AFR 185s too big for my 289?

Cobain03 · Dec 1, 2009

well i was going to do a 347 build, but decided to just build my 289 cause of money issues. head cam intake swap and be little more fun and a LOT cheaper. i already have the heads, was going to use them on the 347.

will they work on my 289? or should i switch to the 165? havent decided cam yet, intake will probably be the stealth.

jcp123 · Dec 1, 2009

185 sounds a little heady for a 289...good if it's a big revver but probably not a great combo for the street.

Z06killinSBF · Dec 1, 2009

They will run great with a nice tight lash solid roller. The 289 is supposed to spin anyways. If you don't want them I'll take them.

Decurion · Dec 1, 2009

Probly wont hurt anything, but a bit overkill for a small engine. You could run a high lift cam to take advantage of the big heads, but keep duration short to keep it streetable. May even look into a custom grind roller cam. Seems like a lot of people are doing it, so I dont think its much more than any off the shelf cam.

Cobain03 · Dec 1, 2009

it will be a non roller hydro cam. may go custom route like you mentioned. how much lift/duration would be best for a good street car?

htwheelz67 · Dec 1, 2009

I'd stay less than 220-224.@0.50 around 550 lift but really depends on CR as well as the rest of the combo/usage, with those heads you probably want a smaller cam to keep low end.

rbohm · Dec 1, 2009

afr 185's will work just fine with a mildly modded 289. thats what those heads were designed for. the 185's will wake up the 289 in fact, as they are worth about 40hp just bolting them on.

D.Hearne · Dec 1, 2009

All good advice, but you first need to address the compression ratio loss you're going to see. Are the heads you have now, 58 or 64 cc chambers ? You will want the 58's and preferably milled an extra .030 to ge the chambers even smaller. Any cc change in the swept volume increases exponentially the comp ratio the smaller the engine is.

iskwezm · Dec 1, 2009

my friends dad has them on his 289 with a .560 230* cam, 10.7:1,650 carb and made 444 hp on a engine dyno.Runs very good and streetable with a 5 speed and 4.11's

hivewax · Dec 2, 2009

AFR185 heads, 670cfm Holley SA, THUMPR cam, forged internals... broke the 8" rear.
Now have 9" TrueTrac 3.50 gears.
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Cobain03 · Dec 2, 2009

these heads are 58cc. i believe me engine is around 8.5ish compression now. i have someone lined up to trade to 165's if i should but seems like you all are telllin me to stay with the 185s.

D.Hearne · Dec 2, 2009

If you've got someone to trade for 165's I'd jump on em. They'll be a better match for a 289.

10secgoal · Dec 2, 2009

I wouldn't trade. Worked great on my 9.0-1 308. Even IF you lost a little bit, you'll want them later when you build a better engine, or that stroker.

Cobain03 · Dec 2, 2009

well if im going to take it apart, then i might as well do the stroker.

jabb · Dec 2, 2009

I remember reading an article that compared AFR 165s to 185s on a 302. The 185s made more power across the entire rpm band, even at the bottom end. I don't remember what site it was on but google "Afr 165 vs 185" and you should find it.

As an aside: I'm planning to run the 185 competition heads with a 2.1L Kenne Bell blower when I rebuild my 289

jcp123 · Dec 2, 2009

jabb said:
I remember reading an article that compared AFR 165s to 185s on a 302. The 185s made more power across the entire rpm band, even at the bottom end. I don't remember what site it was on but google "Afr 165 vs 185" and you should find it.

As an aside: I'm planning to run the 185 competition heads with a 2.1L Kenne Bell blower when I rebuild my 289

Interesting...that sounds counterintuitive...the lower air velocities in the larger ports should make things a little more dog-ish down low. Based on the 351C-4v I drove, I'd imagine a similar effect with the 185's on a 289...that motor was a real dog under 3500.

EDIT: Just looked up the articles. It's true on both a 302 and a 347 the 185's seem to outperform the 165's even down low. Still, given that the 45ci spread between those two motors didn't seem to affect that part of the outcome, I doubt the 289's 13 cube deficit vs. the 302 will change the story. I've changed my mind now - go for the 185's!

Enjoy the blown 289. That sounds like a blast!

Cobain03 · Dec 3, 2009

link me?

D.Hearne · Dec 3, 2009

One more thing to ponder is clearance with the stock pistons and 2.02 vs 1.94 valves.

jabb · Dec 3, 2009

AFR 165 cc vs AFR 185 cc Aluminum Cylinder Heads

The dyno graph on page 2 sums it up pretty well. The entire article is a good read though.

Cobain03 · Dec 3, 2009

i had my factory heads worked, installed the bigger valves and i do run a dished piston but i dont think they are "dished" just a valve relief.

AFR 185s too big for my 289?

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