Michael_D

PAC doesn't market their spring that way. I bet they were just BTR springs......

Da Z06

PSI1516ML badass spring!

Im running them at a nominal .050 CB.

jayyyw

Yeah, I was told BTR .660 springs.

If I don't feel LME installed adequate springs, I will be looking at others.

Millenium Z06

I run those same springs, Texas Speed also told me they were made by PAC, a custom spring made for them. I questioned it when I didn't see them on PACs website.
They've been fine for me

jayyyw

The polished PAC .660 spring? I sent a new set of those with my heads to LME. TSP rates them at 160lbs seat and 415lbs open @ 1.810" install height.

Another small tid bit I got was that LME replaced my locks and retainers with another set of BTR pieces. Not sure how I feel about this since the first set was failing. Still not sure what spring was used. Will know more in a few days.

Millenium Z06

The polished .660s are the new spring, my are the old unpolished .660s, about a year old. The polished .660s just came out maybe 3 months ago

Both are the same specs but the polishing of them allegedly helps them live longer.

As for LME, I don't know their work so I can't speak to their character but at this point, I don't trust shops.
Did you see the failure yourself, on your heads? I have the same springs and retainer kit that you do (came on my tsp heads) and when I broke a couple springs (the bad batch that TSP got) they sent me new springs. I installed them myself and saw no signs of retainer damage or locks trying to pull thru.

Point being that I wouldn't be too worried about the retainer and locks used as long as they were assembled correctly and you're at 1.81" .
Those springs should be more than adequate for the cam you're running, you do not want to over spring the engine

jayyyw

I did not see the failure myself. I did notice when I was trying to remove the valves before I sent the heads off, the exhaust valves took significantly more force to dislodge the keepers from the retainers than the intake side. I only got through about 4-5 valves before I decided to reassemble it and just ship them out.

This is my first endeavor with LME so I can't say anything until I actually receive my heads and find out what exactly was done to them. I've heard nothing but great things from them and depending on how this works out, they will be who I use for any further needs.

I'll pull a spring or two from each head to verify install height before the heads are installed.

Millenium Z06

That's not necessarily uncommon. I had to tap my retainers to help them un-seat before I compressed the spring with the spring tool. After that, they came right off with a magnet

jayyyw

It was definitely more that just tapping. I felt like I damn near bent the valve trying to unseat it. I'm not very experienced with the process so it may not be abnormal.

Either way, excited to get it all wrapped up and see how it does.

MTPZ06

Interesting...back in my C5Z days, I recall the PAC nitrite treated springs were the go to (especially with the bad batch of GM LS6 springs). Is that not a thing anymore?

OP, maybe you are looking at nitrited PAC springs...just don't hear that talked about much anymore it seems, but supposedly that was touted as being geared more towards extreme duty applications for longevity. It looks like PAC offers nitrited nano peened springs.

Josh B.

The fact that Johnathan is doing all this in a parking lot, and on jackstands, is just pure hotrodder awesomeness. Can't wait to read your feedback on the LME heads.

Josh B.

Seems like I needed to use a deadblow hammer to tap some off too. They can be stubborn.

Millenium Z06

Yep, that's what I did. Took a couple of valves before I figured that trick out

Millenium Z06

I have a LS7 headed erl 434 in my car now, I'm not sure what the C5 ZO6 Springs are but I know the general go to spring right now for under 660 lift is the TSP/PAC .660s.

MTPZ06

Back when I had my C5Z most were looking at the PAC 1518 Nitrited beehive springs which were rated to .650 IIRC. Those or the 1218's, but they were not nitrited and rated at .625...good for guys that were stock to light mods. Probably a decade since I last paid attention to that subject for the LS6...not even sure if those springs are still in the current PAC lineup. I just don't hear much chatter about the nitrited treating process anymore.

Josh B.

If I were looking for a HR spring package I would go straight towards Comps Conical springs. They seem superior to the cylindrical designs, judging from the literature.

Kingtal0n

Would caution that if you drive the car everyday to always use the weakest spring, and lowest lift cam possible for max robustness. God I hope that is a word. Engine internals can be rated in terms of stress (pressure/area) such as a compressive force, or power output (steady state Joules of work possible) and to exceed these is a mere matter of turning up the boost pressure with sizable compressor regardless of what spring or cam is used. Even if this sometimes means using a more powerful spring, with proper maintenance it can still be a reasonably reliable configuration in a daily driver


(especially when compared to the alternative (not being able to raise boost and needing to increase seat pressure, cam lift, to get the flow desired but having 16 strung out valve guides and enough force to make you wonder how it spins at all, let alone 9,000rpm because again, no boost.)

jayyyw

So, I picked the heads up from my tuner's shop on Tuesday night and got to work on it on Wednesday. Took my time and had it fired up on Friday. Gave it a few heat cycles and drove it around the block. Felt nice to drive it again. My tuner was out of town on a family emergency so it won't hit the dyno until later this week. Getting anxious to see what it's going to do. Will also be tuning a 150 shot on top. May back it off to a 100 shot depending on what it makes on motor only.

I need to get clarification on this, but according to LME, my previous valve job/mill was not consistent and resulted in a variance of CC volume. Either LPE totally fubar'd the valve job or TSP fubar'd the mill. Either way, I don't believe I was at the compression I thought I was at. LME said they are now 65CC so I added cometic head gaskets to bring compression up just a tad bit more.

They installed the PAC springs I sent with the heads and BTR titanium retainers. Install height is 1.810"

All exhaust valves were swapped with stainless valves.

LME 285cc intake and 90cc exhaust port work.

So new setup consists of:
LME ported heads
Milled to 65CC
Cometic .041" gaskets
ID1000 injectors (E85)
Holley Hi-Ram 102mm (phenolic gaskets)
NW102 TB
4.5" JBC Intake
RPM B3 cam
ATI UD balancer
Power Steering Delete
ARH 1-7/8"
Dumped exhaust before axles
SBE
150 Dry shot

Also did a 15" conversion before all this that I have very little run time on. Gunmetal gray Forgestar F14s 17x5 (205/50) and 15x10 (275/50 MT Street R). Hope it'll hook the 150 shot. On the 17s with 315/35 Street S/S it would spin on the hit from a 2nd gear 40 roll at ~3600rpm.

Innovate

jayyyw

I don't even want to hope for a number. I'm just glad there is nothing more wrong with the motor. Should have a couple months of racing before the rainy, cold weather gets here. 630+ would be nice :]