camar0corey

iTrader: (22)

So I have a motor coming to me, and before I stick it in the car I plan on changing the cam out. At least I think I am going to. In any case, I'm thinking of doing the 4/7 swap. Anyone really do this? What all is involved, just swap the plug wires?? Isn't their also another two cylinders you can swap, can you do both? Supposedly its less wear and tear on the motor right?? Just curious before I fill out my cam desires paperwork.

DroppedM6Z

iTrader: (5)

Have not heard of any LTx cars doing it but good luck with it. I'd stick a CC503 in it or a 230/236 and not worry about the other BS. All just IMO

camar0corey

iTrader: (22)

I just want to squeeze as much HP out of it as I can. The motor has forged rods and pistons, and I will be using nitrous. I figure while I get a custom grind if its worth power why not do it?

Anyone else have any opinions on this? I already searched and the thread that popped up had really gone no where, but that was a while back, so someone has had to have done this since.

rasputin

iTrader: (3)

if you get a custom cam, have the cam supplier give you as much information as possible as how to setup your cam + springs + rockers and tune. If not, it will not be worth it and could cause severe damage. Thats the problem with custom cams, they require much more effort and money to squeeze in an extra 5-10rwhp here and there with less duration and better drive-ability. You have to ask yourself if its really worth it for a cam only car making barely more rwhp than an off the shelf cam, where you could make up that space with gears, suspension, tires or what not.

However for a H/C, obviously it works, but LT1 heads don't flow enough, and you don't need over .600 lift to get 5 more rwhp. Off the shelf is your best choice.

zlover129

iTrader: (10)

usually you just need to tell the cam supplier all the info you can, a good cam maker like AI or someone can make a great cam and its usually only about $30 more to go custom

Geneticallybroke

iTrader: (3)

I think the 4/7 swap are for older carb. sbc's (supposed to increase airflow somehow), I doubt it will work on an LT1, but I could be wrong

dhdenney

iTrader: (53)

I always wanted to try the 4/7 swap with the LT1 but never did. Call one of the cam people and have them spec one and while you're at it, ask about the swap.

engineermike

Forget about the 4/7 or 2/3 swap. Class racers have been doing this for a few years to try to get an edge on the competition where the rules are really strict. You're talking about <5 hp difference on engines making 650 hp. On a street LT1, you could gain more by adding 2 deg of duration, swapping to roller 1.6 rockers, optimizing quench, or even adding a throttle body airfoil. Also, for your car, an off-the-shelf cam would be fine.

Mike

camar0corey

iTrader: (22)

Ok, so still no one has actually done it on a LT1??

I have just about every bolt on in the book, minus TB and electric water pump. I might get some head work done, haven't decided yet.

dhdenney

iTrader: (53)

Skip the TB (at least for a while). EWP really won't gain you much either. My advice on the heads is to maybe scout some used ones up for sale, might save some $$.

camar0corey

iTrader: (22)

The only reason I am thinking of getting a TB is I'm looking at getting the Nitrous outlet LT1 plate kit, and I would probably get that in 58mm.

I try to look for used heads, the damn search never works!!!

dhdenney

iTrader: (53)

I always thought the Holley nitrous throttle bodies were trick but I think they were only good for 100 shot dry.

camar0corey

iTrader: (22)

Yeah that and I think they are $500? I know they are way more expensive for a throttle body than one without the nitrous ports, but Nitrous Outlet makes a nice plate for the LT1, or at least I hope they still make it.

The only head work that is done is that the heads/intake have been port matched. I would have loved to have made 400rwhp N/A with a cam and bolt ons, but I guess that is a unrealistic goal??? How much head work would need to be done? Don't know if I want to shell the money out for a LE2 combo or not.

If anyone out there has some used heads for sale that have already been worked over let me know, the search function never seems to be working in the parts for sale thread.

engineermike

Yes, that is an unrealistic goal.

Okay, so you want to do a 4/7 swap on the cam, but you're looking for used heads? Does anyone else see the irony in that?

Mike

Geneticallybroke

iTrader: (3)

quick question, with the optispark how would do a 4/7 swap, wouldn't you have to change the firing sequence?

95greenZ

iTrader: (2)

I'd say you just swap the 4/7 wires on the opti and injectors. To much trouble I wouldn't worry about it.

camar0corey

iTrader: (22)

Yeah, forgot about the injector part of the equation. Guess I won't be trying the 4/7 swap. Can you change the injector firing order in the PCM?? Oh well I'll give up on the idea I suppose.

Whats so crazy about me wanting to find some already worked over stock heads or aftermarket heads that are used??

engineermike

It's crazy because the folks that do the 4/7 swap are spending $20k on a flat top, carbureted 355 (rules mandated). They are spending $5k on "unported" 23 deg standard port location heads. They are running low-tension rings and .018 quench to maximize power. They use ramps so aggressive on the cam that the required valvespring pressure chews up cam bearings if they idle it too low. They use so much overlap in the cam that the valve reliefs must be cut deep enough in the piston tops that they blow through sometimes. They are not looking to save $500 and get a set of used questionable heads, nor are they deterred by 2 injectors being out of sequence. . . I knew that you weren't the type that would want (or need) to do the swap, as I indicated early in the thread.

Don't take this as an insult. Not everyone (including myself) needs to do the 4/7 swap. It's just that some people hear about stuff like this and think it's the "cat's meow" because class racers do it, but there's alot of stuff that they do that have a very small gain and are not worth it for us.

Mike

dhdenney

iTrader: (53)

Yeah Mike helped me out a lot in picking a cam not too long ago. He's got good advice in my opinion. The thing he was saying about the 4/7 swap is that our car's aren't gonna see the benefit of it. I think it was more of an "inside joke" than anything. The 4/7 guys are doing all that crazy stuff for $$$, which some of those things I had never heard about either. I think he assumed if you're gonna go for the piddly stuff, used stuff didn't fit the job description. I'm with you though, get a good cam and some good deal heads and let the big cat eat. If you do find some used heads, get the good names like AI and LE or some flow sheets. Don't skimp on heads but do look for good deals.

LSXNV

iTrader: (1)

there is one rule to follow for the budget oriented hot rodder, KISS (keep it simple stupid). spend the money where it counts the most. the LT1 has been around long enough that custom grinds are almost pointless. and most "customs" from the speed shops are not as custom as one may believe. don't be afraid of used heads, just be cautious. some of us can't afford this stuff new and have to expect a few bad parts. if you buy used buy it locally, so you can see it yourself. or buy it from some on with a good sellers reputation, though that isn't alway fail safe. if i were you, i would buy a stock set of heads and have them checked and ported. go with nitrous as long as you have the bottom end. don't cheap out on the valve train, but don't go over board with exotic pushrods and springs. be honest with yourself on your cam choice. and after you have yourself a well rounded small block, prepare yourself to repair/upgrade everything behind it.