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| Let's talk valve sizes https://www.slantsix.org/forum/viewtopic.php?t=36343 |
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| Author: | NCDemon1971 [ Sat Jul 18, 2009 9:28 pm ] |
| Post subject: | Let's talk valve sizes |
Ok, So far I've heard of the following valves used in /6 heads: *ford 300 six valves *BB mopar valves (dont recall which sizes though, can anybody shed light on this? I have a couple of BB mopar heads laying here) *The common 1.70/1.44 valves What are your experiences and gains (as in how much more noticeable)? Im intrested in the BB mopar setup because I'm poor and that's what ive got laying about 
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| Author: | 66aCUDA [ Sun Jul 19, 2009 7:08 am ] |
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The 1.70/ 1.44 is the cheapest way to go for "new" valves. The Ford valves are not the same shaft size, 3/8 vs 7/16. I also think the BB need cut down to fit a slant head. My02. Frank |
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| Author: | Greg Ondayko [ Sun Jul 19, 2009 7:29 am ] |
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I posted a similar question: http://www.slantsix.org/forum/viewtopic ... tive+valve check it. Greg |
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| Author: | NCDemon1971 [ Mon Jul 20, 2009 6:38 pm ] |
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What needs to be done to the 1.70/1.44's? Are they really drop in's?? |
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| Author: | Greg Ondayko [ Mon Jul 20, 2009 7:35 pm ] |
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Get the Head cut to match the valve size yes they are drop in besides that. Greg |
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| Author: | NCDemon1971 [ Wed Jul 22, 2009 8:33 am ] |
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Wasnt it Charrlie S. that was using backcut stock valves?? Just weighing in all the options for best bang for the buck. |
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| Author: | Charrlie_S [ Wed Jul 22, 2009 8:58 am ] |
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I had a stock rebuilt head on my "low buck" 66 valiant. I had a fresh head on the shelf, that I had milled, to put on the car as an "upgrade". While I had the milled head apart to put stiffer springs on it, I decieded to backcut the valves (I have a valve grinder). I would not recommend just back cutting the stock valves, it will give a small gain, but not worth doing just that. I would recommend doing a back cut, and opening up the bowls together. |
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| Author: | NCDemon1971 [ Tue Aug 11, 2009 10:16 pm ] |
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I became curious also about the ford 300 six valves. What are the valve sizes on these? (1.78, 1.56??) and also other than enlarging the valve seats- is any other work required?? Could 340 springs work with these?? |
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| Author: | 66aCUDA [ Wed Aug 12, 2009 5:33 am ] |
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The stem size on the Ford valves is 11/32 so you have to rebush the guides. You will also have to adjust the stem height. The springs are dictated by cam choice as well. So what lift cam are you running? Also on another note how big an overbore are you planning as these valves need BIG bores to deshroud them. Frank |
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| Author: | NCDemon1971 [ Wed Aug 12, 2009 9:16 am ] |
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Quote: The stem size on the Ford valves is 11/32 so you have to rebush the guides. You will also have to adjust the stem height. The springs are dictated by cam choice as well. So what lift cam are you running? Also on another note how big an overbore are you planning as these valves need BIG bores to deshroud them.
Im thinking .080 over at least, with the use of a .528 cam.
Frank |
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| Author: | raPoM [ Wed Aug 12, 2009 5:16 pm ] |
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Not to hijack your thread,but what is the biggest valve size you should be able to run with a .060 overbore? |
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| Author: | ceej [ Wed Aug 12, 2009 5:29 pm ] |
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Anything beyond the 300 ford valve is going to be shrouded by the bore itself. Minimum overbore is .060" when using these valves. Mine is .045" over, and I tagged the cylinder walls with three of my exhaust valves. Mock up the cylinder head to the block and verify the combustion chambers are correctly aligned over the cylinders before bolting things up. You may need to use offset alignment dowels to correctly position the head. One of the tricks when using valves of this size is to notch the bores slightly where the valves come close. Just don't notch down where the top ring rides in the bore. Stay above it for obvious reasons. It doesn't take a big cut, just enough to make sure there is clearance. CJ |
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| Author: | raPoM [ Wed Aug 12, 2009 5:36 pm ] |
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I heard/read that if you do not cut the head,and only clean the surface up that you may not have issues.Just mill the deck for more comp. I wish we had high compression pitsons readily availible like the small block guys. Sounds like I may need to notch the chamber and the bore if I want to go bigger than the ford valves,correct? |
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| Author: | Fopar [ Wed Aug 12, 2009 9:23 pm ] |
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This is what your head looks like with Ford 300 Cu In valves.  There isn't enough room to go much bigger!!  Then you can do this, picture doesn't show final of work done |
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| Author: | emsvitil [ Wed Aug 12, 2009 9:38 pm ] |
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Quote: This is what your head looks like with Ford 300 Cu In valves.
There isn't enough room to go much bigger!! Looks like you'd have a shrouding problem going that big........... |
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