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OT Question re a 307

Maymyvetteliveforevr

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Joined
Aug 29, 2005
Messages
26
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Ontario
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1975 Dark Blue Coupe
I was having a discusion re boring out a 307 to a 383 stroker. Is that possible? I always thought that the 307 had the 350 block. Wait a sec, was it the 307 or the 305 that they used in the Oldsmobile Cutlass Supreme?
Anyway, can you do it? I would imaging you'd have to bore it more than 60 over.
 

craig32

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Joined
Sep 30, 2004
Messages
482
Location
PA
Corvette
1981 repainted black coupe
307 and 283 have the same bore (3.875) - 327 and 350 have the same bore (4.00). 383 is the latter bored .030 with a 400 crank. (4.030 x 3.75) 305 is completely different from all above. Hope this helps.

Craig
 

bossvette

Gone but not forgotten
Joined
May 19, 2003
Messages
3,233
Location
West Unity Ohio
Corvette
1968 1997
I was having a discusion re boring out a 307 to a 383 stroker. Is that possible? I always thought that the 307 had the 350 block. Wait a sec, was it the 307 or the 305 that they used in the Oldsmobile Cutlass Supreme?
Anyway, can you do it? I would imaging you'd have to bore it more than 60 over.


no the block won't have enough meat in it to go 4.030 you need to start with a 350 or a large journal 327 block to build a 383.
used to be you had to use a 400 crank and grind the journals down to 350 size but now a days they are casting and forging 383 cranks from the manufacturer; Chevy even sells a crate 383 in varoius versions.
My 76 has one built the old way with a 400 crank in a early 4 bolt block it was origionally built in 1990. I am currently building another using a cast 383 crank it will end up in the 68, the newer castings don't (at least mine didn't) need as much clearance grinding in the blocks as the 400 cranks do

FWIW you can machine a 400 crank mains to fit a 305 or 307 block and using the 400 rods and the pistons from the block you use to build a stroker.
the 305 comes out 335 (there are kits out there to build this) I don't know what the 307 comes out to but it will be in the neighborhood of 350
 
S

Scooter76

Guest
I believe that Oldsmobile had their own 307 that came in Cutlass Supremes. It was an actual Olds engine & not a smallblock Chevrolet. Correct me if I'm wrong.
 

bossvette

Gone but not forgotten
Joined
May 19, 2003
Messages
3,233
Location
West Unity Ohio
Corvette
1968 1997
up until a a point in time that the "bean counters" at GM decided that a "corporate" engine would suffice all the different divisions had their own powerplants some even having both small and big blocks. I don't remember exactly when it was but it was not something GM let the public know about ;)

I think it was about the time they started painting the engines "corporate blue" instead of Chevy orange Maybe someone who has a better memory will chime in.

There was a lot of diversity back then 500CI Caddys the Buick Nailhead Olds had the Rocket and even produced a Aluminum V8 pontiac had a 326 and a 426 GM produced everything from a 4 banger on up :upthumbs
 

C3 4ME

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Joined
Apr 29, 2006
Messages
72
Location
Mechanicsville, VA
Corvette
1979 Black L-82 4 speed
Yes, Olds had their own 307. Anyone familiar with Olds engines could easily identify it as an olds engine not a Chevy. The exhaust ports are evenly spaced and come out below where the spark plugs go. Also an Olds on an olds motor the distributor does not go through the intake.
 

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