Slant Six Forum
https://www.slantsix.org/forum/

Cylinder Head Porting Time!
https://www.slantsix.org/forum/viewtopic.php?t=56131		 Page 2 of 4
Author:  CNC-Dude [ Sun Sep 07, 2014 10:31 am ]
Post subject: 
Make sure you open the bowl area up. Just cutting the seats and installing larger valves and not modifying the bowl accordingly doesn't give you much, if any gains.
Author:  DKD [ Sun Sep 07, 2014 12:49 pm ]
Post subject: 
The advice not to install seat is sound however an oversize exhaust valve will not wipe out the hardening. There is enough to go up in size as long as you don't get silly. I generally run 1.5s and have never had any issues.
don
Author:  Josh P [ Sun Sep 07, 2014 10:59 pm ]
Post subject:  Re: Fixed the images . . . .
Quote:
I read about the seat installation and hitting water so decided to not install hardened seats and keep the stock exhaust and just go with an oversized intake and no intake seat
Actually, after I had a head go bad during machining over-sized valve seats Doc weighed in with this little gem.
Quote:
The correct seat size must be used when installing hardened valve seats into a Slant Six head.
There are many sizes to choose from and that size range includes the thickness as well as the OD - ID diameters.
I tend to use 1 7/16 diameter X .200 thick and have never had a problem breaking into the water jackets.
I have seen a number of "break-thru" issues when trying to use the 1 1/2 OD X .312 thick inserts.
The next head I have done I'm going to specify the correct .200 thick seat and expect it to go smoothly.
Author:  SlantSteve [ Mon Sep 08, 2014 4:06 am ]
Post subject: 
I'm sure the .200" seats must be ok,it's obviously been done,but going from a .200" to a .312" depth is over a 50% increase in depth...better make sure those .200" seats are fitted correctly,for both heat transfer,leakage and risk of dropping a seat...Seen that in Cleveland$$$. :shock: out of interest I'll measure what depth my head hit water at...its still sitting here,I used it as an experimental head for porting. The head that hit water seemed to be a better looking casting with less porosity,but the one that worked with the hardened seats had a pretty crappy casting quality,lots of porosity,I was worried about leakage but had it pressure tested after porting...all ok. :D
Author:  SlantSteve [ Mon Sep 08, 2014 5:27 pm ]
Post subject: 
Just measured the seat pockets cut into the dud head. They were 1 7/16 diameter cut .250 deep. I'd say at .200" there would have been the slightest porosity,maybe not,but it would be wafer thin in the problem area,so I'm glad I found it now rather than have issues later. The head I'm using now has had miles on it on a previous engine with hardened seats so I know it's ok ... I hope :roll:
I'm not sure what we got as far as casting quality over here,but over the years I've seen a standard bore slant crack radially just below the deck,it had massive core shift and my good head had lots of porosity. Seen lots of Mopar stock blocks with weld repair too. :shock:
Author:  spacecommander [ Mon Sep 08, 2014 6:15 pm ]
Post subject: 
Quote:
Just measured the seat pockets cut into the dud head. They were 1 7/16 diameter cut .250 deep. I'd say at .200" there would have been the slightest porosity,maybe not,but it would be wafer thin in the problem area,so I'm glad I found it now rather than have issues later
Thanks for the info. Pretty sure for this one I'm sticking to the stock exhaust valve size and not using seats. Will see how it works out when they put in new valve guides (I can't do that) - hopefully the hardened seat will just need to be lapped rather than reground.
Author:  SlantSteve [ Mon Sep 08, 2014 7:23 pm ]
Post subject: 
No problems...sounds like a good plan to me. From what I've been told the seats tend to get pretty tough through normal use,together with the factory hardening I'm sure they should be fine as long as you don't have to get them cut a lot,but it sounds like DKD has had good luck even with larger valves. When you cut out the intakes for the larger valves it kind of helps the blending process a little, I blended mine pretty well and had no issue. Happy grinding! I can still hear the sound of the die grinder after doing mine :D and that was with muffs ,sorry neighbours.
Author:  spacecommander [ Sat Sep 13, 2014 6:18 pm ]
Post subject: 
Yep, those grinders are LOUD! Don't even have all the valves out yet - waiting on another valve removal tool. Did start some porting though as the first intake valve port had a horrible lip under the valve seat. Here's some pictures of before and - well, during, as I'm nowhere near done but it looks a ton better now! Haven't done anything yet regarding cutting new seats or bowl enlargement - just smoothing the really ugly nasties so far. Image Image Image Still looking for a Neway NCU-645 seat cutter on the bay of ease. Still seriously thinking about a 30 degree valve seat on the intake. Have a Neway valve cutter for 45 and 30 degrees, just need the matching seat cutter. Have enginebuilder OS valves. That exhaust valve looks mighty small ;-) but I'm still worried about seats. Is there some sort of lead replacement additive available?
