shiftbyear

What is the largest overbore possible on a 455 olds block? I've heard people say the cylinder walls are .300" thick. Has anyone sonic tested a standard bore 455?

wr1970

It is my understand .125 is max if you sonic test. This maybe be wrong but i think i heard that somewhere. I doubt if there is enough wall thickness left with out hard block with .125 bore.JMO

cutlassefi

Well that may be true on the thrust sides, but unless you come across a block used for a pump etc I have yet to sonic check one that has more than .180-.190 wall thickness front to back. It doesn't matter how thick the thrust sides are, you have to maintain at least .090-.100 thickness at its thinnest point. Otherwise you'll sacrifice ring seal and longevity.

wr1970

No reason to doubt anything in your post and very good info. I know i haven't any reason yet to go more than .06.Thanks for putting your info out there Mark.

oldsfromyell

I have sonic checked all the 455 blocks I have. They all are thinnest in the 3o'clock and 9o'clock positions. They are all fairly close to each other in wall thickness. They all measure in the .180-.190 range on non thrust and upper .200 to close to .300 on the thrust. Can't remember exact thrust thickness but was thick enough was not concerned. My DX I am building measured at its thinnest .204 non thrust. Standard bore. It is now bored to 4.155 so it still has some room for at least one more bore. Always measure a block it is cheap insurance.

joe_padavano

Mark,

Any comments on using a block filler?

cutlassefi

Yes, it will increase your oil temps due to the loss of cooling via the bottom of the cylinder. And there's no guarantee the thinnest spots will be at the bottom. Even though it'll stabilize the whole cylinder to some degree imo you're better of not doing that unless absolutely necessary.

wr1970

So these guys using block filler in a race engine application shouldn't at any bore size because of oil temps. I thought with this block filler a guy goes to a system where the oil is filtered external and cooled before returned. So to keep oil temps down.

cutlassefi

hard to understand that post Neeley.
But I'm guessing you're questioning about oil temps on race engines? If so it's normally not a problem, they normally don't run long enough.

wr1970

Well Mark i guess you are being sarcastic! Could you point out which part of my post was hard to understand? The post i made was about a racing engine!You were suggesting not to do this block filler at a max bore.So what are you saying a street motor? To never use block filler unless necessary in a street platform. At one time on ROP there were a few street cars using block filler to the water pump holes. Now you are saying block filler on a race engine is fine? I am just trying to understand!

oldsmobiledave

The largest overbore possible varies from block to block. Sonic checking is your friend & must be done prior to boring. Consult with an experienced Olds specific engine builder prior to deciding on your final bore. Also carefully weigh the pros & cons of big overbore for your application.


Now, since Mark takes pleasure in accusing me of being vague and muddying the water, I will specifically answer the original question.


My 524 BBO uses a 4.280" bore. That is 0.155" over standard bore. I am not aware of any 455 build that uses a bigger bore than 4.280". Perhaps one of the engine builders does but I do not.


I AM NOT TELLING YOU THAT YOU CAN DO THIS TO ANY GIVEN 455 BLOCK BECAUSE YOU CAN'T.


I DO NOT ADVOCATE OR RECOMMEND THAT YOU TRY TO REPLICATE A 4.280" BORE ON A 455 BLOCK.


I hope I answered your question and also hope I haven't offended some others by providing that answer.......


Oh....and Mark.....have a nice day.

wr1970

507 olds says his old block was block filled just below water pump holes!

cutlassefi

You can use block fill in anything, it'll raise oil temps that's all. That's all I said, plain and simple.

wr1970

Brian 507 told me he used a stand alone exterior filter and a cooler. He was one i was referring to as a street car but there are others. You also said it was hard to understand my post.I ask you to explain!

wr1970

Joe do you have any?I would like to hear your take on this.

cutlassefi

"Shouldn't at any bore size" Don't understand that.

wr1970

Mark i thought anything over a .06 sonic test and if you block fill it would be more than a 468 ci. Were you digging bug crap out just to be sarcastic? Do you see a need for block filler at 468 ci or less?

madmax442

I'll answer for Mark........nope!