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Valve guide evaluation?
https://slantsix.org/forum/viewtopic.php?t=48216		 Page 1 of 1
Author:  Red [ Fri Mar 16, 2012 2:22 pm ]
Post subject:  Valve guide evaluation?
So what method do you guys use?

Lacking a guide bore gauge, only measuring tool I have that's small enough to fit down the guide bores is a cheap-o telescoping gauge (less than ideal in terms of accurate results).

I'm thinking that sliding a brand new valve stem into the guide bores (after thoroughly cleaning them, of course) and checking for side play with a dial indicator mounted to a magnetic base would be my best shot at it.

Or do you just leave all that to the machine shop?

I'm planning to have hard exhaust seats installed (unless the current, majority opinion voiced here is that they're not really necessary for today's pump gas) and know I should have the new guide inserts put in FIRST if they are needed.

Am using EPN 1.70"/1.44" valves with 3/8" stems.

Thanks.
Author:  Rug_Trucker [ Fri Mar 16, 2012 5:34 pm ]
Post subject: 
All oldie Mopars have soft valve guides. Chances are they are sloppy.
Author:  Red [ Fri Mar 16, 2012 5:44 pm ]
Post subject: 
Additional question:
Who votes for bronze guide inserts and who for cast iron? Why?
Author:  DusterIdiot [ Fri Mar 16, 2012 6:10 pm ]
Post subject:  Actually...
Using a mic on the original stems and a telescoping gauge can tell you which are worn the most and how bad... Also follow up as specified with the 'tilt' test as you described with the dial gauge (if an original unrebuilt hi-miler head, you won't need the guage you'll feel the wear spot).

Personally if you are going to run HiPo valves new guides are a must and not even worth checking for wear.

For performance Bronze is the one to go with in terms of durability and will stand up better to harder valve alloys and abuse with lack of lubrication (especially if you use positive seals). Also depending on the valve alloy cast iron has been known to oxidize and the stem and guide can get seized if the car sits for a while (like all fall and winter after race season is over)... If the machinist is installing the guides and you are doing some porting on the head, you can ask him to turn the guides down a bit so they don't protrude all the way in the port, creating an obstruction that you are going to grind off later, saving you some of the hassle in the long run.

-D.idiot
Author:  Red [ Fri Mar 16, 2012 6:47 pm ]
Post subject: 
Valves are EV-8 grade stainless. Only a .448"/.448" lift cam. Engine is just mild for street use, so it probably won't sit around for long periods. Using umbrella seals, not posi-locks. I guess turning down the guides is a trade off: flow for stem support.

Thanks, guys. Appreciate your experience-based input.

Anybody else? Feel free to comment, especially about the hard exhaust seat insert issue. I know that opinions have varied on that one in the past...
Author:  CNC-Dude [ Fri Mar 16, 2012 7:10 pm ]
Post subject: 
X2 on what DI said, not much else to add, he covered all the benefits of using bronze guides vs. cast iron guides.
Author:  Dart270 [ Fri Mar 16, 2012 8:17 pm ]
Post subject: 
For mild street use and no sustained high temps (road racing or extreme hill pulls w/load), then I would skip the exhaust valve inserts.

Lou
Author:  SlantSixDan [ Fri Mar 16, 2012 11:28 pm ]
Post subject: 
Unless you are really throwing together a minimum-cost "get it running and get it gone" head, it is unwise to put together a head without hard exhaust seats. They're inexpensive, bring no negative consequences, and without them, you will experience valve seat recession sooner or later. Today's gasoline is all unleaded. The factory started hardening the exhaust valve seats in order to comply with early-'70s requirements that all engines be capable of operating on unleaded fuel. They didn't do it for fun or because they felt like spending extra money.
Author:  Rug_Trucker [ Sat Mar 17, 2012 6:22 am ]
Post subject: 
Some machine shops try to shy away from installing the hardened seats. Warranties is the reason. Hard to find someone in this area.
Author:  Red [ Sat Mar 17, 2012 9:18 am ]
Post subject: 
"Unless you are really throwing together a minimum-cost 'get it running and get it gone' head"

Nope: tryin' t'get it right the first time is all. Just want some mild performance gains without sacrificing too much longevity/durability. That's why I'm pickin' your brains and fine-tuning my game plan before the fact. Collectively, you've probably already made and learned from most of the mistakes/omissions I'd be likely to perpetrate.

I already have hard seats and bronze guides in my parts stash. Just wanted to double check opinions here before proceeding. At this point, most of the money I spend will be for machine shop labor, since I already have most of the parts and tools I'll need.
____________________

"Some machine shops try to shy away from installing the hardened seats. Warranties is the reason."

Seems to me I read somewhere that there is some risk of small cracks developing around hard seat inserts: if true, maybe that's the reason for their reluctance. Hopefully, I can find somebody around here who's willing to do it.



I'll probably be pestering you guys some more in the coming weeks about other stuff. Thanks again, all, for the input.
Author:  SlantSixDan [ Sat Mar 17, 2012 11:20 am ]
Post subject: 
Quote:
Some machine shops try to shy away from installing the hardened seats. Warranties is the reason. Hard to find someone in this area.
Wow, seriously? It's been an utterly standard, basic, easy machine shop operation for many decades. Sounds like an awful lack of skill, talent, and competence in your area; that's gotta make life difficult. I guess it's like how you can't get a decent selection of auto parts in some places, you can't get a good cell phone signal in some places, etc.
Author:  Rug_Trucker [ Sat Mar 17, 2012 5:50 pm ]
Post subject: 
Santa Cruz? Lots of surfing, and tree hugging going on there! And don't forget the medical marijuana!
Author:  Red [ Sat Mar 17, 2012 7:01 pm ]
Post subject: 
Don't smoke or embrace the foliage, but am guilty as charged on the surf rat count.
Author:  DusterIdiot [ Sat Mar 17, 2012 8:42 pm ]
Post subject:  Unfortunately...
Quote:
Wow, seriously? It's been an utterly standard, basic, easy machine shop operation for many decades. Sounds like an awful lack of skill, talent, and competence in your area; that's gotta make life difficult. I guess it's like how you can't get a decent selection of auto parts in some places, you can't get a good cell phone signal in some places, etc.


Sadly, Dan a few things are becoming a rare item, I'm lucky to have a couple of shops that can do this task, but it always comes with a warning,
if the head is thin in that area when they machine out for the replacement seats, they aren't going to replace the head...

That being said, I've done 3 heads, 2-1976 and one 1980's head and there was plenty of meat for the job to be properly done. Glad I have
guys willing to do the work and support the guy wanting to be different
(my last machine shop visit they were giving me crap because I set a trend, behind my engine and head was a 300 ford, a 4.2 AMC, and an inline 8...get inline!!!)

The sad and the bad is that most machine shops and the current training program are set up for modern cars and their heads...in one case the owner said that new seats is a rare job, most of his performance customers bring in a new set of hipo aluminum heads and he finishes the seat cuts laps the valves, and makes the cut to the mating surface per the CR request...

To make sure that my guys know that I appreciate going to long way around, I make sure when the job is done and everything is good to go, I'll buy lunch...for some reason, they seem to be able to turn my junk around faster...who knows why 8)

-D.Idiot
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