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Old 02-22-2011, 05:47 PM   #1
cuzncletus
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Default Big valves; worth it?

After reading ravenously it appears about a 50/50 poll on the value of bigger intake valves. I'm at that stage where if it needs to happen, it needs to happen now. The engine is a 270 inch, Edelbrock heads, Ross pistons, port and polish work, 2 X 94's (which is a lot of controversy in itself), and a medium hot cam going in a 39 sedan w/ t-5 overdrive.

Also have a fresh generator off a 57 Y-block. Will this bolt in place of the old 6 volt?
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Old 02-22-2011, 06:32 PM   #2
flatjack9
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Default Re: Big valves; worth it?

For a street engine, I would say bigger valves are overkill. Never notice the difference. I would think you would have to install the appropriate front cover and pulley on that generator and then it would bolt right on.
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Old 02-22-2011, 07:21 PM   #3
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Default Re: Big valves; worth it?

I'm a believer in them, but as Flatjack9 said, you may not notice a difference. I think it's all in the total combination.
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Old 02-22-2011, 07:33 PM   #4
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Default Re: Big valves; worth it?

The barrel might be a little bigger on the 57 gen but most of the genny front mounts should match the two bolt pattern. You can get 12-volt fields for the old generator barrels as well.

It seems like most old flatty specialists were more concerned with the valve bowls and the shape of the guide down in the bowl than they were about the size of the valve. Good breathing requires a little work all the way through the intake system to get peak flow. If you want the 1.6" Chevy types on the intakes, you might as well with all the other work done. To get the best out of it you might try getting the straightest shot you can get in those intake ports. Fuel air mix doesn't like to bend much while in route to the combustion chamber. Many bigger inch engines still use 1.5" exhaust valves.

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Old 02-22-2011, 07:59 PM   #5
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Default Re: Big valves; worth it?

I agree they aren't really needed for a street motor. A racing motor would be different.
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Old 02-23-2011, 11:25 PM   #6
Jason M.
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Default Re: Big valves; worth it?

I am building a slightly warmed over 59A and it was an easy decision after reading through my books and threads here to leave the valve size stock.
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Old 02-24-2011, 03:24 AM   #7
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Default Re: Big valves; worth it?

I have a 57-58 Generator barrel and field coils, together with the 6v armature and end plates. Works fine. This is an age old mod.
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Old 02-24-2011, 06:17 AM   #8
Tim Ayers
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Default Re: Big valves; worth it?

Quote:
Originally Posted by Jason M. View Post
I am building a slightly warmed over 59A and it was an easy decision after reading through my books and threads here to leave the valve size stock.

I would really consider using hi-flow 1.5 valves. The difference in flow between Ford stock-type and these hi-po valves is noticeable.
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Old 02-24-2011, 11:54 AM   #9
Bruce Lancaster
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Default Re: Big valves; worth it?

Well, what little I have been able to beat out of actual flow gurus strongly suggests that most flow is through that part of the curtain area facing the piston, and the backside flow is minimal but more than zero (Flatdog actually gave me a number on that).
The guide and bowl work cater to that tiny straight-line shot the air gets, and so does the excess material removal (which can be done on a regular valve on the grinder) on a high flow valve. I certainly have no way of testing the effects of the increase in size of the good part of the curtain area on flow, but I kinda suspect it may be useful because of the importance of that little piece of real estate on a flathead.
1.6 is possible within the existing hard seats, and so that step yould be very inexpensive on an engine being built.
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Old 02-24-2011, 01:18 PM   #10
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Default Re: Big valves; worth it?

Joe Abbins flow testing indicates a 4% increase in intake flow with 1.6" Manley Street Flow stainless steel valves. (Interestingly very little improvement whe installed on the exhausts,) Manley Chevy valves are a little longer than the Ford valves though so it requires shimming to get the correct installed height and resultant seat pressure.

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Old 02-24-2011, 01:43 PM   #11
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Default Re: Big valves; worth it?

Quote:
Originally Posted by blown49 View Post
Joe Abbins flow testing indicates a 4% increase in intake flow with 1.6" Manley Street Flow stainless steel valves. (Interestingly very little improvement whe installed on the exhausts,) Manley Chevy valves are a little longer than the Ford valves though so it requires shimming to get the correct installed height and resultant seat pressure.

Jim
Jim:

Thanks for mentioning that for this is an important step often overlooked. This extra length can sometimes be helpful when using a higher lift re-ground as well.

Tim
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Old 02-24-2011, 02:43 PM   #12
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Default Re: Big valves; worth it?

Not sure of how many of youse guys have JWL"s book, but he addresses this. I've done extensive testing in this area for my book 25 years ago. The shape of the valve head is moer critical than the size.
However, PAW sells a 1.6 OEM valve for 5 bucks and this valve can be used to repair the 52/3 blocks that don't have seats. I dont recommend installing them on old hardened seats as they may come loose.
Last but not least, they offer no performance improvement below 4K.
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Old 02-24-2011, 03:03 PM   #13
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Default Re: Big valves; worth it?

Years ago, I went to visit John Bradley. For years-and-years he had the world's fastest flathead dragster. When I met him, I had all kinds of questions on how to warm up a flathead for the street. When I asked him about which valves I should use, he said, "the ones that say Ford on them." I think he knew that on a hopped up street engine it's wasn't going to make that much difference.

Maybe with larger intake valves it will make five to seven more horsepower at 5000 rpms but your not going to be driving it at 5000 rpms, at cruising speed you might only be getting two more horsepower, and at idle there will be no gain at all. If I had a flathead that already had factory hardened tungsten valve seats as most of them do, I would leave the valves alone.

I love Ford hot rods, for me its more about the history than it is the horsepower. When I pull the heads off of flathead engines and see those original Ford script valves it always makes me smile. Have you ever seen another engine manufacturer that was so proud of their valves that they actually signed them?

I have three friends (one just this week) that searched a long time to find good 59A blocks only to ruin them by trying to bore them out to 3 5/16 or 3 3/8. All these guys hit thin spots in the cylinder walls caused by sixty-plus years of corrosion. I think if you find a good block, only bore it the minimum you have to, don't open the ports more than it takes to get the rough castings out of it and I would not try and put larger valve seats in it either. They already have a tendency to crack from the valve seats, why would you want to remove more metal from this area. It is just not worth risking ruining your block as hard as they are to find.
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Old 02-24-2011, 03:14 PM   #14
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Default Re: Big valves; worth it?

I would think about going to a 60 degree seat before bigger valves. My 50's built 276 was like this. I kept the 45 degree valves in the engine I am building but I did radius the area between the seat and the underside of the head. Help? I hope so.
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Old 02-24-2011, 03:38 PM   #15
cuzncletus
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Default Re: Big valves; worth it?

The flathead I have has NOS Ford valves on factory hardened seats. Looks like a good valve job and some cleaning up of the ports/passages may be the best compromise.
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Old 02-24-2011, 04:10 PM   #16
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Default Re: Big valves; worth it?

Read, read, read VERY carefully what Bruce L wrote. He's giving away the info for FREE, He hasn't even asked any of you for the secret password or handshake. You can't get valves as big as really needed into a flathead, without encroaching into the exhaust valve area. The exhaust valves are actually larger than necessary, thus no help when increased in size. 60 degree seat angles?
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