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Discussion Starter #1
Hey y’all, I’m new here so I hope I’m doing this right. My dad, brother and I just finished building our first Big Block Chevy. Here’s a list of parts we used:

454 4-bolt main block with main studs
AFR 290cc heads
Comp custom hyd. roller (237/241 @.050; .671” / .676” lift / 106 LSA)
L2465-F Pistons, deck clearance between .002 and .005; 10.5:1 compression ratio
Forged crank and connecting rods (ARP rod bolts)
Holley 950 Ultra XP carb
Edelbrock RPM Air Gap intake manifold
Scorpion roller rockers; 1.7 ratio

I don’t have the sheet from the first run when it made 598 HP. The second run it made 595 HP so we switched from the 850 Holley to a 950 Ultra XP and bumped the timing up by 1.5 degrees. It really surprised us by making 623 HP @ 6000 RPM and 604 ft-lbs @4900 RPM. The dyno sheet with the small numbers represents the gains from the carb and timing change. The dyno operator (Terry Walters) will be sending me a video of the 623 HP run in a view days, so for now I only have the video of the first run. Here you go!

https://youtu.be/gjrAGVJJ3og
 

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Welcome! Nice build!
What brand part nr lifters did you use?
 

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Good job! You'll love the feel from that motor. Enjoy! :thumbsup:
 
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Sounds like a nice little street motor. More power than you'll know what to do with. Enjoy it.
 
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Hey y’all, I’m new here so I hope I’m doing this right. My dad, brother and I just finished building our first Big Block Chevy. Here’s a list of parts we used:

454 4-bolt main block with main studs
AFR 290cc heads
Comp custom hyd. roller (237/241 @.050; .671” / .676” lift / 106 LSA)
L2465-F Pistons, deck clearance between .002 and .005; 10.5:1 compression ratio
Forged crank and connecting rods (ARP rod bolts)
Holley 950 Ultra XP carb
Edelbrock RPM Air Gap intake manifold
Scorpion roller rockers; 1.7 ratio

I don’t have the sheet from the first run when it made 598 HP. The second run it made 595 HP so we switched from the 850 Holley to a 950 Ultra XP and bumped the timing up by 1.5 degrees. It really surprised us by making 623 HP @ 6000 RPM and 604 ft-lbs @4900 RPM. The dyno sheet with the small numbers represents the gains from the carb and timing change. The dyno operator (Terry Walters) will be sending me a video of the 623 HP run in a view days, so for now I only have the video of the first run. Here you go!

https://youtu.be/gjrAGVJJ3og

Wow very nice! Please tell me about that pulley and belt setup there?
 
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Discussion Starter #11
Wow very nice! Please tell me about that pulley and belt setup there?
I'm going to have to ask Dad where he got it when he gets home. Right now I can tell you that that it's a serpentine kit with 8-groove pulleys. The kit also came with a power steering pump, just haven't put it on yet.
 

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Sounds like a nice little street motor. More power than you'll know what to do with. Enjoy it.
You're right about that. This will be the most powerful engine any of us have ever driven so far. It's going in a '57 Bel Air post car, probably with the strongest 4 speed that Autogear makes. It should be a ton of fun.
 

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Sounds mean.
 
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Wow very nice! Please tell me about that pulley and belt setup there?
I'm going to have to ask Dad where he got it when he gets home. Right now I can tell you that that it's a serpentine kit with 8-groove pulleys. The kit also came with a power steering pump, just haven't put it on yet.
Yes please. Looks very clean
 
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1968 Chevelle Malibu, upgraded to a 396/TH400 from a 327/PG
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Nice build. That thing has some sauce, that’s for sure.
 
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Was it really ran on 87 octane? Did they try up to 36 degrees timing?

Those 950 XP carbs need some work to run well/clean at idle and part throttle. Can also make some more power. Jmarkaudio on here usually put annular boosters in them I believe as they have a large venturi and poor signal due to that and turbulence. I helped one guy get his dialed in on a 600hp 496, he is very pleased with the results.
 

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Discussion Starter #20
Was it really ran on 87 octane? Did they try up to 36 degrees timing?

Those 950 XP carbs need some work to run well/clean at idle and part throttle. Can also make some more power. Jmarkaudio on here usually put annular boosters in them I believe as they have a large venturi and poor signal due to that and turbulence. I helped one guy get his dialed in on a 600hp 496, he is very pleased with the results.
Yep, 87 octane the whole time. We went as far as 34 degrees total but it didn't like it. Terry runs almost all of his engines on 87. His belief is that in a lot of low-volume gas stations, 93 octane gasoline sits for much longer than 87 octane and as a result loses its octane rating. He claims that 87 octane is used the most and is always the "freshest" gas in the pumps. I'm not sure how true it is, and we'll probably run 91 or 93 in it anyways, but it was interesting to see. As for the XP carb, we're thinking of switching to a 950 Street HP so that we can run vacuum advance and PCV.
 
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