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We received this today from our friends at Back Street Performance in Medina Ohio. A local shop we work with on a variety of projects.
His customer brought in a 40k mile 2004 Corvette he just purchased.. He wanted to have the car gone over to make sure it's mechanically sound and dyno it (not even tune). It was a typical "Show car" in appearance with shorty headers, but no CAI etc.. The car wasn't pulling to redline and the power curve nosed over hard at 5700. In went a new set of Summit SUM-174002 LS6 valve springs. Boom...the engine carries another 600 rpm. Without a change in the tune, it picked up a bit of torque even low in the range. We believe a previous owner wasn't afraid to do burnouts on the limiter and took all the temper out of the springs. So nothing earth shattering here. For $69,99 in springs, the car will stay in the meat of the power-band longer and a healthy reduction in E.T. can be expected.
Short version- USE. THE. RIGHT. FREAKIN'. SPRINGS!!
Or freshen the overworked ones you have once in awhile....
Thank you Summit, for good, but often ignored, advice!
Short version- USE. THE. RIGHT. FREAKIN'. SPRINGS!!
Or freshen the overworked ones you have once in awhile....
Thank you Summit, for good, but often ignored, advice!
I installed a set of the same summit springs with this camshaft along with a new LS2 chain, BTR hat seals, and hardened pushrods in my junkyard 06' LQ9.
perhaps someone with some brains can help me understand this cam card? Is that timing @0.006 for real or a typo? I certainly didn't degree it when I installed it!
I installed a set of the same summit springs with this camshaft along with a new LS2 chain, BTR hat seals, and hardened pushrods in my junkyard 06' LQ9.
perhaps someone with some brains can help me understand this cam card? Is that timing @0.006 for real or a typo? I certainly didn't degree it when I installed it!
SUM-8708R1 has similar .050 numbers to this cam. 232/242 113 + 3 .600/.600. To give you a comparison, our .006 advertised numbers are 281/291. What you are seeing are very slow ramp rates on your cam but nothing out of line or unexpected depending on the manufacturer.
These are the advertised open and close numbers numbers on the cam card I put into a popular valve event calculator
Is this cam actually a large reverse split? Or a typo on the cam card? Someone school me please these are the numbers on the card see my post above for the actual card
ivo 38
Ivc 86 or 74?
Evo 74 or 86?
Evc 34
The The numbers at 0.050 are supposed to be 233 intake in 243 exhaust I'm just confused about the intake valve close and exhaust valve open numbers on the cam card are they flipped? Then it is a reverse split I don't really feel like degreeing it lol I just want to know will say for as much noise as it makes out the exhaust pipes it's absolutely silent under the hood 😎
The lobes are asymmetrical so trying to use the .006" numbers will throw things off. At .006" the opening and closing ramps differ greatly from the mathematical guesstimate of a calculator. The cam cards are generated from the lobes so those will be closer than a calculator. This is why we go off of the .050" numbers. Those will come out very close to the cam card .050" numbers on a cam timing calculator.
Here are the .050" numbers using our calculator with your cam card specs of 233/243 on a 114+5.
Thank you summit for clearing that up for me I've been reading and watching more about the LST lobes and yes you are right they are asymmetrical and they have very lazy openings and somewhat more abrupt but later in relation to their relative center line? closing events. Those numbers at 0.050" I would hope are very agreeable to my setup and the very reason I purchased said camshaft. If I had seen or had to guess an advertised IVC at .006 of 86 I might not have bought it though as I would have thought I had not enough compression to run it (IVC of LS6 cam is like 75 degrees at 0.006?) And I'm only at stock 10: 1, less compression and bigger cam is like having a car with a vacuum leak and unplugged spark plugs haha but this cam is way more streetable than I thought it would have been even in my aggressive setup (Lq9, 3" duals, TCI 3600, and 4.10's). honestly I wouldn't mind to try another of these cams with the same lobes on a few degree tighter LSA!
Why would you buy a cam with particular valve events and not degree the cam to achieve said valve events? This is a real question.
Because it's not 1986! Also this is a junkyard bracket race engine it's making plenty of power with the stock gears and a basic LS2 chain, I don't measure anything on these engines, in this day and age of modern manufacturing as far as I use things for my intended purpose I wouldn't measure something unless there was an actual clearance problem or The performance was less than I expected hell Don't most of you guys measure your push rod preload and the number of turns on your ratchet?, I bet I could put a -5° button in the timing gear without measuring a damn thing and pick up a 10th or two if I needed to This baby scoots!
Why would you buy a cam with particular valve events and not degree the cam to achieve said valve events? This is a real question.
Because cam manufacture has come a long ways (well, except for Comp maybe...lol) and the cam will likely achieve the events advertised as installed.
In case you think my slight against Comp is unwarranted, consider that both TSP and Tooley USED to have Comp grind all their cams. Not any more. TSP does their own after a huge investment in cam machinery, and BTR switched to an "OEM Tier 1 supplier" for theirs. You don't fix what ain't broke....
