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Thread: main cap gaps - plasti gauge
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02-23-2016, 07:15 PM #1The Nitrous Outlet Junkie
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main cap gaps - plasti gauge
so i was having some trouble finding the exact gaps needed for each main cap .... i know that they need to be torqued to 77ft/lbs in three steps (i am going 35 than 55 and 77 last)
several friends and SBC guys i know say .0002-.0008 for all of them ... but i was wondering is that the same for us LTx guys?Last edited by zooguy; 02-23-2016 at 07:26 PM.
94 Formula "budget build" #thebeaterbird
10.177 @128.31 on a lil 250 shot
350, LT1, carb, LE grind cam, th400, 4k stall, ford 8.8 w/ 4.10s
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02-23-2016, 07:16 PM #2The Nitrous Outlet Junkie
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I found this ... but I don't know if I trust it uploadfromtaptalk1456276596181.jpg
Sent from my SM-N910T using Tapatalk94 Formula "budget build" #thebeaterbird
10.177 @128.31 on a lil 250 shot
350, LT1, carb, LE grind cam, th400, 4k stall, ford 8.8 w/ 4.10s
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02-23-2016, 10:46 PM #3Xtreme Member
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http://shbox.com/1/engine_specs.jpg
Clearances depend on what you plan on doing with the motor. The stock ones are known for being tight. If you plan on spinning it high or loading it heavily then shoot for 20-25 on everything.
Sent from my VS986 using Tapatalk96Z M6, ERE-383 #60, AFR 210s, LE cam, 9", Procharger D1, ???whp
95 Roadmaster T-56 swap, LE1s, baby cam, 4.56s, "The Cammaster"
95 Firehawk hooptie, bolt-ons and suspension
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02-24-2016, 09:56 PM #4The Nitrous Outlet Junkie
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Well I got the main caps on ... here are the pics front to back
Front
#2
#3
#4
rear #5
Sent from my SM-N910T using Tapatalk94 Formula "budget build" #thebeaterbird
10.177 @128.31 on a lil 250 shot
350, LT1, carb, LE grind cam, th400, 4k stall, ford 8.8 w/ 4.10s
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03-23-2016, 09:09 PM #5VIP Member
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I'm not a fan of pg! but seeing what you have i would get a set of x bearings. aka extra clearance. the give you a extra 0.001" clearance. street/strip motor. for the rods no less than 0.002" with 0.0025" being the target number. the mains you want to shoot for 0.003" with a low side of 0.0025"
also you can half shell with the x bearings. ie: use a std upper bearing and a x lower if you only want to open up the clearances 0.0005"
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04-05-2016, 04:42 AM #6LTX Regular
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You should definitely be using a bore gauge for measuring clearances. I wouldn't trust plastigage with one of the most critical measurements in the engine.
On my 7k rpm engine I went with somewhere around .0025-.003 for mains and a little tighter for the rods.
Like Big Cat said, I had to use a few different bearing halves to get the right clearance.1996 Z28 SS M6 Polo Green Metallic - Built 355 from my 93
1996 Z28 SS M6 Arctic White - Stock
1993 Z28 Medium Patriot Red - 355 LT1 with M6 and 24x Conversion (RIP in peace)
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06-09-2016, 10:07 PM #7InActive Member
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one thing to remember with the LT1 "if" you build the lower end to LT1 specs run "ONLY" synthetic oil after break in. this is a little known fact about our beloved LT's, if you are planning on running it harder than 5500r's, use vortec specs and then standard oil is fine. the problem is the specs are so tight that when they are wound up, (High rpm) the metal expansion of the crank makes the "gap" even tighter and standard oil cannot flow enough to keep it cool, which causes what is known as thermal runaway. (temp becomes unmanageable) then bearings cease up, the rest is history.
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06-09-2016, 10:10 PM #8InActive Member
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funny fact-I have "NEVER" checked clearances, I pay the machinist to do that, and tell him so when I drop the motor off at his shop. if it blows, he buy's me a new one. I don't have time to check his work, plus they generally like it when you "trust" them. and I'm not running down the track.
p.s. forget the catty remarks, I'm 56 and built my first motor at 15, I have a little experience with this sort of thing. Any way do you double check your accountants work. if you do why do you use him?Last edited by Tinbender59; 06-09-2016 at 10:15 PM.
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