i have been told that olds head will interchange, such as 455 to 260 etc.  Is this correct how much work is required to do this?

I know pontiacs will, but i'm pretty sure they don't on olds.  Most pontiacs have the same size lump of metal they were made of.  ( 350's are the same size as 455's and were the same size as 428's)  I believe olds' were different size however, so I'm thinkin no.

You are correct.  A big block olds head will bolt right up to any small block olds.  However, the intake ports must be matched to the intake manifold.  I'm not completely sure, but i think that the only intakes that have enough material to allow this (without welding on more material), are the edelbrock victor (for small block olds) or edelbrock performer rpm.  I know that a big block head will bolt on to a small block FOR SURE as my 68 cutlass has a 350 with B cast big block heads.  I have a pretty mild cam, but it makes plenty of power for my daily driving purposes. 

Hope this helps

thanks.  

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"small block" and "big block" olds differ mainly by deck height.  Main journal sizes are unique to each family with a few crossovers, but the heads will bolt up.  Most big block heads start with a letter and most small block heads start with a number, but that's not a rule.  Be careful when swapping though.  In most cases putting small block heads on a big block will get you 13:1 compression and tiny ports.  Putting big block heads on a small block will get you 7:1 compression and way too much port for the displacement.

I agree with Ethel... get the Mondello book, its incredible and concise.

I am just curious if any olds guys have put big block heads on a small block??  I have B cast heads on mine (granted its bored to accept chevy 400 pistons), but I've never had problems with the ports being too big.  Its got a pretty mild cam, stock converter, and 3.08's out back.  But its really a very nice driver.  It seems like most olds guys are building big blocks, so its hard to find people running similar setups.  

I had some B-heads on a 403 "small" block.  The 403 has sorta big block displacement on small block architecture.  It worked pretty well for the fact that those heads are based on 50 year old engineering

I have a '67 Cutlass S, and it sports the 330 small block it was born with.  It also sports "F" letter big block big valve heads.  The machinist told me that they were some good ones - off of a 70 442 I think.  Yes you need to match ports, and watch how much material is being ground off.  The cam in my mill is a Crane, and is pretty steep for the engine.  The big heads allowed me to use a more radical cam than would normally be advisable on the small block heads.  It doesn't idle very well, but then it's not a daily driver either.  You have to be careful on what big block heads you install.  Some early BB heads (pre 68) work on a 39 degree cam bank angle,  which was changed for 1968 when the small block 350 CID  (and all the others for that matter) went to a more common 45 degree angle.  I don't think that the components will interchange between the early and late years without some modification.  I read someplace that the pushrods might bind on the head when mixing early or late (or vice versa).  If this occurs, the push rod holes might need to be enlarged some - a pain, but doable.  In my case, the 1967 330 was already using the 45 degree angle, so there was no rub (no pun intended).  The 39 degree angle engines were the top of the line set, like toronados, 98's, and Starfires (with the 425 engines) - there were some others.  The lifters in these engines were also considerably larger.  I haven't seen it yet, but will as I have a '67 Toro that I will working on soon.  I will write you back when I find the build sheet for my 330 (l misplaced it).  I can give you the exact cam specs, bore, and other specifics if you want them.  With the flat top pistons in it, it is running probably around 9.5:1 (maybe 10:1 ?) compression ratio.   The engine screams, and is rock solid.  I am still building up the car, so don't know what its full potential is yet.  But to answer your question directly, yes - my small block has big block heads. 

I will get back to you when I find the build papers.  My machinest was pretty good on getting it all to work.  He did the heads and balancing, and heavy machine work.  I did all the assembly minus freeze plugs and cam bearings.  Good Luck  -  Bowser.

So what would happen if i just went and bolted up a set of 1970-76 455 heads on a little 260 with no modifications,what would be the destruction  

The truth is I don't know much about the 260 - I know that Olds did have a small C/I V8 in the late 80's and 90's.  My Uncle had one in his 83 Cutlass.  However, pretty much as a rule, Olds engines made after '67 run on the 45 degree cam bank angle, so anything '70 and beyond would work.  You would have to pay attention to the chamber size of the head because the 260 (?) is probably a low compression engine.  You can find that out from a service manual.  If the heads you want to use have big chambers, then dished pistons in your engine could net you a low compression boat anchor.  You may need to have them shaved, and use a thin head set (probably metal shims) to get a good compression ratio.  If you are going through the engine completely, then select your slugs based on the chamber size of the head - ie flat topped might be necessary.  You can also adjust compression with a thicker head set if compression ratio is getting too high, but you probably already know that.  Dished pistons may be OK if you have a smaller chamber size head, but a smaller chamber usually means smaller valves and a milder cam.  A real good big block head that you can still find are C heads.  If you can find some off of a '68 or newer engine, they would be some of the best.  They are supposed to be some of the best flowing production heads made by Oldsmobile.  You would have to have hardened inserts put in them in order to run unleaded gas.  Anything after about 1971 will be lower compression smog type heads.  In 1972, if you look at statistics on the engines as compared to 1971, there will be a drastic difference in H/P and torque.  Torque doesn't suffer as much, but lower compression ratios cut H/P ratings in half in some cases.  The 330 small block in my '67 Cutlass puts out almost as much torque and twice the H/P as my sons '73 455.  Now, if his engine was built properly and heads changed and so forth, this would change.  Just remember that the deck heights between the small and big blocks are different - that is why you have to port match your intake.  I suggest you let your machine shop do it - if they goof it up, they have to add the material back in to fix it and it ain't on you.

Good luck with your project.  If you want to see some stats and get more Olds lore, let me know and I can turn you on to some cool sites.  Have fun - Bowser.

One real good site for information is http://www.442.com/oldsfaq/oldsfaq.htm which is full of information about olds mills.  Some of it doesn't agree with itself, but the most common knowledge is that came angle and interchangability is pretty much universal after 1968.  I read up on your 260, and it sounds to be a fair builder as long as you don't want to rev much past 5500 RPMs.  That site did agree with my statement that you have to be careful about chamber size and piston types.  If you are running a 8.5 to 1 engine, you don't want to add the big heads just to lower your net compression a full point.  Try the site - it's a good read.

Bowser

That sounds like an awesome motor.  I'm a big fan of the small block olds.  I think CC should build one (they're in to odd ball stuff right?).  I love mine.  Definitely post the build sheet, I'd love to see what all's been done to it.  

Found the build sheet and will post it tomorrow - found the file in my computer software stuff.  Go figure.  It's all there and will be a good read.  Bowser.