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Valve spring question
https://slantsix.org/forum/viewtopic.php?t=58649		 Page 1 of 3
Author:  spacecommander [ Tue Nov 03, 2015 10:30 am ]
Post subject:  Valve spring question
So I'm getting ready to put the drool tube head that has been ported & oversize engine builder valves installed. It's a ~1971 or so head. Does not have induction hardened seats, which would have been eliminated in the oversize valve install. Did NOT have hardened valve seats installed. Will try to find some lead substitute to add to the gas. Head is going on a 1982 W150 4x4 and will operate at or near the top of its power range due to heavy truck, hills and altitude (5500 ft). I originally installed the 340 valve spring package. Should I reconsider and go back to stock slant six valve springs as the engine won't be turning 5500+ rpm? I'm worried about the increased valve spring pressure pounding out the valve seats. Should I be concerned about this or am I over thinking things?

Tom
Author:  Joshie225 [ Tue Nov 03, 2015 12:15 pm ]
Post subject: 
Unless you are running a high lift cam and high engine speed the 340 springs are overkill. I would probably use the standard 318 spring, but I don't know what cam you're running. The last I knew most catalogs showed the 225 and 318 as using the same valve spring. The somewhat lighter slant six spring appears to have been superseded.

As long as you're not running too lean under power the vales and seats should be fine, but I'd want a wide-band O2 sensor for tuning.

I just noticed the truck is an '82. Still hydro cam?
Author:  spacecommander [ Tue Nov 03, 2015 12:34 pm ]
Post subject: 
Quote:
. . .
I just noticed the truck is an '82. Still hydro cam?
Yes, for now. Have a torquer cam to go in at a later date - that one is mechanical. Read about drilling out the bottom of the mounting stud so the hydraulic rocker oil bolt fits in to the head. Offy 4bbl and 400CFM Carter AFB re-jetted for 5500 feet. Might try a offy 2 x 2bbl weber setup sometime in the future.
Author:  Reed [ Tue Nov 03, 2015 12:53 pm ]
Post subject: 
What the time comes, if you are interested and remember, I am always interested in cheap used factory hydraulic slant six parts. Cams, lifters, rocker arm assemblies (shafts, too!).
Author:  spacecommander [ Tue Nov 03, 2015 4:03 pm ]
Post subject: 
Quote:
What the time comes, if you are interested and remember, I am always interested in cheap used factory hydraulic slant six parts. Cams, lifters, rocker arm assemblies (shafts, too!).
Ok, when the entire project is done - could be next Spring - I'll let you know. Guess it's hard to find the hydraulic stuff, I posted a "wanted " here for the rocker arm assy so I could get it clean and have it fully installed on the head before I did the head swap. No replies other than a link to new stuff.
Author:  SlantSixDan [ Tue Nov 03, 2015 4:25 pm ]
Post subject:  Re: Valve spring question
Quote:
So I'm getting ready to put the drool tube head that has been ported & oversize engine builder valves installed. Did NOT have hardened valve seats installed.
Why on earth not?! Sorry to have to be blunt, but that was a seriously unwise omission. This is 2015. Hard exhaust valve seats have been utterly standard practice in head rebuilds for at least a quarter of a century now. There is no good reason to leave them out, and every good reason to put them in. Seriously, you should hold off on installing this head until it's back from the machine shop a second time from having the seats put in.
Quote:
Will try to find some lead substitute to add to the gas
That won't save your seats, it'll just foul your spark plugs and drain your wallet.
Quote:
Head is going on a 1982 W150 4x4 and will operate at or near the top of its power range due to heavy truck, hills and altitude (5500 ft). I originally installed the 340 valve spring package.
That's more reasons stacked on top of more reasons why this head needs hard seats. Halfaѕѕed work will only cost you money and cause you strife in the long run. Even with the nuisance and cost of the head going back to the machine shop to finish the job, you'll still be time and money ahead versus putting the half-baked head on as it is.

