LT4 LT1 vs. LT4

[Vettelt193]

The springs aren't strong enough sometimes, If you look at the part numbers from LT4 to LT1, the springs are different... I think LT4 is rated at 100 lbs, LT1 80 or 85lbs... basically they aren't strong enough... Some people go with 1.6's and have no trouble at all, others do... it is usually only one spring, but you have to change them all... I haven't ever seen a problem with the intake side, they are always exhaust.

If you want the 1.6's, and are cheap... you may end up doing the job twice, and have a Vette that is sitting in pieces for a few days while the springs come in.

-In my case, I helped a friend put 1.6's on his Z28, and it didn't work... I bought a full set of 1.5's and we split them... after that, a company started splitting them, but (and this is driving me nuts now) i can't remember which one

 

[RubyDropTop]

Okay, so if I'm following you correctly - if I put all LT4 springs on the car with the 1.6 roller rockers, then I should not have a problem, right? It's only a problem when the LT1 springs remain on the car and are not swapped with the LT4 springs? Am I following you?

 

[Vettelt193]

yes, the LT1 springs are (sometimes) a problem... swapping springs will solve the issue...

you don't necessarily need LT4 springs, I am pretty sure crane cams will have springs that will work with their rockers, and they should be cheaper than GM if you go through one of the big discount performance parts sellers

 

[RubyDropTop]

I was planning on purchasing the rockers from Jeg's - they have the Crane Cam Gold rockers that came as the standard equip. on the LT4 (but you probably already knew that. ) I'm looking forward to the project, once the weather turns cold and the car is in for hibernation anyway. Besides the spring upgrade, I thought that there were a few other things that needed to be upgraded as well such as retainers, locks and shims. What do you think? Sorry if these are dumb questions...I'm not as mechanically inclined as many of you guys are.

Thanks for all of your insight.

 

[Vettelt193]

If you get the Crane Cams Gold self aligning rockers, then nothing else is necessary (except the springs)...

If it is a long winter project anyway, I would get the 1.6's and try it out... if they don't work, get the springs (you could also buy them both, try the rockers, and return the springs if you don't use them)... The springs won't give you any extra power, so they are just a waste of money (and they aren't cheap!) if the springs you have now will work (and if you have the time to burn anyway) You should be able to do the rocker install in a day at most (even doing them twice if necessary)

-What else do you have done to your car? The 1.6's will mimic a mild cam swap (total lift is your cam lift X rocker height, so the rocker is a multiplier for the cam), it won't be truly worth the extra lift unless you have a bit of intake work done, as well as some exhaust work... any time you do work to your engine air flow, you have to look at the big picture... how is the air getting in, where is it going, then how is it leaving... any bottle neck in the system will kill your power.

-A side note, what are your future plans for the car? If you want to do a cam in the future, pick the cam now, then back track from there... many cams require a certain rocker height, and 1.5 seems to be the most popular rocker... You don't want to spend a bunch of money on 1.6's if you will need to go back to 1.5's for a future cam swap.

 

[Vettelt193]

Oh, the reason you don't need anything else is the self aligning tip... Normally, a roller rocker would want to twist away and off the valve, because there is nothing holding it in place, the self aligning tips keep it where it needs to be

 

[RubyDropTop]

The motor is basically as it came from the factory, really. The only "modification" that I have done under the hood is a K&N air filter with an open air lid. I took the factory air lid off and put it aside, and purchased the open lid from Corvette Central. Has it increased horsepower? I seriously doubt it, so I guess that was more of an aesthetic thing to do.

I really don't have any cam swaps in mind for the car - I didn't want to get that involved with taking it apart. As far as the exhaust goes, I personally feel that the stock exhaust that is on the car is rather restrictive...I just haven't figured out what to do about it yet.

 

[RubyDropTop]

Okay, thanks for the self-aligning explanation...that makes sense.

Oh, the reason you don't need anything else is the self aligning tip... Normally, a roller rocker would want to twist away and off the valve, because there is nothing holding it in place, the self aligning tips keep it where it needs to be

 

[LT1Vettepilot]

The springs aren't strong enough sometimes, If you look at the part numbers from LT4 to LT1, the springs are different... I think LT4 is rated at 100 lbs, LT1 80 or 85lbs... basically they aren't strong enough...

I'm not sure about the tensile weight of the springs, but the big difference is the LT-4 springs are oval shaped while the LT-1 springs are round. (looking at the side of the spring, the wire is oval shaped vs round)
This was done to allow the higher RPM without spring binding.

I've never heard the idea 1.5s on the exhaust and 1.6s on the intake. Sounds like an idea though...let us know if you remember which company sells the mixed set.

 

[JohnnyC]

Buy the LT4

I recommend buying an LT4. There is NO faster Vette for that price. You'll run circles arround the other LT1'd C4's, and give the C5 drivers a big surprise.... where they paid twice as much for a slower Corvette. Just make sure you can spot the Z06.

Don't worry about the GS paint scheme, there are plently of LT4's "hidden" is regular painted color cars.

Specs on my LT4 are 360 hp (306 rwh).... and 3.45 rear end.

Go with the LT4, you'll REALLY thank yourself when the time comes to pass or race someone.

Good Luck, let us know what you deside on buying.

John

 

[jstkrsn]

Summit Racing has a mixed set of their own brand on their web site. Only $180 Was thinking of trying them myself.