New LS7 build in my shop...Pics inside!
07-16-2008, 12:07 AM
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New LS7 build in my shop...Pics inside! Building another Ls7 today...
400+ cfm w/ intake manifold bolted on
LS7 heads 2.200 tit valves..CNC ported
.703 lift cam
CP gas ported pistons
4340 crank & rods..just some cheapies!!!
Carb intake...has bungs for possibly future EFI..right now its Davinci Carbed
MSd 58x ignition
Heres a few pics from my shop..Have to make some headers real quick..
400+ cfm w/ intake manifold bolted on
LS7 heads 2.200 tit valves..CNC ported
.703 lift cam
CP gas ported pistons
4340 crank & rods..just some cheapies!!!
Carb intake...has bungs for possibly future EFI..right now its Davinci Carbed
MSd 58x ignition
Heres a few pics from my shop..Have to make some headers real quick..
07-16-2008, 11:09 AM
#7
TI is great but does not heat cycle particularly well, thus it is best, not great, for intake as opposed to exhaust valves. The LS7 TI valves use lash caps on the TI intakes and there have been numerous "dropped valves" Even aftermarket TI valves (probably by the same forge) warn of a very limited life. Some as little as 500 miles!
I have cleaned up a few engines with dropped (pulled the valve head off) that were virtually destroyed.
Commonly used on race engines but changed often and with light springs.
I have cleaned up a few engines with dropped (pulled the valve head off) that were virtually destroyed.
Commonly used on race engines but changed often and with light springs.
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07-16-2008, 11:11 AM
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07-16-2008, 11:14 AM
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TI is great but does not heat cycle particularly well, thus it is best, not great, for intake as opposed to exhaust valves. The LS7 TI valves use lash caps on the TI intakes and there have been numerous "dropped valves" Even aftermarket TI valves (probably by the same forge) warn of a very limited life. Some as little as 500 miles!
I have cleaned up a few engines with dropped (pulled the valve head off) that were virtually destroyed.
Commonly used on race engines but changed often and with light springs.
I have cleaned up a few engines with dropped (pulled the valve head off) that were virtually destroyed.
Commonly used on race engines but changed often and with light springs.
Usually the good Ti valves have hardened tips so no lash caps are needed..
No problems with life on the Ti valves.
I thought the dropped valve LS7 issue was more spring related.
07-16-2008, 11:27 AM
#10
Katech has a great Spring/Retainer setup that is extremely light, totals 78 grams combined weight, tailored for the LS7 heads. Spring pressure 130 on the seat, 370 open and is good to 700 lift, single beehive spring. They use PSI Max Life springs, and are VERY durable.
Keep in mind 427cidLT5, that the GM Ti Valves DO need lash caps, so if you're running the GM ti valves, make sure you get those lash caps, otherwise major disaster will ensue!
07-16-2008, 11:49 AM
#11
DW is the authority on TI valves and they do most of the forging. They are fussy about the coatings to harden the tips or provide steel tips.
There was an acknowledgment of problems with the LS7 valve forgings about 18 months ago.
PSI 1511 springs are the best for lighter valves. On that I agree with Katech. They are in everything we build. The .700 is more than PSI rates them for however.
10-4 on the lash caps> absolutely
There was an acknowledgment of problems with the LS7 valve forgings about 18 months ago.
PSI 1511 springs are the best for lighter valves. On that I agree with Katech. They are in everything we build. The .700 is more than PSI rates them for however.
10-4 on the lash caps> absolutely
07-16-2008, 12:10 PM
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I agree about the spring relation to the dropped valves. Guys running way too much spring for a softer metal, not a good plan. I trust that GM wouldn't put failure prone valves into their flagship motor, especially since they endurance test them for 100,000 miles.
Katech has a great Spring/Retainer setup that is extremely light, totals 78 grams combined weight, tailored for the LS7 heads. Spring pressure 130 on the seat, 370 open and is good to 700 lift, single beehive spring. They use PSI Max Life springs, and are VERY durable.
Keep in mind 427cidLT5, that the GM Ti Valves DO need lash caps, so if you're running the GM ti valves, make sure you get those lash caps, otherwise major disaster will ensue!
Katech has a great Spring/Retainer setup that is extremely light, totals 78 grams combined weight, tailored for the LS7 heads. Spring pressure 130 on the seat, 370 open and is good to 700 lift, single beehive spring. They use PSI Max Life springs, and are VERY durable.
Keep in mind 427cidLT5, that the GM Ti Valves DO need lash caps, so if you're running the GM ti valves, make sure you get those lash caps, otherwise major disaster will ensue!
Depends on everybodys idea of durable for the PSIs??? I got 15k out of em...dropped in a new set and got rid of my high rpm miss.
Whats considered durable for mileage?
I was curious why they went with lash caps on the DW Ls7 valves? Cost maybe? I've ran the DW stuff in my SB2 with hardened tips...no need for the lash caps.
For this LS7...no PSI springs or DW valves.
Last edited by 427cidLT5; 07-16-2008 at 12:19 PM.
07-16-2008, 01:21 PM
#13
15K miles on a high revving spring is absolutely durable. With most high-lift springs expect to see around 10K miles, and I'm talking about dual-spring setups, not bee-hive, which would see even less, and even less on top of that at 7k+ rpms.
The PSI's are rated at only .625" lift at a 1.8" setup on the seat. But, the katech retainers setup the springs at 1.85 on the seat, with a coil bind of 1.1", so, 50 thou within coil bind puts you at 700 lift. I'm running 650/670 lift int/exh, and am at 8K miles, I don't go past 6700 rpms, and I haven't had a problem thus far. But as a precautionary measure, i'm swapping the springs out for a new set, and am going to test the pressures to see how they're holding up to my setup.
The PSI's are rated at only .625" lift at a 1.8" setup on the seat. But, the katech retainers setup the springs at 1.85 on the seat, with a coil bind of 1.1", so, 50 thou within coil bind puts you at 700 lift. I'm running 650/670 lift int/exh, and am at 8K miles, I don't go past 6700 rpms, and I haven't had a problem thus far. But as a precautionary measure, i'm swapping the springs out for a new set, and am going to test the pressures to see how they're holding up to my setup.
07-17-2008, 09:22 PM
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