The Ford Barn

pistonbroke · 01-12-2022, 03:03 PM

Hi All, I'm looking at new valves for my 255. On some them I see a indentation in the top of the valve head. Mine are flat. In these engines where any extra compression is a bonus will this cause any significant loss ? I know the earlier mushroom valves in my V12 had something like this so what do my fellow barners think? I'm all ears. Tim

supereal · 01-12-2022, 03:08 PM

At our shop we use Chevy valves. They are more available, and somewhat less expensive.

pistonbroke · 01-12-2022, 05:22 PM

I've not ruled out the chevy valves. My next question would be , are the chevys any better with a basically stock engine. We haven't cut the new seats yet, so like always I'm asking questions to learn as most of my knowledge is from the 1970s and far from complete. Tim

51 MERC-CT · 01-12-2022, 05:56 PM

Quote:

Originally Posted by pistonbroke

I've not ruled out the chevy valves. My next question would be , are the chevys any better with a basically stock engine. We haven't cut the new seats yet, so like always I'm asking questions to learn as most of my knowledge is from the 1970s and far from complete. Tim

The Chevy valves are no better or worse but you have to use the correct valve keepers, spring retainers and springs along with any necessary shims to obtain correct spring pressure.

Bored&Stroked · 01-12-2022, 07:26 PM

On a typical factory Ford engine, the valves with the indentations were for the intakes and the ones with the flat tops (no indents) were for exhausts. They were made from different material - with the exhausts having a tougher material that was designed to handle the heat.

I typically use SBC 1.6" exhaust valves for both intakes and exhausts - as I like the longer lengths as I use smaller base-circle racing style cams. Also, on my valve machine I rework the undersides of the intakes to remove some of the thickness and help streamline them for better flow. I don't like the thick exhaust valve profile on the intake side.

As 51 MERC noted, what is key is that you setup the whole valve/guide/spring/retainer package to have the correct installed height and resulting spring pressure - given what your application needs (stock, performance, racing, etc).

Pete · 01-12-2022, 08:08 PM

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I just couldn't resist commenting on this.
Many moons ago one of the "know it all" guys that used to hang out at our shop saw me putting a set of stock dish top valves in a street engine and commented that they would lower the compression so far that the engine would barely run.
That engine went through several owners and 4 years later ended up in the championship car. A street stock circle track car.

01-12-2022, 03:03 PM	#1
pistonbroke Senior Member Join Date: Feb 2021 Location: Perry Mo. Posts: 482	new valves for my 53 merc Hi All, I'm looking at new valves for my 255. On some them I see a indentation in the top of the valve head. Mine are flat. In these engines where any extra compression is a bonus will this cause any significant loss ? I know the earlier mushroom valves in my V12 had something like this so what do my fellow barners think? I'm all ears. Tim

01-12-2022, 03:08 PM	#2
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: new valves for my 53 merc At our shop we use Chevy valves. They are more available, and somewhat less expensive.

01-12-2022, 05:22 PM	#3
pistonbroke Senior Member Join Date: Feb 2021 Location: Perry Mo. Posts: 482	Re: new valves for my 53 merc I've not ruled out the chevy valves. My next question would be , are the chevys any better with a basically stock engine. We haven't cut the new seats yet, so like always I'm asking questions to learn as most of my knowledge is from the 1970s and far from complete. Tim

01-12-2022, 07:26 PM	#5
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: new valves for my 53 merc On a typical factory Ford engine, the valves with the indentations were for the intakes and the ones with the flat tops (no indents) were for exhausts. They were made from different material - with the exhausts having a tougher material that was designed to handle the heat. I typically use SBC 1.6" exhaust valves for both intakes and exhausts - as I like the longer lengths as I use smaller base-circle racing style cams. Also, on my valve machine I rework the undersides of the intakes to remove some of the thickness and help streamline them for better flow. I don't like the thick exhaust valve profile on the intake side. As 51 MERC noted, what is key is that you setup the whole valve/guide/spring/retainer package to have the correct installed height and resulting spring pressure - given what your application needs (stock, performance, racing, etc).

01-12-2022, 08:08 PM	#6
Pete Senior Member Join Date: May 2010 Location: Wa. Posts: 5,408	Re: new valves for my 53 merc Sponsored Links (Register now to hide all advertisements) I just couldn't resist commenting on this. Many moons ago one of the "know it all" guys that used to hang out at our shop saw me putting a set of stock dish top valves in a street engine and commented that they would lower the compression so far that the engine would barely run. That engine went through several owners and 4 years later ended up in the championship car. A street stock circle track car. Last edited by Pete; 01-12-2022 at 08:29 PM.