about 6 months ago i picked up a 283 v8 for nix.. im moving to a new place, and need to downsize my collection of cool stuff.. so i pull the heads of it , theres maye a 2-4 thou (max) lip at the top of the bore. under the mains cap the main bearing reads 010. im guessing this means they are 10 thou under size.. now i have no way of miching this block or pistons without dragging the whole lot to an engine re-builder and having only a couple of weeks to go ... can i tell from the piston? all i can find is a small circle on the inside above the gudgeon, inside the circle is the number 39, then under that (within the circle) is 1419 the only other indication is stamped into the top of the pistion is .125 i read recently these 283's can be bored out to 120thou oversize (!! ??) thanks;;; crate
measure the piston or the hole with a tape measure, if its bored out .125, it should measure right at 4 inches. is the lip you are measuring carbon buildup or an actually wear ridge?
I had a 301 (283+ .125") and it flew!! Ran low 14s in a heavy 55 hdtp with a one wheel wonder 4.11!! YOu can't go any further than that, if a slight hone job will clean up the bores you're good to go...if not....you'll have to sleeve the block to save it I think.
hate to be the bearer of bad news, but if this block has already been punched 1/8 (the 125 on top of the piston would indicate that) and now has a noticeable ridge, its pooched.
cool thanks for that .... it does measure right out to 4 inches,, i would say the ridge is more of a carbon build up ..
If you can get a good top ring off of one the pistons, stick it down in an empty bore about 1 to 1 1/2 inches down, then get a feeler gauge and measure the ring gap, shouldnt really be more than 20-28 thousanths, I shoot for 18 thousanths on a top ring, but thats after being bored, and that ring might be worn a bit, you might try a few to get a average. you will be alright with .024-026 for a street motor, .028 is about max before you start having stuff get by the rings, so a 9.5 compression street motor will last a good while. just depends on what you want, but it will run pretty good. Hone it good with some new rings, bearings and polish the crank, you'll be surprised
Actually, take it a step further: 1) Place the ring just below the ring ridge. Measure the end gap. 2) Push the ring down 3" in the cylinder, use a piston upside down (no rings on it) 3) Measure the ring end gap at that position. Difference in thousandths of an inch divided by 3 is the amount of taper. .008" or less is acceptable, in diameter. (3.14 X diameter is circumference, so 3 is the factor. Remove ridges, Ball hone cylinders, install cast iron rings. 301 is a great combo!
this is great !!,, the piston in my pic, took about 3 swipes with a worn out brass wire brush to reveal the 125 stamping on the top..that piston is from number one in the block.. when i fit it back into the block , the skirts are noticeably grabbing the walls, .. I think its fairly tight in there ..the chambers in the heads will take a similar time to clean up - there are no burnt valves - but will be re-seated . there is a small (1/2'' by 1/16'') at one end of a main bearing just showing through the white metal.. i havent as yet completely striped the motor - ill save that for after the move hoping ive found the worst of it i have heard these motors can be pretty wild when bored out , only looking for a cruiser with a bit of excitement once in a while!! looking at a 74 350 4 barrell intake ,, not too special just for fun thanks guys .. will keep you posted
Another note on 301s. Only earlier blocks will go that far (.125) as a rule. Somewhere in 1961 I think, can't remember for sure, the walls must have got thinner. Every 301 I remember from like 63-64 were boilers. Probably right around the same time is the blocks you could run a 327 crank in without it hitting anything, couldn't run the 327 crank in the earlier 283 blocks without some clearancing. Ok, I'm babbling now, 283s the cool sbc.
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