Learning from experience
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Staging Lane
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Learning from experience
Well i finally figured out why my brand new 408 had a bust at low throttle and wouldnt make horsepower above 5600 rpm. Turns out it was in the PRC LS3 heads, apparently at low throttle, the intake valve was shrouding and heads would not make any power above 5600 rpm. Just a word of advice dont use these heads on a 4.030 bore. I went to TF 225 and solved all my issues.
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Staging Lane
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Good luck, I made 468 at 5600 but there is still room for more, also my tuner had a similiar build a month ago with same heads and he had the same results. And yes everything was bought for compatability but the problem is the size of the bore with the LS3 intake valve. Just trying to help people not make the same mistake i did. People will tell yall that this work on a 4.030 bore with no issues but just beware, i tried it and did not get optomal results.
#6
I find it hard to believe that the PRC heads are the culprit for your low numbers/problems. So you merely swapped the heads ? Did you ever contact TSP regarding your soft numbers/disappointment?
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Staging Lane
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Believe what you want, i can assure you they were the problem, but it was not the PRC heads , like i said before it was the bore/ LS3 valve problem
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#8
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You got caught up in the hype despite ALL available information saying they clear a 4.00 bore but really need a 4.065. You tried a 4.030 and then manned up and admitted your mistake and tried to help others but there are going to be those who will never believe, because we all know a huge port and a huge valve always make more power even when the valve is blocked by the bore.
I believe most folks will understand you were stating you bought the wrong heads not that the heads were anything less than quality pieces.
I believe most folks will understand you were stating you bought the wrong heads not that the heads were anything less than quality pieces.
Last edited by 96capricemgr; 01-06-2013 at 10:52 AM.
#11
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Well i finally figured out why my brand new 408 had a bust at low throttle and wouldnt make horsepower above 5600 rpm. Turns out it was in the PRC LS3 heads, apparently at low throttle, the intake valve was shrouding and heads would not make any power above 5600 rpm. Just a word of advice dont use these heads on a 4.030 bore. I went to TF 225 and solved all my issues.
#16
Staging Lane
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iron 408, diamond pistons 4.030 bore, callie rods, callies crank, FAST 102 LSXr intake, FAST 50# injectors, PRC LS3 66cc heads, Caddie lifters, Stock rockers with trunion upgrade, 102mm tb, SD tune, racetronix pump with hotwire kit, comp cam 621-624 lift,duration at .050 235-251, 113 LSA. Kept having a bust at 2800 rpm, until we tuned with SD, fattened it up to make air heavier and fixed the bust. Makes peak horse at 5600, does not drop but levels out to above 7000. Also using NGK TR6 plugs with .032 gap.
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Did the earlier model PRCs have issues that were corrected with present castings. These heads were bought in 09 and been new in box since then.