Head Nuts OR Cap Screws

equeen · Sep 24, 2012

Okay, so I don't know the difference between a "Cylinder Head Nut" @ 50-55 lbs torque and

a "Cylinder Head Cap Screw" @ 65-70 lbs torque.

That's why I'm posting this.

I believe that it's going to be "bolts" that come out when I remove the head on my '50 Ford 8N in the morning. Then replace the head gasket and put the "bolts" back in as specified on pg 130 of the Ford Service Manual. What's the torque on these "bolts" and what's a "cap screw". I know what a nut is - me.

Thanks.

Jock(OR) · Sep 24, 2012

A "Cap Screw" is a fancy name for a bolt.

Early engines had studs (threads on both ends) that stayed (or were supposed to stay) in the block when the nuts were removed to remove the head. The torque values for "nuts" apply to these.

If you have bolts holding on the head, use the "cap screw" torque value.

TheOldHokie · Sep 24, 2012

(quoted from post at 18:25:49 09/24/12) Okay, so I don't know the difference between a "Cylinder Head Nut" @ 50-55 lbs torque and

a "Cylinder Head Cap Screw" @ 65-70 lbs torque.

That's why I'm posting this.

I believe that it's going to be "bolts" that come out when I remove the head on my '50 Ford 8N in the morning. Then replace the head gasket and put the "bolts" back in as specified on pg 130 of the Ford Service Manual. What's the torque on these "bolts" and what's a "cap screw". I know what a nut is - me.

Thanks.

Loosely a "hex head cap screw" is a hex head bolt.

The "technical" difference between a "screw" and a "bolt" is defined by ASME B18.2.1 and is exceedingly detailed and arcane. If you really want to go there a concise summary of the principle differences is provided by Machinery's Handbook.

TOH

R Geiger · Sep 24, 2012

I assume you are going to check to make sure the head is not warped before you re-install it.

equeen · Sep 24, 2012

Local engine shop can check for warped head.

Anything a country boy with no fancy shop can do to check for warped head?

TheOldHokie · Sep 24, 2012

(quoted from post at 20:53:10 09/24/12) Local engine shop can check for warped head.

Anything a country boy with no fancy shop can do to check for warped head?

All you need is a high quality straight edge and a feeler gauge. Then follow the easy instructions in the link below. A quality (.001) machinist's straight edge will run you $40 and up.

How to Measure Head for Warpage

For a Ford flathead anything under .005 is fine.

TOH

tn8n · Sep 24, 2012

if you have a good undamaged (not bent, dinged, etc.) metal straightedge or ruler, you can turn the head upside down and hold the straightedge along the mating surface of the head in several places. if you can see daylight under it you'll know it's warped. look longways along the edges and side-to-side between cylinders. won't be super super accurate, but if you can't or don't want to take it to a shop it can't hurt.

R Geiger · Sep 24, 2012

I use a good straight edge ruler long enough for head. If warped you will see it and then take it to the machine shop for milling. If too much is taken off the pistons may hit head requiring more work. If milled check with no gasket and no bolts and turn engine over and watch head for movement.

Head Nuts OR Cap Screws

equeen

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Jock(OR)

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TheOldHokie

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R Geiger

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equeen

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TheOldHokie

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tn8n

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R Geiger

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