a distributor up front?!?! ooo *drools*

anesthes

iTrader: (12)

That's because GM is smarter. Everyone knows Ford guys are idiots who throw parts at things. Any fast ford racer at the track will tell you, he got there from his Chevy friend helping.

Unfortunately, like the Ford crowd, we have our share of retards too.

Sure they can. Just because you had a problem with yours, on a 22 year old car doesn't mean it didn't work for the previous 20 years.

If I side step the clutch on a 3.1 powered v6 it will roast the tires too. But I'm not 16, so I'd rather keep my tires.

A 69 351 (W or C?) makes a lot more power than a mid 1980s anything by the way.

haha. Welcome to thirdgen! You are going to fit in great here.

And my farm tractor would pull your cougar all the way home, but whats the point?

Which 5.7?

Because like the Ford idiots, they read some stupid magazine article and decide all of a sudden they need some spiffy injector.

Like I said, we have our share of retards too.


No we don't really care. I've built 500hp 302s and 500hp 350s. Nor do I care about stock anything, stock thirdgens were equally garbage as stock mustangs, so give it a rest. Unless your pulling the front tires off the ground or trapping over 120mph I'm not interested in hearing about it.


That is wonderful.

-- Joe

StringRust

iTrader: (2)

anesthes

iTrader: (12)

Actually if it's 1969, I guess it has to be a 351W, so ignore my C or W question.

C didn't come out until 1970. C was a heavy pig anyway.


-- Joe

resinlake

anesthes, I miss the mIRC chats with you and the other guys.. how have you been? You may not remember me, but you guys helped me with a few things. Was it you or the other guy who patrols?

anesthes

iTrader: (12)

That would be me.

Irc.. That was some years ago now. What was your handle on IRC?

-- Joe

IROCVegas

The thing is, my cougar has a stock fmx 3 speed automatic in it, and it will break loose on real asphalt that has been weather washed/cleaned unlike the streets in vegas that all seem to have a slight film on them. And no, I don't constantly cookie my car. I'm just saying that from a launch I have to be careful or I'll smoke the tries through all 3 gears and never touch the brakes. I discovered this once by accident when the throttle return spring bracket folded back on my carb (edelbrock) after I rebuilt it and I had the key switch laying in the floor so I couldn't shut it down until I got clear of some houses first.

You know the story... just finished a major repair and want to see how she runs, right? well, all I know is when I launched I was just wanting to see what kind of acceleration the car had for a few secs and then let off. I let off and the damned spring bracket let loose which meant the car stayed floored. I had just cleaned the contacts in the key switch because it wasn't starting right and the switch was laying in the floor, out of reach.

By the time I got clear enough to reach down and shut it down there was a plume of beautiful black tire smoke about 70 feet high where I started, and at the end of the run it sounded like John Force. My friends came up to see what was going on shortly afterward and they said that was the best sounding run they had ever heard.

And I only had ONE pizzed off neighbor who threatened to tell my "mom" (wife). That was pretty funny too because my wife at the time was only a year older than me. You should have seen her face when people would call her my mom. She hated it. It's not that she looked that much older, it's that I look that much younger.

Great memory. Thanks for helping me bring it back.

IROCVegas

now you're talking. The only problem (from what I remember about the cleveland) is that there's a lot of machine work involved to get it up to 408 inches. A lot of block relief (?) needs to be done, which means less material in the block to hold those eight sliding sticks of dynamite together. Too bad the Pantera's gone, but good score on the cleveland if so.

My little brother is a cleveland nut. If it was me I would stick with a windsor but only because of budget. The clevelands do rev faster and all but that windsor is bullet proof compared to it.

Good luck.

gregsz-28

iTrader: (1)

Sounds like your Ford vehicles have their share of problems, too.

Air_Adam

This is just another "my d*ck is bigger than yours" Chevy/Ford arguement, nothing more. The Cleveland has its benefits over the Chevy, and the SBC has its benefits over the cleveland. They are not the same engine. They were designed for different purposes and in different time periods. One is not necessarily better than the other, unless you are talking about one specific purpose. Its like comparing the LT1 to the 5.0HO or the LSx to the 4V Mod motor.

RED_DRAGON_85

breaking the norm here, i will say that ford did a great thing coming up with the 4v OHC type motor and sticking with it.
chevy tried, but did it too soon and it didnt catch on.
those 5.4's can hold their own and thats no joke.

PV9685

"why does everybody rave about the bosch type3 (FORD) injectors when they put them on?"

I think this is somewhat irrelevant as neither GM nor FORD produce BOSCH products. Bosch is a separate company that both GM and FORD have outsourced through. However, the fact that GM produced it's own injectors via Rochester/Delphi over the years proves that they have put forth more effort to streamline the manufacturing process. Although there have been difficulties with many injectors manufactured by both Bosch and GM, it is difficult for a company to produce fuel injectors and know how they will perform after 20 years of abuse.

Stephen

iTrader: (12)

Yeah...My 22 yr old, 87 GTA with 200,000 miles, is always breaking down in this 100+ heat here in Texas. NOT!!!

If we get under down to 100, its a nice cool day outside! I have zero problems & my car fires up, within the 1st crankshaft revolution of starting.

keeslinger31

What was the question again

resinlake

PV9685-

I enjoyed working on those injectors too! Man, was I ever a freak about quality control!