259 Cubic inch engines 3.5625 Bore X 3.25 Stroke (3 9/16 X 3 1/4) 259 compression height : 1.727"-1.733" ----------------------------------------- 289 Cubic inch engines rod length - 6.625, piston pin diameter - .875, rod journal diameter - 2, bore - 3.5625, 289 compression height - 1.591"-1.597" --------------------- Standard and Avanti 289 Cubic inch R1 / R2 engines 289 Cubic inch engine - 3.5625 Bore X 3.625 Stroke (3 9/16 X 3 5/8) CID = Bore X bore X Stroke X # of cylinders X .7854 ------------------------------------- 304.5 cubic inch engines Avanti R3/R4 engines 289 cubic inch overbored 3/32" (.09375) same stroke 3.5625 + .09375 = 3.65626 ( 3 21/32") Notes: You must be very careful when overboring to this degree. The R3 blocks were specially selected by the factory to have almost perfectly centered bores so that the R3 304.5 cid bore would not excessively thin or penetrate the cylinder wall. ------------- Ford 312 CID Y-block standard pistons can be fitted to a Stude 289 with a .156 overbore which yields 314.93 Cubic inches. Ford 6 cylinder pistons can also be used and reversed in the cylinder for better torque ( more info when received) ----------- As it happens, 305 Chevy pistons will only work if you bore out a stock 289 by 140 thousandths. I just did it. Scared the hell out of me boring the block that much but it looks to be OK or so I'm hoping when it all gets reassembled. The stock Chevy 305 piston is 3.700" and a stock 289 is 3.56 or thereabouts. The deck is height is a little less too but that helps reduce the compression ratio to run better on the swamp gas they call gasoline these days.( Keith Mar 02) From the centre of the pin to the top land was 1.55". You have to have the rods sized to accept the larger wrist pin for a 305 Chebby piston. I got a nice set of hypereutectic pistons for $185 Cdn. Dirt cheap. --------- The 289 piston pin height is 1.591" to 1.597". The 259 is 1.727" to 1.733". I have no idea what the 305 Chevy is but think it might be somewhere in the vicinity of 1.54". (TH Mar 02) --------- The biggest (bore) I ever did one was .147" and running two Paxtons finally after about two years running it cracked a cylinder wall. The biggest I have heard of was .187". If you drove it hard, I would think you might have some heating problems if you didn't increase the cooling system accordingly. Ted --------------- (In the Chicken Hawk) The pistons are Ross with full floating pins and spiral locks in the pistons to keep the pins in and the rods are Carrillo with the big end made to take Chevy bearings so I could use the "H" type racing bearings. The pistons have a 27cc dish to get the compression at 7.5 to 1. Carrillo has priced me out of any more of theirs even if they are the best money can buy. I gave $1200 for the set in the '51 and have a set to put in the Avanti but last summer I ordered a set for a fellow in England and they were up to $!750!!!!! I checked with Crower and they will make them but were about $1300 last time I checked. The Stude rod is surprisingly strong and if you polish them, shot peen and use ARP bolts, they will stand a lot of HP. I never broke one and was using two Paxtons with 14 pounds boost but only went to the Carrillo when I put on two turbos and knew I was going nuts with boost. I thought long and hard about spending the money for the Carrillos but figured if they saved an engine they would be worth the $1100. To me, their price is too much now. Ted ------------------ They are not an urban legend, I even passed up buying a "big block" from an ex Studebaker engineer when I lived on South Bend in 1964. He had 3 blocks in has garage, a Bendix fuel injection unit and more. I actually dropped a R3 piston in one of the blocks and the bore was perhaps 1/8 bigger. He claimed they just "messed' with the sand casting, going though a few dozen blocks to get a few good ones. JP Mar 2002 --------------- Added October 2002 ---------------------------------------------------------- ////////Just ultrasonic tested my 1957 289 block. I had already bored the block .055" to finish hone for .060"-over pistons, but I wanted to go larger if possible. I have heard various ideas on the biggest allowable bore for Studes. Well, the bottom of my driver's side bank of cylinders were .138" to .194" thick (at bottom of bore towards camshaft bores). So, .060 is as big as I would go. The other spots tested were .210 to .280". All bores were checked, top middle and bottom, front, rear and both sides. Moral of the story: if you're boring a Studebaker V8 over .030", you need to consider checking wall thickness. Especially if supercharging. ////////////////// Glad you said something Mike. I was considering taking my '57 supercharged 289 out to at least the 304 cu in that the Avanti is supposed to be. Hmmm, that brings up some interesting thoughts and questions. Did Studebaker make blocks especially for the Avanti? I've heard some wild stories about how much boring a Stude V8 engine can take, a bunch over .100 is what I've heard. Since there is no doubt that our '57 blocks are not capable of handling such a big bore, how the hell did Studebaker do it? I know we had core shift problems too. When was the change made, if any, to allow for big bore jobs? Maybe the 232 & 259 could take a big bore? I'd sure like to get the straight scoop. Thanks a million Mike, I might have been