Thickness of head casting under the valve spring seat???

[wsa111]

Does anyone know the thickness of the head under the valve spring on a C or D head. 78-82 era.

Does anyone have a sawed off crossection of the head showing the thickness of the head below the valve spring. Thanks Bill

 

[falcon60]

Bill,weren't there a couple pictures posted somewhere here that showed the ports in a cut-up log head? Maybe the spring seat areas were visible in those shots,but I'm not sure where to look for them right now. It's been a year or two ago....

 

[Hot 6t Falcon]

Ken Thompson posted the "head slices" at
http://fordsix.com/forum/viewtopic.php?t=48073&highlight=

in the Hardcore section.

Hope it helps.
Dennis

 

[wsa111]

Dennis, thank you very much.

I need to spot face the spring seat to a 1.700" installed height.

Then get valves .125" longer so i can get a final 1.825" installed height.

Reason being i am checking out the possibility of installing a camshaft with .580" gross lift & a spring with 140# seat pressure & 340# open pressure. That requires a valve spring with a 1.825" install height.

This is on a cast iron head. Bill

 

[FALCONAROUND]

The valves he installed on that loghead cutout, are frickin' ginormous!!!

What size valves are you putting in this one?

What kind of power will you make with a lift like that?

Im hoggin out a loghead right now and im pretty close to the water jackets on it, and want to know what is the largest valve i can run.[/list]

 

[wsa111]

The valve size is 1.75" I & 1.5" EX.

The camshaft i have in mind is a solid lifter.

The intake duration is in the 260 area & the exhaust is in the 280's.

The camshaft is a very agressive design with the lift & duration @ .050" close to that of a larger camshaft.

It will provide more midrange torque & still provide more top end power.

This camshaft will require lifters with a small oiling orifice in the lifter contact area for extra lubrication.

It will also require a 1.825" installed spring height to accomodate the radical lift. Bill

 

[FALCONAROUND]

the guy with the cutout pics, he was installing 1.8 something vavles and 1.6 something exhaust vavles, how did he do that?

 

[Anlushac11]

the guy with the cutout pics, he was installing 1.8 something vavles and 1.6 something exhaust vavles, how did he do that?

Biggest Classic Inlines sells is a 1.84" int and 1.56" exhaust.

I suppose someone could rig a SBF or Chevy exhaust valve of 1.60" and go up to a 1.80" int size.

 

[FALCONAROUND]

Are these 1.84 and 1.56 valves something that require major machining? Or do they only fit the 250 head? I have a 1970 Log head I"m playing with here.

I'm going to use the wonderful search button and look for other examples...

 

[wallaka]

Seems like there would be a point of diminishing returns due to valve shrouding. How much more would 1.84" valves actually flow vs. smaller diameter ones? I am skeptical that it would be enough to make a difference.

 

[FALCONAROUND]

I support that statement.

But, where's the cutoff? Will the 1.84 need chamber machining to fit?

What's the next smaller size valve to use? 1.80? I was planning on using a 1.75 intake and 1.499 exhaust {Ford made }

If there's a larger exhaust than 1.5 that will increase exhaust flow which will invariably be better than a couple thousandths larger intake valve...

That make sense?

 

[wallaka]

I support that statement.

But, where's the cutoff? Will the 1.84 need chamber machining to fit?

What's the next smaller size valve to use? 1.80? I was planning on using a 1.75 intake and 1.499 exhaust {Ford made }

If there's a larger exhaust than 1.5 that will increase exhaust flow which will invariably be better than a couple thousandths larger intake valve...

That make sense?

Makes sense. Exhaust and intake valves are the same alloy, so stock 200 intake valves at 1.6555 could be used. Or, the SI portflows at 1.5" will flow better than stockers due to the undercut stems, radiusing, and swirl-polishing.

 

[Anlushac11]

There is a old thread here that states going to larger valves helps mid range and top end but you lose bottom end throttle response.

I am planning 1.84" int and 1.56" exh since I will be running a T3 turbocharger, 8lbs boost, a turbo cam and big exhaust and 3.73 rear gears.

I will need to get the valve seats machined for larger valves. My dad will be doing the porting and polishing and unshrouding.

I have a old 66 head ported and polished that is going to be my guineau pig for milling off log and makign a sheetmetal intake for fuel injection (Think bigger log with 60mm throttle body on end). If all works out on that then I will upgrade that head with big valves.

The 78 log head is going to get a normal port and polish and big valves.

 

[FALCONAROUND]

That sounds great!