dre

I will be getting a 455 bored out. I've been getting mixed reviews on rather to bore the block +.010, +.020, or +.030. From what I've learned so far, your horsepower comes from your cam and heads(correct me if I'm wrong). What would be the best application for street performance but trying to remain as close to stock as possible? Also, what size cam would be recommended? And if anyone has a set of "C" heads they are interested in selling please let me know!

507OLDS

Bore it the least amount needed,as long as there are piston available.This way,the cylinder walls are as thick as possible for better cooling,and you have more material in there,if/when you need to bore the block again.

Olds64

I agree with Brian.

Once you take your block to a machinist he or she will measure cylinder "out-of-round" with a dial bore gauge. These measurements will tell you how much you have to bore the cylinders to make them true.

citcapp

X3 on all of the above advice.

rocketraider

Just remember that anything other than .030, .040 or .060 is usually a custom made piston for Oldsmobiles, and that can turn into major expense.

507OLDS

They were making +.020 455 pistons. I have 2 of them.However,these are hypertectic,not forged. My be worth looking to see who has the smaller bore sizes,but +.030 might be the logical way to go.

dre

I've seen some +.010 and +.020 pistons. What are the advantages and disadvantages to going with forged versus hypertectic?

Coltonis

I have no idea what your thread title is talking about - this seemed like a perfectly interesting thread to me.... not even remotely boring.
*ba-dump-ching*

Bobsw32

If your machinist does not have a torque plate there are a couple of us here on the board who let members use theirssss

dre

Lol!

dre

Ok everyone, I've been doing a little more research. As I am putting together my parts list I will have a KB flat top piston +.030 w/2 valve reliefs Keith Black/KB Pistons IC886KTD-030 - Keith Black ICON Premium Forged Piston and Ring Kits, aluminum roller rockers, a Lunati Cam Lunati 60805LK - Lunati Voodoo Cam and Lifter Kits. I was told that I would need a stall of about 3,200-3,500. This is going to be street, no racing. I'm told with this combination of Piston, and cam I should get a 10.4:1 compression ratio. Can someone please share the expertise? Also, what is the size of stock Ga heads?

Coltonis

Wow my parts list looks alot like your parts list...lol.

Now keep in mind I have no expertise, but I have been researching heavily as I go along on my own project. Since I have been looking at much of the same stuff I guess I'll chime in.

Here are my thoughts:

First to answer your question, Ga heads are supposed to be 80cc according to CO's tech section. Machining can change that though.

Those are the same pistons I was debating. If you haven't found a compression ratio calculator yet I recommend a google search which should pull one up pretty quickly. That is going to be much more accurate than the "ballpark" ratings piston Mfr usually list since piston dish, diameter, head chamber size, stroke, and even head gasket thickness, etc. all effect the CR. (And I'm told even CR calculators leave a bit to be desired since they don't usually account for cam timing) I'm not saying the 10.4 CR is wrong or anything but i like to compare various parameters and see them get calculated before I trust things.

From what I've read 10.x CR is teetering on the raggety edge of detonation when pump gas is used, so say hello 92 octane.

I too was leaning towards a Lunati Voodoo kit, however your selection is a bit bigger than the 60803 that I was looking at. Big cam's make power higher in the rpm band. That is why the high stall torque converter is recommended no doubt.

Again, I've never driven anything with a 3500 rpm torque converter, but an online discussion I came across on the topic had a few guys that were describing anything over 2500 as turning your gas peddle into an ON-OFF switch. Which they disliked driving in traffic.

If memory serves its also going to mean that cruising on a freeway will be very inefficient below that 3500rpm mark. Getting good fuel economy while highway cruising is usually the result of the transmission staying in its upper gears allowing the engine to spin at low rpm.

(Hey all - That brings up an interesting notion. I'm not sure what would happen if say a 2.56 differential gear was used with a 3500 stall. At like 65 mph the tranny 1:1 3rd gear would settle the engine into about 2000rpm. Would it just waste energy due to the TrqCvtr slipping? Be a dog to accelerate? Or, would something bad happen like blended tranny fluid burning up or engine stalling out???)

At any rate, its all stuff to think about before trading in your money for parts. I'm sure some of the resident forum Guru's will have more definitive advice. (And maybe correct anything above that is lies.)

dre

Well I called Summit Racing and gave the the part# for the cam that I'm looking at. The gentlemen stated that a 3200rpm-3500rpm would destroy my transmission. He recommended a torque converter with a 2200-2500rpm stall.

As for a cr calculator, I just got a Mondello Performance technical book and there was one in there. I'll see what the cr comes up as now that I have an idea of the Ga heads. However, I've been looking at getting 68-69 C heads. What is the size for these when they have big valves?

kenbarls

Perfect advices! I agree to all advices.

TripDeuces

That cam is listed for 2400-6200 rpm range. If you want to keep this a street car then shoot for that lower number of 2400 for a converter. Not sure what the Summit guy is talking about when he says that bigger converter will 'destroy' your transmission means but if he's talking about heat he's correct. Bigger converters generate more heat so a trans cooler is advised. Other then that he sounds like a moron when they make statements like that. According to BTR all BBO heads are 82cc except the 'D' at 69.75cc. This is assuming you haven't milled the head to straighten it. Every .006 inch removed lowers the volumn by 1cc approx.

ziff396

60803 Voodoo is perfect in mine for the street. 9.7 compression and 2500 stall. It still pulls hard @ 6000 though when I forget to look at the tach It has happened a few times now. So far so good with the bearings.