Cam Choice Advice
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Teching In
Joined: Oct 2019
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Cam Choice Advice I’m building an s10 to strictly bracket racing. The budget is on the tight side, but I’m willing to spend money where I need to for reliability. The engine I’ve got is a aluminum block 5.3 with flat tops (with the valve reliefs) and 799 heads. Also single plane carb intake with a 750 Holley. It’s going to be bolted to a th400 with somewhere in the range of a 4-4500 stall converter. Nothing too crazy. It will be for 1/8 only so also a good amount of gear. I’ve been trying to decide on a cam and am leaning toward the Cam Motion Junkyard Dog which is 232/244 111+4 LSA and .621/.604 lift. I also found the Summit Pro LS cam 8702 which is 236/246 110 LSA and .612/.612 lift. My worry with the Summit cam is that with more duration and the tighter lobe seperation I could run into PTV clearance issues. Also am I trying to go too big. This motor will be strictly race so I care nothing about idle quality or drive ability. Wide open throttle is all I’m worried about. The Summit cam is a hundred bucks cheaper, but I know some of the summit/jegs brands can be a little sketchy at times on quality. Any input would be greatly appreciated.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
The Summit cams are proving to be good. The best advice to be given here is to call Summit and tell them what you said here (or have them read it...) and let them advise which cam to use
Last edited by G Atsma; Nov 18, 2019 at 01:03 PM.
Id use the 233/239 from TSP.
Their dual springs are the best for the budget and they make the cams and ti retainers in house.
Give us a call we can get you a deal on the kit!
1 877 232 9701
Their dual springs are the best for the budget and they make the cams and ti retainers in house.
Give us a call we can get you a deal on the kit!
1 877 232 9701
I also found the Summit Pro LS cam 8702 which is 236/246 110 LSA and .612/.612 lift. My worry with the Summit cam is that with more duration and the tighter lobe seperation I could run into PTV clearance issues. Also am I trying to go too big. This motor will be strictly race so I care nothing about idle quality or drive ability. Wide open throttle is all I’m worried about. The Summit cam is a hundred bucks cheaper, but I know some of the summit/jegs brands can be a little sketchy at times on quality. Any input would be greatly appreciated.
I use a 850 proform and vic jr intake
Valve springs are the TSP dual .660 with Ti retainers.
No valve float to 7200rpm pulls HARD passed 4500
this is in my 3300lb street car with 4000 stall and 3.08 gears with NO drive-ability issues so its certainly not to big for the track.
this doesnt help you but here is a quick idle Video
been wanting to take it to the track but still need tires
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Joined: Jan 2008
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From: Ohio, Georgia, Nevada, Texas
The SUM-8702 would be a good choice for what you are doing. The SUM-8700 through SUM-8705 cams were out a little earlier than the Pro LS cams. When we were putting together the lineup, the narrow lobe separation and subsequent valve events led us to classify them as single plane cams. That has worked out well. They are mostly based on GM road-racing grinds, so they are pretty easy on the valvetrain. The SUM-8706 through SUM-8721 make up the truck cams, turbo cams, and N/A cams
Thread Starter
Teching In
Joined: Oct 2019
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I run the Summit 8702 in my 6.0 and had no PTV clearance issues with 243 heads on and a .045 headgasket
I use a 850 proform and vic jr intake
Valve springs are the TSP dual .660 with Ti retainers.
No valve float to 7200rpm pulls HARD passed 4500
this is in my 3300lb street car with 4000 stall and 3.08 gears with NO drive-ability issues so its certainly not to big for the track.
this doesnt help you but here is a quick idle Video https://www.youtube.com/watch?v=agGKW28h0Qw
been wanting to take it to the track but still need tires
I use a 850 proform and vic jr intake
Valve springs are the TSP dual .660 with Ti retainers.
No valve float to 7200rpm pulls HARD passed 4500
this is in my 3300lb street car with 4000 stall and 3.08 gears with NO drive-ability issues so its certainly not to big for the track.
this doesnt help you but here is a quick idle Video https://www.youtube.com/watch?v=agGKW28h0Qw
been wanting to take it to the track but still need tires
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,233
Likes: 1,522
From: Ohio, Georgia, Nevada, Texas
You will likely want to go with a 7.425 pushrod to get the proload we're looking for.
