Murphy Posted October 11, 2011 Share Posted October 11, 2011 I see on various posts where people list their engines size in cubic inches........Some show a 355 or a 383 or 385. Are the dimensions (CI) after a 350 block has been bored to say .030 or .050? Quote Link to comment Share on other sites More sharing options...
bigscaht Posted October 11, 2011 Share Posted October 11, 2011 i have a 355..which is basically a 350 bored .030 over...not sure but i have the math formula around here somewhere to calculate it all!! Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted October 11, 2011 Share Posted October 11, 2011 I use this site for calculators - it's great: http://www.wallaceracing.com/Calculators.htm Quote Link to comment Share on other sites More sharing options...
Murphy Posted October 11, 2011 Author Share Posted October 11, 2011 so the guys with a 383 have a different crank to get a longer stroke? Is this still using a 350 block that is bored some dimension? Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted October 11, 2011 Share Posted October 11, 2011 A 350 with the 3.75 stroke (400 crank) is a 377 with a .030 overbore, or a 383 with .060 overbore. Â The 400 crank in a 350 became so popular among hot rodders that Chevy finally made their own 383 crate motor a few years ago. Quote Link to comment Share on other sites More sharing options...
Murphy Posted October 12, 2011 Author Share Posted October 12, 2011 How will I know which crank/stroke is in my 350? I know it was bored .030 by previous owner & the crank was not replaced. Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted October 12, 2011 Share Posted October 12, 2011 Chances are you have a regular 350 crank - 3.48" stroke. Â If somebody put a stroker crank in your 350, chances are that it would have to be externally balanced (like the 400s were from the factory). When you use the 400 crank, you need the 400 balancer and flexplate. The balancer is weighted more on one side (of the inside by the hub) and the flexplate has a weight about the size of a pack of gum near the teeth. There are some exceptions such as when somebody has the crank itself balanced with some heavy metal so they can run a regular balancer and flexplate, but that's expensive and not too common. Quote Link to comment Share on other sites More sharing options...
Murphy Posted October 12, 2011 Author Share Posted October 12, 2011 What is the stock bore? playing with that calculator I need bore,stroke,cylinder # ? Since mine is bored .030, I'll just add that to the stock bore #, correct? Quote Link to comment Share on other sites More sharing options...
Winston Wolf Posted October 12, 2011 Share Posted October 12, 2011 Chances are you have a regular 350 crank - 3.48" stroke. If somebody put a stroker crank in your 350, chances are that it would have to be externally balanced (like the 400s were from the factory). When you use the 400 crank, you need the 400 balancer and flexplate. The balancer is weighted more on one side (of the inside by the hub) and the flexplate has a weight about the size of a pack of gum near the teeth. There are some exceptions such as when somebody has the crank itself balanced with some heavy metal so they can run a regular balancer and flexplate, but that's expensive and not too common.  I wouldn't say that is true. In fact you'd be hard pressed to find an externally balanced 383 or non stock 400 now-a-days. Summit lists qty 53 3.75" stroke 2 pc main crankshafts, of those, 47 are internally balanced. The 6 they have are all cheapy cast ones from 160 bucks to 250 bucks. When doing a 383, you started with a 350 and wouldn't want to buy a 400 balancer and flywheel, since you can use the 350 stuff with the correct crank.  Just don't want to send somebody down the wrong path. Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted October 12, 2011 Share Posted October 12, 2011 A 350 with the 3.75 stroke (400 crank) is a 377 with a .030 overbore, or a 383 with .060 overbore.    huh? a 383 is a 350 block bored .030 with a 3.75" stroke  388CID with a .060 overbore Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted October 12, 2011 Share Posted October 12, 2011 I think at least on most of the earlier 350's the oil pan rail must be notched for the crank/rods to clear....that might be one indicator.... Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted October 12, 2011 Share Posted October 12, 2011 400 oil pans are pushed out at the rails for rod clearance. Most aftermarket pans are clearanced for longer stroke. Â Small Block bore/Stroke 262 3.67/3.10 265 3.75/3.00 267 3.5/3.48 283 3.875/3.00 302 4.00/3.00 307 3.875/3.25 327 4.00/3.25 350 4.00/3.48 400 4.125/3.75 Quote Link to comment Share on other sites More sharing options...
