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| Replacing Valves https://slantsix.org/forum/viewtopic.php?t=19518 |
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| Author: | 60 Pioneer [ Tue Sep 05, 2006 11:04 am ] |
| Post subject: | Replacing Valves |
I have the valves removed from my Slant head and I have a couple of questions before I rebuild. First, if I replace the valves with stock size valves, do I need to do anything with the valve seats? I read that in the past mechanics used to lap the seats with an abrasive compund to "set" the new valves to the seats. Is this something that is still done? I am definately replacing the seals, they are as hard as a rock, but can I re-use the old springs, retainers, and locks? I would imagine that the springs get "soft" after 46 years. SS Dan, you stated in my last post that I should be careful going with oversize valves on a mildly built motor because of port gas velocities. I think that this is definately something to take into account. But out of curiousity, at what point would oversize valves make a difference? I had stated that I am going with a fairly mild cam, like the MP244 or the Erson 254, but I am tossing around going with something slightly bigger, like the 270. My one constant that I am set on is the 2x1 Carter Intake with the Dutra Duals. I guess my question is how cam and valve work can the dual Carters supply before they become the bottleneck in the system? Thanks again for any and all replies. |
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| Author: | LUCKY13 [ Tue Sep 05, 2006 11:32 am ] |
| Post subject: | |
60 Pioneer , IMO you would be better off to go with the Oversize valves. Not real big but 1.70 & 1.40 valves. With the 2x1 intake and a cam I think you would gain alot of power from them. Also milling it would help with this combo alot to for more compression. I would just lightly work on the ports. Slight bowl blending & clean up the ports with port match to intake. Dont go porting them out alot and this would help your combo with power down low & up top. Get you local machine shop tp put in Hardend seats & do a 3 angle valve job with them also. This sounds like a fun combo to enjoy driving, not overly built but still with good power all over. Jess |
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| Author: | 60 Pioneer [ Tue Sep 05, 2006 11:48 am ] |
| Post subject: | |
Lucky13, Yeah, I plan on decking the block to get at least 9:1 compression. I have to decide were I want to end up with the compression, I don't want to end up pinging. I've measured the volume of my combustion chamber...came up with 58-59cc. I have to borrow a depth mic and measure my stroke and deck height, then settle on an over bore. I checked out some past post on the Forum here and there is mention of going with hardened seats because the tempering on the stock head will get machined away with O/S valves, but there is also a caution to make sure that you don't run into the water chambers when you mill for the hardened seats. Sounds a bit like a Catch-22. I've been reading up on porting, I might try some minor work myself, just don't want to end up ruining the head. |
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| Author: | LUCKY13 [ Tue Sep 05, 2006 1:05 pm ] |
| Post subject: | |
Yea you dont want to port to much on this light of a combo. But alittle bowl work & cleaning ports will help alot without loosing any bottom end torque. Hitting water ports when going hard seats would not be good for sure. I dont know maybe some are having this problem. But I would atleast look into exhuast seats for it. But even with no hard seats if its not run at idle or out of tune for a long time you can get by, the valve job just dont last as long and need a regrind after so many miles. I would guess 30 to 60.000 miles would show signs of needing a regrind if all was good and the seats wasnt getting beat out from no lead. You can get a lead additive if its still on the market. Jess |
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| Author: | 60 Pioneer [ Tue Sep 12, 2006 1:46 pm ] |
| Post subject: | |
I'm still curious about what i need to do, if anything, to the stock valve seats if they are in good condition and I am replacing the valves with stock valves. When I pulled the head, the intake valves were in decent condition, but the tops of the exhaust valves were pretty crusty. Anybody have any opinions on installing new valves with original seats...other than going with the oversize valves? Thanks, All |
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| Author: | slantzilla [ Tue Sep 12, 2006 2:10 pm ] |
| Post subject: | |
Don't go halfway. Get the valves and seats done as well as the guides. On an old motor put springs, locks, and keepers on too. The stock stuff is not that expensive and will be cheap insurance. Personally I would put some bigger valves in with a bowl cleanup. The valve size is designed for 170 cubic inches. Going to bigger valves will not kill any power, and will gain some. As stated before, pretty much leave the ports alone except for cleaning out boogers. |
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