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just recently had my motor built and a few of my intake valves were messed up so my engine builder went about and put some new stainless Steele valves in there. My question is will I run into any valve float with the car boosted? I currently have .660 lift springs brian tooley. Will I have to go with stronger springs? Is the stainless valves any good compared to the stocks.
Also do you run lash caps with them? I read you don't and you do. I'm going to open the valve covers to check if there installed. The valves are Manley Severe Duty Series Stainless Steel intake Valves
Last edited by Richie333; Sep 19, 2018 at 08:38 AM.
All the sodium valves should have been pulled, and new SS valves (and even guides if needed) should have fitted to the heads!!!!
The problem with the sodium filled valves, is they end up with too much slop to the guides, this causes a less than ideal square seat of the valve to the head seat on closing, and ends up with the sodium valve snapping with the valve head in the cylinder to destroy the motor.
So although the sodium filled valves help to transfer heat to the entire valve and lighter, its the thin walls of the valve the problem on a high reving motors, which cause them to get looser to the guide in record time (some LS7 heads where sloppy from the start with the guides not the correct size to start with), and why they end up snapping from the off square seating to the head seat isntead.
As for the SS vavles and a motor that will rev less than 8K, would not worry any downsides to the SS valve over the sodium filled valve.
As for boost on a LS7, missing the point big time. The LS7 with stock intake starts choking for more air about 6.3K, so although it will rev to 7K, the low boost amounts are just to get the motor to breath correctly to the 7K mark (about 6lbs of boost).
Worse yet on a N/A motor, there is just not enough room under the hood for a intake that will flow to 7k cleanly for the motors needs as well. So there is where low levels of boost for the LS7 on a C6 comes in handly, since it will fit under the hood.
As for dumping big amounts of boost to a LS7 motor, that you would to a say a LS3 block, not no, but hell now. The LS7 has higher compression to start with, and the thinner cylinder liners will not take that kind of pressure.
LS7 cylinders liners and take a good look at how much the have been shaved next to each other.
On the other hand, LS3 cylinders with block support between the cylinder as well.
To bottom line it, if you were looking to make a motor that make huge numbers with boost, should have went with a LS3 or LS9 motor to start with instead. These motors/blocks can take higher boost amounts, and produce some very high HP numbers. On the LS7, you only throwing about 6-7lbs of boost at the motor, to take you to the 650hp at 7K instead.
Really, where the LS7 shines is in a N/A use, and for a HP road coarse car. The motor make plenty of torque/HP down low to grunt the motor out of corners, and unlike the LS9 that make liner torque just off idle isntead, you don't need to use PTM to limit the motors instant output to keep from roasting the tires out of every corner isntead.
All the sodium valves should have been pulled, and new SS valves (and even guides if needed) should have fitted to the heads!!!!
The problem with the sodium filled valves, is they end up with too much slop to the guides, this causes a less than ideal square seat of the valve to the head seat on closing, and ends up with the sodium valve snapping with the valve head in the cylinder to destroy the motor.
So although the sodium filled valves help to transfer heat to the entire valve and lighter, its the thin walls of the valve the problem on a high reving motors, which cause them to get looser to the guide in record time (some LS7 heads where sloppy from the start with the guides not the correct size to start with), and why they end up snapping from the off square seating to the head seat isntead.
As for the SS vavles and a motor that will rev less than 8K, would not worry any downsides to the SS valve over the sodium filled valve.
As for boost on a LS7, missing the point big time. The LS7 with stock intake starts choking for more air about 6.3K, so although it will rev to 7K, the low boost amounts are just to get the motor to breath correctly to the 7K mark (about 6lbs of boost).
Worse yet on a N/A motor, there is just not enough room under the hood for a intake that will flow to 7k cleanly for the motors needs as well. So there is where low levels of boost for the LS7 on a C6 comes in handly, since it will fit under the hood.
As for dumping big amounts of boost to a LS7 motor, that you would to a say a LS3 block, not no, but hell now. The LS7 has higher compression to start with, and the thinner cylinder liners will not take that kind of pressure.
LS7 cylinders liners and take a good look at how much the have been shaved next to each other.
On the other hand, LS3 cylinders with block support between the cylinder as well.
To bottom line it, if you were looking to make a motor that make huge numbers with boost, should have went with a LS3 or LS9 motor to start with instead. These motors/blocks can take higher boost amounts, and produce some very high HP numbers. On the LS7, you only throwing about 6-7lbs of boost at the motor, to take you to the 650hp at 7K instead.
Really, where the LS7 shines is in a N/A use, and for a HP road coarse car. The motor make plenty of torque/HP down low to grunt the motor out of corners, and unlike the LS9 that make liner torque just off idle isntead, you don't need to use PTM to limit the motors instant output to keep from roasting the tires out of every corner isntead.
this hands down has to be the best write up I've ever received. I should have said a little about my build. I did break a piston in my stock ls7 when I was NA so I went with a dart shp block with fully forged internals. Nothing is no longer stock inside only thing stock are the ls7 casting. All the intake valves were pulled (8 of them) and replaced with stainless valves. And the valve seats were also replaced. So everything is new. I was more just worried about adding the extra weight and messing something up or worrying about dropping a valve and destroying my motor. So I have 3 choices
1-take my heads back off and replace the valves again back with TI intake valves
2-run them as is maybe change anything somebody recommends when running SS valves to control them.