Murphy Posted October 12, 2011 Author Share Posted October 12, 2011 This is GREAT info from everyone, thanks! Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted October 12, 2011 Share Posted October 12, 2011 Originally Posted By: 72 LS5 Chances are you have a regular 350 crank - 3.48" stroke. If somebody put a stroker crank in your 350, chances are that it would have to be externally balanced (like the 400s were from the factory). When you use the 400 crank, you need the 400 balancer and flexplate. The balancer is weighted more on one side (of the inside by the hub) and the flexplate has a weight about the size of a pack of gum near the teeth. There are some exceptions such as when somebody has the crank itself balanced with some heavy metal so they can run a regular balancer and flexplate, but that's expensive and not too common.  I wouldn't say that is true. In fact you'd be hard pressed to find an externally balanced 383 or non stock 400 now-a-days. Summit lists qty 53 3.75" stroke 2 pc main crankshafts, of those, 47 are internally balanced. The 6 they have are all cheapy cast ones from 160 bucks to 250 bucks. When doing a 383, you started with a 350 and wouldn't want to buy a 400 balancer and flywheel, since you can use the 350 stuff with the correct crank.  Just don't want to send somebody down the wrong path.  Sorry to steer ya down the wrong path! I haven't had a small block in a while and was just going by what I remembered - things have changed a lot. Please scratch that info about the externally balanced stuff. That's the way they USED to do it!  And the 377 is the standard bore stroker, 383 is .030 over - I need a cup of coffee..... Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted November 3, 2011 Share Posted November 3, 2011 To confuse the issue further, I thought a 377 was a 400 with a 350 crank and bored .030 over? No? Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted November 4, 2011 Share Posted November 4, 2011 That is correct. And you can build a real screamer with a .030 over 400 and a 327 crank that is a 352 Â Or a .030 over 400 and a 302 crank is a 325 both of these engines will need to be turned hard and will need lots of valve spring. $$$$ Quote Link to comment Share on other sites More sharing options...
Blake350 Posted November 7, 2011 Share Posted November 7, 2011 I like that listing showing all the various bore/stroke combos-I notice most of them have a relatively short stroke relative to the bore-I remember hearing when the stroke is shorter than the bore dia the engine is referred to as 'undersquare' was this just a local talkin after too many Michelobs? But does that configuration make for a more mechanically sound engine? I would think it would less inertia with a smaller stroke-just thinking out loud-engine gurus please comment/set me straight thanks Brian Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted November 7, 2011 Share Posted November 7, 2011 Actually a engine with a bore larger than stroke is "over square". Shorter stroke engines are said to rev better. Bigger bores unshroud the intake valve next to the cylinder wall helping flow. and it is easier to get big valves in a large bore engine. Piston speed is slower in a short stroke engine. It is also said that long stroke engines create more torque because the piston is exerting the same force on a longer lever. There are lots of theories out there and a bunch or talented guys making them work, or going different directions and making big power. Quote Link to comment Share on other sites More sharing options...
Blake350 Posted November 7, 2011 Share Posted November 7, 2011 Thanks Mike-I vauguely remembered 'under over and square' were in there somewhere-but I had it reversed after all those years-makes sense-the higher rev vs higher torque on the 2 combos- I do find all the theories of operation and the way air fuel and fire react in different mechanical combinations to give such diverse power curves quite interesting-these engine threads always provide great info-so I will step off and let the discussion continue ... brian Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted November 8, 2011 Share Posted November 8, 2011 400 oil pans are pushed out at the rails for rod clearance. Most aftermarket pans are clearanced for longer stroke. Small Block bore/Stroke 262 3.67/3.10 265 3.75/3.00 267 3.5/3.48 283 3.875/3.00 302 4.00/3.00 307 3.875/3.25 327 4.00/3.25 350 4.00/3.48 400 4.125/3.75 Â Oo you forgot one Mike: 305 3.735/3.48 Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted November 8, 2011 Share Posted November 8, 2011 Guess I did, hard to forget the 305! Well maybe. Quote Link to comment Share on other sites More sharing options...
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