396 crank and stroke
 

hey guys im wodering if there is a better crank i can get for my build,I am not necessarly looking for a forged crank although i will be using forged pistons since i will be using some nitrous,I've been told that i could use a crank from a 400 but im wondering if it will mess with the stroke,or will it make no difference in looking for another one? thanks fellas.

you would want to use a chevy 400 not a pontiac 400 but i do not particularly know how easy it is or if it is possible to go to the larger journal size for a 400 crank for the LT1. you would also need a rear main adapter since LT1s do not use a 2 piece rear main seal. also a 400 crank is a 3.75" stroke which would be good for a 38x CI depending on your bore.

would using the 400 crank give it a longer stroke? Im looking at trying to spin the motor at 7,500 rpms and to get it to rev ther quick,thanks for the reply bud.

yes, the stock LT1/350 is a 3.48" and the 400 is a 3.75"
the 400 was not designed as a high reving motor so i am sure you will need some balancing on the rotating assembly for it to get there without the motor vibrating to pieces. are you dead set on more cubes? the stock crank will rev to that RPM fine

there is a lot of good reading on the SBC with specs/differences/interchangeability that you can readily find from a few google searches like this
https://ls1tech.com/forums/lt1-lt4-m...s-stroked.html

My advice to you is to spend the extra money on a 4340 forged crank with a 1pc rear main seal because though you can put a 2pc rms crank in the block with the additional adapter you will have to spend extra money for the flywheel/flexplate because the stock stuff WON'T work with the 2pc crank. So by the time you add in the ~$150 for the adapter plus the cost of balancing plus the cost of the flywheel/flexplate you'll end up spending the same money you would for a good 4340 1pc forged crank. Plus for the rpm you say you want a cast crank won't live long.

A 396 is a 4.030" bore with a 3.875" stroke. To my knowledge there are ZERO cast cranks made which have a stroke like that. Then you want to spin your engine to 7500rpm. Cast cranks and 7500rpm go together like a porcupine and a baloon. Have you figured the cost involved of getting an LT1 to spin to 7500rpm? You will need a large camshaft, a single plane intake, and an aftermarket pcm along with some good cylinder heads.

theres a reason they dont make a cast crank with that stroke and 350 mains.........

The stock PCM will let you spin to like 7050 MAX RPM So make your cam selection accordingly Unless you want to buy an aftermarket PCM & those arent cheap!!! My 396 build goes like this so far Callies Dragonslayer 3.875 crank , Howards billet rods 5.85. + bearings Thats 2065 to the door!!! 400 for the LT4 shortblock! Then the Dart Pro 1 heads are 1030 shipped plus another 1000 for porting & larger valves Thats not including the roller rockers , extreme LT4 timing set, machine work = 1000 Then when you get your 396 LTx built Youll also need a built trans mines a 4L80E plus youll need a S60 rear diff for nitrous on top of all that Ive got 2 kits for my maf ends & still need a direct port!! Then theres all the electronics to control all that LOL Break out another thousand! Then when you build all that youll need a daily driver thats good on gas because your Fbody just became a race car :) The other guys will chime in if Im too far off LoL

OH & get the 400 crank out of your head its a 2pc not a 1pc A 383 is a 3.75 stroke But a 396 is 3.875 If you want bigger a 408 is a 4in stroke BUT it might take more blocks failing before you find one to use!!!!! Read more & plan better!!!

you can run a 2 piece crank in these blocks moroso and stef's both make a main adapter its what im running

warrior customs i like your sense of humor lol

LoL Just bein Honest bro!!! Yes you can use a 2pc crank But Why Unless youve got one layin around or found a guy almost givin away his LT1 stuff Just my 2 cents Not tryin to piss off anyone!! The cheapest route you can get away with is Scat or Eagle stuff If I remember right Compstar quit importing 1pc 3.875 cranks IF you dig & look hard theres deals out there to be had my rods were 783 on sale now the same sight is 9xx for em Remember this though Your motor is Only as good as your Machine Shop :) So choose wisely!

If you think a cast crank is a reasonable choice or a stock 400 crank is a good place to start then
STOP
you are going to accomplish nothing but piss away money on a massive mistake.


Not what you want to hear but the best advise anyone could offer you right now.

If you approach a shop with this idea and they are receptive RUN, if they laugh at you and get the guys from in back to listen to this joke then maybe they would be the right place to go.


The Eagle 3.75 stroke cast cranks regularly break in modest 383 turning 6500. A few guys will say they work but those are mostly older builds and quality seems to have gone downhill in more recent years.

You need to put a lock on the hood of your car and give the key to someone else for safe keeping till you get a clue.

True or not, that's about the most asshole statement I have EVER seen. Learn some manners!!! It's sounds like you got your ass kicked a lot in high school and now you're standing up to people on the internet to feel good about yourself. (and like you need it kicked NOW!)

LMAO!!!!! I like this guy! From what I hear about 96capricemgr from people that have met him, your description is just about perfect.

In all seriousness though, spend some time in here READING and researching. It can be tough at times, because you'll have to sift through a lot of bullshit from know-it-alls with 12 second cars. Go on ltxtech.com and ask the same question, you won't get any flak over there.

I can be just as direct in person, but I never had anyone come up to me at the track and propose such a bad idea.

Plus the guy was here a month ago asking about what domed piston to use in a 396 for 91 octane. https://ls1tech.com/forums/lt1-lt4-m...-pump-gas.html
Run the numbers once and using zero for the dome size, .020 deck height as if the block was just trued not cut heavily, 56cc chamber(high side of stock), .039 Felpro gasket and that is high 12s compression with horrible quench so it is likely to detonate on 91 octane and that is without the dome he wanted.

Then he is trying to figure out how to use a crank that is the wrong stroke for his displacement goal, too much trouble and too weak for his rpm goal. I went looking to see if I could figure out what year the car was to see if his pcm could support his 7500rpm goal since we know the 94-97 one's can't and found this.

https://ls1tech.com/forums/paint-bod...s-plastic.html

The best thing he can do is stop trying to buy anything for the car because he is so far off base. I would rather see him put the project on hold a year and endup with a nice piece than support his bad ideas now, see him fail and give up or just not have the cash to fix it.

Now that was much better said. You did not come across as such an asshole. I agree, there needs to be a lot more studying on his part before he buys ANYTHING for his car. To make a point to someone though, there are better ways than being a hostile dickhead.

Its my first build ever all i have is the block in the machine shop being worked on, i have not blown money on useless parts,thats why i get on here and do more research to find what I need.

Oh he's still an asshole, but knows his shit. :thumb:

Yeah dont even consider a cast stroker crank like said unless you want this to happen:
http://i893.photobucket.com/albums/a...-32-04_343.jpg