Hey guys,I have a 65 383 Polara convert, all original including top. I have owned it for 20yrs. The motor hasnt been touched until I owned it. Only mods are a electronic dizy, and a roadrunner cam and a set of 915 heads that I paid to have them redone before I installed (cost me a [censored] load at the time). I had a custom dual exhuast that soon rusted and just recently installed a factory OEM system from Waldon. Now thats its quite. I hear a putt, putt putt from the exhaust and know immediately that its a burnt valve. I only had 10k on the new 915 heads. Getting screwed once I now want to be sure I do It right this time.I want to rebuild the 516's CC and sell the 915's. What should I have done to the 516"s besides the valve job, seats and brazz seats? What springs should I order and should I just shelve everything and buy aluminum heads?

with what it would cost to do up some low perf 516's done right for longevity (valves/valve job/surfacing/ bronze guides) it might be better to go ahead & spring for some Stealths. It'd be a good investment now & when you (later) decide to drop in a stroked 400 in it.

Pull the 915's and have them looked at. Might be cheaper to fix the one bad valve and run them. To sell the 915's, even if you have them fixed, IMO resale value will be less than what you'll sink into those 516's.

From what I have seen, any time you buy china heads, and it doesn't matter who sells them, they need to go to a machine shop, and gone through just to make sure they are ok. So it is going to cost money no matter which way you go. I like the idea of the stealths for a stock looking aluminum head, but I wouldn't put them on without going through them. You're in box that is hard to find a good way out. Been there.

It sounds like a survivor car. That prompts me to say keep it original.

If you are going to be driving the car regularly then it makes sense to use a higher performance head.

Before you put a nickel into your iron heads, get a written quote. Then you will be able to make comparisons. As neither of the heads you own have hardened valve seats, maybe the cost of that should be included.

The main problem with aftermarket heads seems to be too little clearance between valve and guide. Correcting that takes a machinist or adding to your tool chest.

If your estimate is over $1000 your decision is made for you.

Here are two choices:

1. The Sidewinder head as sold by Moparts Racing, owned by Todd Marsh, known here as Sasquatch. Contrary to what some are saying, this is a Chinese head you can run right out of the box, For $895 you get a pair of bare heads and valves. Then you consult with Moparts Racing for spring, retainer and keeper packages. They get assembled with discrepancies corrected, then ship to you.
http://mopartsracing.com/parts/Sidewinder.html

This head casting is also available from ProMaxx, but it seems to be more expensive. I guess their profit margin is fatter..

2, If you must have an original looking head or are absolutely bucks down the Stealth head is the one. This head is delivered to your door for $1000 a pair. Literally hundreds have been run right out of the box without failure. Some have had the guides too tight to the point of sticking the valve. The heads are assembled with springs 130# on the seat and total allowable lift of 0.510. They use generic springs and retainers and Comp keepers.
I'd disassemble the heads and take them to a local machine shop, have them correct the guides, mark each valve to the hole it is for, correct any seat problems, and then I'd take the whole mess back home and assemble it. This head has been in production for around 10 years and early production issues have been dealt with.
http://store.440source.com/Stealth-Aluminum-Cylinder-Head-COMPLETE-SINGLE-HEAD/productinfo/200-1055/

There are many better heads than these but they cost more and won't work any better on a street car. Either one unported is worth more than 500hp.

Your assuming its a burnt valve, perform a cyl.leakdown test first before pulling the trigger.

Are you sure it isn't an exhaust leak?

Remember that 915 heads have a larger chamber than 516 heads. Gotta worry about compression ratio when changing the heads.