AFR 185s too big for my 289?

Cobain03

Active Member
Aug 27, 2003
996
0
36
Lexington, Ky
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.
 
  • Sponsors (?)


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.
 
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.
 
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.
 
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 :D
 
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 :D

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!