Originally Posted by ls3fox

@Summitracing Thanks for the reply I did look at the other cam you recommended as well but thought maybe it was a little small for a 6.0

I put your 8720r1 cam in my last truck and that pulled great from 3500 up I'm just looking for something better down low

Originally Posted by Abs

what size engine was in your last truck? I am considering the 8720 for my 04 GTO.

Originally Posted by ls3fox

It was a 6.0 as well it sounded good and pulled great from 3500 up

Originally Posted by Summitracing

@Abs,

Thanks for checking in on the thread. The cam you're describing is the SUM-8713R1 .550/.550, 222/232, 112+5 with 3* of overlap but with .600" lift instead of .550". There isn't a plan for a high-lift version of the 8713R1 anytime soon. You could go with the 8713R1 and get what you're after. You might be down 5-10 hp/tq at most being .550" vs. .600". If we're talking about a racecar dependent to put food on the table don't give up any hp/tq. However, that doesn't sound like that's the case here. Plus you could go with our budget-friendly LS6 Style springs.

Regarding the SUM-8715R1 with specs of .600/.575, 222/234, 115+3 with -2* of overlap. It was designed with a little later intake valve closing for top-end power. You could get our adjustable upper timing gear to advance the cam timing 2-4* bringing the powerband down more in your desired range. With the 8715R1 you would need our .600" lift beehives.

If an adjustable upper timing gear doesn't interest you look at the SUM-8720R1 you mentioned. Specs are .600/.600, 218/227, 112+2 with -1* of overlap. Spec'd similar to the GM "Hot Cam" but with more aggressive yet safe lobes. We spec'd it with .600" lift to get that extra 5-10 hp/tq across the range. It would work great in a stockish 5.7 LS1 with an M6. Would you make more peak hp/tq with the 8715R1 you sure would. That brings us back to our comment about the use of this combo. The 8720R1 would come close to the 8715R1 at peak but be better on the low-end with its earlier IVC and later EVO. With what you're describing you're after we think this might be the way to go. It'll have a nice steady lope but be easy to tune and live with. You'll have a nice wide powerband making it a joy to row through the gears if you feel sporty. Pair it with our .600" lift beehives and it will be plenty happy!

This gives you three options. If you'd like to go down a rabbit hole of how we look at cams check out this article and our cam timing calculator.

Originally Posted by Abs

Thanks again for this and I did want to ask you real quick about Richard Holdener's video of the Stage 2 turbo cams where he tested your 8720 and 8706 in a 4.8L N/A engine. The 8720 performed better down low and also basically the same up high. Do you think this is because it was a small 4.8L LS? Would the results be similar on a 5.7L or greater LS? The test basically made the 8706 look inferior and not worth the time as compared to the 8720.

Originally Posted by Cramer4918

Hello Summit! This thread has been a great read for sure!
I am working a '61 Biscayne with an LQ4/4L60E combo. I acquired the car in the middle of the swap. The LQ4 was bone stock with the exception of an LS1 intake. I have since swapped in the 8720R1 High Lift Combo, ported 243 heads, and LS6 intake. Unfortunately for me, I did not pull the motor completely to inspect how the internals looked. Long story short, after a short time of maybe an hour of run time for idle tuning and drivability, the oil pressure began to drop to roughly 12 psi at idle. The oil looks like a Glitter Fest unfortunately. The rebuild will consist of Gen IV rods and LS2 pistons. So, the new setup will be Gen III 6.0 block/crank, Gen IV Rods and LS2 pistons, 0.051" Head Gaskets, ported 243 Heads milled .010", and LS6 intake and ported stock TB. It doesn't need to break any land speed records, but I would like enough low to mid-range torque so the land yacht of a car can get out of its own way if needed. Will the 8720R1 combo that I have be sufficient enough to do what I am wanting? Guesstimated HP/TQ?

Originally Posted by Summitracing

@Cramer4918,

Thanks for checking in on the thread for a recommendation. Our starting point would be inspecting the cam and lifters. With the engine failure and metal going through the engine we would make sure they're in good shape. Inspect the cam surface to make sure it isn't rough or has any pitting. It's a good idea to flush out the lifters and pushrods in a parts washer. We'd hate to see you get this back together and end where you started. A thorough cleaning of the block would also be at the top of the list.