(I have btr .660 springs in there now and my new cam is .660 lift... rpm said they run the same springs with the cam) but wasn't sure to upgrade to some PAC .700 to be safe. But if I don't need them or if it'll add to much spring pressure I rather not.
3-buy a set of stock heads and start Completely fresh with new valves and valve seats with some port and polish work.
I would like to run my current heads due to me already having so much money in this build and I'd hate to fork another few thousand out but if it's needed then I will do it.
When people are running the SS intake valves what are they changing to make sure there good and not going to float around or bounce around under Higher rpms (6500-7100) or so.
OP, are you for sure that your intake valves were replaced with solid SS, not the exhaust valves? Intakes were Titanium (Ti), and are quite pricey...but I personally would not be running solid SS intake valves on a rebuilt set of LS7 heads.
OP, are you for sure that your intake valves were replaced with solid SS, not the exhaust valves? Intakes were Titanium (Ti), and are quite pricey...but I personally would not be running solid SS intake valves on a rebuilt set of LS7 heads.
yes that's what I was worried about. I'm positive they were the intake. I guess 2 were bad and he replaced them with stainless. If I would have known before I would have bought new TI ones and did it right the first time.
this hands down has to be the best write up I've ever received. I should have said a little about my build. I did break a piston in my stock ls7 when I was NA so I went with a dart shp block with fully forged internals. Nothing is no longer stock inside only thing stock are the ls7 casting. All the intake valves were pulled (8 of them) and replaced with stainless valves. And the valve seats were also replaced. So everything is new. I was more just worried about adding the extra weight and messing something up or worrying about dropping a valve and destroying my motor. So I have 3 choices
1-take my heads back off and replace the valves again back with TI intake valves
2-run them as is maybe change anything somebody recommends when running SS valves to control them.
(I have btr .660 springs in there now and my new cam is .660 lift... rpm said they run the same springs with the cam) but wasn't sure to upgrade to some PAC .700 to be safe. But if I don't need them or if it'll add to much spring pressure I rather not.
3-buy a set of stock heads and start Completely fresh with new valves and valve seats with some port and polish work.
I would like to run my current heads due to me already having so much money in this build and I'd hate to fork another few thousand out but if it's needed then I will do it.
When people are running the SS intake valves what are they changing to make sure there good and not going to float around or bounce around under Higher rpms (6500-7100) or so.
Dear God...your builder recommended SS intake valves with .660 springs and you have a .660 cam? Will you have float? Absolutely. I wouldn't recommend .660 springs with a .660 lift cam even if I had the Ti valves...that's just pushing the edge IMO.
Dear God...your builder recommended SS intake valves with .660 springs and you have a .660 cam? Will you have float? Absolutely. I wouldn't recommend .660 springs with a .660 lift cam even if I had the Ti valves...that's just pushing the edge IMO.
im 100% with you I was thinking of getting some .700 PAC springs.
Another question is I was to pull the heads can I just drop the new TI valves in there or do they need any machine work? Heads are freshly machined with new valve seats. Just didn't know if anything else had to be done. If I can just pull my current heads and change valves may cost about 1000 or so I can save a lot of money. Rather then paying 2500 or so from starting over
im 100% with you I was thinking of getting some .700 PAC springs.
Another question is I was to pull the heads can I just drop the new TI valves in there or do they need any machine work? Heads are freshly machined with new valve seats. Just didn't know if anything else had to be done. If I can just pull my current heads and change valves may cost about 1000 or so I can save a lot of money. Rather then paying 2500 or so from starting over
I would get a second opinion on the work done at this point, rather than just try to drop in some Ti valves. The Ti valves need to be tumble polished anyways, as they are too abrasive for most guide material. I'd send the heads off to AHP...Kohle keeps tumble polished Ti intakes in stock, as they do tons of LS7 heads. I have a set of AHP heads on my car...tumble polished OE Ti intakes, Ferrea f2042p 1-piece hollow stem stainless exhaust valves, Moldstar 90 (MS90) valve guides, PSI 1511 beehive springs w/Ti retainers and OE rockers rebuilt with CHE trunions.
I would get a second opinion on the work done at this point, rather than just try to drop in some Ti valves. The Ti valves need to be tumble polished anyways, as they are too abrasive for most guide material. I'd send the heads off to AHP...Kohle keeps tumble polished Ti intakes in stock, as they do tons of LS7 heads. I have a set of AHP heads on my car...tumble polished OE Ti intakes, Ferrea f2042p 1-piece hollow stem stainless exhaust valves, Moldstar 90 (MS90) valve guides, PSI 1511 beehive springs w/Ti retainers and OE rockers rebuilt with CHE trunions.
what's your lift on your cam? I was also told by another good machinist that a roller rocker arm would be better with that high of lift.
i will call AHP tomorrow
what's your lift on your cam? I was also told by another good machinist that a roller rocker arm would be better with that high of lift.
i will call AHP tomorrow
I kept my stock cam. I just wanted to fix the guide issue...my '09 had 14/16 guides beyond GM service limits with only 15K street miles. Decided to go with some nicer than OE parts, like the F2042p's and the PSI 1511's.
Yes, roller rockers should be considered with .660+ lift. Crower shaft mount system is nice, and reasonably priced...but you'll have to have AHP machine the heads to accept the shaft system. Really, much more than ~.630 lift is where the OE rockers start to no longer display an ideal wipe pattern.
C6 z06 stainless Steele intake valves
