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crandall
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Joined: 17 Apr 2011
Posts: 10
Location: Grand Foks , ND
418.86 points



PostPosted: Wed Apr 27, 2011 11:06 pm    Post subject: Reply with quote

http://www.summitracing.com/parts/BRO-1021004/

see if that one works^^^^^
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clay
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Joined: 24 Nov 2002
Posts: 3209
Location: South Carolina
318129.23 points


1972 Chevrolet Nova

PostPosted: Thu Apr 28, 2011 10:45 pm    Post subject: Reply with quote

One problem I see with those heads is the spring package. They list max. valve lift at 0.525" which is pretty typical from what I've seen on a 1.250" o.d. spring. It is almost always beneficial to run a 1.6 rocker at least on the intake and more beneficial on a 383 than say a 305. With any decent duration on a hydraulic roller and a 1.6 rocker you will easily exceed that lift. I would look for something that would give you 0.600" lift to work with. You probably won't run quite that much lift but it gives you room to work. Clay
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crandall
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Joined: 17 Apr 2011
Posts: 10
Location: Grand Foks , ND
418.86 points



PostPosted: Fri Apr 29, 2011 12:27 pm    Post subject: Reply with quote

ok thanks for the heads up!!Sorry i do have a question though , now is that the rating its giving due to the springs that it comes with or am i able to change that with different springs?...... thanks agian for the help!
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clay
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Joined: 24 Nov 2002
Posts: 3209
Location: South Carolina
318129.23 points


1972 Chevrolet Nova

PostPosted: Fri Apr 29, 2011 2:52 pm    Post subject: Reply with quote

It is due to the springs partly but it is affected by several things. Valve length, retainer, locks and head machining all affect the lift that can be safely achieved. Usually you have to go to a taller installed height to get more valve lift. Look at it this way. If you have a 0.500" tall spring and compress it 50% you can have 0.250" lift (theoritical example) - if you have a 2" tall spring and compress it 50% you can have 1" of lift. Valves can be had in stock length or you can buy +0.100" or other length valves. You can buy a +0.050" lock set that will give you more installed height. The valve pocket can be machined deeper (to a point) for more height. Another potential problem area is the valve seal style. Sometimes a factory style seal will be on a huge boss that won't let the valve go down very far even though the springs would allow it. Late model Vortec heads are a classic example of this and are limited to around the mid 0.400" lift range. If I were choosing heads I wouldn't go any smaller than a 200cc port size - a 383 can easily use it. Look at RHS heads. I haven't used them (af2 has though)but they have a wide range of port sizes and are reasonably priced. Clay
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