dirtydave289

Some of you might remember me asking about my 289's horsepower a time or two a month or so back..

well I have more questions

Ok..

'66 289
4 barrel holley
weiand intake
mild cam
headers
bored .030 over

Other than that..it's all stock
unless a distributer adds hp i don't know
There may be some other little things on the engine the previous owner didn't tell me
but we'll assume there isn't

I've heard time and time again that heads are the best thing for HP on my 289

Now..few questions
What would you say my HP is as of now?
What if i exhaust port matched my heads, what hp then?
HP with a good set of GT40's?
And I also have some '69 302 heads in my shed...are they basically the same as the stock '66 289 heads were?

I know that's a lot to think about lol

Thanks a LOT to anyone who can help me out with some of these

67mustang302

Prolly about 220ish real horsepower. They used gross hp ratings in the 60's, so translated into real world power, the 225 of back then is more like 190hp. Intake cam and headers is prolly worth about 30hp give or take. A set of iron GT40 heads would prolly bring you up to around 250-270ish. Hard to say without knowing which intake and which cam you have, plus other little odd bits and details. Some modern aluminum heads and you can prolly get over 300hp. That's all at the flywheel though, not the rear wheels. But again, depends on the cam, intake, compression, exhaust yadda yadda etc.

cmanf

Hey Dave see if anyone you know has a Gtec or pick yourself up a dipc gauge not too bad on price for a xmas list item.

dirtydave289

Awesome thanks for the info

I have aluminum pulleys and little things but i'm not sure if they make any power difference

i'm still a noob lol

67mustang302

The pullies will help if they're underdrives.

dirtydave289

do underdrive pulleys add decent amounts of hp or just give a small gain over stock pulleys?

middiepride

if i were u, i would be putting those 69 302 heads on and not buying the gt40's. as far as i know, or have been told, the 69's are basically old school gt40's so you would be spending money and not having to....

67mustang302

Underdrive pullies can add as much as 10rwhp, or a bit more depending on the setup, but I don't think you'd pick that much up. Every little bit adds up though, and areas like that don't affect the drivability adversly.

dirtydave289

I could already have some heads for all I know lol

The car came with the '69 302 heads in a box so I'm not sure if the engine has stock heads and the 302 were just random back up heads or something

or if the 289 used to have 302 heads and now has something better

htwheelz67

post all your specs........then you can get a more accurate hp guess. 69 heads are no better than any other 289-302 head, they are nowhere even close to a gt-40 head which are not a whole lot better than the C90E 351w head, valves are still 289-302 size and chambers are slightly big.