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This van will be your chariot into Valhalla, shiny and chrome.
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Jan 4, 2016 05:50
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literally a fish posted:SBC enthusiast goons! I know at least one of you has to have a set of Vortec 5700 heads (1996-2002, the Gen1 SBC 5700, not the LS one - This One, In Fact which is also known as the 806 casting it seems?) lying around somewhere. If I'm lucky, maybe you even had the guide bosses machined to raise the max valve lift! If this was 10 years ago I'd have been able to hook you up with my used ones  The L31 heads are great, just gotta machine those bosses (as you already know) and get an intake that fits them. I've never heard of an actual TBI Vortec, just the garbage spider-injector factory setup. I did find references to a GMPP TBI intake but it seems to be quite spendy. If you want to stay TBI, get a carb manifold and an adapter plate.
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Jan 4, 2016 07:05
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literally a fish posted:I need the valve covers too, as it turns out. I think these might have roller lifters too which could theoretically be useful. I don't think you do, actually. Your '92 van should already have the centerbolt-style valvecovers on it. When I did my L31 heads, the shop that declared my original '70 castings unfit for further use sold me a couple of random SBC valvecovers off of their pile of used stuff for $20. I don't think they came off of another L31 since this was in 2002 or so. The lifters would be in the shortblock, not the heads, and again a '92 might already have roller lifters. The factory rockers on the L31 were probably just regular stamped-steel non-roller pieces. I can't recall if my L31 heads came with rockers or if I just reused the ones that were on the old heads. Edit: This thread is really appealing to us SBC nerds here
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Jan 4, 2016 23:43
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You don't need a 'convert to roller lifter' kit, that's for early SBC blocks that were only offered as flat tappet only. A '92 block, even if it came with a flat tappet cam, is ready to use a roller cam and the cheap factory rollers, instead of the expensive retrofit rollers.
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Jan 5, 2016 00:09
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It's because the airflow is so irregular at low RPMs that the engine is flipping between rich and lean over and over. Idle drops -> low airflow -> mixture becomes richer -> idle raises -> mixture leans out again -> idle drops again... A big lumpy cam is going to lope a bit at idle anyway. Adding a big roots blower means a small RPM change results in a big airflow change.
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Jan 7, 2016 15:20
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I'd say that's a perfectly AI suggestion because it might be cheaper than actually retrofitting the factory roller cam setup to the '92 block. The only possible downside is the L31 block will definitely not have any provision at all for a mechanical fuel pump. You know, for if the fuel injection magically falls off and you just have to slap a tunnel ram and a pair of four barrels on it.
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Jan 7, 2016 17:49
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Yes, you'd need the engine, all accessories on it, and the full fuel injection / harness / ECM. No reason for a megasquirt unless you've already got one or are trying to set the engine up without the stock harness / ECM. The GM ECM is pretty thoroughly hacked at this point and can handle just about anything you want to throw at it. You would probably want the transmission to match the engine, too. Seems like '92 could be a non-electronic 700R4 / 4L60, an electronic 4L60E, or a 4L80E. I don't know if there's any "LS" or "non-LS" 4L80Es out there, but there is definitely an early / late 4L60E split. '92 will be well on the early side, any GenIII should have the late version with a separate bellhousing.
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Jan 7, 2016 22:48
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Raluek posted:You can, with a flex plate adapter I think. But if you're swapping in an LM7, why not just get the trans its computer is already expecting? The mounts and overall length and such should be the same, right? Yeah, I found this that covers some of the details. The GenIII flexplate / crankshaft are at a different depth relative to the transmission than the original SBC/BBC. But I will wholeheartedly recommend just grabbing the 4L60E with a donor engine - you can tune the transmission at the same time as the engine and it is vastly more flexible than what you can accomplish with the 700R4. If the mount for the transmission doesn't quite line up, it's still a truck - unbolt the crossmember, bolt it to the transmission, drill new holes wherever the crossmember lines up and bolt it there.
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Jan 8, 2016 00:23
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Because the stock cam in the 5.3 is tiny. Even the stock early LS1 cam ('97-'00) is worth 67hp over the LM7 cam: Car Craft did a comparison.
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Jan 8, 2016 22:25
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You just blew my mind, I always thought the Astro had a full S10 chassis underneath.
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Jan 18, 2016 21:33
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You Am I posted:Really? I always thought the 5.3lt would be 327ci, considering it is a classic Chevy V8 size The only LS to hit a "classic" displacement is the LS7, and they fudged it a bit because it's something like 427.9 cubic inches and they can't possibly call a Chevy engine a 428. The LS1/LS6 are 346 cubic inches, not the good old tree-fiddy.
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Feb 25, 2016 06:20
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| # ¿ May 11, 2024 14:24 |
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PhotoKirk posted:There was the era of Town & Country vans that liked to eat transmissions. Early 2000's? My brother had one. I'm pretty sure that era is "all of them".
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Aug 3, 2016 21:30
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