TSP/PRC Head Porting
 

I've been reading threads like crazy about cylinder heads and I've seen a couple people who have sent their LS7 heads to TSP to have the guides fixed/replace the intake/exhaust valves. Does anyone know what Ti intake valve and SS exhaust valve they use? Also curious with anyone's experience having your LS7 reworked by TSP/PRC. I'm not worried about flow/power as I'll be leaving the stock cam, replacing lifters and potentially TSP new roller rockers. Thank you.

They were were one of the shops I looked at early on based on the action center article. Great price for the CNC port work, probably great machine work and turn around. However, I emailed TSP and had to follow up a few times to get a response. My understanding is they CNC the old guides out as part of their CNC porting program and replace with bronze as standard. My understanding is their guides are not compatible with the stock or beehive type springs. As such, once you buy their guides, you are into a dual spring and retainer set up. The issues for which I still really don't have clear answers are:

1) As the factory guide is being CNC machined out, does TSP take the opportunity to correct any valve guide location or angle issues as it is known, some of the LS7 heads not only had a concentricity issue but also the distance between the guide and rocker fulcrum centerline was inconsistent?
2) TSP has stated they will install a "steel" guide for an additional cost. I have no idea what they are calling a "steel" guide. Powdered metal comes in several different formulations with different properties and I am not sure why an OEM type guide would be an additional cost.
3) Exactly what is done with the factory Ti valve stem finish? It is widely thought that Ti and bronze guides do not get along well together. Katech has success using a moly coating on their Ti intake valves with a factory rocker but then again, you have to buy their valves to use the bronze guide. AHP has had success refinishing the stock Ti intakes using a PM or MS90 guide. I have personally not seen consistent long term success using the OEM Ti valve with a bronze guide. (my own fixed heads, stock cam 07 Z06 has this combination and the intakes are shot after a very short time).

I'm real close to TSP and they have a great shop. I went with them for my custom ground, 8620 core camshaft off their Landis LT1VE CNC cam grinder, but I just wasn't sold on the way they addressed rebuilding the OE GM LS7 heads.

• While I have no doubt they have a great CNC program that produces great CFM flows, I wasn't as certain with how they addressed the LS7 valve guide issue, (which was the sole reason for me doing my LS7 heads to begin with.) If you want new valve guides on your LS7 heads, it adds $150 to the price which to me, sort of made me question how familiar they were the LS7 cylinder head (and it's issues.) I honestly do not remember if they told me they were steel guides or bronze, but they can/will use your factory Ti intake valves. If you do have them replace your valve guides it requires new valve springs because of the larger O.D. of the aftermarket valve guide that they use.
• AHP doesn't have this problem and are the only LS7 cylinder head shop out there that I am aware of offering proprietary aftermarket valve guides utilizing superior to OE/GM powdered metal guides or the creme-de-la-creme Moldstar 90 beryllium-free copper valve guides, either of which will work with the factory valve springs if you so choose. Powdered metal is essentially sintered steel, or cast iron, but there are many different formulas, for example, AHP's powdered steel valve guides are much stronger than the stock, GM PM guides.
• TSP is also not a very big proponent of single beehive valve springs which if we were just talking about the factory GM beehives, I could understand (they are cheap junk,) but the PSI beehives are some of the best valve springs on the market and are ideal (Katech spintron-proven) for the LS7 and moderately higher lift camshafts. Many folks do choose a double valve spring, and TSP does use good PAC valve springs, but that just wasn't the route I was looking for in my build.
• As for the valves, only Del West does the tumble-polishing as I am aware, of their Ti valves so unless TSP was sending them off to Del West, I'm not sure I'd want to reuse the factory Del West Ti intake valves. Many including Katech believe that bronze valve guides are too soft for Ti valves, and that is why Katech adds an additional Mo coating to their valves. You have to remember that Ti valves are exotic in nature, are not usually found in a production motor, and have historically been reserved for high-end professional racing applications where cost was far down on the list of priorities. Typically when Ti valves were called for, they would be used with Beryllium copper guides and seats, which only further increased the cost of the decision to go with Ti valves. BeCu was desirable because Ti valves tend to run hotter because they don't shed heat as quickly as stainless steel valves. If you are going to go with the factory DW Ti intake valves on bronze guides, you'll definitely want to ensure they are at least stronger Manganese bronze guides. The DW Ti valves have a chromium-nitride coating to them to help reduce the abrasiveness of the surface of the valve, which is also the reason why Del West began additionally tumble polishing (at the bequest of GM) these valves, as well.

