Summit's bringing out the Big Guns!
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Honestly, even the SUM-8729R1 is probably too big. Maybe with more compression or 427+ cubes. The DCR is only 8.1 with your setup.
This would drive better with an earlier IVC and have the same aggressive idle:
https://www.summitracing.com/parts/sum-8711r1
Stage 4 Pro LS Cam, Extra Clearance 234/248 113.5 +3.5 .625/.605 Lift
At most maybe this one with a decent stall (or wide ratio manual) and 3.73+ rear:
https://www.summitracing.com/parts/sum-8709r1
Stage 4 Pro LS Cam 238/246 113+3, .625/.605
Last edited by 68Formula; Mar 1, 2024 at 05:29 PM.
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From: Ohio, Georgia, Nevada, Texas
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@Summitracing thought you'd be interested in some testimony from a BG1 user on another forum.
Cliff Notes:
With the mid-length headers and camshaft not playing nice together, it was time to bring out the Big Guns.
Fast forward... upgraded the same setup with the BG1 to better match the headers/exhaust, and had the same tuner recal. Hasn't hit the dyno yet but...
I'm happy to report that the car absolutely rips now. It also pulls very hard until it hits the 6800 rpm limit, so I may raise that,
My tuner said judging by the MAF readings he thinks the car is putting north of 525 hp to the tire. So who really knows, but the seat of my pants would believe that it has 65 more ponies than before."
Sounds like a satisfied BG customer. Example where cams really prove their worth in certain setups.
Link to the full thread if interested: https://www.pro-touring.com/threads/...am-expert-here
Congratulations and well done.
Cliff Notes:
- Combo was a LS swapped Mach 1 418 stroker with custom cam ~ 247/258 111+0.5 (updated specs in post #20) and 11.5:1
- 1 -7/8 mid length headers with 3in collector to 3in exhaust X-pipe to 3 in warlock mufflers then smooth transition to 2-1/2 in tail pipes
- 102mm TB, FAST LSX 102 intake, stock LS3 heads
With the mid-length headers and camshaft not playing nice together, it was time to bring out the Big Guns.
Fast forward... upgraded the same setup with the BG1 to better match the headers/exhaust, and had the same tuner recal. Hasn't hit the dyno yet but...
I'm happy to report that the car absolutely rips now. It also pulls very hard until it hits the 6800 rpm limit, so I may raise that,
My tuner said judging by the MAF readings he thinks the car is putting north of 525 hp to the tire. So who really knows, but the seat of my pants would believe that it has 65 more ponies than before."
Sounds like a satisfied BG customer. Example where cams really prove their worth in certain setups.
Link to the full thread if interested: https://www.pro-touring.com/threads/...am-expert-here
Congratulations and well done.
Last edited by 68Formula; Dec 6, 2024 at 09:26 AM.
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@68Formula,
Thanks for sharing this awesome feedback and detailed testimony! It's always exciting to hear how our products are performing in real-world setups. We're thrilled to know the BG1 cam has made a noticeable difference and has another satisfied customer ripping down the road. Thanks for thinking of us, and congrats to the owner and the tuner for a well-executed setup!
Thanks for sharing this awesome feedback and detailed testimony! It's always exciting to hear how our products are performing in real-world setups. We're thrilled to know the BG1 cam has made a noticeable difference and has another satisfied customer ripping down the road. Thanks for thinking of us, and congrats to the owner and the tuner for a well-executed setup!
Happy New Year to you guys! Ok, I got one for you. I am building a serious, brass knuckle 71 AMX w/ a 392ci 4.155x3.622. Will have AFR 230v2 heads, otb w/ better springs and 1.8 Comp rockers. I plan to turn this thing hard. Will have 4l80 trans, 4000rpm converter, probably Circle D or Dice. I'm going hunting Lambos/McLarens since I am in SoFlo. Will get street driven completely, but needs to turn up hard. Which of the Big Guns you think is a good fit? Car will have full 3.5iin exhaust, probably a Hi Ram w/ dual throttle bodies.
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Happy New Year to you guys! Ok, I got one for you. I am building a serious, brass knuckle 71 AMX w/ a 392ci 4.155x3.622. Will have AFR 230v2 heads, otb w/ better springs and 1.8 Comp rockers. I plan to turn this thing hard. Will have 4l80 trans, 4000rpm converter, probably Circle D or Dice. I'm going hunting Lambos/McLarens since I am in SoFlo. Will get street driven completely, but needs to turn up hard. Which of the Big Guns you think is a good fit? Car will have full 3.5iin exhaust, probably a Hi Ram w/ dual throttle bodies.