telling a sad story here if you didn't pass along that good information. I would never have checked, just believed what I heard. Any one else see such variances in block thickness? It looks like we would be doing all of Studebakerdom a real service if we put the "bore a Stude as much as ya want" urban legend to bed. Sonny >>Sonny- First of all, you're welcome. Next, I'm not suggesting that every '57 289 block would have the same cylinder wall thickness as I found with mine. Nor am I making any judgements about 1957 parts vs. any other year. I'm just saying, since I've found that thinner-than-typical walls can occur, it is a good idea to do ultrasonic checking before boring for extra-large bores. Your block may be perfectly fine for big bores, so don't get discouraged. There may indeed be a degree of core shift in my block. But if it is in my block, I'm sure there are others out there like it, or worse. Many of the spots I checked were .265" to .285"-thick after boring .055". If the walls were originally .292"-thick (.265+.055/2), uniformally, to begin with, you could bore to 3.750" and still have .197"-thick walls. (By the way, when I removed the freeze plugs there was not much corrosion, so I don't think the walls were eroded. Some Stude V8's collect a ton of corrosion in the water jacket.) I didn't mean to start a controversy. I just wanted to report what I found>>>> ------------------- Lordy, I hope I'm going to be ok. Ted will recall me finding 3 cracked pistons in my R2 and a big ugly gouge in #3 hole when the pinch bolt nut dropped off the wrist pin and allowed the pin to walk until it jammed up on the rod and proceeded to do a number on the cylinder wall. Took the block up to a reputable machine shop (still crossing my fingers!) and found out the p/o had already punched the block out .060". By the time the scoring was taken out of #3 the bore was 3.68" and there were no pistons out there to fit that bore. A 305 Chevy uses a 3.70" piston so that's what we did. That's .140" over but before we did that I spoke to John Erb about pistons and boring the block. His concern was the oil gallery running past #8 to the oil filter base but once the block was bored to 3.70" there was still plenty of meat left in the cylinder wall and no where near the oil gallery. So I'm really praying now that the cylinders were perfectly cast and I'm not going to have a cooling or blow-by problem once its reassembled. Pray for me people! Brooksie ----------- Thanks again Mike and I understood exactly what you were saying. What I was saying is that I, (and I think many other Studebaker enthusiasts), understood that a Studebaker engine block had a capacity for easily accepting a large overbore. It is common knowledge that Studebaker blocks have a propensity for core shift. I don't think you started a controversy, I think you have illuminated a very important and valuable point. It might be that core shift, (or more correctly unusually wide variations in block and cylinder thickness), is more of a factor than was previously understood. I think that your advice to have the block examined by ultrasound is extremely valuable. Large overbore and core shift would normally not be any concern for a person who isn't interested in getting the most performance from their Stude V8. However, the fact that piqued my interest and questions from your first post was that you found such a wide variation in the thickness of the cylinder walls. Also, the .060 overbore that you did to assure a margin of safety, (in your particular engine), would not bring the bore size of your engine up to the bore that was ROUTINELY used in the Avanti type engines. I was wondering if there was a notable difference in the quality control for different years or type, (partial flow vs. full flow). Is there some other factor in the manufacture of the engine that might help us determine which years or what areas might require closer examination for a particular application, OR, if any concern was warranted at all! Whew! One thing that we do know for sure is that Studebaker V8 engines can take punishment, and are not known for failure under extreme conditions. The type of supercharger used on the Stude imposed a relatively small amount of stress, and I think the fact that it uses so many head bolts makes it more than capable of handling that job. In particular, Ted Harbit and others have proven that they can take phenomenal pressures and repeated high rpm punishment at the race track. However, and once again, I understand that if a block must be bored in the larger sizes, (and even for the non-performance application), it should be thoroughly examined and ultrasound tested. One other nagging question for me, (I've asked about this and it seems that none has the answer), I am under the impression that the Stude block has a very high nickel content, and THAT might be a factor in the ability to handle punishment even with wide variations in cylinder thickness. I don't know, but I DO know one thing, it's a curse to be trained as an engineer and not have the answer! --------------- Sounds like a good idea, because you can't generalize. There is a lot of variation in Studebaker blocks, but I have never seen one that was a problem with 0.060 over bore. Gary L. ------------------- If I recall correctly, the speaker at Tri-State 2001 in Asheville, NC worked in the engine