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Working over stock LM7 heads?

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Old Oct 13, 2010 | 10:16 PM
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Default Working over stock LM7 heads?

A local shop around where I live will do a P&P and a 6 angle valve job on my stock heads for only 280 bucks including replacing my springs with his own specialty springs, everyone i've talked to says the guy does real quality work. I was wondering what kind of gains i would see out of this if i installed it with some longtubes. Any input would be nice!!!
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Old Oct 13, 2010 | 10:28 PM
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Make sure he blends the bowls to the VJ (if the throat of the seat gets opened up) after he does the valve job as well. IF you want him to go a little further have him work on the transition portion of the ports and pay attention to the short side radius. Those areas combined with the multi angle valve job will be where you see your gains in flow.

Is he throwing larger intake valves in? Exhaust valves?

Specialty springs??? I'd be asking a bunch of questions about. Spend some coin and pick up some PAC 1218's at least. That'll be good insurance for if you go with a cam above .550" of lift in the future.
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Old Oct 13, 2010 | 10:34 PM
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if your gonna do that i would have him install at least a set of 2" intake valves and mill down the heads a bit...
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Old Oct 13, 2010 | 10:53 PM
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I know for a fact he blends the bowls and i'll have to check into the springs and valves, but it sounded like a pretty good deal to me. How much rwhp you think i could get out of a job like this? I was "guestimating" around 35-40
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Old Oct 13, 2010 | 10:55 PM
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And the cam I had in mind was a TSP 220/220 on a 112 LSA, and i'd be running a stock converter until i can save the money for a Circle D, what can i say? I'm a college kid and it's a work in progress haha
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Old Oct 13, 2010 | 11:29 PM
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Originally Posted by 04Sierra5.3
And the cam I had in mind was a TSP 220/220 on a 112 LSA, and i'd be running a stock converter until i can save the money for a Circle D, what can i say? I'm a college kid and it's a work in progress haha
Thats a good cam for a 5.3 I bought the same cam it will be here tomorrow. I know guys that ran the stock converter for a year with the same cam..
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Old Oct 14, 2010 | 11:02 AM
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Anyone know what kinda numbers I can expect? And what's the lowest LSA you guys would recommend without messing with my idle too much, this is a DD
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Old Oct 14, 2010 | 11:59 AM
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Originally Posted by 04Sierra5.3
Anyone know what kinda numbers I can expect? And what's the lowest LSA you guys would recommend without messing with my idle too much, this is a DD
You will easily see a 50+ rwhp with the TSP 220 can and *IF* the guy ports the heads correctly and they are milled to 58cc +/-....

-112 lsa will lope/be choppy...114 will be like stock/little lope..and 116+ will idle smooth with exceptions of course
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Old Oct 14, 2010 | 11:40 PM
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Default very informative article on 5.3's

Hello , Car Craft bought a j-yard 5.3L to play with and see what kinda #'s they could get . First they put a carb and manifold and a MSD ign/coil controller and headers for baseline #'s which brought it to 335 hp and 350 tq. Then they installed a cam, springs n I believe lifters which they said the springs were necessary with the cam because cam raised not only power but redline to 6800. HP increased by 96 to 431 and tq. to 360 . Then they tested engine with 2 different cyl.head pairs with the cnc'd and 2.00" in. and either 1.57" or 1.6" ex. valves which produced 459 hp and 398lb./ft. at something like 5400 and 4400rpm's respectively . Check it out at Car Craft.com and type in "how much power from a Chevy 5.3L" it's easy to find and worth reading imo .

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Old Oct 15, 2010 | 01:49 AM
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I'd be very concerned about someone doing a p/p job + valve job + springs for $280!

I'm not calling this guy out, but that price just doesn't make sense to me. I'm a firm believer in "you get what you pay for"
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