Compression Ratio?
Headers primary size? Long tubes or mid-lengths.
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11.5:1, flat tops on a roughly 68cc chamber-may tweak that a bit, 1 7/8 primary'at a min, going to look for stepped 1 7/8-2in if I can find a set that fit for not an insane price, gears-IDK. It's not a drag car and I need it to go 170mph+. I have an rpm limit of around 8-8200rpm in mind. 27in tire. Probably will be in the 3.50-3.70 range, but I have not done the final math yet.
Are the pistons fly-cut for valve clearance?
Last edited by 68Formula; Jan 2, 2025 at 10:03 PM.
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Yes, dual 4500 TB's, injected and yes it's a 4.155 bore Wiseco flattop with valve reliefs. Don't worry about the lift, I will make it fit, lol I am just curious what cam Summit recommends for the combo. As is, I'm leaning towards BG1, but will see what opinions come back. I probably need something custom for this app, but it's going to be budget-ish out of the gate. I have heads, I have the shortblock, i have the trans, I just need to put the rest together Eventually, it will get a 10-71 screw blower on my LSX block w/ Brodix or CID heads, but this is the baby motor to get the car on the road.
You have an estimate on the final vehicle weight?
Thread Starter
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Joined: Jan 2008
Posts: 2,235
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From: Ohio, Georgia, Nevada, Texas
Happy New Year to you guys! Ok, I got one for you. I am building a serious, brass knuckle 71 AMX w/ a 392ci 4.155x3.622. Will have AFR 230v2 heads, otb w/ better springs and 1.8 Comp rockers. I plan to turn this thing hard. Will have 4l80 trans, 4000rpm converter, probably Circle D or Dice. I'm going hunting Lambos/McLarens since I am in SoFlo. Will get street driven completely, but needs to turn up hard. Which of the Big Guns you think is a good fit? Car will have full 3.5iin exhaust, probably a Hi Ram w/ dual throttle bodies.
11.5:1, flat tops on a roughly 68cc chamber-may tweak that a bit, 1 7/8 primary'at a min, going to look for stepped 1 7/8-2in if I can find a set that fit for not an insane price, gears-IDK. It's not a drag car and I need it to go 170mph+. I have an rpm limit of around 8-8200rpm in mind. 27in tire. Probably will be in the 3.50-3.70 range, but I have not done the final math yet.
Yes, dual 4500 TB's, injected and yes it's a 4.155 bore Wiseco flattop with valve reliefs. Don't worry about the lift, I will make it fit, lol I am just curious what cam Summit recommends for the combo. As is, I'm leaning towards BG1, but will see what opinions come back. I probably need something custom for this app, but it's going to be budget-ish out of the gate. I have heads, I have the shortblock, i have the trans, I just need to put the rest together Eventually, it will get a 10-71 screw blower on my LSX block w/ Brodix or CID heads, but this is the baby motor to get the car on the road.
Happy New Year, and what a killer project! That AMX is shaping up to be an absolute monster.
The SUM-8729R1 (“Big Gun 1”) looks like a great fit for your build with its .625/.605 lift, 240/247 duration, 115.5+5 LSA, and 12.5° overlap. However, given how stout this combo is, you might also consider the SUM-8730R1 (“Big Gun 2”), which offers .625/.605 lift, 242/251 duration, 116+6 LSA, and 14.5° overlap. We’d even take it a step further to get the most out of the 8730R1. With your 8,000+ RPM target, running an adjustable timing gear to reduce advance by 2° would extend the intake valve closing to 53° and optimize exhaust timing for your setup. This adjustment would not only enhance midrange response when that 4,000 converter hits but also help carry power to your 8,000 RPM target.
Be sure to verify PTV clearance, especially if you mill the heads. For the 1.8 rockers, we recommend dual springs with Ti retainers (minimum 160 lbs. seat and 450 lbs. open) along with our HDR thick-wall pushrods for added stability.
For the exhaust, your plan for 1 7/8"+ long tubes and a 3.5" system sounds solid. Since shelf long-tube options for an LS-swapped AMX aren’t readily available, a Header Builder Kit, like those from Stainless Works, may be the way to go.
Let us know if you'd like to refine the cam specs or explore other options as you finish the build. We can’t wait to see this beast hit the streets!