Only pointing this out because I know you like to be accurate - the CrN coating isn't there to make the Ti smooth, it's there to protect the valve from wear. The CrN coating is rough and they are tumble polishing them to smooth out the applied finish. :cheers:

I agree that there was room for improvement on the Del West PVD applied CrN coatings on their Ti intake valves for GM's LS7/9 and LT4 motors, and that was what the additional tumble polishing proposed by Del West to GM (at their request,) was intended to make the valve even smoother, on the valve stem in particular. However, I am of the impression that the PVD-CrN coatings on valves are in fact, in part at least, intended to provide additional reductions in friction, (i.e. smooth.)

http://www.sinusvalves.com/en-us/pvd...tride_coating/

https://cimg4.ibsrv.net/gimg/www.cor...d8a366d92e.jpg

Thanks for the comments! Alot of the same questions it seems. I keep going back to AHP w/ MS90s, Johnson 2110s, (would that require new pushrods?), and probably PSI 1511s. Then after that just learn to drive the car :smash:

You will definitely want to measure to be certain, but comparing apples to apples, the Johnson 2110 SLR's lifters require a little less pre-load than the stock GM LS7 lifters, so you'd be wise go with slightly shorter PR's to begin with. There is little need to go to a full-on short-travel lifter on a street-driven car, so the 2110's fit the bill very well. Johnson suggests .035" +/- .010" whereas the GM LS7 lifters are somewhere between .100" to .120". By going with new PR length, you can take that opportunity to increase the PR strength with a better constructed, chromoly hardened PR's.

That is pretty much the combination I have landed on as well. My 2110s are on order but I see AHS has added the PSI 1515 springs as an option. Along with a price increase on their package 4 but that's business. I fully expect to have to change pushrods.

Whoever told that TSP guides cant be utilized with beehive style valve springs does not know what the heck is talking about.

Personally, I ran TSP CNC ported stock LS7 castings with PSI LS1515ML and LS1516ML beehive springs without issue.

Yes.

First: The 2110 cup is .045" higher than the LS7 lifter
Second: Recommended preload on the 2110 is .035" -.040"
Third: If the head has been milled it will most likely require new PU
Forth: If a new VJ is performed, the valve will sink deeper into the seat and may require a new PU depending on type of lifter and reload requirement

Remember VT measurements are critical since we are stacking tolerances, so your measurements must be on point for a happy valve train.

I was primarily referring to stock springs and assumed the PSI springs would use a thicker spring if anything. In any event, this is from the TSP site: **If stock guides are replaced, stock springs can not be used due to the larger O.D. of the aftermarket guide. Spring kit must be replaced with aftermarket as well.

Seems to me that's referring to the stock spring not being big enough, not that beehives are incompatible with the guide. Over .600/.625, I think I'd rather have a dual spring anyway

Not an issue if you use a quality beehive from PSI. I'm not a big fan of the stock GM beehives, but even the new GenV LT4's use the same $4 beehives from the LT1. PSI origins go back to Hendrick Motorsports in NASCAR in the late 1990's. Valve springs, and in large part valve springs from PSI, revolutionized the entire sport of NASCAR back in the late 1990's by allowing the motors to rev higher and for longer periods of time. Look them up to learn more, it's a pretty fascinating story.

Katech has been using the PSI 1511ML's with their Torquer LS7 110/116 cams for years, which has a max lift of .648" on the exhaust side. I believe that I have read some folks check their PSI beehives upwards of 20,000 miles and measured no discernible measure of wear in the spring; always interested in learning more to see just how long one might be able to go on those springs, on that cam.

The camshaft lobe profile will make a big difference on the valvetrain wears, so having an LS friendly lobe can make or break how well your entire valvetrain holds up. Katech even has a new Torquer LT1 camshaft with lifts at .643"/.655" (219/233 and 118 LSA) that they still recommend to run the PSI 1511ML's. According to Katech's website, they say that in the LS7, Katech installs the 1511's at 1.850" and at that height, the 1511 has 113 lbs of seat pressure and is good for lifts up to .700"! I thought Kohle told me once that they like to install the 1511's at 1.83" which (according to PSI's website) gives the spring a little more seat pressure at 118 lbs and slightly more desirable Distance to Coil Bind. He also said he thought .650" was the highest that he would want to go with the 1511's and if you want to go slightly higher, PSI has a 1515ML or a new 1516ML beehives.

https://cimg6.ibsrv.net/gimg/www.cor...9a3c9adbd0.jpg
https://www.psisprings.com/calculate/

PSI beehive are second to none. The PSI 1511, 1515 and the 1516 are badass springs.

Agreed. When I researched my head fix parts combo, I searched far and wide for a very long time and I couldn't find a single example of a properly installed PSI 1511 beehive spring failure...or improperly installed for that matter. Can they? Sure...anything can fail, but I still haven't seen one.

I was told by TSP that they use the CHE bronze guide and they will only use a duel spring because of the size of the guide. The OD of the spring is larger using that guide. I would have used them but they don’t have a beehive spring that would fit.

Lol oh boy...looks like they just wanted to make something up so you didnt run a beehive (out of their comfort zone perhaps).