Built Your ShortBlock?
05-16-2009, 04:11 PM
#1
Built Your ShortBlock? This summer i blew my 346 @ 414rwhp. 
So i am going to build a low compression LS2 402 for a turbo setup.
I have been doing alot of reading on here and i read "How to Rebuild GM LS-Series Engines"
Seems like it is very complicated to build a shortblock with all the tolerances and clearances. One mess up and your screwed?
I would like to know from guys who built there shortblock (does not have to be a 402) how hard was it? I have never built a cars motor before. I have seen and played with the "ins and outs" of my LS1. I have built go-kart, dirtbike, atv, etc motors before.
It would really help me out if i heard from some people that have only built one or two of these motors.
Please let me know how it went, was it hard/easy, what was the outcome, was it worth it, anything i should know before hand?
-Kenny
So i am going to build a low compression LS2 402 for a turbo setup.
I have been doing alot of reading on here and i read "How to Rebuild GM LS-Series Engines"
Seems like it is very complicated to build a shortblock with all the tolerances and clearances. One mess up and your screwed?
I would like to know from guys who built there shortblock (does not have to be a 402) how hard was it? I have never built a cars motor before. I have seen and played with the "ins and outs" of my LS1. I have built go-kart, dirtbike, atv, etc motors before.
It would really help me out if i heard from some people that have only built one or two of these motors.
Please let me know how it went, was it hard/easy, what was the outcome, was it worth it, anything i should know before hand?
-Kenny
05-16-2009, 07:54 PM
#2
my first motor build was my 427. Its not difficult, just make sure you have all the necessary tools. Also make sure you cover all your bases and double check your clearances. The book you mention covers the build fairly well, if you follow it step by step you'll be just fine. Building a motor also creates a sense of pride for the builder, its awesome just telling ppl that you built your own motor.
05-17-2009, 12:39 PM
#4
I did the build on my 403. Its def. cheaper to buy a pre assembled short, but you're not assured that its set up the way YOU want. Things to pay close attention to:
crank center line bore- have it honed or bored accordingly
thrust-crank end play
bearing clearances- different between iron and aluminum and clearance for
HP level also be sure bearings are correct for YOUR crank
radius. Aftermarket cranks have larger fillets
deck the block- per the piston height and head gaskets to be used for proper
quench. requires mock up with bearings, torqued, etc.
balancing the rotating assembly
checking for crank interference around entire bearing surfaces- just because the block has been line bored/honed doesnt guarantee you wont have a spot
on the side of one of the bearings that isnt scuffing the crank
purchase the proper high quality fasteners and check with your machinist
if using studs on the bottom end. Mine insisted that I use a small
steel bb (called bullets) under the studs or they may back out from
the aluminum expanding.
check cam bearings for signs of scuffing or tight spots
X2 on red02Hawks post. Check, double check. BTW I havent got mine installed yet so I'm still waiting to see if I checked good enough!! LOL?
crank center line bore- have it honed or bored accordingly
thrust-crank end play
bearing clearances- different between iron and aluminum and clearance for
HP level also be sure bearings are correct for YOUR crank
radius. Aftermarket cranks have larger fillets
deck the block- per the piston height and head gaskets to be used for proper
quench. requires mock up with bearings, torqued, etc.
balancing the rotating assembly
checking for crank interference around entire bearing surfaces- just because the block has been line bored/honed doesnt guarantee you wont have a spot
on the side of one of the bearings that isnt scuffing the crank
purchase the proper high quality fasteners and check with your machinist
if using studs on the bottom end. Mine insisted that I use a small
steel bb (called bullets) under the studs or they may back out from
the aluminum expanding.
check cam bearings for signs of scuffing or tight spots
X2 on red02Hawks post. Check, double check. BTW I havent got mine installed yet so I'm still waiting to see if I checked good enough!! LOL?
05-19-2009, 11:38 PM
#6
One question.. how are you going to check and set clearances in your garage?
Do some pricing and you will see that the labor end (assembly) of the build is the least expensive part of it. Build it incorrectly and you've wasted about $2200 on parts. Unless your an accomplished builder (if you were you would not be asking ) I would leave to a pro.
