I have a 72 cutlass with the 455, it is simply an amazing car, yet I'd love to get some more power. I know I'm definitely not getting the power out of a 455, because my 0-60 is awful. In high budget I'm looking for part upgrades 1 at a time.

The exhaust goes over the diff and is a stock muffler, I'm thinking about going with a straight piping with dynomax mufflers for performance, the exhaust seems a little badly flowed.

I am also considering new gears, it really seems that it has 2.73s, yet I'm not sure yet. What gears would be your preferred? 4.10s will put my top speed at like 80, which will hurt in 1/4s; I have stock axles, 265/60/17 Radial T/A's too. They are a bit old and spin badly

I think a lot of my acceleration is bad due to the sheer amount of wheel slip I'm getting when flooring it, and it has an open slip diff.

So really factoring things, I know a 442 had an LSD with higher gears, 3.73's? What would be the worst factor hurting my acceleration

The transmission really seems weared out too because I'm hearing the engine go hard and sometimes it doesn't stall, but really won't accelerate that hard.

I love BBOs and know they are capable of much higher, and am not in any way smacking on them, I'm just wondering why my car is a bit slow for a 455 - It's tying with F150's in low end acceleration


Thanks!

 

Start with dynomax exhaust - it's what i'll do on the road. Or go big with a performance cam. 4.10s are bad if you plan on 1/4th with everything stock. Go 3.73's

 

Start by

#1. Figuring out what heads you have.
#2. Figuring out what compression you have.
#3. Getting a Rear wheel dyno done to see what the engine is putting down to the ground.

That should give you a basis to build on and where to improve.
Otherwise it's just a dreamers paradise throwing parts at an engine reading hyped up magazine HP increases.

Because contrary to urban myth, not all big blocks were fast.
Depends which 455 build you have. Some were pigs.

Mid 70's some were ~250hp only.

 

As Aces said, a dyno will tell you were your at, and most places with a dyno will offer tuning to give your motor it's maximum power and/or mileage.
I had a 3:42 gear in my 69 442, and found it to be great overall!
I'd start with those two changes, and go from there.

 

As mentioned, best starting with the small stuff. Check engine vacuum, and the carb secondaries are opening. Pull and lube up the dizzy, as the centrifugal advance shaft is known to gum up. 72’s are lower compression, so not the most powerful, but still plenty of torque. My engines higher compression, with headers and dual 3” exhaust. Went from a 2.56 open diff to 3.73 posi and 700R4 tranny. These have a 3.05 1st and 0.70 lock up od 4th, so a good way to go. Compared to yours now, like having a 4.47 axle in 1st and 2.61 axle in 4th, so highway cruising will be about the same.

 

Just curious, mwhat does all this mean?
Upgrade a DD 1972 cutlass to street DD with more power?

Also, do you have single exhaust right now?

 

upgrade a daily driver 1972 cutlass to a street daily driver (to show it will be not only for drag) with more power

 

Dual exhaust w/ Edelbrock valve covers, 2.5 inch pipes , stock mufflers, 442 tip

 

I guess yiou know but the chrome valve covers don't help you that much. Are you running manifolds or headers? If manifolds, are they the proper dual exhaust manifolds or the single exhaust ones with a block off plate?

 

Make sure of what rear gear ratio you have. 3.23 or 3.42 will make a big improvement. Do you have dual exhaust?Improve to a 2.5 dual exhaust sys. Do a tune up make sure the secondary's are opening.
Gene

 

The manifold reads 402 295 LH with a W. Bein 69 - '74 W 402295 LH; Cutlass, 442, W-30, H/O. So no headers

 

It could be that 40-odd years of wear and a chassis made in no way for performance are what's letting you down. What are the 0-60 times, btw?

 

A bit under 7.5 seconds roughly

 

That seems about right for a car with 2.73s and a 1972? 455. That was the second year with lower compression, so the engine won't be as powerful as a similar unit from 1970. I would start with a gear upgrade, probably a 3.42 or 3.55 posi to keep driveability intact, while also boosting the performance quite a bit.
Only after that would I start taking a good look at the engine, and possibly reworking it (compresssion, heads, cam, etc.).

