Engine: Bore Centers

[CarCrosswordDan]

Are all Studebaker V/8's based on the same bore centerline diminsion from the smallest of '55 224 to the '64 304?

[PackardV8]

Yes, all Studebaker V8s are 4.500" bore centers - same as small block Chevys.
Yes, all 224", 259", 289" and 304.5" use the same 3-9/16" bore block, albiet with the full-flow oil filter provision added in mid-'62 or so and the '64 R3/R4s having a factory overbore of .093".
The only different block was the original Studebaker 232" V8 of '51-54" which came with a 3-3/8" bore diameter.

jack vines

[CarCrosswordDan]

Jack, Thanks for the reply. Think the Chevys were 4.4 inches. Weren't all the 304s overbored no matter what tune they were? On another note, were the heads for the V/8's ever redesigned for bigger valves and better flow? Thinking maybe the 304s were. Thanks

[StudeRich]

The original Paxton Products Div. built, Studebaker South Bend factory installed 304.5 c.i.d. R3 Engines installed in the 9 Avantis so equipped, all had large intake port, large valve, special casting, improved HEADS made of unobtainium! Now very rare and priceless.

All other 1955 to 1964 V-8 Heads, including Avanti R1 and R2 though Compression varies slightly, are all basically the same.

[R2Andrea]

The R3/R4 blocks started out as standard (3.56" dia.) blocks EXCEPT that they were required to be free of any repairs and had 4 of the coolant transfer holes drilled to a smaller diameter. Paxton Products bored them to 3.65" and machined 2 notches to help unshroud the larger valves used in the R3/R4 heads. The R3/R4 heads were designed for the larger bore (3.75" and 3.875") engines (320, 343 and 360 CID) which never made production. These heads had larger (taller) intake ports, larger diameter valves, and had the valves spaced .250" farther apart than the standard V8 heads.

[CarCrosswordDan]

StudeRich, appreciate your reply, I thought they were different. So, all 304s were either R3's or R4's, correct? And all R3's & R4's had the new and improved heads, right? Also, R3's were supercharged with an obvious lower compression and R4's had the higher compression and two AFBs. Were such heads cast of aluminum? What about the intake manifolds, aluminum as well? Were blown R3's fed through a 2 or 4 or multiple carb setup? Were ealier blown 289s fed though 2 or 4 barrel carb? Did all 304s have hydraulic camshafts or did they go mechanical? Did any of the other V/8s have mechanical camshafts? Do you have production numbers for '64 304 applications other than the 9 Avantis you mention with the R3? Many Thanks, CarCrossword Dan

[CarCrosswordDan]

Jack, it seeems to me that starting with the '51, 232 (3.38 bore and 3.25 stroke), for '55 they only overbored the 232 by 3/16 to 3.56 and stroke remained the same. Same year they kept the 259 bore for the 232 at 3.56 and desroked to 2.81. In '56 the took the 259 from '55, left the bore the same at 3.56 and increased the stroke to 3.63. Then in '64, for the 304 they simply bored the 289 to 3.65. From all that, the majority of the engines had a very long stroke compared to their relative bores, making them torquey but hard to wind up. The only exception being the smallest at 224 c.i. Based on that, I'd expect the 259, 4 bbl to actually run fairly well in a light car. Is that your take?
Thanks a lot,
CarCrosswordDan

[PackardV8]

starting with the '51, 232 (3.38 bore and 3.25 stroke), for '55 they only overbored the 232 by 3/16 to 3.56 and stroke remained the same.

In a technical discussion, correct terminology is critical to clear communication. The 232" blocks have a 3-3/8" (3.375") bore. In 1955, Studebaker substantially changed the interior core patterns to enlarge the bore from 3-3/8" to 3-9/16". The '55-and-later blocks are thus very different and the 232"s cannot be safely overbored to 3-9/16". In 1964, Paxton products overbored a few blocks by .093". The blocks were identical otherwise.

very long stroke compared to their relative bores, making them torquey but hard to wind up.

Not really. Studebaker V8 stroke length is shorter than some, longer than some, but right in the middle of most other V8s. The 3-5/8" stroke produces exactly the same torque as the 3.00" stroke 283" SBC - so much for "torquey." The 259" has the same 3.25" stroke as that noted hi-revving SBC 327". The 289" has a much shorter stroke than the rodder's current favorite crate motor toy, the 383" SBC.

Whatever the stroke, the Studes wind up just fine until they run out of breath. It is the lack of intake manifold and head porting, plus the short cam timing which is the limiting factor; nothing to do with the stroke length.

The reason some feel the 259" revs quicker than the 289" is the same head and cam is effectively "larger" when it has fewer inches to feed. Thus, the 259" does not run out of breath as quickly as does a 289". For example, at Bonneville this year the Salt2Salt team was shifting their 183" V8 at 7,500-8,000 RPMs. The R2+ cam they were using makes max horsepower at 5,000 - 5,500 RPMs when used in a 289". Thus, RPMs is about breathing.

At some point, stroke length does impact durability. One would not want to turn the 4-3/8" stroke Champion at 8,000 RPMs for very long.

jack vines

[CarCrosswordDan]

Jack, Thanks a lot. Really appreciate the info.
CarCrosswordDan

[R2Andrea]

There were several 299CID R2 Prototypes, but, other than that the rest of the R3s and R4s were 304.5 CID. The R3/R4 heads were cast iron and the intakes were cast aluminum. The R3 used a single AFB which was enclosed in a cast aluminum pressure box, unlike the R2 which had an adapter fitted to the carb throat using a stud and wingnut. Studebaker never used hydraulic lifters in the engines they manufactured. There were 9 Avanti and 1 Commander 2 dr sedan with R3s and 1 Daytona Hardtop with an R4 which were built on the assembly line. All are 1964 models and all still exist, tho they don't all have their original engines. The R3 and R4 Bonneville record cars did not have their engines installed on the line.

[PackardV8]

The R3/R4 heads were cast iron and the intakes were cast aluminum.

One of our long-time expert SoCal members has seen iron R3 intakes. I believe him in all things Studebaker and he knows an R3 when he sees one, but has anyone else ever seen an iron R3 intake?

jack vines

[jlmccuan]

One small correction, Jack. The 2010 Salt to Salt engine ran an R2+ cam from Fairborn. The 2011 engine ran a different cam reground by Comp Cams, 0.511" lift and a bit more duration than most folks think you can get on an R2 core, too. I've posted the cam card specs before and Digger verified all the specs by direct measurement after installation. Actually, Digger told me he got a little better than the advertised 0.511" lift, even with the stock rockers. Must have been a "good" set. The R2+ was pretty radical in 183 cubic inches and this cam was even more aggressive. I didn't drive the 2010 engine, but heard and saw every pass it made. Actually got to make a pass with the 2011 engine and from 6500 to 8000rpm it was unbelieveably sweet and came on very strong above 7000rpm. It would have been interesting to have tried a pass pulling 3rd up over 8000 as it begging for more, but with a good week and an engine that was still very much alive and well it was determined that discretion was the better part of valor and we should go home with everything healthy for Digger to examine after our return.