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317 Heads on 5.3

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Old 02-06-2017, 11:04 AM   #1
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Default 317 Heads on 5.3

So as I've searched the internet it would seem that the 317 heads are best suited for boosted applications when bolted to a 5.3L engine because of their large combustion chamber size. I've also read that some head milling and flat top pistons can help mitigate this. I've also read that the larger valves over the smaller bore of the 5.3 vs. the 6.0 from whence the 317 head came can cause shrouding.

My budget would really like me to make due with what I have, which is this. 5.3L block, 317 heads, truck intake & drive by wire throttle body, power glide transmission (newly rebuilt with stock gear ratios), as of yet undetermined final drive ratio (rear end gear ration, wheel and tire size not yet finalized).

Here is the application. 1940 Chevrolet 1/2 ton pick up. Patina truck not a rat-rod. Should weigh just under 3000# when finished. The goal is for it to sound nasty, be very hard on tires, and a hell of a lot of fun to drive. Not intended for long trips. A few hundred miles in a shot max to an event or whatever.

Machine work is being executed by a reputable local engine machine shop. The heads will be surfaced for flatness which should help boost the CR and we'll go with flat top pistons for the same reason.

Bottom line is this - the universal opinion seems to be not to use the 317 heads on a 5.3 unless you are boosting. Is this gospel truth for those of us who won't be racing and geeking out on every little detail every weekend and constantly upgrading and tweaking things for a few extra HP and to shave a little off of our ET? Is this really going to be a dog? Is the valve shrouding the kiss of death? Assuming this combo isn't the biggest mistake ever, what cam get's me where I want to be? I was kind of leaning toward Comp Cams 54-416-11 until I started to get nervous about the heads. http://www.compcams.com/(S(10nkh0ib3...csid=1087&sb=0
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Old 02-06-2017, 12:51 PM   #2
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If this engine is going to be N/A I would run the heads that are on the engine or find some 243 or 799 castings. If you swap out the dished 5.3L piston for a flat top and reuse the 5.3l heads you'll end up in the 10.5-11.0 compression range.
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Old 02-06-2017, 01:09 PM   #3
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Conan, I don't have the heads that came with the block. The only heads I have are the 317 casting heads. I understand that ideally the 243/799 castings would be preferable.

How bad will the results be? Horrific? or just less than ideal?
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Old 02-06-2017, 02:10 PM   #4
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Sorry I thought you had a complete 5.3L long block and the 317's. So with a flat top piston and unmilled 317's (71cc combustion chambers) your going to be around 9.1:1. It's not going to be a total dog but it will be on the sluggish side.
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Old 02-06-2017, 02:18 PM   #5
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Sluggish meaning noticeably poor performance that will have me disappointed every time I drive it or sluggish meaning still fun to drive sounds great but just not as good as it could have been? Should I be considering a different cam?
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Old 02-07-2017, 02:02 PM   #6
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If this were my project I would be selling the 317's and buying a different set of heads. I would be shooting for 10:1 - 11:1 compression if it were me. You should be able to find a used set of heads for the same price as a new cam.

By sluggish I mean part throttle and low end grunt will be will not be as crisp and fast revving as the engine would be on a full point or more compression.

I under stand saving some $$$ but I'm the type of person that will let my project sit for a little more time to have the final product be everything I was expecting/wanting. Doing the job twice will cost you more in the end.
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Old 02-07-2017, 02:06 PM   #7
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Conan,

Thank you. That is exactly the detail I was looking for. I think I'll get the long block finished up and hold off on the heads for a bit. Plenty of other work to do as this is the very beginning of the project. I'll keep my ear to the ground for better heads and pounce when the moment is right.
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Old 02-07-2017, 02:45 PM   #8
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What part of the country are you in ?
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Old 02-07-2017, 02:47 PM   #9
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I live in Utah.
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Old 02-07-2017, 03:28 PM   #10
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No ****, I'm in park city, where about are you ?
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Old 02-07-2017, 03:34 PM   #11
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Riverton
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Old 02-07-2017, 10:45 PM   #12
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So do you have a 5.3L short block already bought ?
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Old 02-08-2017, 08:42 PM   #13
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Do you have the 5.3L short block already ? You just need some heads ? I got a couple of contacts in SLC that probably would have a set or two of LS heads.
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Old 02-08-2017, 08:46 PM   #14
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Yes I do. What would a pair of 243/799s run? What do you think I could I get for my 317s?
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Old 02-08-2017, 09:00 PM   #15
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I'd say some where between $100-$400 depending on if they have been freshened up or if they are untouched right off an engine. They might be 241's but with a clean up milling they would work nice on a 5.3 with flat tops. I'll call the machine shop I use tomorrow and see what they have and what they want and send you a PM.
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Old 02-08-2017, 09:02 PM   #16
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Let me know if you come across anything.
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Old 02-08-2017, 09:14 PM   #17
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Can do.
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Old 02-10-2017, 08:18 AM   #18
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Sent you a PM.
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Old 03-20-2017, 03:31 PM   #19
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I'd have to agree with SANPENGYOU as well. I've got a 5.3 w/ 317s and it's fairly sluggish below 3k but that didn't bother me too much, But if I had a recommendation I'd say find some stock or aftermarket heads JUST MY OPINION tho. Let me know what ya do I'm curious
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Old 03-20-2017, 05:50 PM   #20
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So I found an LS-1 and 4L60E combo out of a 2001 Camaro with 67k miles that was complete with computer, harness, exhaust, everything. I did some quick calculations and with all of the bits and pieces still needed to make the 5.3 work it was cheaper to go with the complete setup from the Camaro. In addition it will certainly be much simpler for me. And no ugly truck intake as a bonus. So I went ahead and put the Camaro setup into "inventory".
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