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#1
03-13-2005, 07:18 PM
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I am wondering what would happen if I were to install a set of blueprinted 350 small valve heads on a 400. One guy told me that the C chambers are smaller and would create too high of compression for a 400 to run on pump gas. I doubt this for some reason.Is he right? The reason I ask is that I already have the date coded 350 and would only need a 69 400 short block. Also, were there any Judges that had 400 w/two barrel carb?
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I can do all things through Christ, which strengthens me.. |
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#2
03-13-2005, 07:18 PM
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I am wondering what would happen if I were to install a set of blueprinted 350 small valve heads on a 400. One guy told me that the C chambers are smaller and would create too high of compression for a 400 to run on pump gas. I doubt this for some reason.Is he right? The reason I ask is that I already have the date coded 350 and would only need a 69 400 short block. Also, were there any Judges that had 400 w/two barrel carb?
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I can do all things through Christ, which strengthens me.. |
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#3
03-13-2005, 07:26 PM
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Your '69 350 heads would give you compression too high for pump gas. Heads from a '71 and later 350 would have bigger combustion chambers and work much better.
There were no 2 bbl Judges but there were 2 bbl GTOs.
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1966 GTO 1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60' 1969 Bonneville Safari- cross country family cruiser. . 1979 Trans Am 400, 4-speed, 4 wheel disc. View from the drivers seat racing down Atco Raceway- http://www.youtube.com/watch?v=GhYDMdOEC7A Ride along in the other lane-http://www.youtube.com/watch?v=mIzgpLtF_uw |
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#4
03-13-2005, 07:29 PM
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Depends on chamber cc, as most 350s were lower compression than performance 400s. No Judges were equipped with 2bbl carbs.
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"The great obstacle to discovery is not ignorance...but the illusion of knowledge." Daniel J. Boorstein "Gas is STILL your cheapest thrill!" Your opinion of me is none of my business. |
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#5
03-13-2005, 09:41 PM
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Had 1968 350 heads (casting # 17) on a 400. The compression was a bit high for pump gas. For the price I paid for all new intake valves (burnt due to low octane), I could have bought good used 400 heads.
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Junk is something you've kept for years and throw away three weeks before you need it! |
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#6
03-14-2005, 05:09 AM
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Thanks for the advice.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Women don't want to hear what YOU think. They want to hear what THEY think in a deeper voice! </div></BLOCKQUOTE> 
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I can do all things through Christ, which strengthens me.. |
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#7
03-14-2005, 06:17 AM
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I disagree, I cc'd my #17 heads to be 80cc. I believe this brings a 400 around 9.3:1. I would think built correctly 93 octane should be fine. All the chambers I have seen, 350-400-455, all have the same basic design. it looks like some are cut deeper and or the cut on the side of the spark plug veries to change the cc range. you'll neeed to cc the heads to know if they will be correct for your engine.
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1979 Firebird Trans Am 301/4spd (Now 428) 1977 Firebird Formula 400/Auto 2007 Grand Prix GXP 5.3L |
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#8
03-14-2005, 07:41 AM
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I also disagree. I have run those same #17 heads with no issues either. I have also run 72cc chamber heads(factory stated size) with pump gas and no pinging. You just need to pay attention to detail. After chamber work and tuliped valves the heads came in around 76cc.
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"Artificial intelligence is no match for natural stupidity." |
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#9
03-14-2005, 03:48 PM
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<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 74Grandville:
it looks like some are cut deeper and or the cut on the side of the spark plug veries to change the cc range. you'll neeed to cc the heads to know if they will be correct for your engine. </div></BLOCKQUOTE> I have to agree there. The 47 heads that should be on a '69 350 are supposed to be 73cc which would push a .030 400 to 10.3- 10.4 which unless everything is perfect is gonna give you detonation. When the heads are off check the volume of the combustion chamber then you'll know for sure.
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1966 GTO 1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60' 1969 Bonneville Safari- cross country family cruiser. . 1979 Trans Am 400, 4-speed, 4 wheel disc. View from the drivers seat racing down Atco Raceway- http://www.youtube.com/watch?v=GhYDMdOEC7A Ride along in the other lane-http://www.youtube.com/watch?v=mIzgpLtF_uw |
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