I've begun the slow process of doing up a pair of 416 casting heads. (Slow just because I dont often make the time for these things) I'm planning on getting the guides done because a few of them are a bit worn and I was looking for new 1.94/1.60 valves on jegs and the cheapest I found were the bottom end Manley valves for $6.99 each. Now I know this isnt that bad, but I cant see spending $111.84 plus shipping on valves when I only spent $50 on the pair of heads at the junkyard. Now the question you're likely to laugh at: can I take the 1.94 and 1.60 valves off a pair of 350 heads and use them with the new guides? Would I have to give these valves to the machine shop when I get them to install the guides or is this idea just a plain no go?

 

If it's not worth new valves, why is it worth new valve guides?

As long as the valve guide clearance is acceptable, you can do anything you like.

 

What is considered acceptable clearance? I have a 0-1" mic, but no tools to measure inside the guide bore. When I grab a valve stem without the springs on I can slightly wiggle them back and forth. Also, how much power would I leave on the table by keeping the stock 1.84/1.5 valves instead of upgrading to 1.94/1.60?

 

Usually it's the guides that wear, not the valve stems. The stems are much harder material than the guides.

 

Don't worry about the contrast between the cost of cores and the cost of quality replacement parts. You can go the junkyard and buy 1000 sets of $50 heads, and STILL not have good-quality valves; only a giant pile of stock garbage.

I'd recomeend not getting those cheeeep valves. Those are really only good for class-limited situations. The ones to get are the 10721 and 10728 http://store.summitracing.com/partde...AN%2D10721%2D8 and http://store.summitracing.com/partde...AN%2D10722%2D8.

Yes there is a HUGE difference between 1.84" valves, especially stock ones; and good-quality 1.94" ones, especially with the undercut head.

The usual method of repairing guides is either to use the bronze inserts such as from K-Line; or drilling out and replacing the entire guide (about a ½" diameter thing...) Getting the inserts installed will cost you around $125-150, getting the whole guides done will be around $200 or a little more.

By the time you buy valves, guides & work including cutting them for good seals (if you use the stock guides either with or without inserts), springs, and all their hardware, spring pocket work, guide plates and all their work, and so on, plus porting, it's pretty easy to see why working up a set of stock heads like we all used to do back before the advent of CNC casting (since we had no choice), is no longer a real attractive deal. You can buy new aftermarket ones for less than 15% more than the cost of prepping stockers; and have VASTLY SUPERIOR heads to begin with, instead of old stock crap as your basis for work.

It's pretty hard to decide at what point you're spending too much on stock heads; but if you're looking for a budget build and you're willing to cheeep out on valves to that extent but have a set of cores that needs guides, then it's probably wiser to throw those away and go buy a better set of $50 cores that you can just run the guides as they are.

 

I'm not terribly worried about these guides, they are much better than the guides in the 350 heads im running right now. I just wanted to see if it would be a good idea to replace them and if I could mix old with new, I know you cant mix old lifters with a new cam so I wanted to make sure this wasnt the same deal. And yeah, this is a pretty low buck approach so I guess I'll just get the bigger valves from stock junkers and go from there. I plan on getting some AFRs in a year or two, these are only to help bridge the gap with my friends Trans Am. I got tired of being blown away, I'd settle for just losing by a bit. :P