Do some pricing and you will see that the labor end (assembly) of the build is the least expensive part of it. Build it incorrectly and you've wasted about $2200 on parts. Unless your an accomplished builder (if you were you would not be asking ) I would leave to a pro.
05-20-2009, 12:37 AM
#7
I would advise that if you aren't absolutely comfortable doing your own work. I spent three months on top of my tech school training learning how to do nothing but make high performance engines work and last, and it takes a lot of years to really develop that kind of skill. A big power engine (or any engine that is expected to last) must be fully blueprinted, period. If you don't have the precision measuring equipment to do it, and you don't plan on doing it frequently, you would be better to have a reputable builder do it for you than purchase 2K worth of dial bore gauges, indicators, micrometers, ring files, rod vises, degree wheels, etc. Just my opinion.
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05-20-2009, 08:58 AM
#8
One question.. how are you going to check and set clearances in your garage?
Do some pricing and you will see that the labor end (assembly) of the build is the least expensive part of it. Build it incorrectly and you've wasted about $2200 on parts. Unless your an accomplished builder (if you were you would not be asking ) I would leave to a pro.
Do some pricing and you will see that the labor end (assembly) of the build is the least expensive part of it. Build it incorrectly and you've wasted about $2200 on parts. Unless your an accomplished builder (if you were you would not be asking ) I would leave to a pro.
Other than that i see your point.
05-20-2009, 11:00 AM
#9
Driveway?Most of the home builders just throw the stuff together and dont even check clearances. They figure if the thing turns over without hitting or catching anything they've done a great job and saved thousands. BUT they dont know to check or set them or have never even heard of deflection and how much to account for it. (some shops dont do this well, imagine someone with little to no experience)
Some guys though are very good at what they do and can build an engine properly. Have the right tools and a machine shop they trust close by so it's not a huge deal for them.
05-20-2009, 01:21 PM
#10
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I don't think building a motor for a turbo setup is wise to do at home...one of the keys of making them live is to make sure EVERYTHING is 100% right...
Just my $0.02
Just my $0.02
05-20-2009, 02:12 PM
#11
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Like some other ppl said it probaly wont be much more expensive to buy a short block from a company on here.
I built the 346 in my car. Its not that bad to put a 346 together.
A stroker motor requires alot more stuff to be done, and costs alot more money.
I built the 346 in my car. Its not that bad to put a 346 together.
A stroker motor requires alot more stuff to be done, and costs alot more money.
05-20-2009, 02:19 PM
#12
well my buddy owns a machine shop, so i borrowed his Sunnen bore gauge. Along with my Brown & Sharp dial calipers and micrometers, i measured all the clearances. Then i took all my parts down to his shop and he double checked my clearances, is this cheating?
05-20-2009, 08:10 PM
#13
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If you truely have experience with other motors id say you would be fine.
Im hoping to assemble the my 370 myself, stock crank, though ill be extra careful with everything. I suppose if it comes apart, its money wasted, but i have no interest in buying a new block, and the cost to have my block shipped somewhere for them to assemble it would be stupid high. And i dont trust anyone in my town to build me a motor.
05-21-2009, 01:37 PM
#14
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Personally, if you're going with a turbo set-up look at using LS3 Block with stock bore and stroke. Throw in forged components and be done with it.
I have done a few motors when I was younger, but todays motors are much more technical and require special tools and knowledge. I would buy a short block from a reputable builder and just sell your old one.
I did a forged 416 but in retrospect, I should have just done a stock cube LS3. I'm only looking for 650 RWHP as any more than that does not really hook up well in a vette.
There have been a lot of guys who tried to build their own motors that wind up taking a bath when something goes wrong.
Either way you go, good luck
I have done a few motors when I was younger, but todays motors are much more technical and require special tools and knowledge. I would buy a short block from a reputable builder and just sell your old one.
I did a forged 416 but in retrospect, I should have just done a stock cube LS3. I'm only looking for 650 RWHP as any more than that does not really hook up well in a vette.
There have been a lot of guys who tried to build their own motors that wind up taking a bath when something goes wrong.
Either way you go, good luck
