Will Vortec heads bolt on and function correctly on 1975 383 stroker short block - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
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Old 04-11-2013, 01:18 PM
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Old 04-11-2013, 03:24 PM
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Originally Posted by techinspector1 View Post
How about a little math.....
383 with flat-tops (7cc eyebrows) and 64cc heads will create 11.1:1 static compression ratio, requiring a camshaft in the 240@0.050" tappet lift range that makes power from 3200 to 7000. The L31's would have given up way back in the 4K range somewhere due to their tiny little 170cc intake runners trying to feed 383 cubic inches, so you'd be left with a detonating turd. Bad plan from the git-go in my opinion. L31's will make a nice torque motor for the street when bolted on a 383 with 9.0 to 9.5 static compression ratio, where you can use a mild cam and take advantage of the low-end grunt of the combination.
Same motor with 68cc heads creates 10.4:1
Same motor with 72cc heads creates 9.98:1
Same motor with 75cc heads creates 9.68:1
Same motor with 76cc heads creates 9.58:1
Same motor with 78cc heads creates 9.4:1
Same motor with 80cc heads creates 9.2:1
I recommend running the lowest static compression ratio possible so you can run a mild to modest camshaft that the computer will tolerate. FYI, a 383 will want ~200cc intake runners. Even if the L31's would allow a lower SCR, they have 170cc runners that will run out of air pretty quickly, compared to an aftermarket head like an AFR195 or a good ProFiler 195 head.
That was my first thought, the CR. My vortec 383 has 10:38:1 with -12cc pistons. I would use D cup pistons too and not dish.
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Old 04-11-2013, 03:34 PM
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Originally Posted by Hick_101 View Post
I have recently done a 400 sbc with vortec heads. The flat top pistons will not be enough to get the compression down. you will need some sort of dish.. i ran -4cc dish and that still put me pretty high compression. The vortec heads will also need to be redone to aceppt a larger cam. The original springs cannot open as much as what your going to want. There are a couple of ways to fix it. I used beehive springs but there is a way to machine them to handle better springs also. If you have any questions or need any part numbers just private message me.
Sounds like he's on a budget. There are .450 lift cams that will work great for what he wants. What are you wanting performance wise? Sound? Etc...


205-D minus the inner damper
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Old 04-14-2013, 02:26 PM
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Yes, and a small budget at that. The cam that is in it is a .450/.460
Performance wise, this is to push snow and pull a trailer with a 55 1st series (where the bigger budget is). Not so much a short run, but a long haul, with power to climb the hills and pull anything out of a ditch short of a CAT crawler.
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