what exactly is the difference between a ls1 style crank and a regular small block crank? i look a pictures and the look exactly the same... i read that the have bigger main journals i think the same as a 400 small block... is this true? and i also know that they use a different firing order, so would the rod throws(i guess that is what they are called) be in different locations? and what is that wheel thingy for near the back of the crank? and is the rear seal bigger? just wanna know all the differences.

 

I dont know what pictures you're looking at but... there's nothing remotely close to the same about them. About the only thing you can use from an LS1 on a SBC are some bolts.

 

when did i mention anything about using one on an older chevy engine???
...you did not answer any of my questions...
i wanna know what the differences are... main journal size? rod journal size? if the rod journal placement (rod throws i think is what they are called) changed because of the firing order? and what the gear looking thing at the back of the crank does?

 

Mains: 2.56 (400=2.65, others=2.45)
Rods: 2.10
Stroke: 3.90

The rod journal placement as far as firing order isnt any different. The LS1 firing order is just a couple of cylinders switched, its the same pattern otherwise.

The 'gear thing' is a reluctor for the crank sensor pickup.

I cant say much about the rear seal.

The oil pump is crank driven off the front of the crank.

Usually when people ask about what the differences are in 2 parts, they actually want to know what they have to do to use one in place of the other. In case you or anyone else was wondering, and whether you want to know or not, its impossible.

 

The cylinder spacing is also different.

 

So i could take a LS style cam (or one with the same firing order) and put it into a regular small block and it will work fine? that is the REAL reason why i ask...i heard that the reason for the change in firing order was to get better fuel efficiency and power...is this true?
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i read that the bore spacing stayed the same as the old small blocks?

 

no ls series engines cams will not work in any non LS ENGINES...If u want to change the firing order then what you want is a 4/7 swap cam... all the big cam makers have them...

 

i waslooking at those but they are all huge, and dont seem very streetable...unless someone makes one with the 4/7 swap but with a more streetable spec, like, 218/228 @.05 and less than .6" lift...you know...if someone makes the kind, point me towards them...

 

i could get a custom cam made, from the XFI grind, with the LSx firing order, with the same specs as the 268XFI cam, is it worth the money? will the firing order make a noticable difference in fuel economy and power? it is going into an LT1 by the way...and i know that a lot of other things put together make the LSx engines so efficeint, but i read that the cam was one of the key things...

 

putting the 4/7 swap cam in a LT1 will work but make less of a difference in performance do to the reverse cooling of the LT1... the 4/7 swap is generally done to reduce cylinder/head temps of 2 specific cylinders firing right after each other... givin the better cooling of the LT1 i dont think you would see much of a gain....you want a better cam go with the LT4 hotcam and 1.6RRs

 

Actually the cylinder spacing is identical. Its the only carried over dimension of any real use.

No. The cam is nowhere near the same. Like I said, you can use some of the bolts. Some have drilled the rockers and used those.

The heads and intake are why the LS1 performs well.

 

Hot Rod magazine did a test on the 4/7 swap and found up to 12.9 extra HP on a big 492 BBC race engine, and the swap helps load the main bearings more evenly so it may increase bearing life. I heard it also makes your Chevy sound like a Ford?
http://www.hotrod.com/techfaq/113_07...ams/index.html

 

Its got nothing to do with cooling. It is to change the fact that two firing sequences in the stock formation would breathe from the same side of the intake runners in a row.

The 4/7 splits them up giving more even airflow and fuel distribution.

 

Exactly right. It helps air/fuel distribution... mainly, evens it out. Its also a somewhat 'smoother' running firing order, compared to the original Gen 1 FO, as well.

 

how is that smoother? you will always have 2 cylinders firing right next to each other...

instead of the 5/7 firing your will have the 2/4 firing ... no matter what...you will have the intake charge drawn from the same side... it does help with fuel/air distrubution as in certain cylinders are always going to run hotter in a gen 1 SBC... the LT1 does alot to even out the cylinder temps with the reverse cooling....

to say that moving the adjacent firing cylinders closer to the front of the block where the coldest coolant enters has nothing to do with the increase in performance is.... near sighted. to say the least

 

I heard that the LSx firing order was the same as a ford 302 windsor...