Or like this
The Ford 300 valves are the absolute biggest valves you can fit in a head without notching the combustion chamber walls for clearance. Here is a picture of my "big valve" slant six head with Ford 300 valves installed:
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| Oversize valves? https://slantsix.org/forum/viewtopic.php?t=30728 |
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| Author: | Reed [ Wed Aug 27, 2008 8:35 am ] |
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Or like this The Ford 300 valves are the absolute biggest valves you can fit in a head without notching the combustion chamber walls for clearance. Here is a picture of my "big valve" slant six head with Ford 300 valves installed:
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| Author: | NewLancerMan [ Wed Aug 27, 2008 9:40 am ] |
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Quote: http://tinyurl.com/Oversized-valves
Almost. You got to the website and put in the URL you want to shorten and it autogenerates one for you. Here's a little video on how it works:Like that? http://www.youtube.com/watch?v=LTCb-jbCZU |
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| Author: | wvenable [ Wed Aug 27, 2008 1:22 pm ] |
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Reed, what size are the Ford valves? How much additional macine work did you have to do? Thanks, Wayne. |
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| Author: | Reed [ Wed Aug 27, 2008 2:14 pm ] |
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I take it back, the bore in the combustion chamber has been notched slightly to clear the valves. The notch is 3.48 inches on average across the head. The intake valves are 1.78 and the exhaust valves are 1.55. I ran this head on a stock 198 and on a 225 with .030 oversize pistons. The valves cleared both bores fine. The head spent a couple months at the machine shop and cost me roughly $500 about nine years ago. If I remember right, the valve stems were narrower than the stock valves so the shafts needed to tbe bushed, and the valves were a touch too long so they had to be cut down and re-groved. The head also had to be massaged so the valves would seat. However, this is from my nine year old memories, so I am not certain that it is all true. |
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| Author: | Joshie225 [ Wed Aug 27, 2008 3:15 pm ] |
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Ford 300 valves are 1.78" and 1.56" with 11/32" stems. The length is good which is why they were adopted. When I put these valves in my '66 Dart road racer's head I had the exhaust cut down to 1.45". The head needed new guides anyway so putting in 11/32" guides rather than 3/8" was not an issue. The only other thing to be aware of is you'll need new retainers and locks. It's not a problem if you're already buying new stuff you just get the Ford style parts. The Engnbldr valves at only $64 with stock size stems and locks are a bargain. I then spent $390 at Portland Engine Rebuilders to have the seats cut oversize, hard exhaust seats installed, the guides replaced, and an .100" mill. The milling was $80 more than just resurfacing the head, but raised the compression ratio from 8:1 to 9:1 for my engine. I am doing the porting work myself. |
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| Author: | wvenable [ Wed Aug 27, 2008 4:53 pm ] |
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Reed, Josh, thanks for the info! I know that oversize valves is a common topic and old hat for many of you, but I am thankful for your advice! 
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| Author: | bigslant6fan [ Sun Aug 31, 2008 4:52 pm ] |
| Post subject: | OS valves |
I agree, SI makes them for clifford performance |
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