Onto the recommendation. The SUM-8720R1 would be a good fit for this combo. Specs on it are .600/.600, 218/227, 112+2 with -1* of overlap. It'll have a nice steady lope to it. You'll be in much better shape right out of the gate with the basic foundation of an LS2 vs. the LQ4. The added compression and better heads will give you added hp/tq and better throttle response. The port work and milling are the icing on the cake. You'll have good low-end power/tq with a strong mid-range. If you were feeling sporty you could easily carry power out to 6,500+ with our .600" lift beehives. It'll work with a stock torque converter but would benefit from a 2,500+ converter and 3.55+ gears.

We'd guesstimate this to be around 475hp and 415-430 lbs.-ft. of torque at the crank.

Originally Posted by Abs

did the cam survive or will you have to get another? I am eyeing this same cam for my 04 gto because I am also looking for a low to mid range torque cam. I looked up the weight of your 61 biscayne and it's listed as 3500+, which is actually about 200lbs lighter than my 04 gto. I think this cam will be perfect for us. Their 8715 ghost cam performs really well, but it's better at the top end. The 8720s exhaust performance is basically about equal to the 8715s even though it has 7 degrees less duration because it has .025 more lift and a more aggressive lobe. So it only has 4 degrees less intake duration (which actually helps down low) and a tighter lobe separation, which also helps in the low and mid range too. I think you should run in it and let us know how it does. Especially since it sounds like you already have it. Makes the decision even easier.

Originally Posted by Keith

I had a question about the Summit 8707. In this description, it says that it'll pull cleanly to 7,000rpm with as little as 150lbs of seat pressure.

https://www.summitracing.com/parts/sum-8707r1

But, when I look at this listing with the cam and springs, the springs included have 130lbs of seat pressure, but state in the Q&A that it'll go to 7,000rpm.

So, I'm curious. What spring rate/seat pressure is needed?

P.S. I already have the cam, just trying to figure out the springs.

https://www.summitracing.com/parts/SUM-174004

Originally Posted by Abs

I say use SUM-174005. They have a 140lb seat pressure and cost the same as SUM-174004

Originally Posted by Summitracing

Hi there, part of the problem we run into with spring pressure rating is knowing what type of spring the customer prefers and will likely use.

Anything Pro LS cam up to .525 lift was designed for o.e. springs. The .550 lift cams use LS6's. The .600 lift cams were designed around SUM-174004 Pac beehives. Originally, the .625 intake lift cams were designed around the common Pac .660 duals sold by TFS, BTR, and TSP. SINCE then, we added the SUM-174005 .630 lift Pac beehives and they've been working great too. We've added notes here and there to run them at will.

Getting back to customer preference, a lot of people liked the redundancy of duals. The problem is they need extra pressure JUST to control the added weight of the inner spring and large diameter retainer. A beehive only deals with itself and a very small diameter and light retainer. They aren't breaking and we have customers turning 8k comfortably with stainless valves, so people are getting used to them with time.

Lastly, we like the trunnion kitted factory rocker best and the Pro LS lobe design intensities are designed around using them.

Originally Posted by Summitracing

@Cramer4918,

Honestly, we wouldn't hesitate to go right back to the 8720R1. It fits the bill for the combo and what you've described as goals.

If you wanted something a bit on the rowdy side we'd think about the 8713R1. Your cubic inches, compression, and gears pair well with it. Specs on it are .550/.550, 222/232, 112+5 with 3* of overlap. It'll have a strong steady lope. The 8713R1 pulls strong from 2,500 on up and carries out nicely to 6,500 with budget-friendly LS6 style springs. If you have the SUM-174004 .600" lift beehives from the 8720R1 even better. The Trailblazer SS converter would be ok with it but it would shine with a 3,000+ stall converter.

The intake valve opening is basically what sets the idle quality. The earlier we open the intake valve before top dead center the "choppier" the idle will be at the expense of idle vacuum. The 8720R1 has a -1* IVO @.050" compared to the 8713R1's 4* IVO.

Check out these two articles for a deep-dive into how we look at cams.
- A History of Camshaft Specs and Choosing the Right Cam
- Consider Individual Timing Events When Choosing a Cam