gretchen/jason Posted April 24, 2007 Share Posted April 24, 2007 So my 350 sbc oil pump locked up on me so i figured rebuild time is at hand . Just happens i have a friend at a machine shop who just happend to have a sbc 400 crank that he turned for a 383 swap .Oh and im trading my 400 for work on the 383 . i only paid 100$ for the 400. One quick question before the main question . I was hitting 300 horses to the tire with 7 lbs of boost and lots of ring blow by . With a 383 how much more power could i expect to see ive been told a 383 is good for another 30 horses or so . The main question .................. Now he sugests using the sbc 400 conecting rods seeing as i have a whole set from the sbc 400 block i just bought . Or if i use the rods to a sbc 350 id have to get different pistons . Which way would be the better way to go ? He claims if i use the 400 rods with the stock 350 pistons i have to make sure not to rev it over 6,500 rpms but im assuming if i use the 350 rods get oversized pistons i could rev it even more . But seeing as ill be getting a cam with a 6,200 rpm limit im sure the 400 rods would be ok but this is why im asking as im not to sure . Plus i needed the rebuild due to piston ring blow by with my supercharger hopefully gapless piston rings will solve that problem . Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 24, 2007 Share Posted April 24, 2007 6" rods. Not only is the rod angularity lessened, improving piston ring seal, etc. but the pistons will be lighter too. Probe makes a 383 piston for a 6" rod that has no ring supports, since it uses a tight, high ring package. Granted, the oil ring is 1/8", but still has good control, from my experience with this design in a 400. Either 6" or step down to the 5.7" 350 rod. The angulartiy will be higher, piston heavier, but not horrible. I'd stay away from the 5.565" 400 rod though, for all the reasons above. Quote Link to comment Share on other sites More sharing options...
icewtr Posted April 24, 2007 Share Posted April 24, 2007 So 300 hundred with boost before.... thats basicly a stock 350 then with whatever poweradder ya had then right .. og course the new motor will make more power than that .. i had 237 at the wheels with a junk rebuilt 350 that was 400 bucks and all stock and no poweradder at all..... so just figure out your rod and piston choices and have fun ... my current 383 is putting over 350 to the wheels all motor and over 450 with a little NOS... Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted April 25, 2007 Author Share Posted April 25, 2007 Sounds like the 5.7 350 is a better choice i assume id have to bore the block 30 over though or at least that is what ive seen in the 383 assemblies in the catalogs when they use a 5.7 rod it gets a 30 over piston .I will look into this a bit more about rod length . I wish i could get the poawer like icewtr has with no power adder but i failed to mention i live at 6,000 ft above sea level . When i ordered the engine it was posted as 290 horses and 310 ft lbs of torque . When i dynoed it it only had about 230-240 horses thin air maybe or maybe the carb set up who knows thats why i added the boost . A 7 lb boost pulley only produces 4 lbs of boost here so i added a 11 lb pulley and got 7 lbs of boost . Jason Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted April 25, 2007 Share Posted April 25, 2007 Pete has it right. Go with better rods. Eagle H beams can be had for $350 which is well worth it. Even the SIR's are better than stock. Quote Link to comment Share on other sites More sharing options...
icewtr Posted April 26, 2007 Share Posted April 26, 2007 wow that is some elevation.. i see why the power loss... Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted April 26, 2007 Author Share Posted April 26, 2007 Now if i stick with the 5.7 rods and dont get 30 over pistons will that still work just wondering as rings will cost me almost 300$ . I had figured on getting new rods as the stock ones might hold up for only so long dont wanna rebuild because i was cheap . Jason Quote Link to comment Share on other sites More sharing options...
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