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you mean this 350/L31 4 Bolt main Short Block Assembly... (http://www.sdparts.com/product/1255...ckAssembly.aspx)
YIKES I didn't know you were talking about a NEW short block. I thought you had located a used, low mileage roller short block in somebody's back yard for a couple hundred bucks!!! You certainly don't want to be cuttin' and slingin' pistons out of a NEW short block. The Chevy pistons listed are -13cc's. The KB's I referred to are -12cc's. Close enough. The actual c.r. with a 0.000" piston deck height and Fel-Pro #1010 gasket works out thusly: 716 in the cylinder, 65 in the chamber, 13 in the piston, 0.0 in the piston deck height and 8.9 in the gasket. 802.9 / 86.9 = 9.24:1 with a 0.039" squish. I wouldn't worry about the difference between 9.24 and 9.5 static c.r., although if it bothers you, you could have AFR take a thin cut on the heads to reduce the chambers a little. The rule of thumb is that each 0.006" cut removes 1 cc. Although the GM manual lists the 10105117 gasket as being compatible with aluminum heads/iron block, the forum at Sallee Chevrolet recommends using the Fel-Pro 1003 at 0.041" compressed or the Fel-Pro 1010 at 0.039" compressed, saying that either one will do a better job than the 10105117. Because the FP 1010 is thicker, you'll have to cut the decks to zero piston deck height to get the squish at 0.035" to 0.045" as suggested by most automotive authorities whom I have read. There are others, including some on this board, who feel that a slightly looser squish will also work to quell detonation and allow lower rated fuel to be used in a motor. Frankly, it scares me a little to advise you to disassemble a brand new and fresh short block to cut the decks. Like I said, I wouldn't begin with new stuff anyway, so I would have no reservation about modifying the block for the optimum squish, but when you have the whole shebang sitting there, fresh and ready for heads, it just makes me cringe a little to tear into it. Why don't you try to find out what the piston deck height is on that new short block and let's go from there. As far as the valve springs, coordinate with AFR and the cam provider to match the springs to the grind and have the correct springs assembled on the heads when they ship. |
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techinspector1...let me just start with this... the stock engine was a 305 and i was gonna do work on that..but someone told me i was limited with what i could do with that block and suggested i find myself a 350...so thats what i did...and i just happened to stumble upon the 350/L31..so i figured a 350 is a 350..and the price seems reasonable.
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Hey weaz, it's Jim again. Perhaps you might inquire what SD would charge to deck the block if it had not already been done on the one that you were looking at? Specifically, if they can bulid one that way for you ( a shortblock that hadn't already been assembled yet). That would be prefferable to milling the heads. If you do go with the AFR {180/65's} and take good care of your engine, they'll be around for a long time. -Jim
Last edited by j.d.brown.042964; 10-02-2008 at 10:47 PM. Reason: spelling/underline important sentence. |
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maybe i could ask about this one as well... dont know if theres much of a difference other than a 2-piece rear main seal, and 12cc dished cast aluminum pistons..
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okay techinspector1..heres what i found out...nothing..i called them three times...the first person i spoke to didnt sound too convincing or sure of himself..he said it should be able to get 400-450(max). asked about deck height..didnt know squat(said maybe .010 but not sure).i ended conversation but was not satisfied..so i called again..different person this time..asked him deck height as well..he said one its a factory replacement for trucks, two the deck height should be .025...i dont think i believe him 100%(also seemed a little rude).he also stated that the 350/L31 has been discontinued since March..so i asked why its advertised on their site still..he didnt know why...ended call..called a final time...got the person i spoke with first..told me the block was not discontinued..it seems like their tech people dont have a clue about anything...do you or does anybody else know or can suggest where i can check out a block(with rotating assembly) for a descent price?