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I’m building an s10 to strictly bracket racing. The budget is on the tight side, but I’m willing to spend money where I need to for reliability. The engine I’ve got is a aluminum block 5.3 with flat tops (with the valve reliefs) and 799 heads. Also single plane carb intake with a 750 Holley. It’s going to be bolted to a th400 with somewhere in the range of a 4-4500 stall converter. Nothing too crazy. It will be for 1/8 only so also a good amount of gear. I’ve been trying to decide on a cam and am leaning toward the Cam Motion Junkyard Dog which is 232/244 111+4 LSA and .621/.604 lift. I also found the Summit Pro LS cam 8702 which is 236/246 110 LSA and .612/.612 lift. My worry with the Summit cam is that with more duration and the tighter lobe seperation I could run into PTV clearance issues. Also am I trying to go too big. This motor will be strictly race so I care nothing about idle quality or drive ability. Wide open throttle is all I’m worried about. The Summit cam is a hundred bucks cheaper, but I know some of the summit/jegs brands can be a little sketchy at times on quality. Any input would be greatly appreciated.
Yes. WAY too big. I would want at least a 6.0 for those cams. Or a 6.2
I would want an explosive mid range to hit the converter real hard and pull hard to a 7000-7500 ish shift point. The cams you're looking at would need to be revved to 8k maybe more in a 5.3 IMO
Dynamic compression probably pretty low with those big *** cams too which would make it a dog. You'd have to run them in the calculator to see though..
I'd likely look in the 225-228 intake mid 230 ish duration range with 600-620 lift, on a 112-113 lsa with little or no advance in the cam.
A imagine a cam in the 23x/24x duration range will shift the average power so high in the rpm range you wont fully utilize it. I'd want a cam that's explosive from 4k-7500. Not one that comes alive at 6k
Get with Cam Motion or Summit and have a cam spec'd for your setup.
I could be wrong, I'm not cam yoda, but I have seen many donkey dick cammed cars get taken out by small cam cars.
Last edited by 00pooterSS; Nov 19, 2019 at 11:16 AM.
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Verdad Gallardo Funny thats very close to our asa cam...but not having advance on the cam and a 112 or 113 lsa will effect the dcr quite a bit. Youd want that up a tad to provide some better bottom end and ear5 mid range and boost the mid range some also.
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From: Ohio, Georgia, Nevada, Texas
One thing to remember is the 8702 sounds big with a 236/246 duration and it would be too big if it had the typical 113 LSA of an injected cam because the intake valve wouldn't close until 51 abdc (if 0 advance). With the 110 LSA, we're getting more into old school carbed small block territory with 48 abdc closing to pump up the cylinder pressure to make up for short and uneven runners in a carb intake. You'll be able to get away with it due to your 4000-4500 converter...if you didn't have that, we agree we'd want to pull the intake closing point back to 43 or so.
So what are we left with: I/O 8 btdc, I/C 48 abdc, E/O 53 bbdc, and E/C of 13 atdc. for 21 degrees of overlap. That's going to be tight on valve clearance and it's by design on the intake opening and exhaust closing. You may find yourself advancing or retarding the cam a degree or two to get it to go, but we don't think you'll need to flycut..(but you will need to check). The 799 heads unmilled are going to help the situation, but if you find extra piston to valve...certainly get the heads whacked by whatever you can. We're generally shooting for .060 intake and .080 exhaust...but we've run less under certain circumstanced where we've got HDR pushrods and a good spring package.
So what are we left with: I/O 8 btdc, I/C 48 abdc, E/O 53 bbdc, and E/C of 13 atdc. for 21 degrees of overlap. That's going to be tight on valve clearance and it's by design on the intake opening and exhaust closing. You may find yourself advancing or retarding the cam a degree or two to get it to go, but we don't think you'll need to flycut..(but you will need to check). The 799 heads unmilled are going to help the situation, but if you find extra piston to valve...certainly get the heads whacked by whatever you can. We're generally shooting for .060 intake and .080 exhaust...but we've run less under certain circumstanced where we've got HDR pushrods and a good spring package.
