[m4696]

I have a sbc block with a casting number that was used for 283 and 327. It has a date code of 1962. Can this block be bored to 4" as a 327? Would the only difference in this block be the bore size? It has a forged crank with 2 bolt main.

[BOBCRMAN@aol.com]

MOST of these blocks can be bored to 4". Back in the day I bored many of them. Check to see if the cam hole is well centered in the end boss casting.. These are the better blocks.

[m4696]

hey I appreciate that info. A question I have is, did the factory bore these out of the same exact block or did each displacement have its own block even though the casting shows was used for 283 and 327. I got the casting info. from mortec.com

[m4696]

Another question I have is what happens when you take a bore a little bigger than was originally suggested? Would you have overheating issues, fast wear, or just cant bore again. Im sure 4" we be pushing it on that 283.

[techinspector1]

Originally Posted by m4696

Another question I have is what happens when you take a bore a little bigger than was originally suggested? Would you have overheating issues, fast wear, or just cant bore again. Im sure 4" we be pushing it on that 283.

Normally, when the cylinder walls get too thin, the motor will overheat. I didn't understand why until I read the explanation from the late, great Smokey Yunick. He used to cut windows out of blocks, pans and so forth, installing glass windows and a good light so he could run the motor on the dyno and actually see what was happening inside the motor as it ran. He said that as the wall get thin, there is insufficient mass to cancel harmonics generated by the piston rings as they "skid" up and down the walls. Yep, he said they skid, rather than gliding smoothly along the walls. These harmonics, if uncancelled by walls thick enough to have mass enough to cancel them out, will be transferred to the coolant side of the wall and separate out little air bubbles that then cling to the walls and prevent cooling water from reaching the walls to carry heat away. Result, an overheating motor. He said there needs to be a minimum of 0.135" wall thickness to do the job. Now, you can take Smokey's word for this or not, but in my opinion, he was the best "seat-of-the-pants" engineer and engine builder that there ever was.

Any good automotive machine shop worth its salt will have an ultrasonic "beeper" wall thickness tester to determine wall thickness of your block.

[31fordcoupe]

If you did go to a 4" bore on a 283 block, what would the cubic inch displacement be? These cam factory with the small journal 3" stroke cranks correct? Would you use standard 4" pistons on this setup with a 283 crank? What rod lengthy would you use? 5.7?

[ericnova72]

4" bore + 3" stroke + 5.7" rod = guess what?? - a regular old 302 Chevy. This is how the factory did it in 1967.

[31fordcoupe]

eric,

So I could put a forged small journal 283 crank into a small journal 327 block, with 4" pistons and 5.7 rods and end up with a 302 correct? I believe that is what you are saying. And if that is the case, what small blocks were made by Chevy that were small journal? I know of the 327 and 307 blocks (and I guess 302 blocks), but were there any 350 small journal blocks?

Couldn't you use a 283 crank with 5.7 rods and standard 4" pistons in a large journal block but just utilize those main bearing spacers and use the small journal 283 crank in a large journal block? Also, what pistons would you use (I am not certain what height of piston would be required with a shorter 3" stroke)?

[geezer69]

i believe the old 283's had thicker walls than the other sbc's.

[SSedan64]

283 Block Info. >> http://www.chevytech.com/1c4o5.html
Other SBC Info. >> http://www.chevytech.com/1c1.html
http://www.chevytech.com/