I know this is a long shot, but would anyone have an idea of approximate horsepower for a '72 L75 U code 455 with a W-30 cam, .030 bore, Hooker 3 in long tube headers, Edelbrock Performer intake, Holley 770 Street Avenger and HEI ignition?

 

WHICH "W30" cam?

1966-67 308/308
1968-69, 70 MT 328/328
1970-71 AT 285/287
1971-72 MT 294/296
1972 AT 286/287

 

Trying to find out now..is there that much of a difference depending on which cam?

 

Yes.

 

Dave, I think your best answer will be to have the car dyno'd and remove all guess work.

 

I'll play

1)1972 U code 455 factory rating 250 HP with dual exhaust
2)W30 cam unknown year generic 20 HP
3).030 overbore-------------------------- 6 HP
4)Long tube headers------------------ 20 HP
5)HP Edelbrock Performer intake--- 0 HP
6)Holley 770 Street Avenger--------- 0 HP
7)HEI ignition----------------------------- 0 HP

You may see something out of the bottom three (#5,6,7,) but I'm not confident enough to put a number to it.

-------------------------------------------- 296 HP

Maybe with a nice tune to blend all 300 HP net.

3800 LB race weight and you should hit 100 MPH in the 1/4 mile. Like a 1972 X code...

http://wildaboutcarsonline.com/membe...0_Test_1-6.pdf

 

While I won’t predict the exact numbers, I bet I’m pretty close.


Im predicting somewhere between 250 and 550 rear wheel hp. 😏.


Put it on a chassis dyno and tell me how close my guesstimate is.

 

Dave, I guess the question I'd have for you is more along the lines of 'are you happy with the way it performs or do you feel a bit let down"? Your U code CS should be plenty enough power to roast tires anytime it wants and basically it's the same as the non W30 71 442s. I can't remember from your earlier introduction of the car but was the engine rebuild by the PO for racing purposes? If it was it's strange he kept that rear end intact. JMHO - drive it and enjoy it. You've done so much to improve the car over it's original debut.

 

​​​​​​Oh trust me Allan, it'll get sideways from a roll and scratch second gear if I'm on the carpet, so no worries there😀. It's just that I've always been curious as to the numbers. And thanks for the compliment 😀

 

With the exception of broken parts, few things cause more heartache than a dyno. No matter what the number, it’s never enough, some smart *** will always tell you something is wrong with your combination (and never miss an opportunity to tell you their engine made twice the power on half the budget) and “there is more in it”.


Dynos are a tuning tool. Chassis dynos are difficult to make accurate comparisons, the same car might make wildly different numbers from dyno to dyno, or even day to day. How the operator calibrates and runs the test has a big influence on the numbers.

Having said that, a dyno tuning session is a worthwhile investment. Just be prepared with lots of carburetor tuning parts, spare spark plugs, and the desire to actually get something out of it. If all your interested in is just a ballpark figure, check out some of your local speed shops around your area. There are several around here that have open houses with a “dyno day”. For 50 bucks, they will run the car on the rollers and give you a dyno sheet.


I’ll share one of my first dyno stories.

I drove part of Power Tour in 2005 (I think it was 2005?). The stop that day was in St Louis, at whatever track in that city. I decided to put my car on the mobile dyno (first time I had ever dynoed the car). If I remember correctly, it made something like 320-330hp. After the test, a guy started asking questions about my combination and what the car ran. I told him the car ran 12.40, then in typical smartass fashion, he then ask what it ran without the nitrous. 🙄 He basically called me a liar and said a 3900# need more than 330 to run mid 12s. Ok, since we are at a track, my next stop was the staging lanes.

Later he stops to talk and again asks about the timeslip. I don’t remember the exact time, but it was in the mid 12s. Once again, in typical smartass bench racing mode, he suggest I “turn off the nos” (another reason I despise the Fast and Furious movies!). Now I’m kinda pissed off, I told him I’ll do better than that, for my next pass I’ll turn on the bottle!! I’m guessing he stuck around to see the much improved time because he wouldn’t talk to me again.


My point to all this? If the car runs well, who cares what the actual numbers are? Dynos are great tools for testing and improving.

 

I like this ^^^^

 

And that's that with that...good advice and replies from you all...I'll put this to rest😀

 

Yeah the difference can be huge. Fellow member twilightblue28A lost 6 MPH and 1.2 seconds in performance going from his factory original 1970 W30 auto cam to a factory 1970 W30 stick cam. He swapped back to original and gained the performance back.

Even if you never go to the track you will feel that difference on the street.

In the end the combination has to be just right...

https://classicoldsmobile.com/forums...mission-127131/ (post #6)