department at Studebaker and said that the 289 could technically be bored .250. ---------- I know of a 289 that was bored to be a 317 cubic inch, and last I knew the 1961 Hawk it is in was at the SNM, and is a Flamingo color. I don't know offhand how much it was bored, but it ran damn good up, and down, I-55 the day I rode in it. Sam --------------- Well is it just his block or should we look into this more? I have some very ambitious plans for my engine Lee and I sure would hate to see parts of it escaping through the louvers in the hood! Overheating would be another problem, maybe why the Avanti tended to have overheating problems. I dunno.............. Sonny -------- I was told that to safely bore over .060 use a early block and a bypass oil filter, it's something about a full-flow blocks oil passages making it hazardous to bore past .060. ---------- Now you tell me! And here I am running ,080. Guess I better not go to Nitrous injection. Maybe that's why it runs hot. Stude bob has a 321 inch block that was run in a big truck for a few years. Alex M ---------- I think Mike addressed it pretty well. I'm sure we could hear all kinds of stories about how much it's possible to bore one. It just depends on how much core shift a particular block has. I have not heard of anyone having a problem with a .060" bore though. I just had the Tomato bored .060" (we're allowed .070"). I know of several that have been bored .120" without a problem and some even .187" but one that did this had trouble keeping it cool when pulling it hard in his truck. When I was going to use 3.680 six cylinder Ford pistons several years ago, the machine shop messed up one cylinder and I had to go and extra .030 to clean it up and that made the bore up to 3.710". This .150" overbore gave 313". I was running a supercharger and this engine held a couple years until the converter gave out and instead of going across the line at 6200, it went to 7000. I don't know what the boost was but it cracked a cylinder wall and I had a sleeve put in it. The only real safe way to know is like Mike said and that is to have it checked. You might remember though that if the thinest part is a certain figure, and you are going to bore it .060" or whatever, you will only be taking half that amount off that thinest side. Ted =========== ----------- That would be Jon Meyer. I believe he said .125 over without problems, and that the proposed 370 was a thicker wall essentially bored .250 with a stroker crank. Too bad it never saw light... or did it? ask Meyer! ---------------------------------------------------------- As I've related before - I've got this ex-R3 block #B112 that has been fitted with standard AMC 304 pistons. That's three and three quarter inches bore. Or roughly 321cu.in.. This engine was done by Mr. Myer some dozen or more years ago for one Lionel Stone. Mr. Stone installed it in a 64 model 3ton truck with a 5-speed. He subequently drove it cross-country at least once and much more locally. On one long run, the oil perssure gage hose broke (from being old and brittle). Lionel pressed on in the truck until the engine seized up. the engine was built again and returned to the truck. There it served until Linoel sold it to a Stude-thusiast who put the truck into daily service as a welding rig. The owner drove the truck in such fashion that he lugged it quite a bit. This caused a piston to crack. But what really disabled the truck again was when the cam gear and the nose of the cam snapped off. Thru some weird circumstances the truck ended up in my hands. I kept the engine and sold the truck to RebelStude. The engine is all ready to go back together when I find the time to do so. My feelings are that hogged out to 321 and forced to serve in a heavy, heavy truck by someone who was not particularly adept at driving such a rig proves the mettle of these engines. More than one person of technical repute has said that Studebaker did NO special selection of blocks for high performance applications. "Robert Kabchef" ---------------------------------------------------------- ............ a +.125" piston for the Stude 289" will be a special order forging. There aren't and haven't been any direct replacement cast pistons. Over the years, I've modified the Stude rods to accept Ford, Chevy and AMC cast pistons when a CASO build was needed. I've ordered custom forgings from JE, Venolia and others. I've most recently used Ford 3.680" pistons, which are +.117" over. ......... not all Stude V8s will safely bore to +.125". Recently, even after sonic testing, in a rear cylinder, we hit an isolated rust pit at .060" and had to sleeve the block. The most cost-effective big cube build I've done lately is boring the Studebaker V8 rod small ends to accept Ford 3.680" pistons with pressed pins. This gives a 308". The pistons have to be carefully specified, as they're available for 4-cyl, 6-cy and 8-cyl, each with differing compression heights. In reality, you'll most likely not notice the difference between a .060" over 299" and the .117" over 308" and since .060" over pistons are readily available and require no rod mods, it's way more cost-effective. J.V. (Oct 2017) --------------------------------------------------------------- Note: This file is occasionally updated with more robust information ---------------------------------------------------------------