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Newbie3191 06-28-2010 07:26 PM

trying to build a 357
 
Im new to building performance motors so i was looking for help from anyone who can give me pointers on how to get the best but not too expensive parts but i want all input on the project. I was going to build a 383 stroker but when i broke down the motor it already was bored over 40 so i guess i will stick with the 357 all input will be appreciated

zildjian4life218 06-29-2010 07:31 PM

Quote:

Originally Posted by Newbie3191
Im new to building performance motors so i was looking for help from anyone who can give me pointers on how to get the best but not too expensive parts but i want all input on the project. I was going to build a 383 stroker but when i broke down the motor it already was bored over 40 so i guess i will stick with the 357 all input will be appreciated

Why not make a 385? All a "383" is is a .030" 350 block with a 3.75" stroke. All you have to do is put the 3.75" stroke crank in your .040" block. That will yield a displacement of 385ci. Summit has rotating assemblies that come balanced and include rings, bearings, rods, pistons, and crank. That is the best way to do it if you are just starting out. Consider this and let us know. Also let us know about what block you have. Like if its a 2pc or 1 pc rear main seal. Also the casting number will be helpful. It is located on the driver side bellhousing.

Newbie3191 06-30-2010 05:19 PM

well i know it is a 70's model motor i will get the casting number though but how do you know what size crank you have i mean are there numbers or something i can find. and i already have the pistons i guess all i would need is the crank and connecting rods. would i have to get my block worked on too? and what size cam would you use my cam has the number cmc 1539. thanks for the input i will look into it

zildjian4life218 06-30-2010 05:35 PM

Quote:

Originally Posted by Newbie3191
well i know it is a 70's model motor i will get the casting number though but how do you know what size crank you have i mean are there numbers or something i can find. and i already have the pistons i guess all i would need is the crank and connecting rods. would i have to get my block worked on too? and what size cam would you use my cam has the number cmc 1539. thanks for the input i will look into it

Well if you want to use a 3.75" stroke crank you will need different pistons. You will need to add up your stack to get your deck height. This is an important measurement when you start to change stroke, rods, and pistons. The SBC has a deck height of 9.025". This means from the center of the crank to the top of the deck surface is 9.025".
Ill show you how to add up your "stack". This consists of your piston pin height + your rod length + half your stroke.

Now we need to see what we know. The crank stroke is 3.75" You need to divide this in half because stroke is from TDC to BDC and we are measuring from the center of the crank to TDC. This will give us a measurement of 1.875". Now add the rod length which for this build a 5.700" rod will be fine. So now the measurement is 7.575".

Now the only missing measurement is the piston. We know we want to end up at 9.025" so just subtract 7.575" from 9.025" and you will get 1.45". So we just found out that the piston pin height should be 1.45". BUT SBC engines are not the best cast blocks and can vary corner to corner and block to block so i would aim closer to a deck height of 9.000"-9.015". Like I said go to summitracing.com go to the engine section and select roating assemblies and then go through and choose chevrolet, 350, gen I, and then 3.75" stroke, 5.7" rod and you will figure it out.

Hope this wasnt too confusing im not the best at explaining things. Oh yeah the block will need a little notching done to it to clear the crank. Or take it to your machinist he will know what to do

If i were you it seems that you are new to this and i would just to a freshen up on your 357ci and do a vortec head swap and a cam swap. LEarn slowly and dont rush it. You will be able to get 350-400hp with a decent cam.

Newbie3191 06-30-2010 05:49 PM

yeah i was already going to buy the vortec heads. what size cam do you recommend

zildjian4life218 06-30-2010 05:57 PM

Quote:

Originally Posted by Newbie3191
yeah i was already going to buy the vortec heads. what size cam do you recommend

I read about a lot of people having good luck with comp 286h cam and the vortec heads. I havent run this combo so can't say for sure. It really depends on what you want out of the car. If you have enough gear and stall and compression for the cam. Also if the power band is where you want it

cobalt327 07-01-2010 09:13 AM

Quote:

Originally Posted by zildjian4life218
I read about a lot of people having good luck with comp 286h cam and the vortec heads. I havent run this combo so can't say for sure. It really depends on what you want out of the car. If you have enough gear and stall and compression for the cam. Also if the power band is where you want it

zildjian, not being nosy, but do you really mean Comp 486H or did you mean 468H? I'm thinking it's just a typo...

zildjian4life218 07-01-2010 10:08 AM

Quote:

Originally Posted by cobalt327
zildjian, not being nosy, but do you really mean Comp 486H or did you mean 468H? I'm thinking it's just a typo...

im not 100 percent i thought it was the 268h.

cobalt327 07-01-2010 10:10 AM

Yeah, 268 NOT 286. Or 4-anything.


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