I've had more than one or two comp ground cams go to 7200 repeatedly and reliably with factory GM LS6 springs and the new summit racing LS6 springs seem also to be without issue in my setup.
In reference to the original topic of the thread...
Originally Posted by Summitracing
His customer brought in a 40k mile 2004 Corvette he just purchased.. He wanted to have the car gone over to make sure it's mechanically sound and dyno it (not even tune). It was a typical "Show car" in appearance with shorty headers, but no CAI etc.. The car wasn't pulling to redline and the power curve nosed over hard at 5700. In went a new set of Summit SUM-174002 LS6 valve springs. Boom...the engine carries another 600 rpm. Without a change in the tune, it picked up a bit of torque even low in the range. We believe a previous owner wasn't afraid to do burnouts on the limiter and took all the temper out of the springs. So nothing earth shattering here. For $69,99 in springs, the car will stay in the meat of the power-band longer and a healthy reduction in E.T. can be expected.
This reminds me of something I've seen in the past. When these engines were still relatively new and cam swaps were much less common, a lot of folks were looking to get the most out of their stock internal setups. Occasionally, this led to hand-held tuners being used to bump rev limiters to ~6600rpm with the stock cam and springs. This was really a bad idea for repeated use on the stock springs, and often resulted in the sort of issue seen above (weakened/prematurely worn springs, sometimes worse). While stock LS1 springs are certainly not robust pieces by any means, they should not be behaving this badly at just 40k miles unless they were in some way abused. So, like Summit stated above, either a previous owner basically lived at the rev limiter or perhaps someone had bumped it at some point for a period of time (which seems plausible as headers had obviously been added somewhere along the way as well), then returned it to stock settings prior to sale.
I cannot BEGIN to tell you how many motors I've had people bring to me, that just didn't seem right, and I fixed em in an afternoon for cheeeeep and returned em, and they COULD. NOT. BELIEVE. I gave em back the same car; and all I did was, change the valve springs. Hell, I did it to myself not too long ago, in my humble LM7 truck with the stock cam that if the lobes were *****, Clearasil would be all they need instead of a bra. I figured I had it apart anyway, might as well make an improvement, and was not at all prepared for the improvement I got. Probably 500 more usable RPM AT LEAST, maybe more. Plus, it ran altogether smoother and quieter, and just altogether BETTER, up high.
Summit man hit the head right dead-center on the nail with that one.
One other remark we'd like to make is that .006 is primarily used in conjunction with .050 and .200 to get a decent idea of intensity. There's not a lot of actual flow around the valve at .006" opening though. For that reason most people still use the .050 numbers when determining and setting the characteristics of the cam. Have a good weekend folks.
I like the price of those springs. Strikes a good balance for daily driver.
Originally Posted by Summitracing
His customer brought in a 40k mile 2004 Corvette he just purchased.. He wanted to have the car gone over to make sure it's mechanically sound and dyno it (not even tune). It was a typical "Show car" in appearance with shorty headers, but no CAI etc.. The car wasn't pulling to redline and the power curve nosed over hard at 5700.
Buy a few cars, with 160-200k miles, from original owners. Then pretend they have 40k on them, which can seem plausible. Looks like the seller did that instead.
This thread sold me a set of these springs. Just received them today actually. Hoping for a quick lifter and 243 swap and be back on the road. Thanks for the great price on them!
In reference to the original topic of the thread...
This reminds me of something I've seen in the past. When these engines were still relatively new and cam swaps were much less common, a lot of folks were looking to get the most out of their stock internal setups. Occasionally, this led to hand-held tuners being used to bump rev limiters to ~6600rpm with the stock cam and springs. This was really a bad idea for repeated use on the stock springs, and often resulted in the sort of issue seen above (weakened/prematurely worn springs, sometimes worse). While stock LS1 springs are certainly not robust pieces by any means, they should not be behaving this badly at just 40k miles unless they were in some way abused. So, like Summit stated above, either a previous owner basically lived at the rev limiter or perhaps someone had bumped it at some point for a period of time (which seems plausible as headers had obviously been added somewhere along the way as well), then returned it to stock settings prior to sale.
I used to see listings in craigslist all the time for stock LS1 vehicles and then there would be another listing of a bunch of bolt-on parts and probably a handheld programmer being sold by the same lister haha buyer beware
This thread sold me a set of these springs. Just received them today actually. Hoping for a quick lifter and 243 swap and be back on the road. Thanks for the great price on them!
Thank you for noting the price. We worked VERY hard to get these springs priced at this point. The folks that work at Summit Racing have the same budgets as anyone. We like making great parts that we can afford to put on our own cars!
$69 springs and there are hundreds of different cams out there to choose from mild to wild it's a no-brainer guys sorry to jump all over this thread but I jumped all over those springs for $69 like you wouldn't believe lol.
04-13-2021, 06:12 PM
The simplest thing you will read all day. 
