dman0712

I would like to know how this build sounds. 455 block bored .60 over. stock crank with eagle rods and forged flattop kb pistons. main studs. oil restrictors in main saddles. melling high vloume oil pump and deep pan. comp hydraulic roller cam 528 in. 547 exh. lsa 110. duration is 248 in. 254 exh. C heads mildly ported with 2.075 int valves and 1.710 exh valves. full 1:6 roller rockers. rpm intake and holley 750 dp. This will be in a 79 t/a. car will be mostly a street car with occasional track time. wont be spinning the engine over 6000. What power numbers can i expect?

captjim

They don't make an rpm intake for a 455, otherwise it sounds pretty good.

dman0712

my mistake i meant torker intake. Do you think i cam make 500ft/lbs torque with this combo or no?

dman0712

or would i be better off using the same pistons with a 425 crank? Does eagle have the rods that would work?

AJCDFIN

Hey; Unless there is a reason for the +.060" overbore - I would stick to +.030" overbore, otherwise disregard this.

cutlassefi

They supposed to now, although I don't think it's ready yet. Or he can always use the PP Dual Plane.

IMO - If you're not going to be spinning the motor over 6K (which you won't with a nearly stock bottom end 455) then you don't need that much duration. For mostly street I'd go with more lift and less duration. 750 is a bit small, and unless you have a 4 speed ditch the double pump idea.

If you're going to bore it .060 over make sure it's done with a Bor-Tru and honed with a torque plate to take advantage of that, otherwise just go .030 as mentioned. And if my math is right then true flat tops with roughly 80cc heads will make your compression a bit too high for the street.

MI455

torque is easy with a 455! i'd wait till the rpm air gap comes out for the bb.

rtpassini

isnt a 455 rated at 500 ft lbs of torque stock?

csouth

Not sure when the Performer air gap is coming out, but the PP intake Cutlassefi is referring to is also and air gap and its available now.

csouth

Not all. I've seen some listed as low as 370ft/lb for factory specs.

dc2x4drvr

Out of curiosity...will you have enough room under the hood for the Torker?

70 cutlass s

If he has the regular Firebird hood should work fine. If he has a shaker hood than he will run into problems, but should be able to make it work.

oldsy

Can you let me know how it goes with the build?I have a 455 that will soon be going a 79TA also.

rtpassini

i have one that i will be putting in my 80TA

rtpassini

isnt that just due to the government changing how they are rated?
all these motors are exactly the same arent they? except for different heads.

csouth

The government didn't change how HP was rated, the emissions regulations caused the manufacturers to change the way they were built. The heads(flow rates) and pistons(dish)changed on these motors drasticly after 1973 if I'm not mistaken? Take a look at the pistons. Both 455 from 2 different HP\Compression motors. The 1630 looks like the piston from my friends 76 455 and the 1631 is like one I pulled from my 1968 455.

csouth

The government didn't change how HP was rated, the emissions regulations caused the manufacturers to change the way they were built. The heads(flow rates) and pistons(dish)changed on these motors drasticly after 1973 if I'm not mistaken? Take a look at the pistons. Both 455 from 2 different HP\Compression motors. The 1630 looks like the piston from my friends 76 455 and the 1631 is like one I pulled from my 1968 455.

cutlassefi

Actually they did change it a little. I was always told that from 71 on the engines were rated with all belts, full exhaust and an aircleaner as well. Before that the water pump was independently driven, no aircleaner, and no exhaust system.

Do the math, in 70 a 350 4 Barrel was advertised at 310hp, in 72 it was 200 with dual exhaust, 180 with single. 1 full point of compression change normally equates to about 7-10% in hp/tq. Even with just a minor stock cam change the difference in the 2 years is anywhere from 100-130 hp. Just 1 1/2 points or so of compression and cam change won't make that much of difference. In fact I think most of the non W series cams weren't that much different anyway were they? Correct me if I'm wrong on that.

So bottom line, 1 3/4 points (at best) of compression alone isn't responsible for that drastic of a change in hp ratings.

Run to Rund

In 1971, GM went to low compression to be compatible with then-available unleaded fuel. At the same time, they went to net HP ratings instead of gross ratings that wwere used before.

joe_padavano

I'm guessing you're not old enough to remember 1971, because the gov't absolutely changed the way manufacturers rated HP. Through the 1970 model year HP was rated in the "gross" form, with the engine on the dyno using the dyno air inlet, dyno headers, and no accessories. Starting with the 1971 model year this was changed to SAE net ratings, which included the as-installed air cleaner, exhaust manifolds, and accessories. Coincidentally, emissions requirements started to make a difference in output in the 1971 model year as well, namely a drop in compression ratio to allow all new GM cars to run on low lead gas, but for that year the manufacturers listed both the old gross HP rating and the new net HP rating. As an example, the 1970 W-30 was factory rated at 370 HP (gross). We can debate the accuracy of that number in another thread, but that was the factory rating. In 1971 the W-30 was rated at 350 HP gross (thus a 20 HP reduction due to the compression drop and emissions requirements) and 300 HP net. You can easily see that the majority of the reduction in HP rating was due to the test method, not the emissions requirements.

BIGJERR

If your going to spend the money on eagle rods why bolt the boat anchors to the end of them,I sure would go with as light as quality piston as you could afford,Dont forget to notch the block for clearence on the thicker eagle rods(As I remember this doesnt always have to be done its a per block casting deal)............Jerr

J-(Chicago)

Just a few notes, from my experiences.
72-76 455 pistons kind of sucked, they had a 40cc dish in them. Soup bowl/ashtray pistons.
I have never had a 71 motor, but I'll take a wild guess that those pistons sucked too.

The 68-70 455 2 barrel motor pistons had a 30 cc dish, which was a little better than the soup bowls. The 68-70 high compression pistons didn't have much of a dish at all. Don't quote me on this, but I berlieve those only had a 10-12 cc dish.

Olds 350 pistons were a different story. 68-70 had between 6-12 cc dish i believe, and 71-72 had the crappy soup bowl/ashtray pistons.
73-79 were 14 cc pistons, and the compression loss on those motors was because of the #8 heads' big chambers.

oldsy

Hey moderator.I keep getting the replies to my email.Im not dman

joe_padavano

If by "getting replies to my email" you mean that every new post shows up as an email to you, that's because you have checked "instant email notification" in your user profile. Log into the User CP and uncheck that.

83hurstguy

flat top pistons in a big block will give you a ton of compression. You don't need that much compression and that much cam to make 500 ft-lb of torque. You could use some Speed-Pros with Eagle Rods (stock will work), 9.8ish:1 compression, mild port work, a hydraulic roller, and be right there... check this build...

http://highperformanceolds.com/phpbb...p=12074#p12074

csouth

Thanks for clearing that up, but you're right... I was still crawling around looking for my bottle...

rtpassini

thanks for the link!

im loving that alternator setup!! i wish there was a better pic of the underside.

AJCDFIN

Hey; here is a good article about the HP changes....Don't forget what role the insurance institute played.




http://ateupwithmotor.com/terms-and-...orsepower.html

cutlassefi

I think a few of us already said this but a good article nonetheless.