Author:  spacecommander [ Sat Sep 13, 2014 6:22 pm ]
Post subject: 
Oh, I'm not going to touch the valve guide bosses until new valve guides get installed - haven't done a measurement with a new valve inserted but think the valve guide wear is too much to not warrant replacement. Then I'll grind the valve guide bosses and then cut the new intake and maybe? maybe? maybe? the oversize exhaust. I want torque more than anything as this will be a truck motor.
Author:  DKD [ Sat Sep 13, 2014 7:23 pm ]
Post subject: 
Bore the guides out for replacement. As for .500" od.
THEN remove the guide boss completely with your grinder.
Precut your replacement guides and taper the end where it goes into the port. Keep the length very close to the original guide.
Install them from the spring side to the proper position.
And yes DKD has had excellent results installing oversize ex valve WITHOUT seats . If you go from a 1.40 valve to a 1.50 valve That is only .050" grinding needed. Hardening appears to be about .090" deep.
I have one head that has 6 years on it. I have 2 on the current one. And I did a street version in the mid seventies I put 60000 miles on. Early unleaded fuel was death but the later versions don't cause as much trouble. Use of stainless valves also makes metal transfer less of a problem.
don
Author:  spacecommander [ Sat Sep 13, 2014 10:06 pm ]
Post subject: 
Quote:
Bore the guides out for replacement. As for .500" od.
THEN remove the guide boss completely with your grinder.
Precut your replacement guides and taper the end where it goes into the port. Keep the length very close to the original guide.
Install them from the spring side to the proper position.
And yes DKD has had excellent results installing oversize ex valve WITHOUT seats . If you go from a 1.40 valve to a 1.50 valve That is only .050" grinding needed. Hardening appears to be about .090" deep.
I have one head that has 6 years on it. I have 2 on the current one. And I did a street version in the mid seventies I put 60000 miles on. Early unleaded fuel was death but the later versions don't cause as much trouble. Use of stainless valves also makes metal transfer less of a problem.
don
Thanks a ton for the info! Will grind some more tomorrow then get the head cleaned and talk to some local machine shops on Monday regarding boring for new guides. Still looking on the bay of ease for the proper cutter. Anybody have any experience in 30 degree intake valve seats?
Author:  CNC-Dude [ Sat Sep 13, 2014 10:35 pm ]
Post subject: 
If there was any real value or marketing potential for it, everyone would be doing it, but they aren't. I'd say take advantage of Chrysler's tens of thousands of dollars in research and development, if not hundreds of thousands they've spent, and enjoy what they created for you with their investment.
Author:  DKD [ Sun Sep 14, 2014 4:24 am ]
Post subject: 
30 degree seats. At very low lift (under .100" they flow slightly higher but the opposite is true as lift rises, so there is no gain to be had that will show up in performance. 45 has proven to be a very good compromise which is why 99% of all heads are done that way. Fight the urge to be different. Feed the urge to be better. A well done 3 angle valve job with a 45 deg seat is as close to ideal as it gets. The only thing above that is a full radius seat as in Lotus 225 HP engines used in the Cortinas and such. I have serviced them which requires installing a fresh seat premachined in perfect position. Our heads do not have enough meat for such a venture, Seats were about 3/4 of an inch in depth and were very expensive. 428 Ford was the last serious performance engine to still use 30 deg seats but they have gone the way of the dodo bird for very good reason.
don
Author:  spacecommander [ Sun Sep 14, 2014 2:06 pm ]
Post subject: 
My only reason to think about 30 degree intakes was the massively undersquare design - huge stroke versus piston diameter - and wanted to get fuel/air in to the cylinder as fast as possible as the piston is moving down the cylinder bore so fast. Didn't want a kooky cam profile - just wanted to get the valve open quickly. Guess I'll stick with the 45 degree on this one and if I really go nuts and build a motor from the crank up - then maybe consider the 30 degree. Or just say "pfft" and turbocharge the thing. ;-)

I took out a second intake valve - same as the first - a huge "lip" under the seat that looked like a wall to the airflow. Ground back on the port rear side (opposite intake mating surface), removed ridge around valve guide. Also burned out one of the windings in my Dremel. :evil: Should have waited for the large grinder and flexible shaft to arrive from the bay of ease.
Author:  CNC-Dude [ Sun Sep 14, 2014 5:22 pm ]
Post subject: 
Chrysler engineers knew all this stuff 50 years ago when they designed, tested and produced this engine, so there is no need to try and retread where they already have been. If there had been any benefit to a 30° seat angle they would have done it without question. They determined that 45° was the best given all the engine parameters they consider when doing there extensive R&D programs, so I doubt you'll find any benefit or gain from it yourself, so you'll be fine with it as it is.
Page 2 of 4 All times are UTC-07:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/