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As far as finding a good shortblock assy. with a company that will stand behind it, KEEP LOOKING, and make sure you feel "comfortable" with the company that you will be giving your hard-earned money to, BEFORE you shell out any clams. Hopefully you are not in a rush to get rid of your money, as this buildup is a decision you'll have to live with for quite awhile. You've now got a pretty good idea of what you're looking for, perhaps not EXACT, but at least a pretty good idea...so take your time researching your potential supplier(s). One other poster had given a link to a shortblock package from Summit, and they're at least a well-known, nationally recognized company with an excellent reputation (to protect) as a speed equipment supplier. Jeg's is another main player, so they'd likely be a good option as well. The newer style block with 1pc rearmain seal is generally considered to be an improved design, and the factory use of OEM hydraulic roller cams and lifters should illustrate the OEM's confidence in that design. That is not to say that the older (gen.1) engines were neccesarily BAD, just that improvements have been made in some areas that have proven to be beneficial in performance and reliability. But in the end, it's your dollar, so spend at least as much time researching your potential supplier(s) as you have on coming up with the parameters of your build, and you should be very satisfied with the end result. -Jim |
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im still gonna try and find out some more info on the blocks i posted earlier...since i called a bunch of places and no one can tell me what i need to know..im goin strait to the source...i called a chevy dealer...and they are gonna call GM and get the specs i need like monday or tuesday...i was looking at this and was considering getting it (http://www.streetperformance.com/par...-12561723.html)
even though its a little more than i was looking to spend...or maybe just buying a bare block...then a rotating assembly.... Quote:
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This is the most complicated 350 build I have ever seen. Theres no reason for it to be this complicated. ALL new GM 350 short blocks have a .025" deck height unless its the blueprinted ZZ4. Which doesn't matter at all, I don't know why people have you so worried about deck height and compression ratio. The ZZ4 short block is a great short block for just about any build. Its the short block Edelbrock uses on all their 350 crate engines, even their 500hp supercharged motor and I'd be surprised if it wasn't the short block used to do the AFR dyno numbers. I was looking into doing the exact same thing you are a couple months ago. The L31 is a good motor, those P/M rods will work fine, but the block won't accept a mechanical fuel pump which will be a bit of a headache later on and though I hate to bring it up... the ZZ4 ($200 more?) will get you that 9.5:1 compression ratio thats just about perfect for pump gas with those 64cc AFR heads and will accept a mechanical fuel pump . Even if it only works out to 9.0:1 or even a high 8 it doesn't matter at all, DON'T WORRY ABOUT IT!! A half point of compression isn't worth any of the machining costs let alone the circles these guys have you running around in.
Forget about all this machine shop B.S. The short block is built and brand new with a warranty. Take that ZZ4, slap on some AFR heads, your cam of choice, and you'll have a blast in that camaro. |
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I have to go along with the last poster, It's absolutely stupid to think about buying a new short block then taking it apart (voiding warrant) and machinery it. If that was the case, and you felt so confident about your engine building skills, then just go purchase a good block and have at it, then come back later on and tell us how bad it all went. I build engines and have machine work done all the time, it's not cheap. To bore and engine (V-8) with torque plate bolted on, your looking at $400-450.00. Aline bore the mains, theres another $150.00-200.00. Deck the surface, $150-200.00. Clean, check and service rods, $150-300.00. That just the block and rods, balancing and other services add up quickly. For someone like you, that isn't that experience with engines, you are wise to go with a short or long block. I would stay with the L31 or ZZ4, they are good engines for the money and have a major brand warranty. The heads should also not be this hard to choose from or with so much drama, I would call all the major builders and do my selection from there customer//thecnical/knowledge/ service you get. If they are screwed up before the purchase just think how they'll be once you have a problem.
I also think you are missing a major option if you don't at least call and talk to some of the more popular/knowledgeable engine builders out there. There is a very good chance you can get your engine completely built, tuned and tested for the same cost as if you would piece-mill the thing together. |
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Although I'm not posting advice any differently than I would to any other on this board who is a first-time engine builder, this particular build involves a factory short block, something that I wouldn't start with in the first place. Investing $4,000 into a build means checking everything and optimizing it in my opinion. But in the end, that's what it is, my opinion and the way I do things.
At this point, I will respectfully yield to the gentlemen from Canada and Cincinnati and bow out of this thread. |
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