thoughts on my 408 LQ9 carb cam combo
#1
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thoughts on my 408 LQ9 carb cam combo
Hi, i'm building a LQ9 408cu motor for my 1973 HQ GTS Monaro (Australian muscle car), 1400kg's, T56 magnum 6 speed 3.7:1 diff, 27" tyre. it wont be a drag car, just a tuff streeter, weekend car.
I just wanted some opinions if i'm on the right track with my combo.
LQ9 crate motor, 408 stroker kit, 11:1 comp with 68cc Gm CNC LS3 heads. Victor Jr manifold & carb. Comp cam 281LRR HR13 part number 54-469-11
•RPM Range: 2000-7000
•Advertised Duration (IN/EX): .281" / .297"
•Duration @ .050" (IN/EX): .231" / .247"
•Valve Lift w/1.7 Ratio Roller Rockers (IN/EX): .617" / .624"
•LSA: 113°
Heads Flows
LIFT (inch)INTAKE EXHAUST
0.039 27.612 21.037
0.079 60.714 44.679
0.118 87.3 75.053
0.157 124.341 103.872
0.197 161.414 127.083
0.236 195.628 147.451
0.276 223.566 167.097
0.315 251.641 186.501
0.354 275.218 206.322
0.394 294.406 222.84
0.433 311.917 234.353
0.472 327.475 242.617
0.512 340.917 247.045
0.551 348.538 249.514
0.591 351.323 252.371
0.630 359.135 255.246
0.669 365.137 257.451
0.709 361.738 259.69
0.748 364.504 260.962
0.787 369.196 262.666
Thanks in advance,
Cheers,
Wes.
I just wanted some opinions if i'm on the right track with my combo.
LQ9 crate motor, 408 stroker kit, 11:1 comp with 68cc Gm CNC LS3 heads. Victor Jr manifold & carb. Comp cam 281LRR HR13 part number 54-469-11
•RPM Range: 2000-7000
•Advertised Duration (IN/EX): .281" / .297"
•Duration @ .050" (IN/EX): .231" / .247"
•Valve Lift w/1.7 Ratio Roller Rockers (IN/EX): .617" / .624"
•LSA: 113°
Heads Flows
LIFT (inch)INTAKE EXHAUST
0.039 27.612 21.037
0.079 60.714 44.679
0.118 87.3 75.053
0.157 124.341 103.872
0.197 161.414 127.083
0.236 195.628 147.451
0.276 223.566 167.097
0.315 251.641 186.501
0.354 275.218 206.322
0.394 294.406 222.84
0.433 311.917 234.353
0.472 327.475 242.617
0.512 340.917 247.045
0.551 348.538 249.514
0.591 351.323 252.371
0.630 359.135 255.246
0.669 365.137 257.451
0.709 361.738 259.69
0.748 364.504 260.962
0.787 369.196 262.666
Thanks in advance,
Cheers,
Wes.
#3
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carbs.
Hi, thanks for the reply. I was thinking a QF850 or maybe 950, but was thinking 950 might be a bit big. also thinking of changing diff ratio to 3.9. Any idea what vacume would be like at idle with this cam/combo?
#4
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I like this combo it should tear up some pavement!! I would recommend going to at least a 950 carb on that thing. Call prosystems and they will hook you up. They recommened a 1000 for me. Better yet it will be custom tuned, and you will not have to touch it!!
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You already have a thread on this unless I am missing something:
https://ls1tech.com/forums/carburete...ead-combo.html
https://ls1tech.com/forums/carburete...ead-combo.html
In regards to cam, a guy i know that is pretty switched on recommended going custom cam grind, and said this would be what he'd put in it, "go to a 238 IN and 248 EX lobe with .650/.630 IN/EX lift on a 110 LSA " i think he is a bit more of a efi guy though but very handy. he said try Chris Straub and see what he says.
Cheers,
Wes.
#10
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disagree, that sounds spot on.
i went a 236/246, 613/613, on 110 on a 6.0 with ls3 standard heads but 12.0:1 comp, running a 1000 custom holley done by eric at horsepower innovations.
i went a 236/246, 613/613, on 110 on a 6.0 with ls3 standard heads but 12.0:1 comp, running a 1000 custom holley done by eric at horsepower innovations.
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