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Old 11-21-2012, 02:16 AM   #1
IMM/ou812
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Default 434 sb chevy with AFR 245 heads

Just finished a customers 434 sb chevy based on a Dart SHP block and Scat rotating assembly.
The AFR 245NPP heads are untouched except for milling to get compression at 12:1.
Used a 50/50 mix of 91 pump and 110 sunoco fuel, Holley 950 true carb, mildly ported SV intake and a custom IMM solid roller cam.
Rockers are 1.7/1.6 TD's, and Crane .180 offset ultra pro lifters. Pretty basic street/strip build that made 643HP at 6500rpm and 571TQ at 5200 rpm with a very streetable cam.

Here's a video and I'll post some pics in a bit....
http://youtu.be/1NjeYzKbXy4
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Old 11-21-2012, 02:22 AM   #2
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Default Re: 434 sb chevy with AFR 245 heads

http://img824.imageshack.us/img824/2176/dsc00192qet.jpg
http://imageshack.us/a/img341/853/dsc00189j.jpg
http://imageshack.us/a/img845/2413/dsc00184hp.jpg
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Old 11-21-2012, 02:26 AM   #3
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Default Re: 434 sb chevy with AFR 245 heads

Very nice street engine well done.
How much timing did it take on the 50/50 mix ?
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Old 11-21-2012, 02:29 AM   #5
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Default Re: 434 sb chevy with AFR 245 heads

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Very nice street engine well done.
How much timing did it take on the 50/50 mix ?
32.5 degrees was best. I tried 31, 32, 33, 34, and 36 but 32.5 was best avg. power from 4000-6800rpm.
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Old 11-21-2012, 03:40 AM   #6
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Default Re: 434 sb chevy with AFR 245 heads

Nice job. how well did the headers match up to the exhaust ports? Looks like that pipe is smaller than the port.
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Old 11-21-2012, 01:02 PM   #7
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Default Re: 434 sb chevy with AFR 245 heads

Pretty good actually. The headers did crowd the port a bit, but not enough to be a problem.
Mike Jones was close, he said 630HP at 6500rpm so I'm happy!
I'm positive if I had used a quicker and large lobe we would have seen 670 or more but my customer wanted to cap the rpm peak at 6500 AND have a decent idle so this was the compromise.
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Old 11-21-2012, 01:52 PM   #8
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Default Re: 434 sb chevy with AFR 245 heads

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Originally Posted by IMM/ou812 View Post
Pretty good actually. The headers did crowd the port a bit, but not enough to be a problem.
Mike Jones was close, he said 630HP at 6500rpm so I'm happy!
I'm positive if I had used a quicker and large lobe we would have seen 670 or more but my customer wanted to cap the rpm peak at 6500 AND have a decent idle so this was the compromise.
When I flowed my 227's and added a 1-3/4 header, air flow dropped about 40 cfm. The corners of the port were covered by the tube. After some grinding on the header opening the flow came back up but never increased over the no pipe numbers.
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Old 11-21-2012, 03:07 PM   #9
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Default Re: 434 sb chevy with AFR 245 heads

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When I flowed my 227's and added a 1-3/4 header, air flow dropped about 40 cfm. The corners of the port were covered by the tube. After some grinding on the header opening the flow came back up but never increased over the no pipe numbers.
It would have been interesting to see if there was any power difference!
I did a small block mopar a couple of years ago for Car Craft, and we had tried 3 different headers.
The most interesting thing was the TTI headers that made the most power were hanging into the port some. The hooker headers that were slightly larger at the flange and tube (1 3/4 vs. 1 5/8 step to 1 3/4 TTI) made less power everywhere! And the 1 7/8 headers made even less....this was a 408 with iron RHS heads, only made 485HP but I was very surprised to see the Hooker header not make more power than the TTI's.

I actually told a friend of mine who was there helping us with parts changing that the Hooker would HAVE to make more power just looking at the flange area! Guess that's why we test!!
Brian
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Old 11-21-2012, 03:10 PM   #10
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Default Re: 434 sb chevy with AFR 245 heads

Not sure what it would have done for power. But it sure sounded awful on the bench.
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Old 11-21-2012, 04:50 PM   #11
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Default Re: 434 sb chevy with AFR 245 heads

Almost identical to my 434 except I have the 235's, 1/2 filled stock block with milodon caps, comp 264/270 at .050 106lsa .672/.672 lift with a 1.6 rocker and 2" lemons headers. We made 667hp at 6700 and 599.8 tq at 5100. It was a couple years ago but I don't think it was ever below 500ft./lbs.
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Old 11-22-2012, 03:56 AM   #12
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Default Re: 434 sb chevy with AFR 245 heads

Quote:
Originally Posted by IMM/ou812 View Post
Just finished a customers 434 sb chevy based on a Dart SHP block and Scat rotating assembly.
The AFR 245NPP heads are untouched except for milling to get compression at 12:1.
Used a 50/50 mix of 91 pump and 110 sunoco fuel, Holley 950 true carb, mildly ported SV intake and a custom IMM solid roller cam.
Rockers are 1.7/1.6 TD's, and Crane .180 offset ultra pro lifters. Pretty basic street/strip build that made 643HP at 6500rpm and 571TQ at 5200 rpm with a very streetable cam.

Here's a video and I'll post some pics in a bit....
http://youtu.be/1NjeYzKbXy4
Can you share cam specs?
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Old 11-22-2012, 11:01 AM   #13
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Default Re: 434 sb chevy with AFR 245 heads

What if any power gains do you think there would be if you swapped to a 4500 carb and intake?
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Old 11-22-2012, 11:48 AM   #14
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Default Re: 434 sb chevy with AFR 245 heads

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Can you share cam specs?
252-258@ .050 on a 112lca. Lift is .714/.685 gross. Smooth lobes too, which I hate but this is a total street car that will probably never see a drag strip. I forget the year of Camaro it's in, but he has 3.55 gears!
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Old 11-22-2012, 11:52 AM   #15
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Default Re: 434 sb chevy with AFR 245 heads

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Originally Posted by slow3rdgen View Post
What if any power gains do you think there would be if you swapped to a 4500 carb and intake?
I'm guessing around 12HP with this combo. But it's not an optimized combo for drag racing, so if I were gonna do that everything would be different to some degree.

I actually didn't want to use this head as the 235 head would have been enough for this build, but he wanted to use them and ofcourse curiosity on my part lead to us using them. I really wanted to use the new SV2 intake, but no endurashine was a no-go for my customer plus the rpm range would have moved up and that was a no-go also.
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