The Ford Barn

v8nut · 03-10-2014, 03:14 PM

I have two cast iron heads for my '35 21 stud engine. They both measure about .007 inches out of flat. (arched upward near the center) I have a nice cast iron surface plate to measure against. Should I pay $100 to $150 to have them surfaced or are they good enough to use? This will be a dead stock engine. 'advice appreciated. Jim

Karl Wolf · 03-10-2014, 03:25 PM

I think that you can run them... You may want to try this: put them face to face with a couple of bolts in their centers... Tighten them a bit, maybe 15-20 ft. lbs. Then measure the distance between them.

If you run them, retorqe a couple of times before loading the engine much...

Please report back as to what you find.

Karl

ford38v8 · 03-10-2014, 03:29 PM

Quote:

Originally Posted by Karl Wolf

...put them face to face with a couple of bolts in their centers... Tighten them a bit, maybe 15-20 ft. lbs. Karl

This is exactly the way heads should be stored while an engine is apart.

Brian · 03-10-2014, 05:35 PM

This is exactly the way heads should be stored while an engine is apart.

Makes perfect sense; didn't know that, thanks

Sixseven · 03-10-2014, 08:26 PM

The gems we learn, thanks - didn't know it either.

Tinker · 03-10-2014, 08:32 PM

Sponsored Links (Register now to hide all advertisements)

Ill throw this out... Really, cast iron heads need to be bolted together or they will warp. Warp more so then being cycled? Maybe so... Does this fit in the storing cranks or cams horizontally vs vert. Curious...

What is the milling of a head for compression about..... (I was using a little sarcasm here)

.

scooder · 03-11-2014, 05:33 AM

Quote:

Originally Posted by Tinker

Ill through this out... Really, cast iron heads need to be bolted together or they will warp. Warp more so then being cycled? Maybe so... Does this fit in the storing cranks or cams horizonially vs vert. Curious..,

What is the milling a head for compression about.....

1st, I have never bolted removed heads together, first time I heard this one. Never had a problem with them sealing after sitting for years not bolted together. Not saying it's right or wrong, just experience.
2nd, if you mill, cut, or scrape material of the head face, it reduces the combustion chamber volume, thereby increasing the compression ratio. Good for power, Good for economy good for efficiency. Peak power may not go up by much, but low end torque goes up very nicely, good seat of pants increase.
Martin.

JWL · 03-11-2014, 06:05 AM

If the "bow" is a slow, consistent, and gradual occurrence in the gasket face it will not be a problem.

jake197000 · 03-11-2014, 07:56 AM

generally .001 per cyl per head is max.but as jwl states there probably fine.

v8nut · 03-11-2014, 06:03 PM

Thanks to everyone for the advise. This forum is a great way to get knowledgeable input overnight. I appreciate it very much. Jim

Ol' Ron · 03-11-2014, 06:53 PM

I don't bolt my heads together but I don't lay them flat either, they are stored on edge. In 56 I worked for a Packard Studabacker garage and we returned all the Packard parts to the factory. One Packard head had laied flat on a shelf for years and had a major bow in it. Laid them on edge ever since.

03-10-2014, 03:14 PM	#1
v8nut Senior Member Join Date: Dec 2010 Location: San Jose, CA Posts: 202	Help! How flat is flat enough? I have two cast iron heads for my '35 21 stud engine. They both measure about .007 inches out of flat. (arched upward near the center) I have a nice cast iron surface plate to measure against. Should I pay $100 to $150 to have them surfaced or are they good enough to use? This will be a dead stock engine. 'advice appreciated. Jim

03-10-2014, 03:25 PM	#2
Karl Wolf Senior Member Join Date: May 2010 Location: Mill Valley,Ca. Posts: 1,509	Re: Help! How flat is flat enough? I think that you can run them... You may want to try this: put them face to face with a couple of bolts in their centers... Tighten them a bit, maybe 15-20 ft. lbs. Then measure the distance between them. If you run them, retorqe a couple of times before loading the engine much... Please report back as to what you find. Karl

03-10-2014, 05:35 PM	#4
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,833	Re: Help! How flat is flat enough? This is exactly the way heads should be stored while an engine is apart. Makes perfect sense; didn't know that, thanks

03-10-2014, 08:26 PM	#5
Sixseven Senior Member Join Date: Jan 2014 Location: Atlanta, GA Posts: 482	Re: Help! How flat is flat enough? The gems we learn, thanks - didn't know it either.

03-10-2014, 08:32 PM	#6
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: Help! How flat is flat enough? Sponsored Links (Register now to hide all advertisements) Ill throw this out... Really, cast iron heads need to be bolted together or they will warp. Warp more so then being cycled? Maybe so... Does this fit in the storing cranks or cams horizontally vs vert. Curious... What is the milling of a head for compression about..... (I was using a little sarcasm here) . Last edited by Tinker; 03-11-2014 at 08:31 AM. Reason: sp.

03-11-2014, 06:05 AM	#8
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: Help! How flat is flat enough? If the "bow" is a slow, consistent, and gradual occurrence in the gasket face it will not be a problem.

03-11-2014, 07:56 AM	#9
jake197000 Senior Member Join Date: Sep 2010 Posts: 349	Re: Help! How flat is flat enough? generally .001 per cyl per head is max.but as jwl states there probably fine.

03-11-2014, 06:03 PM	#10
v8nut Senior Member Join Date: Dec 2010 Location: San Jose, CA Posts: 202	Re: Help! How flat is flat enough? Thanks to everyone for the advise. This forum is a great way to get knowledgeable input overnight. I appreciate it very much. Jim

03-11-2014, 06:53 PM	#11
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Help! How flat is flat enough? I don't bolt my heads together but I don't lay them flat either, they are stored on edge. In 56 I worked for a Packard Studabacker garage and we returned all the Packard parts to the factory. One Packard head had laied flat on a shelf for years and had a major bow in it. Laid them on edge ever since.