[Tim M]

I've not done any cam work on the LT1, but Gen1/2 (which isn't any different) I would change valve springs once a year (~10,000 miles / 7200 rpm hydro cam with a rev kit).

Incredibly cheap insurance to prevent failure which could take your entire engine out.

What I didn't do is swap the lifters over a period of 6 years...had one fail at Sebring and mushroomed the valve tip, rocker arm damage. Had to pull the heads and replace all the valves (went with hollow steps for less weight) and continued on.

Also note, many will say that Ti is a wearable items and will shed pieces under normal use. My retainers looked a bit worse for wear - prefer tool steel if possible.

[KingLT1]

A weak spring is a indicator. Like I said prior you should check them every 10k miles with a spring pressure checking tool. That doesn't mean they need replaced. The PAC dual .650 lift springs I used on my gen 3 LS6 build are still going strong 6yrs and 15k miles later. They were just checked last spring and still like new in regards to pressure specs. The cam I used was a Comp 224/228 .534 .537 112 cam @ 1.7 ratio. I was using SLP 1.85 ratio stock style rockers which brought the lift up into the .580-.590 range.

I agree with Cmitchell that I would personally opt for a cam around .600 lift if using stock style rockers. Factory style slider tip rockers will start to side load the valve stem around .630-.640 lift. Nobody seems to care on LT engines but it was a thing on LS engines and my thing is the top end of the valve trains between both generations are essentially the same. So why is this not being considered in the LT engine industry? Is the geometry different on the LT stuff so they can get away with more lift? I don't think so but surely somebody out there with more knowledge can chime in.

[cmitchell17]

Originally Posted by KingLT1

A weak spring is a indicator. Like I said prior you should check them every 10k miles with a spring pressure checking tool. That doesn't mean they need replaced. The PAC dual .650 lift springs I used on my gen 3 LS6 build are still going strong 6yrs and 15k miles later. They were just checked last spring and still like new in regards to pressure specs. The cam I used was a Comp 224/228 .534 .537 112 cam @ 1.7 ratio. I was using SLP 1.85 ratio stock style rockers which brought the lift up into the .580-.590 range.



I agree with Cmitchell that I would personally opt for a cam around .600 lift if using stock style rockers. Factory style slider tip rockers will start to side load the valve stem around .630-.640 lift. Nobody seems to care on LT engines but it was a thing on LS engines and my thing is the top end of the valve trains between both generations are essentially the same. So why is this not being considered in the LT engine industry? Is the geometry different on the LT stuff so they can get away with more lift? I don't think so but surely somebody out there with more knowledge can chime in.

Does it have something to do with the splay angle on the LT? At least we have symmetrical rocker arms, the genIV offset rocker arms seems like they would be really hard on stuff? Maybe not the valves but more the trunion/bearing on the rocker arm.

[Baddawg53]

Checking valve spring pressure is something I've never done. Is it possible to do this on the car? If I gotta pull the heads I'd just replace them and not bother testing them.

[KingLT1]

Originally Posted by cmitchell17

Does it have something to do with the splay angle on the LT? At least we have symmetrical rocker arms, the genIV offset rocker arms seems like they would be really hard on stuff? Maybe not the valves but more the trunion/bearing on the rocker arm.

LS1,2,6 cathedral heads I believe were all 15 degree with no off set to the rockers and it was still a issue. I believe LT heads are 12 degree so maybe the valve angle allows for more lift on a stock rocker arm as you mention?

Originally Posted by Baddawg53

Checking valve spring pressure is something I've never done. Is it possible to do this on the car? If I gotta pull the heads I'd just replace them and not bother testing them.

https://www.summitracing.com/parts/m...AaAq1PEALw_wcB

You might not be able to test every spring with engine in car but you should be able to check some of them and that will give you an idea of the VS conditions.

[cmitchell17]

Originally Posted by KingLT1

LS1,2,6 cathedral heads I believe were all 15 degree with no off set to the rockers and it was still a issue. I believe LT heads are 12 degree so maybe the valve angle allows for more lift on a stock rocker arm as you mention?




https://www.summitracing.com/parts/m...AaAq1PEALw_wcB

You might not be able to test every spring with engine in car but you should be able to check some of them and that will give you an idea of the VS conditions.

Can you confirm the moroso tool from the link works with LT stuff? I don't forsee any problems since you're just coming in from the top of the spring so it seems there shouldn't be clearance issues, but I know there is a lot of tools that don't fit LT stuff when they fit LS for some reason although it seems like most of them should interchange.

[KingLT1]

It should but I can not confirm that. The only thing I am aware of that it won't work on is DOHC stuff.

[cmitchell17]

Originally Posted by KingLT1

It should but I can not confirm that. The only thing I am aware of that it won't work on is DOHC stuff.

I got mine today so I can confirm when I pull my valve covers off, the instructions do say it's only supposed to be used on aluminum rocker arms, not sure what's up with that.

[cmitchell17]

I don't see how I am going to fit the tool?


I just don't see how there is going to be enough clearance, I really hope Summit will exchange or take this back now. I know there were a lot of different versions, there is very little clearance between the edge of the head and the rocker arms to stick something in around them.

[Baddawg53]

I ordered replacement lifters, Johnson 2110r. Also new BTR springs, rather than trying to test them and if I'm going to have the heads off it'll be an easy swap. I'll be a lot more confident in the valve train after this, and who knows, with the limited travel lifter maybe I'll pick up a few more horsepower with the valves opening a little more...

CMitchell17, did you ever find a spring tester to fit in there, I'd like to get one for checking them periodically in the future.

[KingLT1]

Imo I would go with Comp Conical springs over any of the duals. Much improved Valvetrain harmonics and they will rev out much further then any of the duals. These engines with the same cam will go another 5-600rpm.

[Baddawg53]

Originally Posted by KingLT1

Imo I would go with Comp Conical springs over any of the duals. Much improved Valvetrain harmonics and they will rev out much further then any of the duals. These engines with the same cam will go another 5-600rpm.

Wish it wasn't too late, ordered and shipped ...

Everything I've read has been good with regards to the BTR dual springs. I'm confident they'll be good for my application. My only other thought is about upgrading the valves ... I haven't spent any money on those yet so I'm definitely open to suggestions there

[17MaroSS]

Last week i placed an order with tsp. I went with their vvt2 cam and prc heads, hollow ss valves, che trunnions, johnson 2110r lifters. I'm considering upgrading springs to conical but not sure if it'll really make any difference for my application: going to stay full bolt on e85 heads cam.

[cmitchell17]

Originally Posted by Baddawg53

I ordered replacement lifters, Johnson 2110r. Also new BTR springs, rather than trying to test them and if I'm going to have the heads off it'll be an easy swap. I'll be a lot more confident in the valve train after this, and who knows, with the limited travel lifter maybe I'll pick up a few more horsepower with the valves opening a little more...

CMitchell17, did you ever find a spring tester to fit in there, I'd like to get one for checking them periodically in the future.

Ironically right after I tried that tester (and I couldn't fit it in there by the way and I returned it to Summit) my intake valve seats decided to disintegrate and I completely lost cylinder #7. I am about to get my heads back from the machine shop with new seats finally after almost 6 months.

So all this time I was convinced that a valve spring was going to fail but then it ended up being my intake valve seats.