 

Old-ish thread but i'll throw in my 2-cents. Dont be talked into the "universal muscle car" thoughts. 3.73s are magical for a 350 Chevy, but for a 455 Olds its not the best. These motors dont rev, but thats not a bad thing cause they're torque behemoths so unlike a small block they dont need extra gear to compencate. 3.42s are about the best for street/strip without killing milleage. With a 4-speed you might have a little lee-way with the rear end but still... Now with that said there's a lot more "it works wonders for a Chevy so it will work fiiiine on your Olds" stuff you really wanna watch out for. A tune up should of course be the first thing, then the gears of course, and id recommend headers and a newer intake. Also if youre comfortable going that far a cam swap should do well even with low compression (your heads (assuming 72' Ga) are fine and actually good platforms to build off but your pistons (again, 72's) are friggin' beer mugs man, no joke). If your tranny is already going out you should get it rebuilt, assuming its an auto a shift kit would be nice or you could swap to a 4-speed fairly easily if its not already. Either way if the tranny is giving up right now more gear and a few performance goodies arent going to be any kinder to it so be careful not to kill it if its a daily driver. Without tearing into the motor it wont be a strip monster, but it could very well be a mean plastic-slaying street machine

 

Save your money on the Dyno. Its a dog now you dont need a computer telling you that too. First off make sure your tune is good. Thats where i would start. Check the timing and check the springs in the dizzy. Old ones get sticky and will cause all kind of timing issues. Check the carb, plugs, wires. After all that check your timing again if all is good set your total at 36 and give it another try.

 

I do not know much about engine builds, but I do know that wheel spin means you aren't even getting the power you have to the ground. In a perfect world, you should have zero spin.

Old tires (over 5 years old) lose their softness and stickiness, so wheel spin would come easier. Might be time for a new set of shoes!

What springs do you have? FE2 or Heavy duty? HD springs in the rear, along with newer rubber bushings can reduce axle twist-up on accelleration.
The FE2 frame braces can reduce chassis flex some.

If after this you still have spin, then a limited slip diff will be needed.
Gotta put the power to the pavement! After that, concentrate on the engine (providing it is in tune and running well).
This all sounds logical to me anyway...

Just after rebuilding Lady's suspension, I found I could no longer spin the tires from a standstill. Just a chirp, and she's gone. Rough 0-60 time with a bone-stock 150k mile 350 is about 8 sec (using a video camera on the speedo).

 

I see this alot. Just wanted to verify something.

Is this only due to the low comp pistons and restrictive heads used in the mid 70s, or are there other differences that make this statement true?

 

That 250 hp is probably net instead of gross also. Low compression, low flowing heads and rating the horsepower differently lowers the #'s significantly.

 

Not that easy if you have to drill the crank.

 

DOH! >.< how did i overlook that? haha, he's got a point. Olds 455s equipped with autos from the factory do not have the cranks set up for use with a manual transmission, in which case a tranny rebuild would be the best, and most cost-efficient, route. Nice catch haha

BTW, i typically go by the Gross ratings, honestly despite what is said between Gross and Net it seems that the bone stock rebuilds usually dyno at, or close to, to Gross when finished. Not to mention GM under-rated their motors until at least 02' Who really believes the over-square Buick actually out-torqued the under-square "stroker" Olds?

 

If you have an old stretched timing chain you can loose a good bit of power. Compression check could be in order.

 

Maybe I missed it, but did you say what transmission tou have in the car? A 2.73 rear gear generally guarantees an automatic if that is factory. If auto, is it a 350 or 400? I would agree with the comments to start with all the basic things, before you start making changes. But if you have a 4 speed, what is the condition of the clutch? A slipping clutch will have the engine roaring and the car going nowhere.

As previously mentioned, BPO 455 usually do better with rear gears under 3.50, especially if it is both street and strip. Too low a rear gear will have you riding down the interstate in the right lane, unable to keep up with Hyundae's and Daewoo's, for fear of over heating and over revving.

 

Alot of people like to quote GROSS hp because it makes their car sound stronger IMO.
Rear chassis Mustang Dyno's tell you what's hitting the pavement......that's what counts.
You'll find alot of people never did a dyno to prove the HP they think their car makes.

The fact is ,
NET horsepower has been the proper way to gauge what an accessorized engine makes
inside the engine bay of a car for the past 39 years. RWHP or Rear Wheel Horsepower
is what is actually hitting the pavement through the drivetrain. Alot of guys don't like to use NET
ratings because they feel it neuters their muscle cars horsepower claims.

300hp GROSS doesn't sound so great when it's 240hp NET, so guys tend to claim pre-1972 ratings.
I've met a few people who didn't know the difference between pre-1972 (Gross) and post 1972 (Net)
horsepower ratings and test drove some classics with 325hp GROSS and were not impressed at all.

Sucks if you buy one and don't know the difference either. Always dyno anything you want to buy.
Alot of horsepower claims are horse poo.