Stock valves in low-load, low-RPM, passenger car service with a stock cam will last a decently long time even without hard seats. Bigger valves run hotter for any given engine load. A bigger cam exacerbates this. So does truck/heavy-duty/high-rpm service. You made a mistake. Fix it before proceeding.
Author:  spacecommander [ Tue Nov 03, 2015 4:38 pm ]
Post subject: 
Well, I read through all the posts here regarding this issue and the concern on the enginebuilder oversize valves and corresponding oversize seat was breaking through in to the cooling passages and many people chimed in on experience in NOT installing hardened valve seats. It was NOT done to save money. As a matter of fact I had just originally assumed I would need hardened seats.
Author:  slantzilla [ Tue Nov 03, 2015 6:53 pm ]
Post subject: 
I have 2 heads that have big valves and neither had seats put in. One was used for over 50K miles on the street with 340 springs and never beat the seats out. I've been told the induction hardening goes a lot deeper than people think. I always ran pump gas and never added lead of any kind.

The other head has a ton more spring on it, but never got a lot of street miles on it.

I have seen some guys put seats in and have good luck. I have also seen guys try them and have them drop out. It's a crapshoot.
Author:  Dart270 [ Wed Nov 04, 2015 6:30 am ]
Post subject: 
I think that using stainless valves like the engnblr valves will make it so you don't need hardened seats, due to the dissimilar metals in the valves and head so that no "micro-welding" occurs (causing seat recession).

I have also had heads with no hardened seats that have been fine. I also have heads with hardened seats and have had no trouble with them. I do not skimp on machine shops (spend a little more $$) and I get recommendations before I use any shop.

Lou
Author:  SlantSixDan [ Wed Nov 04, 2015 10:12 am ]
Post subject: 
Quote:
I think that using stainless valves like the engnblr valves will make it so you don't need hardened seats, due to the dissimilar metals in the valves and head so that no "micro-welding" occurs (causing seat recession).
I don't agree. It's the opposite: the greater the difference in hardness between the valve and the seat, the more likely seat recession is to occur. Factory valves are stainless, too, even early ones. When hard seats started, the valve material was upgraded from 21-2N to 21-4N for that reason.
Quote:
It's a crapshoot
It isn't any more of a crapshoot than any other machine shop operation. If your machine shop screws up the install of the hard seats, they'll cause problems. Same goes for the valve guides, the cylinder boring and honing, the cam bearings, the block and/or head decking, and every other thing the machine shop does. There is nothing inherent in hard valve seats that makes them a risky gamble.
Author:  sandy in BC [ Wed Nov 04, 2015 10:42 am ]
Post subject: 
For those of us who have had seats fall out....there was a gamble.

Since then I dont install seats.

Chev valves in 69 head.....no seats no problems,,,,10s of thousands of miles.
Author:  SlantSixDan [ Wed Nov 04, 2015 11:49 am ]
Post subject: 
Quote:
For those of us who have had seats fall out....there was a gamble. Since then I dont install seats.
If your machine shop had loused up some other aspect of their job…say, they didn't ream the valve guides properly, or they put the wrong finish on the cylinder walls…would you then say "Since then I don't have valve guides installed or cylinders bored"?
Quote:
Chev valves in 69 head.....no seats no problems,,,,10s of thousands of miles.
Great, in what kind of service?
Author:  slantzilla [ Wed Nov 04, 2015 11:56 am ]
Post subject: 
With all due respect Dan, putting seats in a Slant head is a gamble. The chamber is too small, the valves are too close together, and manufacturing tolerances on the heads were horrible at best. You can put seats in one head and be fine, and the next head cut through to water at the same cutter depth. The seats end up so close together there is not much holding them in.

It is a crapshoot at best whether I am doing it or Ray Barton.
Author:  Joshie225 [ Wed Nov 04, 2015 11:59 am ]
Post subject: 
Quote:
There is nothing inherent in hard valve seats that makes them a risky gamble.
Risks of installing exhaust valve seats in a slant six head:

1. Water jacket proximity. If the water jacket is breached the head is junk.
2. Insufficient valve seat press-fit dropping a seat into the combustion chamber. If there isn't valve to piston clearance this can wreck the piston and if done at high enough engine speed then the connecting rod trashes the block.
Author:  sandy in BC [ Wed Nov 04, 2015 4:32 pm ]
Post subject: 
......back in the slantsix.com days....

Head to Machine shop for Chev valves with instuctions for no inserts....

.......pickup head....inserts. I bitch and they say no charge.

ding ding ding puff puff ding puff

I drop a core head and they do it all over again without seats....for free.

Luckily damage was limited to above the deck,,,,head and valves were free....but all my chamber work was wasted.

....and this was the Chevvy guys.
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