I was thinking of putting in the lt4 hotcam kit on my 93, there is a set of lt4 heads avail does anyone know if they will bolt on my lt1 & how much more HP do you think that will create?

Thanks

 

The LT4 heads will bolt on your LT1. But, you'll also need an LT4 intake and fuel rails.

 

Also if you are going to go that far, you may as well convert to a late model opti spark unit. The cost is considerbly less than a early non vented opti and they are more reliable. All you need in addition to the new opti is a 95 model year timing cover, LT4 timing chain set, and the vacuum harness.

 

Why does he need to put a LT4 timing chain set?
Can you not just change the timing cover and put the non-vented opti?
I am asking because I am in the same situation and everything that I have read leads me to believe otherwise.
A

 

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You will have to modify the pin on the cam. If I remember right, it is too long unless you use the later cover, opti and chain. Tom was just suggesting that if you have it all apart, might as well upgrade to the better components. But if you are on a budget, then just modify the pin. Lt4 heads will only work with LT4 intake. Linkage and everything else will match up fine. You have the option with the LT4 intake to use the newer fuel rail with the two crossovers.

 

no computer change or anything of that sort??? will the factory lt1 computer work with the changeover ?????????

 

Bam92 is right, you don't need new rails, LT4 rails have an additional crossover in front, but it is not necessary.

Your LT1 computer will work, you don't need an LT4 computer. Just tune your LT1 programming. As for tuning, it's not completely necessary, but as the heads will flow more, its probably worthwhile to do.

In my opinion converting to the newer opti and changing to the newer timing cover is not worth it. The most economical solution is to keep your opti drive assembly (assuming bearings aren't grinding) and replace the cap/rotor with 95+ vented model and add vaccum lines to vent to intake manifold. MSD has a new model for 2005 that is very interesting.

You also don't need an LT4 timing set. You might consider an upgrade to the LT1/4 Extreme Duty set if you are planning on high RPM's, by all means replace your current timing chain (unless you have ridiculously low mileage).

 

How about putting an electric water pump on, getting the MSD opti, & new timing chain to go along with the heads, cam, rockers, & intake?
I like the idea of the water pump, gets rid of the leaking on the opti problem. Also where can I find some infor on the vaccum harness, & what it connects to.

Thanks

 

I would like to know what is more cost effective? having my LT1 heads ported to stage 2, intake matched or going with LT4 heads & intake?

 

engine question Red_Vette_93


When I did my heads/cam, I went with a Meziere water pump, and a GenII opti with a '95 timing cover. I really didn't want to shorten the pin on my brand new CC cam, so I just decided to bite the bullet and upgrade the whole thing.

I don't have access to my part numbers right now, but if you decide to go with the GenII opti, I can get the vac harness part # for you. It consists of two hoses; they both attach to the opti and one end attaches to the intake "snorkle" (the small gray elbow) and the other connects to the intake manifold. You'll need the "nipple" that screws into the intake directly underneath the TB bores - I have that part number too if you want.

As far as your heads go... You'll pay around $1,500-$2,000 to get a stage 2 or better porting job on your existing LT1 heads (that's what I did). If you decided to go with LT4 heads, you've increased your costs exponentially. Here's why... You first need to get your hands on existing LT4 heads (roughly $1,200 or so new). Then you'll need to get a nice red LT4 intake ($200.00 or so). Once you've aquired these, you'll pay to get a stage II/III port job done on the LT4 heads ($1,700.00) and get the LT4 intake port matched ($400.00). You may be able to get away with utilizing your existing fuel rails as I've heard you don't really need the front crossover tube. I lucked out and found a fuel rail assembly from a '94 donor engine. If you opt to buy a new '94-'96 style corvette fuel rail, they're *very* expensive (and no, the F-Body fuel rails wont work).

So by going for the LT4 setup, you'll probably drop at least $3,500.00 or so just for heads/intake. Now, you can also buy AFR competition ported LT4 heads, but they're around $2,500.00/pair. You still need to get an LT4 intake with a port job, so you're still in the $3,000.00 range + the wait time for AFR to get the heads to you.

Hope this helps - feel free to send me email if you need any further info.

 

can I use my LT1 fuel rails or do I have to get the ones with the crossover??
can someone posts some pics of the two so I can see the difference?

Thanks