I'm going to go out on a limb and say around 1100 or less. Have they been milled to the point of no return? What springs?

Another way to look at it is, it's not hard to find some 243/799s for 300 bucks a pair and it's 750 to CNC port/valve job and mill to spec if you ship them to Texas Speed. You would know more about what your getting that way. Low miles or not, used is used.

Will be curious to know what the more senior advisors have to say. I'm giving you my thoughts and opinions based on my current knowledge of what's out there for those heads.

 

Being Stage I, they have the stock valves in them, but have a great port job. What are you upgrading to?

 

I'm assuming these aren't ported 243. I'd say they'd be worth $800.

 

If they are PRC Stage I they ARE ported, with stock-sized valves. Check the TSP/PRC website to confirm.

 

stage 1 used 243's from TSP go for like 700 ish from what ive seen.

stage 1 5.3 heads go for about 600 ish

 

 

7-800$

What motor you doing the 237's on?

 

 

That's a lot of head for a 346

 

 

Man, what a downer. This has me seriously even considering why I should even bother sending my 243s in to get ported next month by TSP if they are not even worth what the port job costs let alone adding a good set of springs to the heads.

Don't get me wrong, I know the market only bears what it bears.

 

If you do hot rodding for its resale value, severe disappointment is in your future! Do it for the enjoyment! Because bottom line, that is the main benefit!

 

Oh I totally get that. I've built more cars than I can count and even raced for several years. Money is still important to me even though I'm far better off these days than my younger years.

Sorry for the mini thread jack OP. Good luck with your project.

 

On a NA 346, the TSP heads aren't giving up a lot, because the engine can only use so much CFM. Larger CC heads might make a few hp more at the top of the rev range.

 

I have been 10.70 at 127 with that head stock cubes.For the investment in new high dollar heads I bet there is not that much there,

 

Because buying used anything modified is a gamble. I had a set of an equivalent heads with a massive port job, (larger than the TSPs as I have both and mic'd them). One head had a pin hole
leak that killed a brand new engine on the dyno due to hydro lock. but you couldn't tell by looking at them and I could have easily sold them for a chunk of cash, if I had no integrity. I did sell them however, someone
wanted to try and repair them, hope he did because they were a great set of heads when they weren't damaged.

 

Same thing happened to me with an old set of SBC heads that I bought used. I even had a machine shop check them out and install new springs/locks etc. Somehow they didn't catch a hole in the water jacket and that costed me a brand new 383 bottom end.

 

 

OP you are best off keeping your current heads over those 237's. A stock cube LS1 is not a good fit with those larger heads