94brick

If I go with 1.6 rr's, Comp Cams Pro Magnums, will I need to upgrade to the LT4 heavy duty springs for my 94? I posted some questions on rr's and have heard some people mention coil bind. How difficult is it to replace springs?

VenkmanP

A few people have reported that they have run 1.6 on stock springs without problems, but the smart move is to replace them.

Somebody else will have to comment on difficulty, but lots of people do it, so it can't be all that hard.

Cherry6speed

The answer is yes, you need to replace the springs. Also, a overhead valve spring compressor, air hold (spark plug) and air compressor is required to do the job safely. Its not too much trouble with a little help and a few beers for your buddy.

1c44ya

when i upgraded to 1.6's i had 54,000 miles on my car and i did not change the springs. I have had "no problem", although i know that many ppl will tell u to change the springs , . . u dont really have to unless,......
you have high milage on the engine, it would be a good idea to change the springs if that applys. I have put about 4,000 miles on my car since the RR upgrade with about half of that being performance driving.
I have a wonderful mechanic that runs a speed shop who builds and rebuilds engines all the time. I would not trust another working on my car, and i trusted his advice in not changing the springs. All i can say is that if you are going to change the RR's and u want to change the springs then go for it , it will only help. But just a note,. . .your current spring's should last for the life of the car. I read somewhere that the reason the lt4 has those springs , is because it operates at higher rpm's up to 6400, and in that senerio the springs are nessesary.
you may also want to change the "esc" (electronic spark control) module to the lt4 esc , also known as the "knock sensor module" . which is located inside your PCM . the lt1 "esc" is very sensitive and will pick up the noisier 1.6's as engine knock and retard your timing , (trust me)

Cherry6speed

Trust? I hate to hear that....The reason you change the springs is because of the increased lift associated with the higher ratio rocker arm, This lift will exceed the compression ability of the stock spring and could lead to coil spring failure. This is not an opinion like many others stated here.

1c44ya

The LT4's new valve springs are made from egg shaped wire for higher seat pressure and improved valve dynamics at higher RPM.
LT4 valves are 2.00-inch (50.8mm) Intake and 1.55-inch (39.4mm) Exhaust valves (as opposed to the 1.94 (49.3mm)/1.50-inch (38.1mm) combination used in the LT1) were made lighter to reduce inertial stress, both intake and exhaust valves are hollow and the latter sodium & potasium filled to improve heat transfer. Valve springs are stronger, with a higher installed seat pressure (100 lbs.in. for the LT4 vs. 85 lbs. for the LT1) and wide open pressure (260 lbs. on the LT4) to keep the valves following the camshaft's contours. Special valve springs, eliptical shaped instead of circular in cross-section (Larger horizontal cross section than vertical), allow a spring with a higher free height to be compressed more for higher operating pressures. LT4 Intake valves weight 85 grams. LT1 Intake valves weight 110 grams. LT4 Exhaust valves weight 75 grams. LT1 Exhaust valves weight 95 grams.

in a nut shell,. . .the springs are stronger and have a higher seat pressure to keep the valves following the camshafts contours,. . as the lt4 has a different cam than the lt1's , so trust that!

Cherry6speed

Good news, I love this forum. It brings out the research in all of us

ToyC4

Personally if I was replacing the rockers I would at least check all the valve spring pressures to make sure they're still within tolerances.

95PoloVert

Well...according to GM, solid height on that spring is 1.26"...so with 1.78" installed height, .520" lift would be solid. Generally .050" is used as the safety factor to avoid coil bind, suggesting that the LT1 spring shouldn't be used to support an application with more than .470" lift.

At 1.6, the exhaust valve would be at .489". Not solid by any means...but less than the generally accepted safety margin.

http://www.fierolt1.com/lt1_vs_lt4_2.htm

http://grandsportregistry.com/lt1vslt4.htm

CAN you run the LT1 spring with 1.6's? Sure.

SHOULD you do it? Depends on who you ask, I suppose...but most don't.

94brick

With that said I will go ahead and change the springs. What is the difficulty level here? Any good links or threads that explain the how-to's of a spring swap?

REDC4CORVETTE

Use the KISS principal.
I installed the comp cam bee hive LS1 springs on my 94 and 1.6 roller rockers,keepers pushrods and titan tops.
Spend the 450.00 and do it right.
Your car is not a volkswagon and cost more than a buck to repair .
Do it right or not at all.
The spring compressor will be the problem.
Stock spring is round and the bee hive is small at the top and difficault to install.
You need compressor tool for spark plug hole NAPA carries that.
I used a neumatic hose from my air wrench to attach to spark plug hole tool.Remove valve covers and losen rockers .
Remove all spark plugs.
Get a magnet .
Presure up the cylender remove keepers and retainer and then spring.
Make sure you buy an LT4 knock sensor $39.95 and install it before you do any work.....
It takes 15 minutes to install in your computer,at the bottom.

VenkmanP

You definitely don't need $450 worth of springs and such just to put 1.6 rr with the stock cam. You can get the whole hot cam kit for that much.

The LT4 springs are more than enough and are about $100 from GMPD. You can get them for $60 or so off ebay from time to time.

Red_Vette_93

"Make sure you buy an LT4 knock sensor $39.95 and install it before you do any work.....
It takes 15 minutes to install in your computer,at the bottom."

so I have to replace this sensor since I'm putting in 1.6RR's in my rebuild. glad I found this out now instead of later.

kwik_ta

***Stupid Redneck Tip***

If you do not have the tools to do the job with the air compressor, rotate the assembly until the piston is on it's upward stroke about ½ way up the cylinder. Remove the spark plug and feed a thin rope (not string... rope) inside the chamber through the spark plug hole. Continue to rotate the piston until it compresses the rope against the bottom of the valve and proceed with the job.

REDC4CORVETTE

Someone on one of the other forms tried the rope trick, caught the rope and put to much presure on the piston and spunn a rod.
The knock sensor should be replaced anyway the car will run lots better,than with the LT1 sensor.
The rope trick works but you need to pay attention to what you are doing.

kwik_ta

Was not aware of that... maybe it isn't such a good idea. While I am a stickler for using the right tool for the job, I am not a big advocate of buying tools that will only be used once. If there is an inherent risk associated with the rope method... it may be best to pay the labor to have it done.

C4Crazy787

NO, The 92/93 cars had their knock module circuitry built into the removable PROM, The LT4 knock module will not work on our 92/93 LT1's.
You must desensitize the circuit, I have the info on how that’s done if you would like it. This is my next project.

VenkmanP

Yeah, but the reason he broke the engine is that after he cut off the rope in the cylinder, and knew he had done so, he just fished around to get the pieces out and didn't pull the head to make sure it was all out. I can't blame the rope trick for that failure.

dgoodhue

I started doing the rope trick, it sucked. I gave up after doing 2 cylinders, the air compressor works much better, it took so much less time.

korvette4u

rope trick...dont even think about it.. do it right or dont do it..

the air compressor way is much better and does two things for you. 1. holds up the valves whilest you replace spring/seals etc. 2) kinda gives you a leak down test/check. listen for ANY noise, like air bubbles in the rad..it may suggest a failing heading gasket...