Can I grind down my own valve stems or do I need to get undercut valves?

 

buy undercut valves, it'll save you alot of money leter when you break one of the DIY valves

 

david vizard did a breakdown of flow gains, based on different things done to a valve. one was chucking it up in your drill, and running it against a grinding wheel, or even grinding wheel in a die grinder (I think you'd need a vise, or 4 hands for that...)
it showed to be worthwhile... but then again, be careful...

I could scan the article if there was interest.


but wait, grinding valve stems, (like the shank?) or grinding the valve head? (like the tulip?)

 

"like the shank" ...I'm considering buying undercut valves, but I have a bunch I could work on myself... I'm wondering if there's any reason that it wouldn't be safe to grind down the stem myself.

 

The reason it wouldn't be safe is because the valve head could pop off while your engine is running.
Less expensive valves like OEM replacement are made by welding the head to the stem. Most of the better ones are 1 pc.
By grinding into a weld like that, you would be seriously compromising the integrity of it.
Unless you really know what you're doing, the risk wouldn't be worth the payoff.

 

Well, I don’t know about anyone else, but I’m interested

Well, there’s nothing wrong with grinding into a weld, in most steels it really shouldn’t be any weaker then the base metal, but real world… well, it depends on how much you trust the quality of the weld and I’m not sure that cheap valves should be trusted, depends on how hard you intend to be on them

 

ask and ye shall receive.

directory

I only scanned his test on the intake, (the start of the exhaust is on the last page.)

The part I noticed the most, was a stock valve, hand ground with a slight back radius on it, (Mod 3), picked up a max of 10CFM @.2" lift, and 0 at max lift. So good for the medium lift areas.
mod4 was to do a 30* backcut on a machine. That actually lost flow at the top lift.... He backs up a lot of his claims with flow bench results, and nifty pictures. The only downside to vizard, is when he describes "new" or "cutting edge" parts, they're 10yrs old by now....

 

thanks...

 

likewise

 

As cheap as the real thing is, designed and made correctly by a company you can actually trust (no experimenting with the possibility of dropping pieces of material into your cylinders that won't compress!!!!), why bother?

http://store.summitracing.com/partde...AN%2D10776%2D8
http://store.summitracing.com/partde...AN%2D10765%2D8