projectheaven

Hello all,

Does Boring a block out give you more horses? Let's say .30 over with the pistons and things being .30 over as well.

J-(Chicago)

depends on the combo. You are starting from scratch I take it?
What parts do you have so far? Just crank, rods, pistons, and main caps?

dan2286

It does increase your cubic inches, so you should see at least a small gain in h.p.

projectheaven

Well,I have everything for the rebuild but if it will give me horsepwer gains my buddy has a kit thats hes willing to give to me if I go .40 over on the block?

Will that make it a 468?

citcapp

The cubic inche are only part of the build. Oldsmobile engines also depend on the dish of the pistons. Olds used different pistons for different compression ratios. You have to decide want you want to use to come up with the hp of the engine along with selectin of heads. valves, intake manifolds and exhaust manifolds. etc to get the hp gains you are looking for.

projectheaven

Ok.So is the type of piston i put in going to determine what my compression ratio is going to be?
I plan on using "C" heads that has been really worked on.A edelbrock intake and headers.I almost forgot the high lift cam for that nice choppy lope out of the dual exhaust.

How does that sound?

J-(Chicago)

You don't even need a high lift cam if you're looking for a cool sound.
They make cams right around stock spec that have the choppy idle sound.
A comp 268H is one example. Stock lift on a 1987 307 motor is .440 If I remember correctly, and that comp cam is around .456

They sound way different however.

J-(Chicago)

shoot for a desired horsepower level, and then weigh your many options on getting to it with your machinist is my best advice.

I'm not sure what your goal is. My gray 85 delta sounds like it's about to burn the tires off of the rims at every stop light, but in reality it's just an 8.2ish-1 compression mid 200s horsepower turd. Make yourself a list of what you want to see happen for you with the project.
Mine was pretty easy to complete lol.
I want it to sound menacing......Check.
I want it to look menacing......Check.
I want it all said and done for under 500 bucks......Check.

Olds64

Ask your machinist how much your block needs to be bored to be true. I wouldn't bore it .040 over if it only needs .030.

Steve O

Bigger bore increases displacement, slightly increases compression ratio and it improves head flow because even that little bit unshrouds the valves...

You will see a little more power with an overbore assuming the compression is the same or higher.

projectheaven

All of that is definitely great advice that I will follow.Especially the cam spec.I thought I had to go with a .480 lift or higher to acheive that rough/choppy idle sound.

Ya learn something new everyday.

The_Jeremiah

Do your self a favor, only need to bore it if it needs it, and bore it as little as possible. Boring all 8 cylinders 30 over gives you around 4 more cubes to play with, not that much. The horsepower gain is not really that noticeable. if you bore it out now, when you or the next guy go's to rebuild it, the block is junk. if you only need to hone it, or bore it 10 over, just do that. makes the block last another 200 thousand miles. you also need to remember your cylinder wall acts as a heat sink, take away that material, and you will run a couple degrees hotter. and sleeved blocks are nothing but junk. try to avoid useless boring at all costs.

Wireman134

Those "C" heads are for a BB Olds. You'd need to spend allot in machine work to get them to work well on a small block. Combustion chambers are to big to start and the port volumes are to big for good low rpm flow. For a street engine you'd be better served with the #7 heads to keep you CR up.

dan2286

I believe he is using a 455.

Wireman134

Sorry for not keeping up, I seen your Youtube video. Just assumed you'd use the 350 block.

Warhead

You don't need a choppy idle,
YOU HAVE WHEELS!

projectheaven

LOL!!!! The choppy idle is a must.I love that sound.I can sit behind a car all day and listen to that great sound.

I'll be using a 455 that I bought 2 weekends ago.I got it for 300 bucks and it came out of a early delta 98.It has everything from the brackets to belts.Even the starter and power steering unit.I lucked up on this one.I heard and seen it run before it was taken out.

MN71W30

I'll be using a 455 that I bought 2 weekends ago.I got it for 300 bucks and it came out of a early delta 98.It has everything from the brackets to belts.Even the starter and power steering unit.I lucked up on this one.I heard and seen it run before it was taken out.[/quote]

If it ran good and has C heads on it seems a little counter productive to tear it down and spend a couple grand on a rebuild. I'm in the same position with a 455 and decided just to re cam the engine and throw it in. I have gone both ways on this and have had good luck when I found a good running, clean burning engine and just went with a new cam. If all the exhaust ports look nice and gray and the oil pressure is acceptable I'd run it. But thats my low budget, save a buck when possible opinion. But you just never know, especially if you have to pay to have the engine installed it could be a big mistake to cheap out. I think those are your options.
Good luck.
That 455 will make that Cutlass come to life.

scrappie

What does this mean? Lots of luck? or Laugh out loud? neither?

Jamesbo

Would you mind elaborating on this. You put in a new cam and did nothing else is the way I read it.

What cam?

What results?

citcapp

Not that much more effort is required to pull the engine down and do a rebuild. The few times I have install a used engine and did not rebuild it I ended up doing so in a couple of years anyway. I prefer to start with a fresh engine because I don't know the history of the used one. In any case if it is a early engine you have to deal with the valve seats to use the unleaded gas if you drive the car a lot. My cars are drivers that I will use when ever the weather permits.

Charlie_brown

Hey so keeping with Project's original question if you keep the motor at stock bore or at the most .30 over can your selection of pistons compensate for how ever much you didn't bore? and just as a question for my build did all the 455's come with the crank that has the "N" or "CN" scribed in the #1 weight?

J-(Chicago)

If it's stock bore, you use stock bore pistons.
If it's .030 over you use .030 pistons
etc etc.
The piston rings must be fit to the final dimension.

Charlie_brown

Right but i guess i'm meaning the different types of pistons like domed.... flat topped .....step dish...... when you go with one of these it changes the cr right but do you select these depending on the heads you have?

Oldsguy

I think it is more than that. You have to consider the total package i.e. Intake, heads, bore, exhaust. The engine is an air pump, anywhere in that train that the efficiency of the pump is degraded it will degrade the total performance. If you stick a rag in the carburetor air horn what do you get? Degraded performance. I only relate this to recommend that you need to take everything into consideration. Look at other builds and see how people have matched certain components with others. For instance, see what other components people have matched to an engine where they have used flat top pistons with higher rated static compression ratios. When I built the 455 in my project I used a build I found that had been used by many people before. Again, at the risk of sounding strange I am going to recommend that you go over to Realoldspower.com and read some of their stuff. They have a huge membership and a nice forum that lists many, many engine builds. This may help you out some, if nothing else, giving you a better feel for how the Oldsmobile engines have been built by others.