Ruby6spd

Can the Lt4 springs handle the hotcam and 1.7 rockers?

Or should I just pony up the $$ and get the comp 918 springs?

If there isn't a need to spend the $$ I will go with the Lt4 spring if it has been shown to hold up. My car will be a non ported head, cam, header and 4.10 gear weekend driver so I won't be abusing the springs on a drag strip or banging it off the limiter ever.

Thoughts?

Mojave

I dont think the LT4 springs will handle a 1.7 rocker with the hotcam, as the hotcam and 1.6 rockers are right at the limit of lift.

snowmaker2000

.

My thoughts are 1.7 rockers aren't going to yield one more horsepower without doing the heads and exhaust. I have the 1.6 roller rockers that came with the hotcam and the power curve moved up about 800rpms. The LT4 springs are tight(.060)! Don't do it.

Now I am finding out that guys with bigger cams and 1.7 rockers are slower than my hotcammed car. Why, because once you exceed the flow of your heads, any additional valve lift or cam gonna hurt your torque like crazy. Go to the track and talk to the talking heads...

95PoloVert

No.

Well, you'll need *something* that can handle .558", which is the hotcam w/1.7rr's. 918's are one of the better options out there, IMO.

hippy

How many people on this forum know that head flow at certain lifts DIRECTLY correspond to the cam lift you choose.

Here's an example: If you have a head that flows 465 cfm at .500 lift and then flows 300 cfm at .550 lift try to figure out what would be your optimum cam lift would be after the rocker arm ratio is figured out.
Can you figure it out? Can you see the daylight at the end of the chunnel?

conv90

You are right.... but your example is too much radical...
And you have to consider that the max lift is achieved only ONE time during the valve opening and for only 1/1000..0 of second.
ALL the time (In crankshaft degree) before the max lift and after the max lift should be considered .
I think that a head that flows better at .550" lift should be feef with a cam with at least .570" max lift even if the head has a little decrease in flow at .600" figure.
-Beppe-

87 rag

I think the hotcam with 1.6 rockers has .525 lift. This is the maximum the LT4 springs allow.

Ruby6spd

I agree on your points for the 1.7 vs. 1.6 when it comes to power with the stock heads. This mod is kind of a stop gap for the summer as I already have the 1.7 rockers. Long term plan is to do the cam now before the summer and then do the heads next winter. Just built a house and have been putting major $$ into patio, fencing, etc and I wanted to defray the cost some. The car already has TPIS long tubes, no cats,corsa exhaust and 4.10 gears along with a tune that will have to be redone when the cam is swapped

I do have "some" knowledge of engine building as I did all of my own work on my 01 z06 that was a 430rwhp car. Just wasn't sure what the LT4 spring was rated on the lift side.

Thansk for the responses