I have been in the possession of a set of slightly used 1969 351W heads for a while now and I am preparing them (cleaning, new valves, springs, decked, etc...nothing major) for installation on my 289. Will these heads effect my compression negatively?

 

Yep. You could put a blower on it to bring it back up though!

 

A good idea, but not for a daily driver.

 

Actually... take a look at your heads and see if the head casting is C9OE-6090. If so they are dandys ! They have the smallest combustion chamber of any factory Windsor head. They'll help you a fair amount on performance but you'll need to pay attention to your timing and fuel grade to avoid detonation and the ever present risk of destructive pinging. I'm sure you've already installed hardened valve seats for use with modern day ( lead free ) gasoline. Trust me on this one, Dean

 

I was VERY careful to seek out 69-70 351 Windsor heads because of the performance they are supposed to give. I am not cutting any corners on these, I learned the hard way about trying to save a dime on engine parts. Hardened valve seats are a given as well as new springs, screw-in rocker studs, replacement valves, and a good cleaning by experts. Nothing major is being done because these are going on a 289, and its probably got around 250 HP so it's not super strong.

 

250 HP with a 289 is pretty strong. Heck, even the HiPo's are only rated at 271. I am lucky to get 190 out of my 289.

 

best 190 hp car youve ever owned?

 

I have various mods, most of which came from the previous owner:
Aluminum Hi-Rise Intake, 750 Holley, Headers, Electric Fan, H-Pipe, slightly stronger cam, .030 bore, and it was supposed to be balanced (this is the only mod that I don't believe, the rest I have proven). The power is at the flywheel, which means my rear-wheel power is unknown. In the near future I am going with some roller lifters, roller rockers, roller timing-chain, the 351W heads...but don't get the wrong impression I'm more into my suspension that I am my engine. I have a few improvements with sway-bars, shocks, and other cool suspension toys.

 

I also have an Accel Billet-Proof Distributor, a low OHM Coil, 10 degrees timing advance and soon to add aluminum water-pump and oil cooler.