****, I didn't notice the 236/246 was on a 110, that does help.
Looks like the 236/246 110 has a IVC of 48.
My rec was closer to 46 IVC but you guys have more experience here than I do so I appreciate the correction.
I was concerned with a 5.3 with stock heads and a 750 having the ability to take advantage of 240 ish degrees of cam though. Just seems like so much cam for such a small motor. But I suppose if it's never doing anything under 4000 it's not much of a concern.
Tech@ws6 I hear ya, but my numbers would have given 46-48 IVC and I figured that would be plenty for hitting a 4-4500 stall.
Summit, how do you guys change up the cam for EFI vs his single plane carb intake? What dynamic are you looking at that changes the valve events and in which way do you want them to change?
Looks like the 236/246 110 has a IVC of 48.
My rec was closer to 46 IVC but you guys have more experience here than I do so I appreciate the correction.
I was concerned with a 5.3 with stock heads and a 750 having the ability to take advantage of 240 ish degrees of cam though. Just seems like so much cam for such a small motor. But I suppose if it's never doing anything under 4000 it's not much of a concern.
Tech@ws6 I hear ya, but my numbers would have given 46-48 IVC and I figured that would be plenty for hitting a 4-4500 stall.
Summit, how do you guys change up the cam for EFI vs his single plane carb intake? What dynamic are you looking at that changes the valve events and in which way do you want them to change?
Last edited by 00pooterSS; Nov 20, 2019 at 12:22 PM.
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From: Ohio, Georgia, Nevada, Texas
****, I didn't notice the 236/246 was on a 110, that does help.
Looks like the 236/246 110 has a IVC of 48.
My rec was closer to 46 IVC but you guys have more experience here than I do so I appreciate the correction.
I was concerned with a 5.3 with stock heads and a 750 having the ability to take advantage of 240 ish degrees of cam though. Just seems like so much cam for such a small motor. But I suppose if it's never doing anything under 4000 it's not much of a concern.
Tech@ws6 I hear ya, but my numbers would have given 46-48 IVC and I figured that would be plenty for hitting a 4-4500 stall.
Summit, how do you guys change up the cam for EFI vs his single plane carb intake? What dynamic are you looking at that changes the valve events and in which way do you want them to change?
Looks like the 236/246 110 has a IVC of 48.
My rec was closer to 46 IVC but you guys have more experience here than I do so I appreciate the correction.
I was concerned with a 5.3 with stock heads and a 750 having the ability to take advantage of 240 ish degrees of cam though. Just seems like so much cam for such a small motor. But I suppose if it's never doing anything under 4000 it's not much of a concern.
Tech@ws6 I hear ya, but my numbers would have given 46-48 IVC and I figured that would be plenty for hitting a 4-4500 stall.
Summit, how do you guys change up the cam for EFI vs his single plane carb intake? What dynamic are you looking at that changes the valve events and in which way do you want them to change?
On a EFI combo, we might dial in the intake opening a little later to match the computer, displacement, flywheel mass etc. to make them easier to tune. The tuner will give the customer something a lot more livable and fun at hardly any expense in power. Carb guys know what they are getting into and easy ways to dial things in. Exhaust closing is often about the piston to valve limitations and how free flowing the exhaust system is...open headers versus y-pipe etc. Our cam's 4 valve events, being in clear increments makes it harder to go wrong.
Here's a current list of cams by Automotive, Truck, Turbo, and Single plane. The events are off the the right and makes it a little easier to see the increments when they are lined up with each other.
Thread Starter
Teching In
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I have to say I’ve been very impressed by Summit through this cam searching experience. To be a budget brand in this market, they are definitely a class act. I tried to message comp cams and they suggested a cam with 226 degrees duration on the exhaust and said that is the absolute biggest my combo could take. Kinda sad what comp is becoming. Glad we have other awesome companies to depend on now.